ROARING IN HORSES

LARYNGISMUS PARALYTICUS )

FLEMING

30114012954585

I

Sto
179

T.Way. id Nat del et lilK .Loudon .

DESCRIPTION OF THE PLATE.

Posterior view of the larynx of a horse which had been
seriously affected with Roaring, showing the alterations
generally observed on the left side of that organ.

a. Epiglottis somewhat deviated to the left side. h. Summit
of left arytasnoid cartilage, which, with its body, c, is depressed ;
in marked contrast to the right arytaenoid cartilage, e /, which
is in its normal position, d. Remains of the left dilator
muscle of the larynx (posterior crico-arytsenoideus) ; all the
muscular tissue has disappeared, and in its place there is
only a little fat and fibrous tissue, cj. The right dilator
muscle of the larynx in a healthy condition, as is also the right
arytaenoid muscle, /, while the left is only represented by a
few muscular fibres at c.

In a healthy larynx, the left side has the same appearance
as the right.

I

I

ROARmCx m HORSES

{LARYNGISMUS PARALYTICUS):

its 3|istovB, f[i\\iwz, OTaitscs, |9rcl3cn:tton,
nnh treatment.

BY

GEORGE FLEMING, C.B., LL.D., F.R.C.V.S., Etc.,

PRINCIPAL VETERINARY SURGEON OF THE ARMY.

WITH A COLOURED PLATE AND WOOD ENGRAVINGS.

LONDON :

BAILLIEEE, T I N D A L L, AND COX,

KING WILLIAM STREET, STRAND.
NEW YORK : W. R. JENKINS, SIXTH AVENUE.

1889.

[All nghls reserved.]

eb i c aie b

TO

THE RIGHT HONOURABLE HIS GRACE

THE DUKE OF WESTMINSTER, K.G., P.C.

CONTENTS.

CHAPTER p^Qg
PREFACE ------- ix

I. HISTORY OF ROARING ----- 1

II. VARIOUS CAUSES OF NOISY RESPIRATION - - - 15

III. PREVALENCE OF CHRONIC ROARING - - - 21

IV. PREDISPOSING CAUSES OF CHRONIC ROARING - - 39

1. Climate - - . , - 39

2. Heredity - - . _ - 41

3. Breed - - . . . - 46

4. Sex - - - . . - 48

5. Size - - - . . - 50

6. Age - - - . .

7. Conformation - - . . - 53

8. Management - - - . - 55

9. Accidental Causes - . . - 57

V. SYMPTOMS AND DIAGNOSIS OF CHRONIC ROARING"- - 59

1. Stridor - ' - - . . - 60

2. Dyspnoea - . . . - 64

3. The Cough - - . _ - 66
Diagnosis

VI. ANATOMY AND PHYSIOLOGY OF THE LARYNX - - 72

Anatomy of the Larynx - . . - 73

Cartilages - - . . _

^•^^ Contents.

PAGE

CHAPTER _ - 78

Muscles - - ' '

Ligaments - " "

Mucous Memh-ane - " '

- 81

Nerves - - ' '

The Larynx as a whole
Physiology of the Larynx

VII. PATHOLOGY AND COURSK OF CHRONIC ROARING -

Course of Roaring - - " "

VIII. CAUSES OF CHRONIC ROARING

Mechanical Causes

Pathological Causes - " ' '

IX. PREVENTIVE AND CURATIVE TREATMENT OF CHRONIC

90

99
104

110
110
115

128

ROARING - - - "

1 Prevention, from a Sanitary Point of View - 1^^^

(a) Exclusion of Unsound Horses for Breeding

Purposes - - ' '

(b) Care in the Management of Young Horses -

(c) Hygienic Management

2. Medical and Surgical Treatment of Roaring

(a) Medical Treatment of Roaring
(h) Surgical Treatment of Roaring

X. THE OPERATION FOR ROARING

1. Operation - " - ' ' ^^^^

2. After-Treatment

129
129
130
132
133
136

146
146

PREFACE.

The subject of the present work has occupied my attention
for more than a quarter of a century, and its increasing
prevalence in recent years has, owing to my official position,
impelled me to devote myself more seriously to its study.
" Koaring," as it is commonly termed, is the symptom of
a more or less grave defect in the horse's respiration,
which is eminently damaging to the animal's value,
and only too frequently to his usefulness. In the words
of an eminent veterinary surgeon of three-quarters of a
century ago, "It is a deteriorating scourge which too
often, for the credit of our profession, consigns the
counterpart of Echpse himself to the shafts of the street
cab."

The result of recent investigations into what has been
hitherto considered, in several respects, an obscure dis-
order, and one for which there was no remedy, is oflfered for
acceptance as a contribution towards the solution of the
mystery which surrounds the morbid condition that

occasions EoariDg, and the devising of measures for its
prevention and cure. I earnestly hope that obscurity and
incurability will no longer pertain to it, and that the in-
vestigations, as well as the surgical procedure which is
here described, and which has been already fully carried
into operation, may remove Roaring from the list of the
opprohria medicorum that still discredits Veterinary
Science.

The value of a simple operation which will remove this
defect in horses, without disfiguring them or impairing in
any way their usefulness, can scarcely be over-rated, so far
as horse-owners are concerned; while, in the interests of
humanity, the relief from distress in breathing in horses so
affected must be no small gain.

Since first venturing on operative procedure in the
horse's larynx, ten years ago, much hght has been gradually
thrown upon the physiology of that organ by the attempts
made to remove the immediate cause of Roaring ; and now
its interior is as accessible to the eye, hand, and mstru-
ment of the surgeon, and can be treated with almost as
much impunity, as any other part of the body. This
marks a great advance in veterinary surgery, and one
which, no doubt, wm largely benefit horses and their

owners. .

The institution of tliis operation haa also resulted m
an immense improvement being efiected in the mode of

producing insensibility in horses, by the administration of
chloroform, which had hitherto not been so satisfactory
as to warrant frequent recourse to it. This improvement
chiefly consists in the much more rapid and safe production
of narkosis by means of a comparatively trifling quantity
of the antBsthetic, and with quicker recovery from its
efi'ects, than when several ounces are slowly inhaled ; so
that there is a saving in time and in the drug, and an
abbreviation of the inconvenience and suffering experienced
by the animal operated upon.

In carrying out the operations on the large number of
horses submitted to surgical treatment for Roaring, I must
not fail to acknowledge the great skill, wonderful dexterity,
and unfaltering enthusiasm displayed by Mr. F. Raymond,
F.R.C.V.S., Army Veterinary Department, who acted under
my direction. To him the success of the operative procedure
on these horses is largely due ; his perseverance, judgment,
and expertness deserve the highest praise, and have elicited
my warm admiration.

As time elapses the operation may be still more perfected
— though I think this is scarcely possible — and its remote
results will be more accurately noted. The experience now
gained will doubtless be added to, and Roaring will conse-
quently become more readily removable by operation, easily
and safely practised, by every veterinary surgeon ; but I trust
the greater advantages to be derived from the preventive

* «

It* * *

xii Pref'acS.
measures here enumerated will not be overlooked, and that
the adage that " prevention is better than cure " will be
kept in view in dealing with such a serious detriment to
the usefulness of horses.

GEORGE FLEMING.

London,

January, 1889.

LARYXmSMUS PARALYTICUS;

OR,

EOARING m HORSES.

CHAPTER I.

HISTOKT OF EOARING.

Next to lameness in horses, defects in respiration are
perhaps of the most importance. To be " sound in wind
and Hmb " comprises, according to the popular notion,
nearly all that is required in a horse ; for unless capable of
moving at a certain, and perhaps rapid, pace, and probably
exerting a great amount of strength while in motion, this
animal would be of little value to man. Certainly it might
be utilized to some extent if slightly lame, or affected only
to a trifling degree in its breathing; but whenever this
limit is exceeded, and the lameness becomes particularly
marked, or the defective respiration is very perceptible, then
the state of the animal is considered serious, so far as its
utility is concerned: for then the defect may either
really impair or altogether abolish its usefulness, and create
an impression that the creature is suffering pain, or is in
distress— an impression which is always unpleasant to the
humane horseman.

To enable it to travel at a high rate of speed, and to
undergo severe exertion, the respiratory organs of the horse

1

2 Roaring in Horses.

are greatly developed; and yet, notwitlistanding this pro-
vision, a very slight cause will render them seriously imper-
fect, limit the employment, and gravely depreciate the value
of what may be otherwise a most valuable animal. For this
reason it is that horsemen have, from the earhest times
paid particular attention to respiration in horses and
though, until recently, they were but httle if at all. ac-
quainted with the nature of the causes which produced
chan-es in this function, and could not even distinguish
between various morbid conditions, yet they appeared to
have readily perceived that there was something wrong,
which they designated by terms generally more expressive
t.n intelligent or elegant. Some of these cant terms have
come down to our own day, and are m common use. _ Nearly
all of them refer to one symptom-that which is most
obvious-the noise caused by obstructed respuration, and to
the differences in the sound. _

Therefore it is that, in old works on farriery, and among
horse-dealersandhorse-copersofnowadays,wemeetwithsi^^^^^^

designations as "roarers.'' "pipers," "wheezers," "-^^-^^rs
"Lnters" "high-blowers." "bellowed bulls," etc., applied to
hfrls which make a noise in breathing: the terms being
intended to mark differences in the quality and intensity of
the sound. Asthma, or "broken wind," and the noises
emit ed from the air-passages during movement (sometimes
Snated " pursiveness ") have usually been applied to the
iT a^ise or causes by those English authorities of the
LTand previous centuries, whose treatises on the diseases

^^K^^rr— e,in Gibson's work,^ which
appe ed in the commencement of the eighteenth century
in whTch he remarks : " We may observe that horses that
Le no inward infirmity blow and wheeze, from an impe.
fection in the passages between the nose and mouth, which
lecuou iu uixo ^ o T.r.r<?p<? as thcv draw in and

happens the more readily to hoises, as iney

1 <' The Farrier's New Guide," 4th edition, London, 1 T-O.

/

History of Roaring. 3

expel their breath chiefly at the nose. ... A horse will
congh pretty often, but especially upon every slight cold,
and at the same time is frequently troubled with a wheezing
and rattling in his pipes : all which proceeds from a thick
mucilaginous matter sticking in the branches of the wind-
pipe." And in Bracken's treatise,i published so late as the
middle of the last century, in pointing out the difference
m symptoms between a broken-winded horse, and one which
has "newly taken a cold," he observes that "upon motion
there wiU be a hissing, whistling sound, and greater heav-
ing of the flanks than in common colds Besides, the

cough does not sound so deep in pursiveness, but on the
contrary zs a short ticlding one, as if it were seated at the
upper part of the larynx." But Wailis,^ about the same-
penod, says that '^wheezing," or "blowing," in horses is
quite different from "pursiveness." "For this wheezing
does not proceed from any defect in the lungs, but from the
narrowness of the passages between the bones and gristles
ot the nose. And further, these horses do not want wind •
for notwithstanding they blow so excessively when exer-
cised, yet their flanks will be but little moved, and in their
natural condition. There are other horses that are thick-
wmded, that is, have their breathing a little more free than
the former ; but neither one nor the other are agreeable or
for any great service. Yet a person may be liable to a
mistake m the case ; for when a horse has been kept a lono-
time in the stable without exercise, he will at the first rid^
mg be out of breath, although he be neither a blower nor
thick-wmded. There are some wheezers or blowers that
rattle and make a noise through the nose ; but this impedi-
ment goes and comes, and is only occasioned by abundance
of phlegmatic stuff; for their flanks will not redouble,

^ - The Farner's and Horseman's Complete Dictionary," 3rd edition,

1-2

4 Boaring in Horses.

neither will they have a cough with it, and therefore they

cannot be pursy." . , i „

These remarks of Wallis are chiefly based on the obseiya-
tions and description of SoUoyscV one of the celebrated
French « ^cuyers hippiatres " of the seventeenth century,
and who is the first writer who alludes to Carnage us he
then designated the noise, and a^. it is still designated m

^ Until the early part of the present century, nothing more
definite with regard to this morbid conditron was known m
England than was published by Wallis. , . ,

In France, however, nearly a century after Solleysel had
described the different kinds of sonorous respirat.on n the
horse-though in a somewhat imperfect manner, it is rue
^Bourgelatrthe illustrious founder of the French veteri-
nafy schcoKand pioneer of modern vetermary rnedicm^^^

give's a ^.^f^Zr^^l^ IV r Stse,
/off "Pnrnao-e ^ puDlishecl m raiib m x>^ ^^^-n

en in r • DLionnaire d'Hippiatrique " (Pans, 17, o
on"; briefly alludes to it when giving the definition o the
term "Cornard," as applied to a horse emitting a no se m
bretthinc Huzard, sen.,' however, compensates foi this

breatnm„. ^ ,„ his predecessors by giving a

the law of warranty {garantie i edlabitoi^ e).

1 " Parfait Mareschal," Paris, 1664.

2 u Memoire sur la Cornage," Pans, 1/85.

3 " Instructions Vdterinaire,' Par is, . ^ Animaux

4 » OorrespondaBce sur la Conservation et Amelioration

Domestiques," Paris ISlO-l^- ^i^^ecine et la Chirurgie Yeteri-

5 " Memoires et Observations sui la iUtaeciu

Eaire," Lyons, 1813.

History of Roaring. 5

d' Arbovcal.i in his remarkable dictionary, gives it a good
reference. But the French veterinarians, who have studied
Roaring more especially from a pathological standpoint,
are Godine, jun.,2Dupuy,3 and Vatel ;4 while articles on it in
the " Eecueil de Medecine Veterinaire " have been furnished
by very competent authorities— as Bouley, jun. (1825), De-
lafond (1833), Leblanc (1834), H. Bouley (1838), Eiquet
<1847j, Goubaux (1848, 1855, 1864); and it has at times
been discussed at meetings of the Societd Centrale de Mdde-
cine Ve'tdrinaire, of Paris. »

Reynal and Renault contribute a long paper on it to the
" Nouveau Dictionnaire Pratique, etc., Veterinaires " (Paris,
1858, art. "Cornage"); and Zundel,<3 in his dicLionary, likewise
devotes much attention to it. Lafosse^ and Trasbots have
published valuable observations, Charon, in 1886, published
a monograph on it," and, in later years, other writers of less
note have contributed articles, more or less important, to
various French periodicals, in which, besides the older term,
"Cornage," we find it designated "Sifflage," "Sifflement"
"Halley,""Ronflement,"etc.

In Germany the subject does not seem to have attracted
much attention, until Gurlt"> almost incidentally alluded to
It m 1832 ; but Glinther, the able director of the Hanover
Vetermary School, dealt with it in a special monograph,^

! ^''^j-^tio^naire deMedecine etdeChirurgie Veterinaires, "Paris, 18->6

- ililements d'Hygiene Veterinaire," Paris 1817

3 " Recueil Veterinaire," 1825 ; " Fluxion Periodique," 1826

Elements de Pathologie," Paris, 1827; "Journal de Medecine
V eterinaire Pratique."

1868 ^869 Imperiale et Centrale de Med. Veterinaire,"

«" Dictionnaire de Medecine, de Chirurgie, et d'Hygiene Veteri-
uaires," Pans, 1874, art. " Cornage." J'S v tion

"Journal de Veterinaire du Midi," 1846.
s " Archives Ve^terinaires," 1879.
:o" ^''^^^^ ^® Cornage Chronique," Paris, 1886.

"Lehrbuchde Pathologische Anatomy, ' Berlin 1832
" "Ueber Hartschnaufen," Hanover 1834. '

g Roaring in Horses.

the first devoted to it. after contributing an article on it to
Nobel and Yi>c-s professional jonmal Gerlach bas de
scribed it in his classical ^vork on " Vetermary Juuspu
dence quoting Fiirstenberg as an observer ; faunther
fun in hil " Myology of the Horse - alludes to .t ; and m
St and Hert'wig's Maga.in" are to ^ fo^md exceHent
papers by Becker (1838). Meeke (J^f )■ H-^^'-K f "j'^
Kielzel and Swanshon (1848), ^-l, < d^ • in the

Herings Stuttgart " Eepertorium fttr Thrcrhedkunde. m h
Vienna « Yierteljahressebrift ".emedrc n m the
Munich " Deutsche Zeitschriftfur Th.ermedic.n (y^^. ). ^
the '■Oesterr.Monatsschritt fur Threrhedkunde (1885^^^^^^^^^

in the " WochenschriftlfUr Thierhedkunde und Jiehzucnt
ha™ appeared papers by various writers, who dcs.^a^e
by the'nUs by .hich it ^V^^T^^.X^'

hfsf^I'tise on the subject which has been pubh^ d rn
Germany, is that issued in the present year by Prolessoi
MoUer. of the Berlin Veterinary School ..

In Italy, where Boanng rs known a^ Come ^ , ^^^^^^^
tolo " " Rantolo larmgeo, it has Deen lu« _j
nvestigation for many years. Professor B-s' *e T^,rm
Veterinary School, having devoted ^-'^l^'^^^l^^^^^

. . Zeitschnf t f Thierheilku.de u.d J^f^^^t^'fs^ ,
. u Gerichtliche Thierheilkunde " Band p. 244, i3

and "Hannoverische J^^^^'f.^^f , pt-des " Hanover, 1866.
der Thierar^tlichenChirurgie," Leipzig, 1881.

History of Roaring. 7

probably introduced by jockeys, farriers, or horse-copers,
who have given us so many of the fantastic and barbarous
designations that are still retained in the vocabulary of the
stable and horse-market.

Eichard Lawrence, veterinary surgeon, Birmingham, is
perhaps the first writer who alludes to " Eoaring " by that
name, in a work published at the very commencement of
the century.i Treating of respiration and its defects, he
writes : " Another imperfection, which may be included in
the class of diseased respiration, is the sound which arises
m breathing, with some horses, when their pace is ac-
celerated. A horse of this description is termed a Roarer.
From my own observation, I have not been able to discover
whether its source is in the lungs, the trachea, or the nose,
though it is probable its seat is in the trachea or larynx.'
Dealers have a method of ascertaining the existence of the
disease by striking the horse under the belly with a whip,
and turning him suddenly round at the same time. If he
groans during this process, they say it proves that he is a
'roarer.' This is probably occasioned by the sudden con-
traction of the abdominal muscles forcing air from the
lungs through the trachea with greater rapidity, in conse-
quence of the pain he feels from the stroke of the whip, as
well as from the bending of the ribs in the action of turning
round in a small compass. This disease prevails to a
different degree in different subjects ; in its commencement
It IS generally manifested by a whistling noise, but in the
confirmed state it is more sonorous, and resembles deepgroan-
mg. In either case it has hitherto remained incurable."

White is the next veterinary writer who mentions Roarino-
In 1802, under this designation, he says in his " Compen-
dium " : " This disease takes its name from a peculiar sound
in respiration, particularly when the horse is put into a
brisk trot or gallop. It seems to rise from lymph that has

Horle'^MSoT"''^"'' Structure and Animal Economy of the

8 Roaring in Horses.

been effused in the windpipe or its branches, which, be-
coming sohd, obstructs, in a greater or less degree, the
passage of air."^ And later the same writer elsewhere
states : " There is another complaint o£ the lungs, or parts
connected with them, and an incurable one, which the pur-
chaser should be guarded against. This disease is named
Roarinq,ivor^ the wheezing noise a horse makes when rode
fast, particularly when galloped up a hill : it is sometimes
so considerable as to be heard at a distance ot many yards ;
but in walking, or moderate exercise, it can seldom be per-
ceived The method which dealers usually employ to
detect this complaint at a repository, whpre no other trial is
allowed, is to whip the horse under the belly and make him
turn suddenly, or by making him leap over the bar ; it he s
a roarer, this sudden exertion causes him to groan. Hnx.
this criterion should never be depended upon when an
opportunity offers of gaUoping the horse."^^

I>ercivall,3 in 1824, treats of Roaring m a more com-
plete manner than any previous English writer, and again
in 1840 he deals with it in -other work,^ though mo^^^
briefly and no more satisfactorily. Youatt m 1833 John
Field in 1837 « Ferguson in 1838/ Turner and Cartwright
fn l849,s Owles in ?854.o Keeve in_ 1858^0 and ,her writers
have devoted much attention to it; while m 1882 1 ven-
tuJed to give the result of my somewhat lengthy experience
and investigations into the pathology of Eoaring.

It was not until the present century had been somewh
advanced, and veterinary surgeons were ^voting more
attention to anatomy and physiology, but especially to
1 " A Compendium of the Veterinary Art," London, 1802.
. "A Treatise on Veterinary Medicine," vol. "^'p^-,: Second p 243.
3 " Elementary Lectures on the Veterinary Art, Part Second, p.
■» " Hippopathology," vol. ii., p. 36.
. ne F*-»»ri.,, vol, vi., p. 183. •

™|- ,. }«.; vol. .xvi.
yteriLrrJournal," 1882, PP. 1, 81. article, "Lary.gism„s

Paralyticus."

History of Roaring. 9

pathological anatomy, that the morbid conditions giving
rise to Roaring began to be seriously investigated. Of
course, errors were common at first, and the causes assigned
were often more imaginary than real; but, nevertheless,
the real sources of the obstruction causing the noise were
anxiously sought for.

So long ago as 1817, Godine found deformity of the
larynx to be, as he supposed, a cause of " cornage."i
Bouley made a similar observation in and Dupuy

describes cases in which the glottis was narrowed and
deformed, through depression of the left arytenoid cartilage
of the larynx.

In 1825, the first marked step in elucidating the pathology
of Roaring, as it is now understood, was made by a very
distinguished French veterinarian, Bouley, who, in dissect-
ing the carcase of a horse that had been seriously affected,
found considerable engorgement of the lymphatic glands at
the entrance to the chest (pre-pectoral) ; and observed that
the left recurrent nerve, which passed through them on its
course to supply the muscles of the larynx, was compressed
by these glands and altered in its structure. He had at
first imagined that the Roaring had been the result of
deformity of the trachea ; but as there was no deformity in
this instance, the coincidence of the noise during life with
this condition of the nerve found on post-mortem examina-
tion, decided his opinion as to the cause of obstructed
breathinff.*

o

The physiology of the nervous system was beginning to
be better understood when these observations were mtde,
and the chief functions of the great nerve of organic life—
the vagus— were known, and this knowledge was applied to
the elucidation of morbid processes. The very important
clinical observation recorded by Bouley, led the veterinary

"Elements d'Hygiene," 1817.

" Compte Rendu d'Alfort " for 1821.

" Recueil de Med. Yeterinaire,"' 1825. * lUd p 330

10 Roaring in Horses.

professor, Dupuy, in the same year to perform experiments
on horses, in which, after dividing or compressing the vagus
or recurrent nerves, he constantly produced the pecuhar
roaring sound; and after the death of these animals the
laryngeal muscles were found wasted. The explanation he
crave of the phenomenon was to the effect, that as the
inferior laryngeal nerves which supply the dilator muscles
of the glottis are branches of the par vagum, of course these
muscles become paralyzed when the nerves are divided or
compressed ; but the superior laryngeal nerves, bemg dis-
tributed to the constrictor muscles of the larynx, and not
beinc implicated in the experiment, these muscles retam
their power, and their antagonists-the dilators-bemg
paralvzed, the glottis is nearly closed-hence the roaring.

This, though not altogether a correct explanation, marked
progress in the right direction.

In 1834, Professor F. Giinther, then director of the
Hanover Veterinary School, asserted that Roanng is due to
wastino- of the muscles on the left side of the larynx, owmg
to loss of function of the recurrent nerve of that side as
since January, 1830, he had found that division of this
nerve produced the sound in breathing, as -11 as the
before-mentioned morbid changes m the muscles of that

The observers of those days, however, did not overlook
the fact that various causes would give rise to noise m
breathing, and these causes are mentioned.

Percivall, our highest vetermary authority -E^Sj^^.^
during Ihe first half of the century, when he V-^^f^^^^
lectures in 1824, showed that the observations of^G^^^^^^^
and Bouley had attracted his attention. He thought, so
?ar as the larynx is concerned, that Roaring m young
horse s due to thickening, with occasional ulceration, o
the laryngeal mucous membrane; he mentions bands of
5ymph ^c?oss the larynx and windpipe, ossification or dis-

1 " Recueil de Med. Vetdrinaire," 1826. " ^1^-

History of Roaring. 11

tortion of these tubes, hepatization of the lungs, and spasm
of the muscles of the glottis. But he likewise mentions
wasting of the muscles on one side of the larynx as an
occasional cause. He says: "Some years have now
elapsed since it was first discovered that the larynges of
Eoarers occasionally presented us with the singular
phenomenon of the muscles on one side being wasted
away or absorbed, while on the other they appeared to
exhibit unusual volume and redness, and. strength of fibre.
Smce the first discovery, everyone almost has met with
cases of the kind ; but no person seems as yet to have
given an explanation of this new piece of pathology."^

Again he writes: "Another, and a not very uncommon
cause of Roaring, is a wasting, or, in some instances, a total
absorption of one or more of the small muscles of the

larynx. I have lately examined a horse of Mr ■ a

remarkable instance of it. In his larynx, upon the near
side, the crico-arytenoideus posticus was very pale, and
shrunk to half its original size ; the crico-arytenoideus
lateralis, the thyro-arytenoideus, and the arytenoideus, were
altogether colourless and scarcely recognisable as muscles ■
but their antagonists, upon the other side, were unusually
red and strong. Now, these muscles, contracting in pairs
are all employed in dilating the glottis ; but, if one set act
by themselves, this orifice is not only distorted, but actually
dimmished m dimension, in consequence of the arytenoid
cartilage of the opposite side being drawn over it. Thus it
IS, then, that Roaring is here produced. How we are to
account for these changes-to what original cause refer
them-is as yet unknown. By some they are loosely spoken
ot as the ultimate consequences of paralysis, or of spasm •
but though these tales may satisfy their employers they
are no more, to the profession, than the baseless conjectures
of their authors, and, as such, are deserving of no comment.'"^

\ i!^^-''*"'"^' °° Veterinary Art," Part Second, p. 253.
Hippopathology," vol. ii., p. 44.

12 Roaring in Horses.

And in 1840 he shows that opinions were much divided as
to the principal cause.

But, previous to this period, Youatt, in his lectures on
horses, when treating of Roaring and its causes, remarks :
" In the far greater number of cases there is distortion,
rendering the muscles on one side useless, and therefore
causing them to waste away. ... The wasting of the
muscles is, therefore, the effect, and not the cause, oi that
which produces Roaring."^ „
About this time Field observed that a frequent cause of
Roaring, in cases of ulceration of the rima glottidis, was
spasm of the glottis. " While the horse is suffering great
pL from the passage of the air over these denuded
surfaces, the instinctive action of the muscles more power
ful than the will of the animal itself, partially closes the
air-tube, and thus lessens the irritation. ^ ^^"^^^^
cases of this kind, and^^ by opening the trachea have
obtained immediate relief."

This hypothesis, however, presumably did ^^ot s^i^
•Mr Field for we find him repeating one of Pupuy s
by producing Roaring i^n a horse, and demon^
strating the cause of laryngeal muscular atrophy . Havmg
ascertained that the organs of respiration of ^J^^^^^^^^^
for farm work were sound I cast ^^^^f^X^^

S fW minutes, galloped -rely ..^^^^^^^^^^^^^^
slightest defect in his breathmg The • ^.

dr^wn out by the ligature, and one inch and ™ '

and immediately on trotting the horse a short distance
such a degree of roaring was occasioned hat, had the
^tion be°en continued, he -uld soon ha^e f^^^^ I^eP
this horse four years, and though his ^^^^l^^^^^
much better, he continued a sad f^^^^^^^^^
time I destroyed him for the larynx, which exliibit

1 " The Veterinarian," vol. vi., p. 183.

History of Roaring. 13

usual condition of wasted muscles on the side deprived of
the influence of the recurrent nerve."i

In the following year (1838), Ferguson found, on making
the autopsy of a horse which had been a Koarer for a long
time, one of the recurrent nerves (left) enveloped and com-
pressed by a voluminous mass of indurated bronchial
lymphatic glands, and the portion of nerve between these
and the larynx was quite different to that on the opposite
side, being greatly wasted and its fibres scarcely distinguish-
able. All the laryngeal muscles which received filaments
from this nerve were so completely atrophied that it was
difficult to recognise their structure, while the glottal open-
ing he described as twisted, the borders of the arytenoid
cartilage partly obstructing it.^

In 1846, Lafosse relates that a horse which, at first, only
manifested Roarmg at intervals, was at last continuously
aflected ; dyspnoea became progressively more marked until,
during a violent attack, the animal died asphyxiated. At
the autopsy, the bronchial lymphatic glands were found
extremely enlarged, brownish in colour, adherent to each
other and to the lungs, and containing pus at various
pomts ; while the pneumogastric nerves were compressed in
them, and almost confounded in their mass.^

Goubaux, a recent director of the Alfort Veterinary
School, in 1848 gave a brief account of the alterations he
had observed in the larynges of horses which had been
Roarers;* and in a communication to the Societe de
Biologic in 1853, seemingly unconscious of what had
aheady been accomplished in this direction by other
mvestigators, he alludes to these observations, and dwells
on the fact that in " chronic Roaring " muscular atrophy on
the left side of the larynx was nearly a constant feature.
In 1864, m another communication to the Socie't^
V^termaire of Paris, he further confirms the fact, and even
\ ^^terinarian," 1837, " Proceedings of Veterinary Association "
^etennanan^ 1838. ^^^,o.rn.l de Veterinaires da Midi," 1840.
Kecueil de Medecine Veterinaires," 1848.

;^4, Roaring in Horses.

asserts that lie never witnessed an exception to the rule ;
he always found the muscles on the left side of the larynx
and the left recurrent nerve in an advanced stage ot
atrophy Professor Trasbot, of the same school, stated in
1879 that from the time his colleague, Goubaux, had
drawn attention to the subject, up to that date, whenever
the opportunity occurred he had examined, post-mortem, the
larynx of every horse brought to the school and known to
have been a Koarer during life, and always with the same
result-the discovery of wasting of the muscles on the iett

side of that organ. i

In a work on the muscles of the horse, published by
Professor Giinther in 1866, it is mentioned that ninety -six
per cent, of horses affected with " chronic Boarmg have
wasting of the left laryngeal muscles, and that it is
extremely rare to find those on the right side involved.
Bruckmiiller, in his Text-Book of Pathological Zootomy,
published in 1869, alludes to Bearing being due, among
other causes, to atrophy of the dilator -^^f « c>f one side
of the larynx : and though he agreed with Gunthei that
an alteration (degeneration) in the nerve supplying i would
produce such wasting, yet his observations led him to
believe that degeneration of the nerve was not always the
cause, but that the muscle weakness might result from
induration after inflammation of its texture, mduced by

mechanical action.^ ,
other writers have confirmed these observaUons though
opinions have been far from unanimous as to tlie pathology
of the morbid conditions which occasion the .mpeded
respiration; and even the immediate cause °' "° ^
3 has ieen much discussed, and is not yet defamtely

decided upon.

1 " Archives Yeterinaire," 1879. ,

. " D e Topo-raphische Myologie des Pferdes," Hanover, 1881^

3 .Srhrbuch der Pathologischen Zootomie der Hausthxere, Yienna,

1869.

CHAPTER II.

VARIOUS CAUSES OF NOISY RESPIRATION.

Noisy respiration may be due to a variety of causes, as any
obstacle situated in the air-passages, and which interferes
with the free movement of the air to and fro in them is
hkely to give rise to an abnormal sound ; and there can be
no doubt that such sound, from whatever cause arisin- mav
be designated "Roaring," whether it is heard durino- inspira"-
tion or expiration, or duringboth of these acts. In order to un-
derstand the pathology of the condition which we are specially
considering, and to distinguish it from the other sources of
noise-production, we will briefly notice some of these

Every horseman is, of course, familiar with the more or
less noisy breathing of horses out of training when they are
subjected to severe exertion; the muscles of respiration
and especially those of the upper air-passages, not being in
a state to dilate these sufiiciently, or to maintain them for
any length of time in a condition which wiU allow the in-
creased volume of air to pass freely to and fro. Fatigue of
these muscles invariably leads to this result

Very often also, excitable horses will make a noise for a

T P-ticularly when the"

head IS held m a cramped position. Some horses also
which are not Roarers, are in the habit of makin. a no se
when pulling at the bridle in galloping, owin. \o to

back the soft palate to such an extent that it interferes

Wx ^'^^^^ passages aTd th

iarynx. So annoying is this noise sometimes to the rider,

jg Roaring in Horses.

that to get rid of it the tonguo is tied down to the floor of
the mouth by a piece of wide tape.

Paralysis of the wings of one or both nostnk wdl cause
noisy breathing, the noise being loudest of
inspiration; the muscle ^vhich ra.ses the false nostnl at th,s
period being incapable of doing so, the part hangs pendulous
Tainst the nasal opening and diminishes the volume of a,r
reauired This leads to difSoult and sonorous breathing.

Thickening of the membrane lining the nasal passages the
nresence of fleshy orbcny tumours, polypi.or diseased or frac-
luednasal,frontal,ethnoid,palatine,ormaxillarybones,crany

other obstniction, as accumulated discharges, or absces es
will "ive rise to noisy breathing ; the sound, however, bemg
; nerally as loud in expiration as in inspiration. Cd^eetions
of pus in the guttural pouches, which are very largely deve-

op'ed on each side of the pharynx in the hoi.e. may hind r
the admission of air to the larynx, as may also tumoms m

tt organ or in its neighbourhood. 1-2^-7°°''^;
membra°ne lining the larynx, and the »

cess-whether specific or '><'^;!-'^''''':;i';!''^J^^Z
thickened or stridulous breathing;

formity of the cartilages entering into its fo™^^: f P^^'^
of its constrictor muscles will produce most d^t.ess n
breathino- accompanied by sounds more or less shriU
tted most lou<ny during respiraUon. Percival^^^^^^^^^^
hands of lymph extending across the interior of the arynx
a a cat Jof Koaring, but these I have never

Ancina Strangles, and inflammation of the paiotid gland
and o°f the textiu-es in proximity to the larynx, fre.u^^

cause sonorous breathing, sometimes of '"^ ^'^^ ^'^^^^^"^
character; as will also foreign bodies lodgedinth^^^^^^^

in any other part of the air-conduits. External pies 1™ 0^^^
these^'either by harness, turno..—

vein or any other cause, wiii olten pruvui^c

vein, 01 ciny cartilagnious

abnormal sounds; and Iractuie or mju y

rings of the trachea, or malformation of that tube,

Various Causes of Noisy Respiration. 17

as the effects of tracheotomy, are far from being a rare cause
of noise production.

Pressure on, or inflammation or destruction of, the re-
current nerves, which supply nearly all the muscles of the
larynx, will certainly quickly induce that kind of roaring
-which is so common among horses, and which will receive
most notice in this treatise. Of course, the same result
occurs if the main trunks— the pneumogastrics— which give
off" these nerves are involved in disease or injury, whether
at their point of origin in the medulla oblongata, or at any
part of their course from the cranium to the cavity of the
chest. This will be noticed hereafter.

Certain kinds of food will produce Eoaring, and perhaps
the most notorious for causing difficult and stridulous
breathing, which may terminate in asphyxia if relief be not
promptly afforded by the operation of tracheotomy, is the
Indian vetch or pea commonly known in this country as
Indian "mutters," obtained from the Lathyrus sativus.
Several remarkable instances of poisoning with this legumen
are recorded.i In France another kind of vetch known as
"Gesse-'chiche," "Jarat, Jarosse" (the flat-podded latyrus—
Lathyrus cicera) is reported to have caused a similar
accident, the noise and distress being most evident when
the horses were put to even slight exercise.^

According to Grognier,^ such accidents are somewhat
frequent, this plant being grown in the South of France for
the food of sheep while they are housed in winter Dela-
fond and Eenault, as well as Verrier,* give interestino-
notices of cases of this kind. One is to the eff-ect that a
farmer in the neighbourhood of Paris kept his horses on
winter tares, chopped and mixed with a small quantity of

1886 (p*337).^"^'""''^ ^"''''^ " ^P"^' ^^^^ ''^^^ '^•^'y'

Pratique de Med., etc., Veterinaires," tome iv., p. 352
Cours d'Hygiene," p. 1 74.
* "Etude sur la Gesse-chiche," Rouen, 18G9.

9

2g Roaring in Horses.

treacle Soon they were attacked with stertorous breathing
of a pecuhar kind. The shghtest exercise continued for
only one or two minutes, would cause loud Roaring, and
the respiration became so disturbed that suffocation ap-
peared impending. One of them, indeed, fell, and continued
in a state of semi- asphyxiation for nearly half an hour ;
but the roaring generally ceased after a few mmutes rest.
In the interval between these attacks the horses were per-
fectly tranquil, respiration natural, and appetite unim-
paired One horse was killed when the Roaring was most
\^ violent, but nothing was found to account for the dis-

Uirban e on examination of the body. The other wa
' Sical y treated for two months, but did not recover, and

™ destroyed during an access of Roaring. The re^^^^^^^^
an autopsy was no more satisfactory than m the othei case.

Verrier reports that of fifty-four omnibus horses m
Rouen, which had been fed for some time on this pea mixed
^ith oats, twenty-nine were affected. Of these, nine died

from asphyxia, after exhibiting ^y-P^^^Vl^^ /"J^"
inspiratory dyspnea, and twenty remamed Roarers. Ihe
TaSy of the latter, however, manifested, m addition,
ll^eL and paralysis in other parts, and some of ^em
parapleo-ia. In those that died from asphyxia acute
FnTammation of the larynx was observed. ^^^^
and others in Germany, have ^^7"
.vith the chick-pea, lucerne and -^'^'^
, Luzerne, WicUn), especially when given green -d m seed

but the most interesting cases of ^l\^^'^f^^^^J^'^ Livei-
McCall3 and Leather,^ as occurrmg m ^l-gow and Live^^
nnl Tn these on a post-mortem exf.mmation ot tlie
Tol "c^^ed. degen'eration of the la.y.geal muscles

"1,"ray r™Ted that paralysis and otbe. serious

1 " Berlin Arcbiv," I880. j. ti„„o"1Rfi8

- Bulletin de la Societe Vet^rmaare d Alsace, 1868.
3 « Veterinary Journal," 1886, pp. 337, 412.
* Ibid., 1885, p. 233.

!

Various Causes of Noisy Respiration. 19

symptoms {Lathyrismus) have been produced in mankind
by the Laihyrus sativus.

One of the most marked symptoms of lead-poisoning in
horses, is the noise emitted in respiration when the animals
are moved at all quickly. Not long ago, in the neighbour-
hood of Bath, I saw a mare and her foal, which was only a
.few weeks old, so seriously aSected in this way, that a little
excitement or rapid movement caused them great distress,
the inspiratory sound being loud and shrill. On the farmi
where these animals were, and which was in close proximity
to lead-works, fowls, pigs, horses, and an ass had died from
lead-poisoning. Such instances are not at all rare, and
the paralysis of the larynx may be due to the action
of the lead upon the peripheral nerves of that organ
(neurotic cause), and perhaps also upon the muscles
(myopathic cause).

_ From these remarks it will be observed that noisy respira-
tion may be due to many causes, some of them of a tempo-
rary nature, others more or less permanent. The " Roarino- "
may therefore be considered as " temporary," or "chronic "'or
"permanent," according as it is ephemeral and dependino-
upon transitory causes, or continuous when the causes persist
^ " Temporary Roaring" may be developed during the course
ot an acute disease of the larynx or the parts around it or
It may arise from any casual obstacle to the entrance of 'air
to the lungs ; the kind and amount of noise varyino- with
the nature and intensity of the disease, or the character of
the obstacle which occasions it. It is generally readily
recognised, for not only is there usually a history of the
case to be referred to, but the sound itself often affords
valuable indications. This is in most cases of a rattlino- or
whistling kind, heard chiefly during inspiration, perceptible
at rest or m motion, and noticed not only at the nostrils and
on auscultation at the larynx, but also at some distance
rom the animal. In extreme cases the respiration is
laborious and distressing; the nostrils are widely dilated,

2—2

20 Roaring in Horses.

and the flanks convulsively heaving; the head is extended
and lowered, the face anxious, the eyes prominent and

In other cases the noise will only be heard during active
exercise, and then only during inspiration, or during inspira-
tion and expiration ; sometimes it varies m intensity, or is
alto-ether intermittent. Some horses, though the instances
are very rare, make a noise in their respiration when they
are at rest, and not during movement. Others emit a noise
during feeding and at no other time ; while those affected
with s welling of the lining membrane of the air-passages or
in which there is any obstacle to the entrance and exit ot
the air from these tubes, make a noise durmg mspiration

""""Arthetrdifferences, and the causes to which they are
due need close investigation in the majority of mstances;
t upon the result will depend the P-^abihty of rem^^^^^^^
measures being successful in restoring the affected animals

'^S;c Roaring." due to the wasting of tl^e
muscles, is that which is by far the most ^^-^-^^^H
.vith; indeed, it is not, perhaps, vergmg on ^-^^jj^
asser that ninetv-six or ninety-eight per cent, of the cases
Tchronic Eoa;ing have atrophy of these --^^ ^
chief post-mortem appearance on exammation ; and it might
to be affirmed thatof these, ninety-nine per cent, show only
alsoDe<i,mi ,„f,„:j„„f the or™ ioTOWedm atrophy,

the muscles on the lelt side ot tne or J.a

those on the right side being --7,;"=f^!,'^^rrson to
to comuensate for the loss of their fellows. The reason loi
this ZX-ity we will notice hereafter, when treating of
h pSw of tl'- «=>-^ "f ^''""" Roaring-the orily
tm we are° now concerned with, as it is very prevalent,
and of all forms is the most serious.

CHAPTER III.

PREVALENCE OF EOARING.

Roaring is much more prevalent in western and northern,
than in eastern and southern countries. In the ktter'
indeed, it is rarely observed among the native horses. In
India, for instance, the indigenous horses are extremely
seldom affected in this way, those imported from Australia
being much more liable; though there appears to be a ten-
dency to disappearance of the hereditary predisposition
which may be present in these exotics. Hayes says : " In
India, Roaring is almost unknown among horses bred there,
although many of their imported sires have been confirmed
Roarers. I have known instances of imported horses— and
one case of a colt bred in India, whose dam, an Australian
mare, was a Roarer— which appeared to be confirmed
Roarers, become, after a time, perfectly sound in their wind.
The disease appears to be nearly as rare among Arabs as it
is among Indian stock."^

Mr. Oliphant, Principal Veterinary Surgeon in India but
whose experience has been chiefly gained in Bengal in reply
to my inquiries, writes: "The two classes of horses I have had
most to do with in India are stud-breds (including country-
breds, as used m the Government service) and Australian
horses In the, studs Strangles was very rife, but the stud-
bred horses were, in my experience, peculiarly free from
Roaring, and I do not think that the country-breds of the
present day, got by Government sires, are any more liable
to It. I have seen a few cases among Australian remounts,
' ' Veterinary Notes for Horse Owners,' third edition, p. 257. '

22 Roaring in Horses.

but not many ; in fact, the disease is not common in the
Service— indeed, it is very uncommon. Amongst race-
horses of all breeds, the affection is, I believe, much more
prevalent, but I have very little experience of this class ot
horse Acute diseases of the respiratory organs do not
prevail in India, owing, probably, to horses bemg kept m
open stables. I except, of course, Strangles in young horses ;
and this disease, one would think, would be the most likely
to end in Roaring. It does not, however, do so ; and the
fact that the race-horses form the class mostly affected,
would seem to point to excessive exertion as the mam

' Inspecting Veterinary Surgeon J. J. Meyrick, C.B also
supplies the following information with regard to India :
"I believe that in eastern countries, as a rule, Eoarmg is
very uncommon. During twelve years' Indian service, i
met with only one case that I can remember but it was a
very bad one. The animal, a remarkably well-shaped Aus-
tralian horse, had been imported only a short time, and was
found to be a Roarer immediately after jommg a battery
of which I was in charge. Whilst looking after various
batteries of artHlery, regiments of cavalry, and Gov—t
studs, as well as while superintending the l^ors^-^re^^^^^
operations of the Punjab, I had to ^-P-^ ^^^'^^^
country-bred horses in tens of thousands, Australians, and
a few sLes of horses from Cabul and Central AsiaJ^esides
many hundreds of Arabs and Persians. Among all the e
as bLe remarked, I never met with a Roarer except the
Australian. It is, of course, just possible that some rnigh
have been affected, but so shghtly as not to attiac the
attention of the officer in charge of them._ . • I neve^^ -et
with a case of hereditary Roaring m India, there being no
Roarers among either the ^tfio- or brood ma^^^^^^ of^^
studs to which I was attached. I should add that 1 have
^if served in the Bengal "ncy, but I have ^^^^^^^^^^^
every part of it, from Calcutta to Peshawar. Mi. Steel

Prevalence of Roaring.

23

served in Bombay, and I understood him to say that he had
met with a few cases of Roaring in that Presidency; but he
quite agrees as to the general exemption of Eastern horses
from it. It is certainly remarkable that I did not meet
with any Roaring among the stud-breds, because Strangles
is said to be one cause in England, and that disease used to
prevail in a severe form in the Government studs of Bencjal
(owmg to the large number of young stock collected in
them), in spite of most ample ventilation and other sanitary
measures. Veterinary Surgeon Glover, of the Army Vete-
rinary Department, tells me he knew a few instances of
Roaring among the Australian racers in India, but he had
never met with Roaring among stud-breds or country-
breds."

Mr. Hart, however, states that " Roaring is very common
in Calcutta, and is most often observed in the coarse-bred
horses which can least withstand the heat, and seem to be
constantly in a state of fever."i These were, in all probability,
imported horses.

With regard to Bombay, Inspecting Veterinary Surgeon
J. Anderson, who has served in India for about a quarter of
a century, has forwarded me the following interesting notes :

"Roaring is comparatively rare in India, and chiefly
affects Australian horses, less fi^equently Arabs, and very
rarely country- breds. In this country it is more usually
found among race-horses, and is comparatively rare amongst
troop, hack, and harness horses. The latter are more sub-
ject to it than the hacks and troopers, they being frequently
over-sized, under-bred, big-headed, and short thick-necked
horses.

"The stamp of Australian thorough-bred that usually
becomes a Roarer, is also a large horse with his head badly
' put on,' with a thick, fleshy, coarse throat, and often more
or less ' ewe-neck.'

"Large, coarse Arabs are also subject to this defect,
^ "Veterinary Journal," vol. xxv., p. 4.

24) Roaring in Horses.

which is hardly over seen among high-caste, middle-sized,
or small Arabs and ponies. I have only met one Arab a
Roarer in all my experience, viz., the chestnut Arab pony
Impulse. The disease made its appearance after an attack
of Strangles, and the animal, although an inveterate Roarer,
ran and won many races in good time for years. The
weather affected this animal more markedly than I have
ever noticed in any other instance. On a clear, dry day he
made less noise, and could gallop his half-mile in three or
four seconds better time than he could do on a dull, cloudy
day, especially if there was any dampness in the atmosphere.
I have noticed this in various degrees in all Roarers m this
country.

"Some of the thorough-bred Australian Roarers are
bouo-ht cheap in Austraha, and brought here for sale. I
have known a few of these animals entirely recover m Oude
and the North- West Provinces, the climate being dry and
well suited to such complaints. _

"Roaring is sometimes contracted on board ship, as a
result of dfsease of the respiratory organs, etc., but I attn-
bute'the majority of cases in Australians to bad stable
management and feeding while in the dealers stables in
Calcutta, where they are chiefly fed on a crushed food which
is largely composed of chopped straw and coarse ergotized
brasses. They are also bedded down on rice straw, which
horses like, and eat greedily. To allow horses to eat nee
straw for any length of time is sure to cause Roaring, i had
a very lea'winded Austrahan, Yanathon who met with
an accident, while running in a hurdle-race - Calcu ta
some years a-o. I had to leave him there ; he got he usual
SrTa^dl largely of rice strawfor about si. we^ or^wo
months, and came back to me an inveterate Roaiei, wbicji
he is t; this day. I have often split ^V^^^;^^
and found the inside mouldy, ergotized and ^^^^^ P^^^^^^^^^
-in fact, this is the case in nearly all badly-preserved coarse
grasses, as the natives do not understand the principles of
hay-making.

Prevalence of Roaring. 25

" Koaring has become more frequent of late years among
Arabs. This I attribute to the great number of two- and
three-year-olds now imported. Formerly there were not so
many young ones imported, and they came in small batches
in native boats called buggalows ; now they are brought over
in steamers from Bussorah, are crowded together under the
most insanitary conditions in large batches of one hundred
and fifty to two hundred— the voyage generally lasting from
three weeks to a month, from Bussorah to Bombay. Durino-
the voyage Strangles invariably breaks out, and generally
assumes a most virulent form, and from the absence of all
treatment, the consequence is that a number of the affected
animals become Eoarers. Among the Arabs I have also
noticed that the larger and coarser the horse the more likely
he is to become a Koarer. This I attribute to the fact that
most of these very large horses, from 14.31 to 15.2 hands
high, are not pure-bred Arabs, they having" an admixture
of foreign blood, which gives them size at the expense of
quality, the pure desert-born horse being an exceedingly
clear- winded animal. °

"Strangles is not so frequent a cause of Koarino- in Aus-
tralians as it is in the Arab in this country, bec'iuse the
former are seldom imported under four years old, and have
generally had the disease before shipment.

" I have observed two distinct kinds of Koaring in this
country : one, which is permanent, and becomes gradually
worse with fast work, and the other, which diminishes as the
horse gets into condition, disappearing altogether while the
animal is kept m racing condition ; on the other hand how-
ever, such a horse, when turned out of work at the end of
the racing season, will again begin to Roar, and continue to
do so while out of work and gross.

"The late Colonel Robarts, a well-known Indian sports-
man,_ was a great advocate for ghee (clarified butter) in
Koaring. He used to give the Australian chestnut thorouo-h
bred mare Music (an inveterate Koarer), i lb of

warm

26 Roaring in Horses.

ghee half an hour before starting for a race. This material
greatly diminishes the noise, and seems to afford much
relief, enabling the animal to gallop without so much
distress. Of late years I have prescribed glycerine in such
cases— siv. to be administered half an hour before running,
or taking violent exercise— and I am certain it is highly
beneficial."

In the Madras Presidency, Inspecting Veterinary Surgeon
Shaw reports lung and air-passage diseases as being rare,
and Roaring, therefore, very seldom noted. Veterinary
surgeons there state that the cases coming under their
notice are few, and some have never met with one. In
the 3rd Madras Light Cavalry there was not a horse so
affected in June this year. He had remarked it among
horses from Northern Asm— i.e., Karnbaghees, Mushids,
Cabulees, Toorkomanees, etc., horses which are reared in
a climate more severe than that of England, and which,
therefore, exposes them to diseases likely to produce
Roaring.

With regard to Australia, I am informed that Roarmg is
somewhat "common, and the evidence just_ quoted with
reference to India would go to corroborate this.

In South Africa the native-bred horses are, according to
all the information I can obtain, particularly exempt from
this defect. An officer of the Army Veterinary Department
Mr Nunn has recently travelled over the greater portion of
the horse-breeding districts of the Cape and Natal Colomes,
as well as those of some of the Boer States, inquiring into
the horse-supply ; and during the whole of his journeys and
residence in the country, he has only met with two horses
so affected. Mr. Rowe, senior military vetermary surgeon
in Natal, where he has been serving for several years
writes • ' I have examined a great number of horses since 1
arrived, and have only rejected one Colonial and two Free
State horses because of Roaring. Imported horses hat
were Roarers when they arrived in the country, are still so,

Prevalence of Roaring. 2T

but in no case have I found the stock from such animals
give the slightest sign of such an affection.' And yet
Strangles is common, and frequently prevails in a wide-
spread and severe form.

But if the native horses are rarely affected with Koaring
in South Africa, it would appear that newly-imported ones
are sometimes very liable to it — especially those from
England. A striking instance of this was afforded in 1879,
during and subsequent to the Zulu War, among the army
horses sent from England. Inspecting Veterinary Surgeon
Lambert, who was then attached to the 17th Lancers during
the campaign, gives me the following particulars :

That regiment left England in February, and arrived in
Durban in April, 1879, with more than three hundred
Irish mares, and some scores of geldings. At the conclu-
sion of the war, when the regiment returned from Zululand
to Natal, towards the end of the year, the horses were sold
by auction, and eagerly bought by the Boer and other
farmers; the mares especially were in great demand for
breeding purposes, as the South African horse has much
degenerated in size and general physique during the last
thirty years, and the 17th Lancers' mares were large and
good of their kind. Mr. Lambert went again to Natal in
1881, in the capacity of Principal Veterinary Surgeon of the
Expeditionary Force sent against the Boers, and there he
made many inquiries as to how the l7th Lancers' mares
had turned out. The answer always was, that they had
proved barren and become Roarers. Mr. Lambert himself
took out a fine horse as a charger, and within three months
alter landmg in Natal the animal was a bad Roarer An
excellent hunting and steeplechase mare, which an officer
ol the 17th Lancers took out in 1879, and sold in Natal
Mr. Lambert saw in a cab at Pietermaritzburo- in 1881 she
havmg become a Roarer, besides proving barren. Colonel
Gore commanding the Inniskilling Dragoons, took out to
iNatal, m 1881, two excellent young horses bred by himself.

28 Uoaring in Horses.

and though perfectly sound on landing, yet were bad
Roarers a few months afterwards. Mr. Lambert observes
that these instances are only a few out of many, and are
somewhat remarkable, because Roaring in South African-
bred horses is very uncommon ; but he notes that size may
have something to do with this, as they are not more than
14 3 or 15 hands high, and in England Roarmg is not
common in ponies. However this may be, it would appear
that, at least on arrival in Natal, the climate is not
favourable to the respiratory organs of imported Engiisii
horses.

Mr Hutcheon, Colonial Veterinary Surgeon, Cape ot
Good Hope, has furnished me with further evidence as to
the immunity of horses from this ailment in South Afnca
Mr. Robertson, a horse-breeder, in the Hantam district ot
Colesberg division, writes : " I would not mmd breeding
from the rankest Roarer you could give me. i do not
beUeve that Roaring is transmitted from the parents m this
part of the country, and I do not know of a single instance
of a Roarer having been bred here. I believe Bnan Bor a
a horse imported in 1863, was a very bad Roarer ; afte he
was here some time he could run two-mile races, and beat
anything in the country. I saw a good many 1^^^ ^tock
but not one of them was affected in his wmd. In om
district Agar (imported) was as bad a Roarer as you couid
g t he could not'wm a hat in England. Six months af er
L ;rrived he won a mile race at Cradock, m a large fieM
of horses, and got stock as sound as possible. I believe
Woldman has gone wrong in his wmd. probably the eftect
of a dose of Strangles ; he is by Catalpa, out o a c—
inare, and was a very soundhorse ^^^^^^^^^^^^^^^^
Esther Stockwell makes a noise, but I am not m the least
afrlid of her stock being unsound. With the exce^^^^^^^^^^^
Woldman, I don't know of a smgle case of a cobn^ied
thoroughbred Roarer, and he was very bad with Strangles
Ihen Hast saw him in Cape Town. Guidenus (imported)

Prevalence of Roaring.

29

is a Roarer, but his stock which I have seen are sound. I
am quite sure that Roarers improve in this country, and
that this is owing to the dry cHmate."

The Commissioner of Police, from inquiries among his
inspectors, who had experience of horses for many years in
the eastern provinces of the colony, the Transkei, Basuto-
landj etc., as well as his own long experience among all
classes of horses under a variety of circumstances, con-
cludes that " Roaring is a disease to which colonial- bred
horses are not liable." The officer commanding the Cape
Mounted Rifles for ten years had not found more than three
Roarers during that period. Mr. Hutcheon's experience is
to the same effect. He writes : " I have also inquired of
the various jockeys, and their united testimony is that
Roaring is very rare out here, Woldman being the only
colonial-bred racer known to have become a Roarer. I re-
member an imported horse (Excelsior) becoming a Roarer in
the early part of 1883. I attended him for Strangles when
a colt in 1881. Buxton, an imported horse, ran from ] 880
to 1883, sound, with an unbeaten record. I saw him the
morning before he ran his last race in 1883 ; he was ill-
suffering from a catarrhal condition of the whole mucous
membranes, with a tinge of jaundice. His jockey landed
him a winner, but the horse could scarcely stand when he
came into the paddock. In less than a fortnight after he
was a rank Roarer, and never ran again. Paul, brother of
Peter, came out here in ]885 a Roarer. He ran at one
meeting, won the trial stakes, but ruptured a small blood-
vessel when running a second race. He was then put to the
stud, and, notwithstanding his services there, I saw him at
the Cape meeting recently ; he ran well for five furlongs,
but could do no more, so that I do not think he has im-
proved. On the other hand, taking into consideration that
he has been serving at the stud for three seasons, he is not
any worse, so far as Roaring is concerned. Amongst or-
dinary-bred horses out here, I have never met with one

30 Roaring in Horses.

Roarer, and only one Broken- winded. All breeders are
agreed that Roaring is not hereditary in this climate."
°For Egypt the evidence is somewhat conflicting. By some
observers, Roaring is reported as almost enzootic, no breed
of horses enjoying immunity. According to Mr. Meyrick,
it is far more prevalent than in England : " In the streets
of Cairo, Arab or Syrian horses can be heard t,o Roar
while drawing the carriages of the gentry. Shortly after
our army reached Cairo at the latter end of 1882, a severe
form of Eever, resembling Anthrax in many respects, broke
out amongst the horses, many hundreds of them bemg
attacked Within two or three months after this outbreak
subsided it was found that an extraordinary number of the
horses h'ad become Roarers. All except a few had been
treated for the Fever, and I am inclined to thmk that these
few had also been aflected, but in so slight a form as to
escape notice. In some cases the only symptoms observ-
able were a quickened pulse and breathing, with a yellow
tino-e of the mucous membranes and loss of appetite. As
mo^re than half of the private soldiers, and likewise the
veterinary surgeons, were in hospital, those eft had so
many animals to attend that slight cases of illness might
easily have been overlooked. On ^^^^S'^'f'^'''''^
examinations of some of those which died I found infiltxa
tions of lymph in various parts of the body. Possibly the
Roaring may have been caused by the pressure of some of
these deposits upon the nerves supplying the arynx. i
afterwards found that a similar Fever is present nearly oi
qu te'very vear in Egypt, and it may perhaps be the cause
Tthe Syrian and Arab horses there so frequently becoming
Roarers.' The cause of the Fever I believe to be maUrious
depending upon the annual overflow of the ^ile, and
tCvated by the absence of sanitary arrangemen s
thr "hout the country. After several months, manj^ of
he Roarers completely recovered, while others —d m
the same condition, or became worse, and had to be cast

Prevalence of Roaring. Si

from tHe army. I found many instances of horses being-
cast for Roaring more than two years after they returned to
England, so gradually did they deteriorate. Small horses
are, according to my experience, less frequently affected
with Roaring than large ones. In Egypt, it may be said
that, practically, all horses are imported, the country being-
so ill-adapted to them, that few are bred in the cultivated
parts. In the desert the Bedouins breed some, but the
desert can hardly be called Egypt proper."

Mr. Case, Senior Army Veterinary Surgeon in Egypt, in-
forms me that Roaring is rare, the horses most affected being
imported— chiefly English ; after them come, with regard
to liabilit}^ Australian horses, then French, Russian, and,
lastly, Hungarian horses. He had heard of only one case
in a native horse, and one case of recovery ; the affection
generally came on without any appreciable cause. From
extensive inquiries he learned that it was very seldom
observed in indigenous horses, and the Egyptians did not
consider it objectionable when it did occur. When he
wrote (August, 1888), he thought about eight per cent, of
the English army horses were Roarers; they were large,
tolerably well-bred animals, which had been affected for
years— probably soon after landing in 1882. The coarser-
bred horses were much less affected. He had never heard
of mules or donkeys becoming Roarers in Egypt.

Mr. Beech, of the Army Veterinary Department, and attached
to the Egyptian Army, mentions that of 470 Arab horses in
that force there are only five affected. He has never seen sL
case in an Egyptian country-bred horse. The Arab horses
from Bagdad, those of large size and probably town-bred,
are more liable to it than those from the desert ; those
from Mesopotamia are seldom affected, and it is all but
unknown in Syrian desert-bred horses. He had never seen
a case among the horses of the Romella and other Anazeh
tribes of Arabs, nor yet among those of the Shammiar
Arabs. When Arab horses are affected, the Roarino- is

32 Roaring in Horses.

never so severe in them as in European horses. Natives
think little of it, and will buy a Roarer as readily as a
sound horse.

Mr. Littlewood, Civil Veterinary Surgeon to the Egyptian
Sanitary Department, remarks that the large white donkeys
used by the better class of Egyptians, and which frequently
cost as much as £70 in the market, are often Roarers ; but
this does not depreciate their value. The native veterinary
surgeons say that recovery is doubtful. He has known
Russian horses to be affected.

In the United States of America, Roaring is prevalent,
and probably a considerable number of the horses unsound
in their respiratory organs are so because of this defect ;
though I am unable to give anything like an approximate
idea as to the extent to which it prevails. But it doubtless
is much more common in the North and West than m the
South— indeed, I am assured that in South America it is
very seldom noticed, especially in the drier regions, and it
is asserted that in Buenos Ayres it is quite unknown and
that Roarers sometimes recover when sent there. In North
America it affects a certain proportion of horses, though i
cannot ascertain what this is.

- On the European Continent it is only too weU known ;
indeed as the historical sketch in this treatise shows it
was first described in French veterinary literature, and tor
nearly a century it has been receiving the serious attention
of all the most distinguished veterinary authorities m
France. Germany, Italy, Belgium, Holland, Denmark, aud
Sweden, as weU as Russia. It appears to be less common
in the East and South than in the West and North.

Reynal^ says that in France it is frequent, though when
he wrote (1858) he thought it was less prevalent than
before-times-a result he attributed to the greater care of
horse-breeders in the selection of breeding-stock, bettei
1 "Nouveau Dictionnaire Pratique, etc., V6t4rinaires," vol. iv., art.
"Oornage."

■ . Prevalence of Roaring. 33

crossing, and improved hygiene, rearing, and training. He
remarks that in that country certain breeds were more pre-
disposed to it than others, the old Norman carriage breed,
chiefly raised in the Cotentin, Bessin, etc., being notorious
for this unsoundness; and he states that, speaking generally,
Koaring is more frequently observed affecting heavy draught-
horses (chevaux de gros trait) than those bred for riding, and
in entire horses than geldings, and males than females. He
asserts that it is often observed in France in certain breeds
of horses obtained from Hanover and Holstein, resembling
the Norman horses of Cotentin. Kiquet estimated, in 1847,
that in Holstein the number of carriage-horses affected with
Koaring was about eight per cent., while it was four per
cent, among those of medium size.^

Professor Goubaux stated at a meeting of the Socie'td
Centrale de Medecine Veterinaire of Paris, in 1868, that
he had examined the larynges of 250 horses, and found
that one-fifth of the number had the characteristic wasted
muscles on the left side, indicating that the horses had been
Hearers.

In the Veterinary Statistical Report of the French Army
for 1883,2 the latest published, I find the number of horses
cast and sold in France because of Roaring is 0-86 per 1,000,
and in Africa O'lO per 1,000. The greater number were in
cavalry, and it appears that horses aged eight and nine
years, and sixteen years and above, furnished the largest
proportion. Charon, veterinary surgeon of the Remount
Dep6t, Caen, shows that the defect is seriously prevalent
among French troop-horses.^ Of the horses purchased at his
dep6t during ten years, an average of 1-62 per cent, of the
geldings and 1-35 per cent, of the mares were Roarers;
this did not include the stallions, among which the defect

1 1< ■

'Recueil de Medecine Veterinaire," 1847.
Recueil de Memoires et Observations sur I'Hygiene et la Medecine
vetennaires Militaires," Paris, 1887.

"Etude sur le Cornage Chronique," Paris, 1886.

Roaring in Horses.

is more frequent. Among horses of tlio Reserve. 3-87 ;
heavy cavalry, 219 ; Ught cavalry. 119 ; and artillery
liorsi, 0-97 per cent., purchased during lour years, were
Roarers. As evidence that the defect is on the
notes that among the horses purchased at his depot m 1880
there were thrice the number of Koarers than there were in
1871 His remarks with regard to Algeria corroborate the
observations of our own army veterinary officers with regard
to India. He asserts that, practically, the disease does not
exist in that country, for since the establishment of

remount dep6ts there ^ ^,^%\^^V"?,f ^.Vd.h
total of 1,515 stallions, purchased by the depots at Blidah,
Constantine. and Mostaganem, since 1845, not a single ho.e
had been cast and sold because of Roarmg. Smce 1878
these depots had also purchased 16.721 troop-horses, and
the defect had not been observed m any of them.

In the Veterinary Reports of the German Army accessible
to me there is no mention of Roaring, though the diseases
Ihi'h it often follows appear to be quite as prevalen among
The troop-horses as among our own ; and if we are to judge
bv the frequent allusions to it in vetermary hterature. it
^'igS be c'oncluded that in Germany it is as common as m

England. . . ,

In Snain and Italy it is very infrequent.

It isCossible now to ascertain to what extent Roaring
nr ta leTam ng horses in the United Kingdom previous to
?r rptnt century When such veterinary authorities as

Prevalence of Roaring. 35

indeed. Thoroughbred horses appear to be most predis-
posed to become Eoarers, and three-parts or half-bred
hunters and carriage-horses come next. Among saddle and
light harness horses, Eoarers are to be found in considerable
proportion, and draught-horses, heavy and light, are by no
means exempt ; but among small-sized horses and ponies
the defect may be said to be somewhat rare. Certain breeds
of horses, and even certain strains, would appear to have a
tendency to become affected when exposed to excitino-
causes. P

But to what extent the morbid state which produces the
noise prevails generally, there is no positive evidence to
show, except that to be obtained by examming the statis-
tical records of British army horses. These may afford an
approximate notion of the prevalence of Koaring amon- the
hghter horses in the United Kingdom, though only° o a
certain extent; for many troop-horses which make a noise
in respiration, if not much distressed during severe exertion
are not reported, and are retained in the army until cast and
sold because of age, or for some other reason-they conse-
quently do not appear in the Casting Keturns as Eoarers
1 lind that the number of troop-horses cast from the Service
owing to this defect was, in

1881- 20 with an average service of 7 years

1882- 27 „ 5,

1883- 35 „

1884- 92 „ ; 4

1885- 55 „

1887-61 „

showing a total of 373 horses during the seven "years 'the
annual strength of the army in horses being about 12 000
Taking four cavalry regiments stationed at Aldershot in

1 During this year many horses returned from Ecvpt affeofP,! w'+t,
Roanng, contracted in that country and th« "7°"^^ attected with
sold. couniiy, and the worst cases were cast and

3-2

36 Roaring in Horses.

July of this yecar, I find that the average number of their
horses which are affected with Eoaring, though doing duty,

is 6'14 per cent. .
The following table shows the ages of these horses, their

regiments, and average service :

TABLE I.

REGIMENT.

1st Dragoons
5th Lancers
14th Hussars
18 th Hussars

Total...

OQ CO CO CQ

5 8

1 11 1512 8 15

1 1 3
2
2

4 1

II 1

6 9 6

o .

< K

>

5 3 3

42 1 9^0 421 1 10-0

16 9 ' 422 1 3-8

17 8 1 280 6-08
20 8 1 423 i 4-72

1 95 8,»^ 15461 6-14

The second table has been compiled from special returns,
and shows as exactly as possible the number of army horses
affected with Roaring, by corps ; it also exhibits the pro-
portion according to age, sex, size, and total number.

From this table it would appear that the percentage
of army horses affected is 5-42, and of course the Roaring
is present in all stages and degrees of intensity.

Prevalence of Roaring.

37

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38

Roaring in Horses.

Taking tlaese figures as an index of the prevalence of
Koaring among horses generally, throughout the United
Kingdom, we might hazard the opinion that at least 6
per cent, have this infirmity, though they may be more or
less serviceable, according to the stage it has reached.

It is possible that it maybe very much higher among the
lighter horses — saddle and harness — of the public : as army
horses, nearly 6 per cent, of which we may admit are Roarers,
are purchased when young, and are carefully attended to,
medically and hygienically, during the whole of their
service ; they are therefore less exposed to the exciting
causes which give rise to Roaring.

CHAPTER IV.

PREDISPOSING CAUSES OF ROARING.

In the production of what I heave termed, following the
example of French Veterinarians, "Chronic Roaring," we
must not overlook the existence and the influence of pre-
disposing causes, as it is only by recognising and endea-
vouring to neutralize them that we can hope to prevent
its occurrence. These causes are numerous and various,
and some of them are more potent and obvious in their
mfluence than others; they may be considered in their
relation to : 1. Climate ; 2. Heredity ; 3. Breed ; 4. Sex ;
5. Size ; 6. Age ; 7. Conformation ; 8. Management ; 9. Acci-
dental Causes.

1. Climate.

In treating of the prevalence of Roaring, in the preced-
ing chapter, there was much and strong evidence given in
favour of the influence of climate as a predisposing cause,
and it was remarked that horses in Western and Northern
countries are much more liable to it than those of Eastern
and Southern regions. Even in Europe this is evident, the
horses of Italy and Spain being very much less affected
than those of England, or Northern Germany and France
Cold and damp climates appear to favour its production
not only because they are inimical to the natural vigour of
horses, but also because the artificial conditions in which
they have to be maintained in order to protect them from
the deteriorating influences of climate, or to improve them
are predisposmg agencies in themselves, tending as they do'

40 Roaring in Horses.

and as we shall presently show, to develop those maladies
which so frequently lead to Roaring.

According to Charon/ Roaring is frequent in the West
of France, and more especially in the Norman Depart-
ments of La Manche, Orne, and Calvados ; while it is less
frequent in La Vendee, is almost unknown to the south
of the Loire, and is still more rare from the banks of the
Garonne to the Pyrenees. Normandy has always been con-
sidered the country in France in which the defect is most
common and has been longest known. Indeed, there is a
Norman tradition that the name by which it is known in
France— "Cornage" — originated there, and was carried,
along with the horses of La Manche and adjoining depart-
ments, into the interior ; it was derived from the similarity
of the sound emitted by the affected horse to that given
out by the horn of the cowherd assembling his cattle.

Ireland is a moist country, more so than England, and
the affection is more common in Irish than English horses,
so far as my experience goes.

Change of climate may also act as a predisposing, or even
exciting cause, as witness the case of English troop-horses
in Egypt and South Africa, and Irish horses brought to
England. An Arab recently imported from India to this
country has become badly affected with Roarmg.

Climates which predispose to diseases of the respiratory
organs are those in which Roaring is most prevalent ; such
are cold, moist climates ; and those in which it is least
known are warm and dry climates— maladies of the air-
passages being rare in them, and horses living much in the
open air. Under the influence of acclimatization m moist,
cold climates, horses bred in warm, dry climates become pre-
disposed, through the diseases common to such inhospitable
regions attacking them and rendering them liable to this
defect.

1 Op. cit., p. 77.

Predisposing Causes of Roaring.

41

2. Heredity.

The question of heredity of predisposition is a very im-
portant one for consideration, as, if it really exists, unlike
climate, it can be controlled. •

Of its existence I think there can scarely remain a doubt.
We do not know when Bearing first began to be observed
in England, but it would not appear to have been much
noticed until within the last century or two. Was the ten-
dency to it imported into this country by foreign horses of
large size ? Godine, jun., long ago asserted that the defect
was introduced into Normandy, in 1764, by Danish stallions
which were Koarers.i May we not have got it among our
horses from a similar source, and about the same time"?

It has been stated that the famous race-horse, Eclipse,
was affected in his breathing. Youatt says: "Eclipse was
a 'high-blower.' He drew his breath hard and with appa-
rent difficulty. The upper air-passages, perhaps those of
the head, did not correspond with his unusually capacious
chest ; yet he never was beaten. It is said that he never
met with an antagonist fairly to put him to the top of his
speed, and that the actual effect of this disproportion in the
two extremities of the respiratory apparatus was not
thoroughly tested."^ Whether this " high-blowing " was the
defect we are now studying, there is no other evidence to
show. Certain it is, however, that Koaring began to receive
attention about this time, and towards the beginning of this
century suspicions of . an hereditary tendency to°it were
being entertained. Soon strong proofs of the reahty of such
a tendency were accumulated and published, and some of
them were sufficiently convincing.

K. Glinther, in Germany, and' Stockfleth, in Denmark
maintained that Koaring is hereditary, and gave evidence in
support of their opinion.

' " ^^^'^ d'Hygiene." . « The Veterinarian," 1833.

42

Roaring in Horses.

In France, Dupuy, early in this century, insisted, from his
observations, upon Roaring being hereditary ; and Girard,
jun., cited the case of the stallion Misanthrope, in the plain
of Caen, whose produce were superb, but one-half, and often
even two-thirds of them, became affected with Roaring,
Reynal refers to many instances of a similar kind, and par-
ticularly alludes to that of a great horse-breeder of Livonia,
who had a fine Enghsh stallion which, when about ten years
of age, became a Roarer without any appreciable cause.
From this time nearly all his produce were affected, more
or less, with Roaring, and among them eight mares which
he kept for breeding purposes. The curious feature in this
instance was that the descendants showed the defect when
ten years old, the age at which the sire was discovered to
be unsound from this cause.

And the evidence obtained in the French Government
studs is further confirmation of this hereditary predisposi-
tion. Charon, from inquiry and observation, states that 60
per cent, of the produce of horses affected with Roaring
become Roarers when exposed to exciting causes, and he
gives a long list of stallions which, themselves undoubtedly
unsound in this way, were the sires of generations of simi-
larly unsound stock. He refers especially to a thorough-
bred stallion, which by his name— Eastham— should be
English; this animal was a Roarer when comparatively
young, but, owing to his fine appearance, he was a great
favourite in Normandy, and much sought after. He unfor-
tunately left a long line of half-bred Roaring descendants,
and Charon declares that there is not a breeder in the
"Valley of the Auge who does not retain an unpleasant
reminiscence of the animal's presence in the country,
through the serious respiratory defect in the stallions and
mares^he produced. To this day these breeders, in referring
to this horse, say "II a du B(^ranger dans le gosier," a
phrase as significant as imaginative. Charon gives a list
of the stallions descended from Eastham which were

Predisposing Causes of Roaring. 43

Roarers, and some of which were rather celebrated. One
of his produce, Chasseur, and his grandson, Carnassier,
became Roarers ; the latter was the sire of the celebrated
Ganymede, out of a mare by Chasseur ; and Ganymede in
turn produced a Roarer bearing the parent's name. Among
the descendents of the latter, Quebec and Troarn are
particularly distinguished as hereditary Roarers; among
the sons of Quebec nine, and of those of Troarn seven,
were affected.

In England, the instances that might be quoted in sup-
port of hereditary predisposition are very numerous and
convincing. Youatt, in his Veterinary Lectures,^ delivered
in 1833, gives a rather notable case, occurring in Norfolk,
which is somewhat similar to that of Eastham in France'
He says :

" There was a valuable stallion in Norfolk, belonging to
Major Wilson, of Diddlington. He was a great favourite,
and seemed to be getting some excellent stock ; but he was
a Roarer, and some of the breeders took alarm at this.
They had occasionally too painful experience of the com-
munication of the defects of the parent to his progeny and
they feared that Roaring might possibly be among these
hereditary evils. Sir Charles Bunbury was requested to
obtam Mr. Chne's opinion on the subject. Mr. Cline was a
deservedly eminent surgeon of mankind ; he had exerted
Himselt in the establishment of the Veterinary Colleo-e • he
was an examiner of veterinary pupils, and therefore it was
supposed that he must be competent to give an opinion He
gave one, and at considerable length : ' The disorder in the
horse, said he, ' which constitutes a Roarer, is caused by a
membranous projection in a part of the windpipe, and is the
consequence of that part having been inflamed from a cold
and injudiciously treated. A Roarer, therefore, is not a
d seased horse for his lungs and every other part may be
perfectly sound.^ The existence of Roaring in a stallion.
^ " The Veterinarian," 1833, p. 66.

44

Roaring in Horses.

cannot be of any consequence. Tt cannot be propagated
any more than a broken bone, or any other accident.' , . .
Sir Charles returned full of glee ; the good people of Nor-
fold and Suffblk were satisfied ; Major Wilson's horse was in
high request ; and in a few years a great part of the two
counties Avas overrun with Roarers, and many a breeder
half ruined."

Among thoroughbred or pedigree horses, the influence of
heredity in leading to the development of this defect is
notorious, and instances will occur to those who have even
only casually studied the subject. Bal Gal, for example, was
a confirmed bad Roarer, and her dam, Cantiniere, was even
worse. Blair Athol's progeny are distinguished for develop-
ing their sire's respiratory disability, and the case of Prmce
Charlie is well known. Lady Agnes is the dam of Ormonde,
and both suffer from Roaring.

Goodwin, late veterinary surgeon to the Hampton Court
stud, in Bell's Life for January 15th, 1855, alludes to the
heredity of Roaring, and remarks : " We have before us
such a remarkable case— one which, in this instance, so dis-
tinctly proves that it is hereditary, and this is so well
known to all turf-men, that I feel no delicacy in giving the
names of Bowstring, Iris, and Longbow, all the produce of
one mare. Miss Bowe, yet not by one sire ; for Bowstring
was got by Amuratti, the other two by Ithuriel— first-class
race-horses, and whose infirmity as Roarers is conclusive
upon .this point. At the same time I am aware that many
instances exist of stallions either being or supposed to be
Roarers, whose stock are wholly free from any symptom of
their sire's disorder ; but I believe that a great deal of mis-
apprehension exists, which has often been the cause of
imparting to stallions the character of their being Roarers
when such was not the case."

Elsewhere,! same writer and Mr. Apperley (Nimrod)
allude to the celebrated mare Marry, by Precipitate, and
^" The Veterinarian," 1840.

Predisposing Causes of Roaring.

45

her dam, who were both Roarers ; the first had a filly by
Sorcerer, which in time exhibited the • same defect, and
transmitted it to her son. Black Jack. Marry produced
three Roarers by three different horses. Markham^ gives
an instance in which, of eight descendants from a Roarer,
six became affected.

Pedigree horses of the heavier breeds, such as shire and
Clydesdale cart-horses, have sometimes this hereditary
weakness.

The transmission of predisposition is, of course, more cer-
tain when both parents are affected than when only one is
a Roarer ; in the latter case the chances are more in favour
of the progeny escaping, especially if circumstances are
otherwise propitious. Besides, the hereditary influence is
not equally manifested in all the produce from the same
stock, as there are often many exemptions, only one-half
or one-third becoming affected when exposed to exciting

causes.

It has also been remarked that age appears to influence
the potency of hereditary predisposition in such a manner,
that a stallion affected with Roaring will beget fewer foals
with the tendency to that weakness when young than when
old. A remarkable example is given by Charon, of the
Haras stallion, Pater, which was a Roarer. Very few of the
produce of his earlier years became affected, but nearly all
those he begot in his old age were Roarers when young.

But in considering this question of heredity, it must be
confessed that a satisfactory conclusion cannot always or
easily be arrived at. The predisposition may exist, but the
immediate exciting cause may never arise ; while certain
diseases occurring in horses which may not have the pre-
disposition are often followed by Roaring. When the
defect appears at a very early age, and without any marked
excitmg causfi, then predisposition may be suspected.

Goodwin, quoted by Percivall, gives the case of the cele-
1 " The Veterinarian," 1839.

4G

Roaring in Horses.

brated race-horso Taurus, which, was a Roarer, and yet,
though he sired a number of foals and fillies from several
mares, none of them inherited his defect, and they won
many races. He came from a stock noted for this disability.

3. Breed.

All breeds are not equally predisposed to become Roarers.

In France, Reynal asserted that the affection was more
frequently observed in heavy- draught horses than in those
used for light draught or riding ; though he mentions the
old Norman race, reared in the Cotentin, and recognised by
the great development of its bony frame, its large convex
face, narrow space between the lower jaw, which is volu-
minous and projects much backwards, as being especially
predisposed.

In Germany, though the heavier breeds of horses are not
exempt, yet the lighter furnish by far the largest percent-
ao'e of Roarers. The Hostein and Hanoverian horses, which
somev.'hat resemble those of Normandy, have been consi-
dered as greatly predisposed to Roaring.

In England, more than half a century ago, Youatt said :
" There can be no doubt of the fact that the majority of
Roarers are draught-horses and horses of quick draught ;
they are not only subject to the usual predisposing causes
of this obstruction, but there is something superadded— the
bearing-rein." At the present day, there can be no doubt
that the lighter breeds of horses are most predisposed. A
recent writer^ states that "Cleveland-bay. coaching-like
horses. Shire and Clydesdale cart-horses, hunters and van-
horses, appear to be most disposed to the affection," and
that "a fruitful source of transmission to our half-bred
stock has been the use of thoroughbred horses, cast as
Hoarers, becoming country stallions."

In my experience, the breed of saddle-horses is more pre-
disposed than any other— a circumstance which I attribute
1 T. Hopkin, " Veterinary Journal," May, 1888, p. 317.

Predisposing Causes of Roaring.

47

to the fact that many thoroughbred race -horses are affected
with Eoaring, which eventually, wholly or partially, incapa-
citates them from further performance on the turf, and
causes their relegation to service as travelling stallions.

Tables II. (p. 37), III, and IV. (p. 48), show that, so far
at least as army horses are concerned, those used for saddle
purposes are affected in larger proportion than harness and
heavier draught horses.

TABLE III.

Beturn of Horses sold for Roaring, from 1st January, 1881, to Zlst
December, 1887, in the Cavalry Begiments serving at Rome.

1881.

1882.

1883.

1884.

1885.

1886.

1887.

Total.

Per .
. Cent.

AflE.

ro*

=0

a

'o

O

at
o
u

s

S?
6p

jS
'aj
O

CO

CD
f-t
c3

1^

m
bo
a
■S

•q

a

a

(0

CO

bo

■|
•3
o

CO
03
F-i

c3

bo

g

to*

0)

&0

1

CO
CE

c3

tn
IM
a

0

0

m
<u
u

C3

.a

IS

'0
0

m
u

C3

bo

g

'0
0

4 years ...

5 ,, ..

6 „ ...

7 ,, ...
s „ ...
9 >. .

10

U „ ..

12 „ ..

13 ...

14 „ ...

2

2

1

3

2
"l

i

2

i
1

3
1

1

2
4
1
1
2
3
1
2
2
2

"2

3
2
3
8
7
11
2
4
2
2
2

2
3
7
4
2
1
1

i

2

3
1
3
5
2
3
4
2
1

i
1
2
2
1
2

5
4
5
1
. 5
4

6
6

"3
5

1
1

i
2

"2

3
2

"i

4
5
1
5
4

6
3
2
2
2
1

"2
i

"2
1
2
1

15
13
18
18
20
29
17
18
10
12
14

1
3
2

10
11
5
9
9
7
3
2

S^15
7^06
9^78
9-78
10^87
15 '76
9^24
9^78
6 -43

6- 52

7- 61

1^61
4-84
3^23

16- 13

17- 74
8-07

14-51
14-51
11-29
4-84
3-23

Total

S

4

4

4

21

2

46

21

26

9

44

13

35

9

184

62

Average I
Strength )

48S9

1630

4526

1509

4649

1549

4T66

1589

4630

1543

4913

1638

5171

1724

4792

1597

Average \
■^ge, yrs. j

lis

9

n

7}

9

11

Si

9

9i

10|

9i

8J

95

9^

Per Cent...

•18

•24

•09

•26

•45

•13

■96

1^32|

•56

•58

•89

•79

•68

•62

1

3^84

3-88

48

Roaring in Horses.

TABLE IV.

Beiurn of Eorses sold for Boaring, from 1st January, 1881, io 31sf
December, 1887, in the Royal Artillery, Royal Engineers, and
Commissariat and Transport Corps.

1881.

Age.

i years ,
6

8
9
10
11
12
13
14

Total ,

Average \
Strength )

3256

Average \
Age, yrs. J

11

1882.

1883.

1884.

1885.

2456

1 '. 2
2

13

3106

2343

Pur Cent... I '21

•04

mi

•41

3262

2461

105

•26

•27

16

3238

2443

61

•12

1886.

1887.

Total.

12

3161

2384

20

•49

•37 -38

3257

10?

83

2457

3394

•33

•61

101

12 82

Per
Cent.

2^44

3^65
10-98
10^'.)8
12-19

9-761

7-32:

6-1
12^)9
14^63

9-76

45

2500

•24 ^15

3230

2443

8-9
2 -22
6^00
8^9
11^11
13-33
,13^33
6-66
13-33
11-11
4-44

-47

9i

2-53' 1-8-!

4. Sex.

It has often been asserted that sex lias influence as a pre-
disposing cause, and that horses are more hable to _ the
defect than mares. This notion was started by Girard jun.,
and is alluded to by Percivall, who writes : " Mares seldom
become Roarers, at least in comparison with horses^ ilns
is a fact, I believe, too notorious among men of horse
experience to admit of doubt, though it is one for which it
appears difficult, if not impossible, to assign any satisfac-
tory reason. However, as I am informed, so stands the fact.

Predisposing Causes of Roaring.

49

It cannot be well founded, for the evidence I have collected
does not in any way corroborate it, neither does that of
Charon. That authority gives statistics of troop-horses
purchased in France during a period of ten years (from
1871 to 1880) ; these were 12,538 geldings, of which 206
were Eoarers, and 9,282 mares, 126 of which were similarly
affected — being 1'62 per cent, of the first, and 1'35 per cent,
of the second. These proportions only refer to geldings and
mares, for according to Charon (and the same remark has
been made by Reynal and others), Koaring is more frequent
among entire horses. He states that the Administration of
the Haras always purchases more stallions than are required
to complete the establishment, because of rejections due to
unsoundness ; and it is estimated that there is an average
proportion of 10 per cent, which are Eoarers among the
purchases. The same writer adds, in concluding his
remarks with regard to this point of sexes, that it is
remarkable that it is among the best-bred and best-looking
animals that most Roarers are found.i

Moeller,2 for Berlin, states that, in his experience, he finds
twice as many horses as mares affected with Roaring ; and
Williams,^ following Percivall,* asserts for England that
horses and geldings are more liable to become affected than
mares, which are seldom Roarers.

My own inquiries have had a similar result to that ob-
tained by Charon, as the preceding tables will show. In Table
III. (p. 47), giving the number and sex of cavalry horses sold
because of Roaring during seven years, from the British Army
at home, the sexes are nearly equal; while in the heavy corps
—Table IV. (p. 48)— the mares are largely in excess. Table II.
(p. 37) also shows that, among army horses generall}^, there is
veryhttle difference in the sexes, with regard to predisposition.

^ Op. cit., p. 31.

- " Das Kehlkopf-Pfeifen der Pferde," p. 42.

3 "Principles and Practice of Veterinary Medicine," 1872, p. 509

* " Hippopathology," vol. ii., p. 40.

4

50 ■ Roaring in Horses.

5. Size.

Size is supposed to have some influence in the genesis of
Koaring, and it appears to be a fact that ponies and small
horses are less frequently affected in this way. Not only m
England is this recognised ; Continental horsemen have
accepted it as undeniable. The Baron Curnieu, for mstance,
a o-reat authority in France on horses and horsemanship,
says in speaking of Roaring : " Le Cornage est une maladie
du -rand cheval;" and again, "Comme le Cornage est la
maladie du grand et gros cheval. il est probable que Ton
continuera de risquer i'emploi des dtalons corneurs, d autant
plus quails ne manquent pas. "1 _ -.o.^.uf

Of the horses in Holstein, Riquet estimated m 1847 that
eight per cent, of the carriage-horses were Roarers, and ot
the smaller-sized horses only four per cent.^

For England, Mr. Hopkin writes : " In breedmg, as we
improve the size and conformation, we also mcrease the
tendency to unsoundness of wind. Taking lo-2 hands
as a medium height of the horse, we rarely hnd one
under that affected with Laryngismus paralyticus, whilst
(with age) when over that height a heavy percentage are
unsound. This has been established by investigations

undertaken for me. a- -^^

•■Little horses are very rarely affected, and in offsprmg
from the same parents, if one be small and the other b.g^
the Roaring will be developed in the latter and not the
forme°- but I beheve if the small one be bred irom and
shon d breed a big one, even if the mate be sound, he ten-
dency to Roaring will return. I have a stnkmg mst^ce m
fbOT mare 15-U hands high, and which I have hunted foi
the Taste gh or nine seasons ; her half brother and s.ster
M hands high, were both Roarers, whilst then- dam was
sound and°Spoonstealer, the sire of aU, was also a good-
.vinded torse.;'^^^^_^^

2 " Eecueil de Med. Y^terinaire," 1 84 < .
» Op. cit., p. 315.

Predisposing Games of Roaring.

51

With regard to the latter remark, as to sire and dara
being sound in their wind and their progeny Roarers, this
might admit of another explanation than that of size, and
inquiry would probably elicit the fact that a progenitor of
one or other parent was a Roarer. Atavism is not at all a
rare occurrence in the equine species, and there are
instances, to my knowledge, which would go to prove that
a predisposition to Roaring may be transmitted indirectly
and collaterally.

Some years ago, it was asserted that heavy cart-horses in
England and Scotland were almost as liable to become
Roarers as thoroughbreds, while roadsters and hackneys
seemed to suffer least ; and in Paris it was stated to be the
same. So far as I can ascertain, this is not the case
nowadays.

Though it is a fact that large horses are more predis-
posed to become affected than small ones or ponies, yet size
cannot be looked upon as nearly so important a factor as
the other influences we have been considering. Eastern
and Southern horses, natives of warm, dry climates, are
small when compared with those of the West and North,
which are reared in a cold and damp atmosphere, and kept
generally in hot, close dwellings, which engender diseases of
the respiratory organs. But even among the large horses
there are such notable exceptions to this predisposition, as to
show that height and weight are not so important as some
authorities would lead us to believe.

Among army horses, the largest are to be found in the
Artillery and Transport, the smallest and lightest in the
Cavalry ; and yet it is in the latter that most Roarers are
reported. Table II. (p. 37) shows this; but it likewise
affords evidence that the larger horses of Heavy Cavalry
are more afiected than those of Light Cavalry.

Charon carefully noted the sizes of horses purchased for
the French army during four years, and found that the per-
centage of Roarers among those of the Artillery was only 0-97,

4—2

52 Roaring in Horses.

while in the Light Cavalry it was 1-91, in Cavalry of the Line
2-19, and in the Reserve horses (Heavy Cavalry) 3-87. Though
theris were more horses unsound from Roaring in the Heavy
than the Light Cavalry, which fact might be adduced in
favour of the influence of size; and though the Artillery
horses were taller and heavier than those of the Cuirassiers
and Dragoons, yet there were far fewer Roarers among them,
showing°that the defect is much less frequent among com-
mon-bred than well-bred horses.

In a tramcar company in London, with an establishment
of about 3,000 horses, which are chiefly hght agricultural
animals from Wales, Roaring is unknown.

Therefore size cannot be considered as of great moment,
in predisposing to the morbid condition which gives rise to
the defect,

6. Age.

Ao-e would appear to exercise a certain amount of in-
fluence in the manifestation of Roaring. Apart from
toxical production, it is extremely rare in foals though it
has been observed in those of six months old. Reynai,
speaking of this defect in French horses, says that with
those which do not leave the country in which they are
foaled, it appears more frequently between two and four
years of age; and with those which are exported to the
great industrial centres, it is not unusual to see it mamfest
itself at from five to seven years old.

From two to seven years of age, horses appear to be most
predisposed to become Roarers in this country, and the
maiority probably become unsound from this cause between
three and five years. This is more especially the case_ with
well-bred, and particularly racing horses. It has been justly
remarked that " not a season passes but some proniismg
animal, having accomplished wonders at two years of age
is good for nothing, or for nothing but short spms, at three
because it has begun to make a noise, and goes on from bad
to worse."

Predisposing Causes of Roaring. S3

Our army statistics do not assist us very much in arriving
at a conckision as to age in predisposing to Roaring. Horsed
rarely receive medical or surgical treatment when they first
become affected, and are consequently not reported ; the
morbid change commencing in many cases very obscurely
and gradually increasing, does not, except in severe cases,
prevent the horses performing their duty until they are
cast, either because of it or of age, or some other disability.
Tables III. and IV., therefore, only show horses sold because
of Roaring, which in the older ones was no doubt present for
many years ; and Table II. gives the ages of those already
affected, but serviceable.

The influence of age must be considered in relation with
the circumstance that young horses are most predisposed
to those diseases which are followed by Roaring, adult
horses being much less liable to them, and therefore seldom
becoming subjects of laryngeal disturbance ; though they
suffer far more frequently than young animals from the
affections collectively and popularly designated " Broken-
wind."

7. Conformation.

Certain conformations have been always more or less
associated, in the minds of horsemen, with a tendency in
horses to become affected with Roaring.

In this country, horses with long thin necks — "Ewe-
necked" — are supposed to be more likely victims than
those with better-formed and proportioned necks. Martin^
has supposed that the processes of development of the
body in young horses predisposes them anatomically: the
heart being pushed farther back and the neck growing
correspondingly long, causes the left recurrent nerve to be
exposed to extensions and pressure at the aorta, which, he
imagines, may impair its conductibility. And Mceller^ isof'the
opmionthat the frequent appearance of Roaring at from three

1 Martin, " Oesterreich. Monatsschrift fiir Thierheilkande " 1885

2 Op. cit., p. 34. . ' ■

54 Roaring in Horses.

to six years of age, when the processes of development are
accompanied by great alterations in form, when the fonna-
tion of the neck in particular makes considerable progress,
and the fact that long necks indicate a special predisposi-
tion to this affection, show that a cause for its appearance
must be sought for in these processes. He thought that
Koaring, often increasing slowly at this period, substantiated
this view. Furstenberg and others in Germany have also
considered the long thin neck as a predisposing conformation.
But my observation leads me to the conclusion that horses
with ail kinds of necks may become Roarers, and that the
neck in question no more predisposes than a short thick
neck If the neck develops in length dunng youth, so will
the organs and tissues in relation or direct connection with
it-nerves, muscles, trachea, oesophagus, blood-vessels, etc.
The same processes of development take place m horses m
countries where Roaring is scarcely known ; and if long
thin necks predisposed to it, we could scarcely expect
camels, giraffes, and creatures of similar conformation to
be at all exempt from this affection. ■ a

Horses with flat sides, narrow chests, and elbows inclined
inwards, have also been supposed to possess a strong
tendency to Roaring, but I cannot find any reliable evidence
to support the supposition. I have seen as many well-
shaped, among them perfect-shaped, horses suflermg from
this defect in respiration, as I have of those with the faulty
conformation just described. -, • -n

A notion of the same kind has largely prevailed m France
with regard to the shape of the head, horses with the fore-
head and face convex {tele husqu<!e) being regarded by
veterinary surgeons and horsemen as much P^'^f P°«f
Roarinc The idea, in all probabihty, was due to the fact
that the old breed of Norman horses, which was notonous
for this respiratory defect, had this unsightly-shaped head,
but though the conformation has, by crossing the race
almost disappeared, the Roaring has not. . Besides, the

Predisposing Causes of Roaring. 55

majority of Italian and Spanish horses have this kind of
head, and yet they are nearly exempt from the noise in
respiration. And Charon has shown how little such a forma-
tion has to do with the defect in question; as among 297
horses which were Koarers, only nineteen had this shape
of head to a marked degree, thirty-three had it but slightly,
and 245 had heads of the ordinary shape.

Another supposed predisposing cause is narrowness be-
tween the branches of the lower jaw, which does not admit
of suflficient space for the larynx, and which is therefore
compressed. This supposition has also been prevalent in
France, but in reality it has no foundation ; as the space,
which is rather variable in dimensions, has been found as
wide in Roarers as in sound horses — demonstrating that
the conformation has no influence in the causation of
Roaring. It is to be observed, however, that horses with
their heads " badly set-on " and diminished space between
the branches of the lower jaw, will, when ridden or driven
with the nose pulled in or to one side, sometimes make a
noise in breathing, but this is different to that of Roaring.

Moeller remarks that horses with a thick fleshy neck and
narrow lower jaw, are worse Roarers than those of the
opposite conformation.

So far, then, as certain conformations are concerned, I
am of opinion that they have very little, if any, influence
on the production of Roaring, the existence of this defect
in an animal of a certain shape being, in my experience, a
mere coincidence.

8. Management.

There can be little doubt that the management^ or rather
mismanagement, of horses often predisposes them to Roar-
ing. The artificial conditions in which they are bred, reared,
and worked, necessitated by climate and the demands of
civilization, and also those measures resorted to for im-
proving them, certainly have a tendency to develop altered

56

Roaring in Horsea.

and more delicate states of tissues and organs, which place
horses at a disadvantage when compared with those which
live in more favourable climates, and are kept in a more
natural way.

What can be more unnatural, for instance, than the
training and racing of horses at two years of age, when
they should be running at large and developing their bodies'
gradually and solidly? The housing, feeding, grooming,
and training lead to abnormal precocity, while the severe
exertions required from such immature creatures must be
a severe tax upon their constitutions. The evidence of this
is seen in training-stables, as well as on race-courses where
horses run in five and six furlong races, and are fit for nothing
else, and at the sales of " cast-offs" and racing " weeds."

We are told that the late Mr. Thomas Parr, "m whose
hands Fisherman won countless Queen's Plates, and
Weathergage, who cost his late owner and trainer no more
than £35, won the Cesarewitch, used to maintain that half
the Roarers in England picked up that distressing malady in
the hot stables of tramers. It was Tom Parr's custom to
have Fisherman, Rataplan, Saucebox, Weathergage, Morti-
mer, and all the many good horses which passed through
his hands, standing in rough-boarded loose-boxes, through
the open chinks of which the wind whistled with cutting
fierceness in mid-winter, while a single rug was thrown
over the loins of his horses. Moreover, he rode these
habitually as hacks along the roads, and occasionally with
the hounds, as had been done many years before by _J\Ir.
Fergusson, who is said to have been asked in the huntmg-
field what he would take for his horse, and to have replied,
' Seven thousand guineas.' The horse in question was
Harkaway, who would have been cheap at that price."

Hot stables, and especially if they are badly ventdated
by predisposing to catarrh, bronchitis, pneumonia, and
pleurisy, hkewise predispose to Roaring. Improper food
may also do so, though of this I have no clear evidence,
except in those cases in which it acted as a poison.

Predisposing Causes of Roaring.

57

The bearing-rein has long been considered a powerful
agent in injuring the larynx, and so leading to impaired
respiration. Percivall, fifty years ago, said of Roaring
horses : " A large proportion of these subjects are harness-
horses, whose necks have been rainbowed by the bearing-
rein for hours together, and whose larynges have been
compressed and trachese distorted by this unnatural and
constrained position of the head and neck." And subse-
quent writers have insisted as strongly upon the injury;
done by the injudicious use of this article of harness. But|
though it may, and does, cause much pain and discomfort'
to horses, yet it is very questionable if it does distort the'
larynx or trachea, or produce Eoaring. Saddle-horses are
more liable to become Roarers than carriage-horses, so far!
as my experience leads me to judge, and they do not wear:
bearing-reins. !

9. Accidental Causes.

What may be considered as the accidental predisposing'
causes of Chronic Roaring may also be regarded as the
most frequent, if not the almost constant exciting, causes
of the imperfection. The occasional causes I have already
alluded to, and among them are some which I believe are
in operation in a very great majority of the cases of Roar-
ing, and especially of horses predisposed by heredity or other
tendencies to become Roarers, I refer to the contagious
and infectious suppurative fever of early age — Strangles,
which is followed so very often by Roaring ; also inflamma-
tion of the air-passages, or fevers affecting these or the
membrane lining the chest (pleura).

Among our army horses. Strangles certainly holds the
first place in predisposing or exciting to Roaring, among
remounts especially, and respiratory diseases come next.
In the French army it is somewhat the same, if we refer to
the evidence which Charon adduces. That good observer had
opportunities for studying this matter which few, if any, of

58

Roaring in Horses.

our veterinary officers can command, and which he appears
to have availed himself of to excellent effect, he being for
many years attached to the Remount Depot in Caen.
During two years— 1879, 1880— he admitted to his in-
firmary 754 horses for various diseases belonging to the
classes I have named, and noted their subsequent medical
history. The result was as follows :

NATUEE OF THE DISEASES.

NO. OF HOHSES
TREATED.

NO. WHICH BE-
CAME
KOABERS.

PROPORTION
PER CENT.

OF
ROARERS.

Strangles -
Laryngeal and

Pharyngeal Anginas
Acute Bronchitis _
Chronic Bronchitis -
Pneumonia
Typhoid Affections

(Influenza) -

; Totals -

.

466

155
44
17

59

13

58
23
4

0

2

12-46

14- 83

23"52
8-47

15- 38

1 754

92

12-20

It is remarked that these horses were from three to five
years of age, and that the maladies were due to climatic
influence, all the animals being under the coup of the
Strangles diathesis (diathese gourmeuse), the cases of
chronic bronchitis being observed in horses recovermg
from that affection. The Roaring was not persistent m
every case, as it sometimes disappeared after several
months ; but when it remained after complete convalescence,
it had all the characteristics of Chronic Roaring.

CHAPTER Y.

SYMPTOMS AND DIAGNOSIS OF CHRONIC ROARING.

Percivall long ago remarked that the term ' Roaring ' is
rather a generic than a specific one ; and 1 have already men-
tioned that it does not indicate a disease, but only a symptom
of a morbid condition of the air-passages of the horse. To
speak of the symptom of a symptom is therefore absurd,
and would be inexcusable here, had not universal custom for
years caused the symptom to be regarded as the disease
itself, and it has been written and spoken of accordingly by
horsemen and veterinarians. It will therefore be understood
that, when treating of Chronic Roaring, the signs described
are those which characterize the condition that in nearly all
cases gives rise to impeded and noisy respiration — viz.,
paralysis of the muscles on the left side of the larynx.

This condition I have ventured to designate "Laryngismus
paralyticus," as conveying, technically, an idea of the altered
state of that organ, and the cause which produces the con-
striction of its passage. Professor Moeller has named it
"Hemiplegia laryngis," which only partially defines the
condition ; and others have termed it " Laryngismus
stridulus," a designation applied to the ephemeral and
spasmodic laryngeal disorder commonly known as whooping-
cough in mankind, and therefore misleading as referring to
the laryngeal constriction (or stenosis) due to paralysis of
that organ in the horse.

The chief symptoms of paralysis of the muscles of the
larynx in the horse are : 1. The noise (stridor) emitted in

60

Roaring in Horses.

respiration ; 2. The difficulty in breathing (dyspncea) ; 3.
The character of the cough. In man, the alteration in or
loss of voice (aphonia) is an early and characteristic
symptom, but this is, of course, absent in the horse ; and
therefore the veterinary surgeon has not the advantage of
it as an aid in the detection of laryngeal paralysis at an
early stage, nor as a diagnostic sign.

1. Steidor.

In the great majority of cases, the existence of this
paralysis is first ascertained by the noise the horse makes
when undergoing exertion, or when made suddenly to
inspire ; but it is, as a rule, when in more or less rapid
motion that the abnormal sound is first perceived. In
healthy or physiological respiration, when the horse is at
rest and the ear is held near the animal's nostril, a faint
blowing or puffing sound can be heard, which is somewhat
prolonged during inspiration, not so long, but louder in ex-
piration. This gentle soft sound is produced by the air
passing through the larynx and air-passages of the head ; it
can be heard more distinctly if the ear be closely applied to
the trachea, and loudest of all in the region of the larynx. On
exertion, this sound is increased, though not nearly so much
in horses which are in good training or condition, as in
those which are not so, or are very fat, or have the abdomen
voluminous— as animals fed on bulky food, or pregnant
mares— such are said to be "thick-winded;" but however
much its diapason may be raised, this sound is still normal.
In Roaring the sound is different— or it may be said that
another sound is added to it— when circumstances cause
the respiration to be increased, and the compound noise
then emitted is indicative of an altered state of the
laryngeal cavity.

The timbre, or tone, and the intensity of the new sound,
vary considerably with the changes in the larjms which
oive rise to them. While the horse is at rest the sound is

Symptoms and Diagnosis of Chronic Roaring. 61

imperceptible, but after a certain amount of exertion or
excitement — depending upon the stage of the disease — it
becomes audible as a faint whistling, rustling, or rattling
sound during the act of inspiration ; in some cases it may
not go beyond this, but in others, again — and they are the
large majority — it becomes louder and deeper, then more
acute, as the speed is accelerated and the exertion exalted :
passing by a series of intonations that are difficult to
describe, but which experience can alone assist in recog-
nising and defining as confirmed or chronic Koaring, and so
enable the expert to arrive at a conclusion as to the stage
the alterations in the larynx may have reached.

In quite recent cases, or those in which the laryngeal
derangement is only slight, the morbid sound is usually
not heard unless the animal is put to a fast gallop ; and
sometimes at the commencement of the disease, the noise,
after being emitted for a short time, disappears if the
exertion be continued ; but if it is more pronounced and
louder at the end of a long gallop than at the commence-
ment, then the case may be regarded as one of confirmed
chronic Eoaring. Tn such a case, the minimum of intensity
is an almost inaudible whistle or sifflement in inspiration,
which in time increases to a " filing," "rasping," or "sawing "
sound — the bruit cle scie of the French hippologist, who,
in describing a Koarer, says, " le cheval scie du bois "—the
sawing respiratory sound being a very apt comparison with
that of wood- sawing, though in some instances it is more
like the sound produced by a saw-sharpener. The Germans
try to represent the sound phonetically by the word
" Chiemend." Percivall was not quite happy in describing
It. " With the whistler's note," he says, " we soon become
acquainted. Whoever has listened to the ' northern blast
rushing through a crack in the window-shutter,' need seek
no description of it. In this instance, the sibilation appears
to be produced by a continuous rush of air through some
narrow pass in the trachea or larynx ; it is seldom or never

62

Roaring in Horses.

heard, therefore, in a state of quietude."^ The Roaring or
WhistHng sound is not continuous, but intermittent, being
emitted during inspiration, and scarcely, if at all, heard in
expiration in recent cases.

In very bad cases of Roaring, the noise is frequently
heard when the animal is only a little exerted or excited,
and it quickly becomes increased to what may be termed
the maximum intensity if the exertion be continued. It is
louder and more shrill, somewhat Hke a scream, or, as
Charon has it, a combination of the "renflement du
sommeil " and the " ralement de I'agonie ;" and it painfully
affects the listener, who almost instinctively realizes the
distress the animal must experience, even did he not
observe its physiognomy. The stridulous noise con-
tinues, either until the horse is mercifully pulled up, or he
suddenly stops when the dyspnoea becomes so severe that
asphyxia is impending. The animal seldom falls, unless
very high-couraged, and those who urge him when so dis-
tressed are either ignorant of his condition, or are too
brutal to consider it.

The loudness of the sound is not so much an indication of
the stage the disease has reached, as its acuteness ; for there
are many horses which make a somewhat loud noise,
but which do not appear to be much distressed in their
breathing, and can undergo somewhat severe exertion for a
comparatively long period. Instances of this kind will
occur to all experienced horsemen, for they are not at all rare
among troop-horses, hunters, and even race-horses. Of the
latter, I need only mention the invincible horse Ormonde,
which though an undoubted Roarer, and making a loud
noise when he won the St. Leger in 1886, yet in 1887 beat
two first-class horses— Minting and Bendigo-at Ascot, in
the most exacting of mile-and-a-half races. We are told
that Shadow could stay any distance, " roarmg like a
bull." On the other hand, there is the case of the famous
• Elementary Lectures on the Veterinary Art," p. 244.

1 u

Symptoms and Diagnosis of Chronic Roaring. 63

Prince Charlie, which in the Doncaster St. Leger in
1872, had the other horses at his mercy for a certain
distance, " when he stopped as if shot," the dyspnoea being
too severe for him to continue. In these two examples the
larynges were in different conditions; in that of Prince
Charlie, the morbid changes had reached an advanced
stage ; in Ormonde and Shadow they were not so
developed, and although there was a certain amount of
obstruction to the entrance of air into the organ, sufficient
to produce a loud noise, yet enough gained access to
carry on the vital function of the lungs. Prince Charlie
doubtless made a whistling, screaming, or stridulous noise,
but I can testify that Ormonde did not, though no doubt
whatever could be entertained that he was affected with the
malady of which we are treating.

The stage which the disease of the larynx has reached,
may also be inferred from the duration of the sound when
the horse has been stopped after exertion. In those cases
in which it is only commencing gradually, or which, though
in existence for some time, it has made no progress, the
noise ceases at once, or almost immediately after the
animal is pulled up ; but in cases in which there is much
alteration, the abnormal sound may be heard for several
seconds — even as long as one or two minutes in very bad
cases— after halting. Ormonde's Roaring ceased immediately
when stopped after galloping.

The noise is also emitted sometimes, and especially in
nervous horses, when frightened or otherwise excited. In
the act of coition, a stalHon which is a bad Roarer will
emit the characteristic sound ; and one of the popular tests
for Roaring is threatening to strike the animal when
placed against a wall— both acts causing a sudden inspira-
tion of air. The sound is also more speedily produced, and
is generally louder, if, during movement, the horse's nose is
pulled in towards the chest, and especially towards the
right side. The reason for this will be understood when
we come to study the pathology of Roarino-.

64 Roaring in Horses.

It may be remarked that, in all cases of Roaring, and
particularly those in an advanced stage, the stertorous or
stridulous noise can be greatly lessened, and the distress
the horse exhibits during exertion apparently reheved, by
diminishing the volume of air entering the nostrils, a fact
which can be demonstrated by partially occluding these by
the hand. This has been taken advantage of by those who
desired to utilize horses otherwise unserviceable, who have
devised an apparatus to fit over the nose, which prevents
the dilatation of the nostrils beyond a certain degree.

In all cases of bad Roaring, there is an expiratory sound
much louder than that of normal respiration, but, of course,
much less marked than the characteristic inspiratory one.
This is produced partly by the larynx and partly by the
nostrils, and corresponds, in the comparison made as to the
resemblance of the sound to sawing wood or filing steel, to
the drawing-back sound of the saw or file in order to make
another cut.

2. Dyspncea.

With regard to the amount of difficulty in breathing,
this will depend upon the stage the disease has reached. In
slio-ht cases there may be httle, if any, difficulty observed,
and the animal's utiUty may not be impaired to any appre-
ciable degree, the unnatural sound alone formmg an objec-
tion- and^'even when the noise is somewhat loud, the animal
may yet be capable of undergoing a considerable amount
of active exertion for a long time. But it may be accepted
as the rule, that the amount of obstruction to the breath-
ing, and therefore the degree of distress the horse must
suffer is related to the intensity and quality of the sound.

The obstruction to the entrance of air to the lungs durmg
exertion, leads to longer and more energetic inspiratory
efforts in order to obtain sufficient for the increased demands
of the body, and also necessitates more hurried expiratory
endeavours to compensate for the delay. In advanced cases.

Symptoms and Diagnosis of Chronic Roaring. 66

inspiration may be prolonged to twice, or even thrice, the
normal period during severe and continuous exertion. It
is obvious, therefore, that in the quickened respiration
necessitated by this exertion, which always requires a cor-
responding increase in the quantity of air taken into the
lungs, when the obstacle to its admission is considerable,
the horse must suffer to a corresponding degree — mentally
and physically ; and the distress occasioned by the hesoin
de respirer accentuates the physical effects of the deficiency,
causing the horse — no matter how courageous— to " stop as
if shot," or, in more common parlance, to "shut up" sud-
denly, when asphyxia is imminent.

This disturbance in the respiratory rhythm is, like the
noise, not manifested when the horse is in a tranquil state ;
but when the Eoaring commences it then becomes evident,
and as the dyspnoea increases the animaPs physiognomy
betrays the amount of distress he experiences. When this
IS great, all the inspiratory muscles are most energetically,
indeed spasmodically, active in endeavouring to overcome
the laryngeal stenosis, in order to inflate the lungs to their
fullest dimensions. The expansion of the thorax, wide and
free at first, appears to become less and less with each inspi-
ratory efibrt ; the loins rise and fall ; the nostrils are like the
mouth of a speaking-trumpet, through their extreme ex-
pansion involving their appendages— the false nostrils—
their special muscles (the inspiratory Zem^ores a Zee nasi)
standing boldly out in their rigid contraction : for without
this muscular aid the nostrils would tend to close, because
of the rapid rarefaction or exhaustion of air in the nasal
cavities. Expiration is comparatively easy and rapid, and this
disproportion in the force required in the two acts constitutes
the peculiar characteristic of the dyspnoea which marks
cases of advanced Roaring; hurried respiration is by no
means characteristic of it. In pulmonary emphysema, or
" broken wind," as it is commonly termed, the converse is the
case. It is the very essence of the self-acting function of

6

66

Roaring in Horses.

the vagus nerve to correct or compensate for impediments
in tlie respiration, by modifications in the mode of breath-
ing. So it is that, if the lungs are imperfectly or Avith
difficulty filled, the inspiratory effort will be longer and
more energetic, as in bad cases of Roaring ; if, on the con-
trary, they are easily filled with air, but can only expel it
with difficulty, then the expiratory effort will be prolonged
and powerful, even spasmodic, as in " broken wind."

When asphyxia is imminent, the mouth is in some cases
open (though it is only under extraordinary circumstances
that the horse breathes through the mouth), and the tongue,
congested and blue, is protruded to give more room for the
larynx, which is pulled spasmodically up and down by its
extrinsic muscles, and if seized externally by the hand can
be felt vibrating. The eyes are prominent and bloodshot,
and the whole countenance is wild and distressed-looking.

In paralysis of both sides of the larynx (bilateral paralysis),
which is extremely infrequent in the horse, the stridor and
dyspnoea are much more severe, and on the slightest exertion
or excitement are quickly developed; so that the animal
can scarcely walk without manifesting these symptoms in
the highest degree.

3. The Cough.

The cough of a horse suffering from one-sided paralysis
of the larynx in an advanced stage, is different to that
emitted when it is healthy, it being described as deep and
sepulchral. The air is expelled suddenly through an im-
perfectly closed glottis, producing a peculiar sound, due to
what laryngoHsts term "phonetic waste of air," followed at
once by a rapid deep inspiration, which causes the charac-
teristic noise, something between a scream and a grunt. It
must be explained, however, that some horses which are
not Roarers will emit a sound resembling a grunt, and such
horses are designated " grunters " ; but the noise is produced

Symptoms and Diagnosis of Chronic Roaring. 6V

by a forcible expiration of air through relaxed vocal cords,
not in inspiration, as in Koaring.

In connection with the cough, it may be noted that the
neigh of a horse which is a Koarer is modified in the same
way as the cough.

Diagnosis.

In alluding to the principal indications which enable us
to distinguish Koaring due to laryngeal paralysis from
noises produced by other causes, the measures necessary
for arriving at a conclusion with regard to the existence of
this condition must also be referred to.

The chief symptom, and by far the most distinctive, is
the inspiratory sound in breathing. I have mentioned
the circumstances in which this is produced when due to
paralysis of the larynx. Experts, when examining horses
to detect the existence of the morbid condition, resort to
various tests. These are moving, exciting, and " coughing "
the horse. Manipulation and auscultation are also re-
sorted to.

The most certain way to detect whether a horse is
affected with laryngeal paralysis, and also to ascertain the
stage which the disease has reached, is undoubtedly to
make the animal exert itself. The amount of exertion
necessary to develop the characteristic sound, and the in-
tensity and nature of this, as well as the amount of dyspnoea,
are the criteria as to the presence and extent of the morbid
state.

For riding-horses, the best test is speed. On level, firm
ground the distance should be greater than on that which
is soft (as soft clay-land or a ploughed field) or ascending,
the object being to cause the animal to respire deeply and
quickly.

Soft or sandy ground should be chosen, if possible, as on
it there is less noise from the horse's feet. The anim'al may

6—2

G8 Roaring in Horses.

be ridden by the expert, who leans forward, the easier to
hear the respiration ; but it is perhaps better if he stand at
a particular point and the horse be made to gallop past,
close to him, with its head as free as is compatible with
control. Some authorities recommend keeping the animal's
nose well in towards the chest when galloping, others curve
the neck to the right side, while others again, gallop the
horse in a circle. The latter demands care, as horses some-
times make a noise— irregular, it is true— when galloped in
a small circle, which yet respire perfectly free when going
in a straight line.

For draught-horses, which cannot be so conveniently
galloped, putting them to draw a load in heavy ground or
up an inchne is the most reliable test.

Exciting or frightening is by no means a sure test,
though often resorted to when the preceding ordeals cannot
be ir^posed. Some horses which are decided Roarers when
galloped or otherwise exerted, will not make a noise when
threatened by whip or cane. Neither is " coughing " a
reliable or possible test in all cases. When the disease is
not very advanced, the cough is but little, if any, difierent
from that of health. And when other morbid conditions of
the air-passages are present, as chronic laryngitis or bron-
chitis, or emphysema of the lungs, these will produce their
own particular effect on the cough, and so modify it. Even
perfectly healthy horses, when the larynx is severely com-
pressed and its dilator muscles temporarily ' paralyzed
thereby, will sometimes emit a cough not unlike that noticed
in Roarers. In other cases, confirmed Roarers cannot be
made to cough, owing to loss of sensibility in the mucous
membrane of the air-tube, from wasting of the nerve sup-
plyino- it, or changes due to chronic inflammation.

Direct manual examination of the larynx itself is valu-
able in ascertaining the condition of that organ, especiaUy
if the muscular wasting on the left side is at all considerable;
and with practice, the expert has generally httle difhcufty

Symptoms and Diagnosis of Chronic Roaring. 69

in pronouncing as to the existence of this wasting. When
the horse's head is somewhat extended, the larynx is more
exposed, and the index-finger can then readily feel its pos-
terior (or superior) surface, which is formed by the wide
expansion of the cricoid cartilage and the dilator muscles
covering it. If the left muscle is wasted, this surface will
be found much flatter on that than on the right side. The
subsidence of the aryta^noid cartilage on the left side, which
is also a noticeable feature in the diseased larynx, may be
hkewise ascertained in the same way. A slight amount of
pressure with the index-finger on the left arytsenoid carti-
lage, in the like manner, will cause a loud noise in respiration,
as if the animal were galloped ; but there is little, if any,
distress. This is not the case if the right arytsenoid is
pressed upon ; as then more pressure is needed to produce
a certain amount of noise, and symptoms of asphyxia are
quickly manifested, owing to the complete closure of the
glottis through the immobility of the left cartilage.

These are the chief diagnostic signs of chronic Roaring,
and they should be sufficient to establish the existence of
the morbid condition which occasions it. We cannot, as
in man, employ the patient's voice to aid us, neither can we
examine the larynx with the laryngoscope or manually per
Oram, owing to the immense length and narrowness of the
horse's mouth, its powerful jaws, and the long obstructive
soft palate. It has been stated that in a case of Roarino- .
Hertwig passed his hand through the mouth into the
larynx, and found the left vocal cord relaxed, the right one
being tense ; and Bassi is reported to have done the same.
But it must be admitted that, for the reasons given, the
attempt is attended with danger, and not at all likely to be
satisfactory. The interior of the larynx can be explored in a
thorough manner by opening the organ through the middle
cnco-thyroid membrane, or the trachea immediately beneath
the cricoid cartilage, and illuminating it by means of artificial
light. Auscultation, also, after excitement or exertion, will

70

Roaring in Horses.

greatly assist, under ordinary circumstances, in the detection
of Roaring.

When noisy respiration is due to nasal obstruction, the
sound is usually heard in expiration as loudly as in inspi-
ration, and is of a snoring character; it may come from
only one nostril, or if from both it is then unequal in
intensity, as is also the volume of air entering and leaving
them. Injuries to, and deformities of, the trachea can
generally be discovered by palpation ; auscultation will
also distinguish their seat if they obstruct the breathing.
In cases of tumour in the trachea, the noise is usually more
pronounced during expiration, as the tube then contracts,
while in inspiration it dilates. In cases of chronic laryn-
gitis {laryngitis chronica fibrosa) observed by Mceller, there
was greater resistance in the larynx on attempting to squeeze
it, but the inspiration could not be rendered noisy by
moderate pressure on the arytsenoid cartilages of either
side. The expiration is also as noisy as the inspiration. ^

As has been already mentioned, swellmgs in the vicinity
of the larynx may cause a noise in respiration; even slight
congestion of the vocal cords may produce Roaring.
Giinther gives an instance in which distention of the
laryngeal ventricles with pus caused sonorous breathmg;
the sound ceased when the fluid escaped by depression
of the head. Moeller also mentions a case in which a large
collection of pus in one of these pouches dragged the
larynx to one side, and occasioned noisy respiration.

Chronic Roaring can scarcely be confounded with em-
physema of the lungs (" broken wind ")• The hurried
breathing in the former, after active exertion, is very difler-
ent to that observed in the latter condition. In lung
emphysema, the respiration, as observed at the flank, is
altogether peculiar and characteristic, and the sound has no
relation to the inspiration noise of Roaring. Indeed Iwrses
aff-ected with Roaring are rarely broken-winded, as di&cuit
inspiration is far loss likely to cause emphysema ot the lungs

Symptoms and Diagnosis of Glironio Roaring. 71

than forced expiration. This fact appears to have been
known to Professor Coleman, of the Koyal Veterinary
College, early in this century, as Mr. Percivall has heard him
say, in his lectures, " that Koarers are generally sound-
winded horses, as far as regards the healthy state of their
lungs."^ The cough attending the latter condition is also
very different to that of Roaring, and the respiratory move-
ments continue abnormal when the horse is perfectly tranquil.

^ "Lectures on the Veterinary Art," part ii., p. 256.

CHAPTER VI.

ANATOMY AND PHYSIOLOGY OF THE LAKYNX.

Befoee attempting to deal with the special morbid condi-
tions which cause chronic Roaring, it is requisite to under-
stand the construction and functions of the larynx — the
part which is chiefly involved, and that in which the noise
is produced. This study is all the more necessary in order
to arrive at a correct knowledge of the medical and surgical
treatment which must be adopted in order to remove the
impediment to respiration, and thus restore the unsound
horse to such a state of soundness as will enable it to
perform useful service.

It must be remembered, also, that without a correct
knowledge of the anatomy and physiology of the organs of
respiration, it is impossible to get beyond the mystery which
has so long encompassed the origin of Roaring in the horse
— a mystery which largely prevails in many quarters, and
which obscures the pathology of the disease to a most
damaging extent. If certain evidence is to be accepted, we
would appear to be no more advanced in this direction than
was PercivaU fifty years ago, who, when noticing the ap-
pearances presented by the larynx of a horse which had
been affected in this w&j, writes : " How we are to account
for these changes, to what original cause refer them, is as
yet unknown : by some they are loosely spoken of as the
ultimate consequences of paralysis or of spasm ; but though
these tales may satisfy their employers, they are no more
to the profession than the baseless conjectures of their
authors, and as such are deserving of no comment."^
1 " Elementary Lectures on the Veterinary Art," part ii., p. 254, 1824.

Anatomy and Physiology of the Larynx. 73

We will, therefore, notice briefly the structure and func-
tions of the horse's larynx, before venturing on the attempt
to elucidate the nature and causes of the changes which
have been considered so mysterious, that nothing but base-
less conjectures could be offered to account for them.

Anatomy of the Laeynx.

The horse's larynx is situated between the branches of
the lower jaw, beneath the lower end of the parotid gland,

•Fig. 1.— upper part and aperture of the horse's larynx.

a a, Arytenoid Cartilages ; h b, Vocal cords, formiug the vars
vocales; c, Yocal or Morgagni's Ventricle ; d, Epiglottis; e, Thyroid
nr.*!- Tbyro-Epiglottidean Ligament ; /, Arv-Epiglottidean

•il' =^.' ; ^ Inferior border of the Arytsenoid Cartilage which

with Its fellow on the opposite side, forms the pars respiratoria)

micTeTrflerrynt"' =

which partially covers it on each side. It is the commence-
ment of the windpipe, its upper opening being directed
towards the spacious cavity at the back of the mouth called

74

Roaring in Horses.

the " pharynx," and its lower opening is continuous with
that of the windpipe, or trachea. It is placed in the same
direction as the latter, which, again, has the same direction
as the neck. Usually it is at an angle when the neck is more
or less horizontal, its long axis being obliquely directed for-
wards and upwards ; but it becomes vertical as the head
and neck are raised or extended. It will be considered as
vertically placed, in order to facilitate description.
" It is, fundamentally, a dense cartilaginous box, made up
of several pieces which can move on each other ; and it is
composed, intrinsically, of cartilages, muscles, Hgaments,
mucous membrane, nerves, and bloodvessels. The latter
need not be alluded to here.

CARTILAGES.

The cartilages wliich constitute the framework of the
larynx are five in number— the Thyroid, Cricoid, two
Arytcenoid, and the Epiglottis.

There are also two pairs of rudimentary cartilages, only
one pair of which— the cartilages of Santorini— may be
noticed in this place.

1. Thyeoid Caetilage {Gartilago thyroidea), Figs. 1, e ;
2,dd; 2,d e.— This is the largest piece in the larynx, form-
ing, as it does, the two sides and a portion of the fi'ont of
the box. Its middle part, the body (Fig. 3, e), is situated
in front, and is a short, narrow, protuberant mass, known in
human anatomy as Adam's apple {pomum Adami) ; it is
usually bony in old horses. It suddenly expands in bend-
ing round, to form the sides or wings (aice) of the larynx,
each of which is a wide, somewhat quadrangular plate,
slio-htly convex externally, concave internally, extending
the whole length, from before to behind, of the organ.
Owino- to its shape, a somewhat large triangular space is
left between the wings in front, which is filled m by an
elastic membrane or ligament, the_ middle crico-thyroid
{ligcmentum crico-thyroideum medimn).

Anatomy and Physiology of the Larynx. 75.

2. Cricoid Cartilage (Cartilago cricoidea), Figs. 1, e ;
2,dd; S,e cZ.— Next in size to the foregoing, this cartilage,
forms a complete ring, like a finger-ring with a very wide
bezel, the narrow portion being in front and around the

Fig. 2. — posterior view of the larynx.

a a, ArytsBnoid muscle— constrictor or adductor of the larynx ; b h,
Jr-ostenor cnco-arytienoid muscles— dilators or abductors of the larynx ;
cc, bantormi's cartilages, appendages of the aryttenoid cartilages : d d,
Posterior borders of the thyroid cartilage ; e e, Epiglottis ; /, Entrance
to tne Jarynx ; g g, Process! musculares of the arytsenoid cartilages.

Sides, below the thyroid cartilage, and next to the first ring
of the trachea; the widely-expanded portion filling up the
space between the wings of the latter behind, and com-
pleting the laryngeal box. On the back, in the middle of

76 Roaring in Horses.

the bezel, is a vertical ridge (Fig. 4>, g). The cricoid and
thyroid 'Cartilages are united by two lateral ligaments {liga-
menta crico-thyroidea later alia), which are in reality por-
tions of the middle crico-thyroid ligament; they are fixed
to the margin of the cricoid cartilage by one border, like the
middle ligament ; their upper border, inside the wings of
the thyroid cartilage, being thin and free, form the " true
vocal cords " {chorda} vocales), or, as they are sometimes
termed, the inferior thyro-arytffinoid ligaments {ligamenta
thyro - arytcenoidea inferiora), from their fibres arising
inside the body of the thyroid cartilage and passing back-
wards to the base of the arytienoid cartilages. Some fibres
also passing in the same direction as these, form a superior
ligament on each side (ligamenta thyro - arytcenoidea
superiora), to form the " vocal bands," which have also been
named the " false vocal cords." The lower border of the
cricoid cartilage is attached to the upper ring of the trachea
by a ligament, the crico-tracheal [ligamentwm crico-tra-
clieale).

The thyroid and cricoid cartilages move upon each other
by two true joints, situated on each side behind, the move-
ments varying the tension of the vocal cords.

3. ARTTiENom Cartilages {Gartilagines arytcenoidecB),
Figs. 1, a a; 2, c c; 3, 6 c; 4, 6 6.— These two cartilages-
very important in relation to the affection with which we
are now dealing— surmount the bezel portion of the cricoid
cartilage, prolonging the depth of the larynx behind, and
curving backwards at their upper margin, where they come
in apposition, forming a ewer-like projection; hence their
name. In shape each cartilage is irregularly pyramidal,
being somewhat like a prism, or three-sided pyramid, m
fact ; there are two angles ,at the base, the surface, of which
has 'a shallow concave surface where it forms a true
ioint with the cricoid cartilage. The anterior angle is long
and narrow, and projects forward into the cavity ot the
larynx ; from its receiving the insertion of the vocal cord.

Anatomy and Physiology of the Larynx. 77

this angle is named the processus vocalis (Fig. 3, 3). The
posterior angle is thick and blunt, and, owing to its receiving
the insertion of the powerful and important dilator muscle
of the larynx, it is termed the processus muscvZaris (Figs.
l,ii; 2, g g ; 4<,ff). The apex of each arytsenoid carti-
lage, and which is bent backwards to form a lip, is actually
made up of a thin piece of elastic cartilage, named the
" cartilage of Santorini " {capitulum Santorini), and cor-
responds to the cornicula laryngis of man. The horse
has extremely rudimentary " cartilages of Wrisberg."

The two cartilages meet in the middle line, where they
are united by a ligament, the transverse arytasnoid (ligamen-
tum arytcenoideum transversum) , and at their base they
are united to the cricoid cartilage by another ligament
(ligamentum crico-arytmnoideum), which forms the cap-
sule of the joint existing between the cricoid and arytEenoid
cartilages. This joint allows of rather extensive movement ;
the two arytsenoids, when acted upon by their abductor
muscles, swinging outwards and upwards from the middle,
around a vertical axis, like a double door hinged in the
centre : so that the vocal cord on each side, attached to the
lower angle of the arytsenoid cartilage, is pulled in the same
direction, and the opening in the larynx between the car-
tilages and cords is thereby greatly increased. This move-
ment we shall have to refer to frequently.

4. Epiglottis (Figs. 1, d; 2, e ef; 8, g; 4, a).— This is a
very elastic piece, placed above the thyroid cartilage, in
shape like a sage leaf, and, except during the act of swallow-
ing, it is curved forward towards the mouth. It circum-
scribes the entrance to the larynx in front, and during swal-
lowing of food or water its flexibility allows it to be pushed
back over the aperture like a lid, so as to close it hermetically,
and thus prevent any foreign matter obtaining admission
during the accomplishment of this act. When the act is
completed, the resiliency of the cartilage, together with the
contraction of a muscle connecting it with the hyoid bonfe

78

Roaring in Horses.

of the tongue, brings it to its erect position again. Its base
is attached to the middle part of the inner surface of the
thyroid cartilage by elastic fibres, which form a ligament —
the thyro-epiglottic— and the lower part of its sides is
connected with the arytenoid cartilages behind, by a fold of
mucous membrane on each side — the ary-epiglottidean
fold (Figs. 1,/; 3, j) — which contains two little bodies, the
■cuneiform cartilages, or cartilages of Wrisherg. It is also
connected with the tongue by three ligaments.

On the outer side of each ary-epiglottidean fold, between
it and the thyroid cartilage, is a depression called the
-" pyriform sinus," or " hyoid fossa," containing a thin mucus
which is secreted by a row of glands lying on its floor. The
sinus on each side meets its fellow behind the arytsenoid
cartilages to form one channel, which passes into the
oesophagus.

: In young animals the cartilages of the larynx are very
flexible, but with age they become rigid, and all, except the
epiglottis, have a tendency to assume a bony density.

Muscles.

The intrinsic muscles of the larynx are divided into two
-sets, according to their functions : dilators and constrictors,
-or. abductors and adductors.

Dilator or Abductor Muscles (Figs. 1, j ; 2, &).—
These consist of only one pair, the posterior crico-aryttenoid
muscles {crico-arytcenoidei postici). As their name implies,
they dilate the opening in the larynx by abducting or
separating the vocal cords from each other. They are the
inspiratory, or rather respiratory muscles of this organ, and
are by far the most important with regard to Roaring.
They are the most powerful of all the laryngeal muscles,
and their full functional vigour is absolutely essential to
perfect respiration.

Arisino- from the bezel surface of the cricoid carti-
lage, and°separated from each other by the vertical ridge

Anatomy and Physiology of the Larynx. 79

which divides it into two portions, the fibres of each muscle
are numerous, and constitute a plump, deep-red, fleshy
mass; they pass obliquely upwards and outwards, and,
becoming more or less tendinous, especially the fibres
towards the outer border, they all converge towards the
processus muscularis of the aryttenoid cartilage (Figs. 1, i ;
2, g), into which they are inserted, and on which they act.
When the two muscles contract (in a healthy condition they
always do so together), they act as levers of the first order
in drawing the arytaenoids backwards and outwards, causing
them to swing on the cricoid cartilage in the manner
already described, and in this way widening the glottis.
The extent of this action will depend upon the require-
ments of inspiration ; but as their special function is to
maintain the glottal aperture always more or less open
(except during swallowing, coughing, and some other acts
of brief duration), these abductor muscles have an un-
ceasing, and therefore fatiguing duty, which demands not
only that they should be larger and more vigorous than the
other muscles of the larynx, but that they be reinforced by
tendinous fibres to relieve them from undue strain in the
perpetual efforts of elevating the cartilages at rather a
mechanical disadvantage.

The Adductor Muscles. — These may be considered as
the antagonistic muscles of those just described, inasmuch as
they, in contracting, close the glottis. They consist of four
pairs, which are named as follows : thyroid-arytanoid, lateral
crico-arytsenoid, crico-thyroid, and arytfenoideus. Of these,
the most active in approximating the vocal cords, and so
closing the rima glottidis, are the aryta^noidei and crico-
arytsenoidei laterales muscles. The former (Fig. 2, a a) are
the smallest of the laryngeal muscles, and situated behind
the arytsenoid cartilages; their action is to bring these
together, and so to diminish the space between them— the
pars respiratoria (Fig. 5, C)— in the larynx. The crico-
arytsenoidei laterales pass, on each side, from the cricoid

80

Roaring in Horses.

cartilage to the processi musculares of the arytenoid carti-
lages, and when they contract they rotate these downward
and inward, bringing the processi vocales of these cartilages
nearer each other, and so carrying the vocal cords into appo-
sition, closing the space designated the pars vocales (Fig. 5,
C). In this they are assisted by the other two pairs of
muscles, which, however, are more concerned perhaps in
the production of the voice, by shortening and elongating
the vocal cords. As the study of the voice has no place in
the subject we are now discussing, further description of
these muscles is unnecessary.

Ligaments. — We have already referred to these.
Mucous Membrane, — The larynx is lined by mucous
membrane, which is continuous with that of the mouth and
its wide termination, the pharynx. The same membrane also
lines the trachea and bronchial tubes, and in the larynx itself
forms on each side the pouch or sac known as the " vocal
ventricle sac," "lateral sinus" {sacculus laryngis, sinus
lateralis), or " Morgagni's ventricle " ; it likewise constitutes
a smaller cavity at the base of the epiglottis, above the
origin of the vocal cord at the thyroid cartilage called the
"middle sinus" or "sac" (sacculus laryngealis), or "sub-
epiglottic sinus." Another sinus— the " sub-arytsenoid "—is
found at the crico-arytffinoid joints. It is covered with
squamous epithehum at its upper part, below this by
ciliated epithelium, and is abundantly supplied with mucus-
secreting (muciparous) glands, which are most abundant
in the vocal ventricles, the ary-epiglottic folds, and the
epiglottis, but none are found in the mucous membrane
covering the vocal cords. The membrane varies in thick-
ness in different parts of the laryngeal cavity, and the
sub-mucous connective tissue is also variable in quantit,y,
being abundant in some situations and very scanty in
others. For instance, the membrane is thinnest and has
least connective tissue, and is, consequently, most adherent,
on the vocal cords and lower part of the aryta^noid carti-

Anatomy and Physiology of the Larynx. 81

lages ; bub it is thickest, most vascular, and loosest, having
much connective tissue, on the ary - epiglottic folds,
ventricular bands, at the lower part of the epiglottis, and
in the ventricles. These parts are, therefore, most liable to
inflammation and rapid oedema — a fact to be remembered
when considering the surgery and pathology of the organ.

It should also be noted, that between the mucous
membrane and the cartilages is a continuous layer of elastic
fibrous tissue, which strengthens the larynx and assists the
movements of the different pieces that compose it.

Nerves. — The nerves supplying the lar3nix are derived
from the tenth cranial or vagus nerve — the pneumo-
gastric, nervus vagus, or par vagum — which more especially
ministers to the functions of organic life. This arises by a
number of rootlets from the sides of the medulla oblongata,
in two portions or nerves, one of which passes down each
side of the neck, after giving off branches to probably all
the muscles of the pharynx and its mucous membrane ;
and a branch — the superior laryngeal nerve — that endows
the mucous membrane of the under surface of the
epiglottis, the glottis, and the greater part of the larynx,
with acute sensation, while sending supposed motor fibres
to one muscle of that organ, the crico-thyroid. In the
furrow on each side of the neck, immediately above the
trachea, the nerve accompanies the carotid artery, and
passing into the chest, detaches most important branches to
the chief viscera in that cavity, as well as to some in the
abdomen.

The branches which require most notice here are those
it gives to the larynx. They are the superior laryngeal
and the inferior laryngeal nerves.

Superior Laryngeal Nerves.— There are two of these,
one for each side of the larynx. Each is derived from its
respective pneumogastric trunk, which it leaves soon after
the latter has emerged from the cranium ; it passes to the
larynx, where it is distributed, as already mentioned, to the

6

82

Roaring in Horses.

mucous membrane, to endow this with sensation, and to the
crico-thyroid muscle, which it stimulates to contraction,
according to physiologists. But veterinary anatomists, and
especially Gllnther, Franck, and Mceller, maintain that the
motor fibres are derived from the first cervical nerve.
Moeller satisfied himself of this by experimenting on horses
while they were in a state of narcosis. He exposed the
crico-thyroid muscle and laid bare the first cervical nerve,
and in stimulating the latter he found the former to con-
tract promptly and energetically ; when the finger was
passed into the larynx through an opening in the middle
crico-thyroid ligament, the contraction of the muscle and
approximation of the cricoid to the thyroid cartilage could
be distinctly felt every time the nerve was excited. When
the superior laryngeal nerve was stimulated, this muscle,
as well as the other muscles of the larynx, was quite
unaffected. It was clearly demonstrated that, in the horse
at least, the muscle receives its motor fibres from the first
cervical nerve, and not from the superior laryngeal.
Moeller also concluded from his experiments that the
latter nerve supplied, in addition to sensory filaments to
the larynx, trophic or nutrient filaments to the muscles.
In one experiment on a middle-aged horse in which respira-
tion was healthy, he divided the superior laryngeal of one
side, immediately before it entered the larynx. The animal
did not exhibit any signs of disturbance or Koaring subse-
quently, and when it was killed, six weeks afterwards, the
whole of the laryngeal muscles on the operated side were
in a state of marked atrophy, evidenced by their smaller
size and pallor. The other horse, also middle-aged, was free
from Bearing until shortly before it was killed, more than
four months after the operation, when advanced atrophy of
the muscles on the same side was noted. In the first case,
the superior laryngeal nerve was found to have undergone
degeneration, but the recurrent did not show any change.
Inferior Laryngeal or Recurrent Nerves.— These

Anatomy and Physiology of tlte Larynx. 83

are also two in number, one on each side, right and left ;
they are given off from the pneumogastric nerve within the
chest, and in consequence of their having to pass upwjards
towards the head, in order to reach the larynx, they have
been designated " recurrent" nerves. They are chiefly motor
nerves, and supply all the muscles of the larynx, dilators
and constrictors, with the exception of the crico-thyroid.
We will consider each nerve separately, with regard to its
origin ; as upon this consideration will depend our arriving
at a correct notion of the proximate cause of Roaring, and,
indeed, of the nature of the morbid condition which
occasions it.

Right Recurrent or Inferior Laryngeal Nerve. — This
nerve arises from the main trunk in the right side of the
chest, at the posterior border of the first rib, and at the origin
of the dorso-cervical artery, round which it bends to get
near the trachea. Along the lower surface of this it passes
forwards until it reaches the base of the neck, where it
places itself beside, but below, the carotid artery, with
which it proceeds up the right furrow of the neck, giving
twigs to the mucous membrane and muscular fibres of the
trachea, as well as to the oesophagus, and at the larynx
sends its terminal filaments to the muscles on the right side
of that organ, with the exception already alluded to. Its
relations are comparatively few, when compared with its
fellow on the left side, as it is only connected with nerves
of the heart and the middle cervical ganglion of the
sympathetic nerve.

Left Recurrent or Inferior Laryngeal Nerve.— The
peculiarities m the origin and relations of this nerve
deserve close attention. It is not detached from the vagus
nerve, like the right one, at the first rib, but as far back as
the base of the heart, at the anterior border of the posterior
aorta, round which it turns to get between it and the left
bronchus, which is close to the great artery, and where it is
related to, the bronchial lymxthatic glands. The nerve is

6—2

I

84) Roaring in Horses.

directed backwards and slightly upwards, bending from left
to rio-ht round the posterior surface of the lig amentum arteri-
osus', and passing over the internal face of the pulmonary
artery ; then it proceeds upwards, inwards, and forwards, to
the lower surface of the trachea, to which it is attached by
connective tissue, and there it is also bridged over by an ex-
pansion of the endo-thoracic fascia, which is connected with
the pericardium. In passing along the trachea, the nerve
gradually ascends to gain the left side of that tube, above,
but very close to the tracheal lyrfiphatic glands. The re-
lations of the nerve to lymphatic glands and to the pleural
membrane are very intimate ; as from its origin until it reaches
the trachea it is placed between the pleura and pericardmm,
and when crossing the pulmonary artery it is enveloped m
a quantity of connective tissue that supports the bronchial
lymphatic glands, while behind the aorta it gives off numer-
ous fibres that may be traced to the surface of these
glands.

Before leaving the bronchial glands, the nerve is con-
stantly found intimately related to a median branch of the
inferior cervical ganglion, and this relationship is mam-
tained to within two or three inches from this ganghon;
some of the fibres of this sympathetic branch also pass to
the surface of the glands. It is also to be noted that the
ano-le separating this nerve from the vagus nerve is partly
occupied by nerve fibres, which pass from one nerve to the
other

Givino- off twigs to the trachea and oesophagus, the nerve
passes out of the chest and up the left side of i-
the same manner as the right nerve, and is ultimately dis-
tributed to all the left laryngeal muscles except the crico-

'^ir^l thus be seen that the left recurrent nerve differs
most materially from the right, not only m its^ peculiar
delations with the pleural membrane and its fascia m
mm diate proximity to most important organs (lungs and

Anatomy and Physiology of the Larynx. 85

heart) and bloodvessels, as well as lymphatic glands, but
also in its greater length. The influence of these anatomical
.pecuharities in the production of Bearing will be fully dealt
with hereafter.

BischofF, Schech, Chauveau (for the horse), and others,
have shown that the spinal accessory nerve gives motor
fibres to the recurrent nerve, which would go to prove that
the two nerves are identical in their function, a circumstance
which should also be remembered in discussing the origin
of Roaring.

The Larynx as a Whole.

Having considered the different parts of the larynx, we
may now view it as a whole.

We have remarked that it is placed between the branches
of the lower jaw, towards their angle, at the upper part of
the windpipe, and the back part of the mouth or pharynx,
its upper opening looking into that cavity, in which it is
suspended from the base of the cranium by the long pro-
cesses or horns of the hyoid bone. Immediately behind or
above it is the oesophagus, which is attached to the middle
ridge on the bezel of the cricoid cartilage.

The cavity of the larynx (cavum laryngis) is described
as divided into three spaces or portions — upper, lower, and
middle ; it opens into the floOr of the pharyngeal sac by its
upper space or supra-glottic portion {aditus ad laryngeum,
introitus laryngis, Figs. 1, 3). This large opening is in shape
that of an equilateral triangle (Fig. 1, g), the base being the
epiglottis in front, while the apex is formed by the two ary-
tsenoid cartilages, and the sides by the ary-epiglottic folds
of mucous membrane (plicoi ary-epiglotticce). It must be
noted that the form and dimensions of the larynx often
differ considerably, even in animals of the same size. In
a medium-sized horse, the length of this triangular space
.in the passive condition is from If to 2i inches, and width
of base . 11 to 1 J inch. Its depth is about 1^ inch. The

86

Roaring in Horses.

lower opening, or infra-glottic division (Fig. 3, 4), is
formed by the cricoid cartilage, which circumscribes it ; it
is continuous with the tracheal lumen, and measures 1|- inch,

Fig. 3.— iKTEpiOR of left side of the horse's lakynx.
■ 1 Supra-glottic or upper portion of the laryngeal cavity. 2, 3, Glottis
or Middle division. 4, Sub-glottic or lower portion. ^; Commencenient
of the jMrs vocale^. 3, Commencement of respiratoria «> Jy[o^^
^cartilage. &, Aryteenoid cartilage, with c, its appendix--the car* 1^^^^^^
^f Santorini'. Posterior or bezel portion of he cricoid cartilage
..Anterior portion of cricoid cartilage. /.Vocal ^o^-ji with entranc^^
to vocal ventricle {sacculus laryngis) immediately above it. /> \otti8^
:h, Basal process of epiglottis, i, Sub-epiglottic smus. j, Ar^-epiglottic
f <;id of mucous membrane, k, Vocal band above the ventricle.

the rings of the trachea measuring from 1^ to 2 inches m

diameter. .

^ The middle or glottic division— the glottis, gloit%s vera,

or, better, rima glottidis—is the most important of the

Anatomy and Physiology of the Larynx. 87

three ; it is about the centre of the cavity of the larynx,
and is formed by the vocal cords on each side in front, and

Fig. 4. — view of the entrance to the horse's laryn?c, seen

FROM the mouth, THE VOCAL CORDS BEING IN THE POSITION
THEY OCCUPY IN TRANQUIL RESPIRATION (EXPIRATION).

ct, Epiglottis, pointing towards the mouth, h b, Aryttenoid car-
riages, c c, Vocal cords thrown rather into relief to make them more
distinct, d, Glottis or opening between the vocal cords into the trachea.
e e, Ventricles of the larynx leading to the vocal pouches or Morgagni's
ventricles, and surmounted by the false vocal cords or bands on which
the letters are placed. //, Processi musculares or angles of the ary-
tsenoid cartilages into which the dilator muscles of the larynx are in-
serted, g, Ridge of the cricoid cartilage.

the bases of the arytsenoid cartilages on each side behind
(Figs. 1, g; 3, 3; 5, CD). The space between the vocal

88

Roaring in Horses.

cords is designated the glottis vocalis, pars vocales, or inter-
ligamentous portion ; that between the arytienoid cartilages,
the glottis resiiiratoria, pars respiratoria, or inter-carti-
laginous portion. The entire space, in what is termed the
" cadaveric position " of cords and cartilages, is in shape
something like a lance-head. It varies considerably in
shape and dimensions during life, however, being that part of
the larynx in whicH movement chiefly takes place, especially in
respiration, the chink through which the air passes having
been appropriately termed "the portal of the breath of life."
It offers for consideration, on each side, the vocal cords,
vocal bands, and aryta3noid cartilages, with the lateral
ventricles. Its narrowest part in front is limited by the
body of the thyroid cartilage and the origin of the vocal
cords therefrom, while its widest part behind is formed by
the cricoid cartilage.

The " vocal cords," or inferior thyro-arytsenoid ligaments,
which extend nearly half the length of the glottis, are two
bands or ledges, paler in colour than the adjacent parts,
and composed of yellow elastic tissue, covered with thin
mucous membrane ; they are capable of considerable elonga-
tion and retraction, according to the movements of the
arytenoid cartilages. Their surface is somewhat oblique,
the free border being slightly higher than the fixed one,
which is thicker ; this allows their thin free margins to meet
more easily and closely in neighing, coughing, and other
acts in .which the glottis has to be closed.

The "ventricular" or "vocal bands," situated above the vocal
cords, are longitudinal folds of mucous membrane enclosing
a small quantity of fibrous tissue, and containing numerous
glands, the secretion of which, mucus, serves to moisten the
vocal cords. They arise from the thyroid cartilage, and are
inserted into the anterior surface of the arytsenoid carti-
lages ; they can be closely approximated, so as to separate
the upper portion of the larynx from the two lower ones,
and thus form a narrow tube with a closed bottom. • This

Anatomy and Physiology of the Larynx. 89

Fig. 5.— diagram of a transverse section of the larynx of a

MEDIUM-SIZED HORSE, THROUGH THE THYROID, CRICOID, AND
ARYTENOID CARTILAGES AND VENTRICLES, IMMEDIATELY ABOVE
THE VOCAL CORDS, WITH THE MEASUREMENTS OF THESE PARTS.

A Front of larynx, or Pomum Adami of thyroid cartilage. B.
Posterior part of larynx. C, Pars vocales. D, Pars respiratoria. 1
ihyroid cartilage. 2, 3, Left and right aryttenoid cartilages. 4, Bezel
of cricoid cartilage. 5 5, Yocal cords— each ^ to If inch long by
I inch at widest part. 6 6, Morgagni's ventricles-from dotted line
L'^^f^ ""f-i^y * 'o'^^.x.'^i'^^ ^' Iiisertion of vocal cords into ary-
Q w'i?.^''w 8, Width of glottis between the latter points | inch.
I'i^h in i^'^t'" S° arytenoid cartilages at their posterior part
i ?1 f each arytenoid cartilage U inch, thickness

lLt!rV 11, Entire length of glottis 3f inches. 12, Length (trans-
verse) of cricoid cartilage 2 inches, thickness 13, Length of thvroid

wYn? of thf t^'^ ^ ^'l^^- Di«tance'bet JeeXch

wing of the thyroid cartilage 3 inches. 15, Mucous membrane lining
the cricoid cartilage. 16 16 16 16, Muscles knd connective tissue ^

90 Roaring in Horses.

approximation occurs during swallowing, and in some other
musculai- movements in this region.

The " ventricles of the larynx " or " Morgagni's ventricles"
(Figs. ], c; 3, /c; 4, ee; 5,6') are two somewhat capacious
sacs or pouches of mucous membrane, one on each side of
the cavity of the organ, the entrance to them being rather
wide and Ivinsf between the ventricular bands and vocal
cords. These sacs are oblong in shape, and pass out between
the upper and lower portions of the thyro-arytffinoid muscles.
They extend only a short distance forward towards the
origin of the vocal cords, but dip down to the base of these,
and are continued behind the processi vocales of the arytae-
noid cartilages. They are very dilatable, have numerous
mucous glands, and permit free movements and vibrations
of the vocal cords.

Physiology of the Larynx.
The essential function of the horse's larynx is related to
respiration, and in a lesser degree to deglutition, as well as
to coughing, sneezing, defecation, and other expulsive
efforts of a voluntary or reflex kind ; it is rarely required
for phonation or voice-production, which is one of its chief

uses in mankind.

It has been already stated that the larynx is always more
or less open, for the passage of air to and from the lungs
except during the acts above-mentioned, the degree _ of
patency depending upon the inspiratory effort. Dm-mg
respiration, the aryta^noid cartilages and vocal cords move
in a combined and rhythmical manner. In inspiration, by
the action of the abductor (posterior crico-arytsenoid)
muscles, we have seen that these cartilages are drawn
upwards and outwards, the cords, being attached to their
anterior extremity, passing in the same direction towards
the sides of the thyroid cartilage, against which they le
flat when inspiration is deep. By this movemeut, the
middle space (rima glotticlis) is enlarged to a degree

Anatomy and Physiology of the Larynx,

91

corresponding to the elevation of the aryt£enoid carti-
lages, and for this reason Ludwig has termed them " posi^-
tion cartilages" {Stellkno7'pel). The larger the volume

Fig. 6.— view of the horse's larynx during laboured inspira-
tion, SEEN FROM THE MOUTH.

r^^A^ ^""^ arytsenoid cartilages, b b, being drawn np-

of air required, the more space must be allowed for its
entrance, and the width of this space will depend upon the
energy and activity of the abductor or dilator muscles as
they may be termed, which elevate these cartilages. When

92 . Roaring in Horses.

the muscles are healthy and vigorous, the space between
the vocal cords at their junction with the arytenoid car-
tilages is two or three times greater than in the passive state
of these muscles (Fig. 6, d) ; should a simultaneous con-
traction of the ary-epiglottic muscles take place, the upper
compartment of the larynx will be also enlarged.

In expiration, the abductor muscles are relaxed, and the
arytjenoid cartilages fall downwards and inwards by a kmd
of elastic recoil, aided, no doubt, by the lateral crico-thyroid
and thyro-aryta3noid muscles, which approximate the
arytjenoid cartilages and vocal cords to each other, causmg
them to move towards the centre of the laryngeal cavity
(Fig. 4). But unless under the special circumstances
already referred to, the adductor muscles do not brmg
these parts into contact, a space always exisiing between
them during expiration for the passing out of air from the
lungs, and which meets with but little resistance from the
relaxed vocal cords, as it easily lifts these aside. This
space is somewhat less than in .expiration, in what is termed
the " cadaveric position" of the vocal cords and arytsenoid
cartilages— that is, the position in which we find them after
death. The function of these adductor muscles of the
larynx is, therefore, not very important in respiration, and
they only act as antagonists of the dilators on certam
occasions. For instance, it has been stated as a clmical
fact, that if inspiration be unduly forced the adductors are
brought into play, and the glottis may then be narrowed
rather than increased. Though they are the vocal muscles
in man, yet in the horse they may be looked upon as con-
stituting, in conjunction with the muscles which close the
supra-glottic portion, a sphincter or ring muscle for the
larynx such as is found around the mouth, eyes, and other
.openings ; but here the opening is maintained always patent
.by the abductors, just as the nostrils are by their dilator
muscles, though they are also provided with a sphincter or
closing muscle. There is this further resemblance between

Anatomy and Physiology of the Larynx. 93

the nostrils and the larynx, that the widening and con-,
traction of both occur synchronously in inspiration and
expiration.

From what has just been stated, it will be understood
that, in order to have respiration performed in a perfect
manner under all conditions of active exertion, the dilator
or abductor muscles must be in the healthiest condition
possible. Various causes may impair the vigour of the
laryngeal muscles, but the chief is diminished supply or
total loss of nerve-stimulus to them ; and how this is effected
can best be made clear by briefly describing what is known
with regard to the innervation of the larynx. With respect
to this subject, however, it must be stated that notwith-
standing the most careful investigations of physiologists
and pathologists for many years, there are several important
points yet to be settled.

When treating of the construction of the horse's larj^nx,
the distribution of the nerves was described, these being the
superior and inferior laryngeal, and a portion of the first
cervical nerve. In elucidating the functions of the laryn-
geal nerves, the way was led by Vesalius, Haller, Majendie,
and Legallois. But it may be remarked that the Greek
physician, Galen, who lived about the middle of the second
century of our era, observed the diflficulty pigs experienced
in breathing, and their inability to scream, after division of
the recurrent nerves ; and Riolan, in 1618, was also aware
of these phenomena as a result of such an operation. But
it was reserved for Legallois, in 1812, to determine the full
significance of section of this nerve on the larynx, and
consequently on respiration, by experiments on young
dogs, cats, and rabbits. He found that all the muscles,
with the exception of the crico- thyroid, received their
motor filaments from the recurrent nerve on each side.
Majendie likewise described the chief points in the inner-
vation of the larynx, though he erred in stating that the
recurrent only supplied the dilator muscle (posterior crico-

94

Roaring in Horses.

arytsenoid). Bischoff afterwards demonstrated that motor
filaments in this nerve were derived from the spinal acces-
sory nerve.

With the superior laryngeal nerve we are not now so
much concerned, and may therefore merely mention that it
is chiefly a sensory nerve, endowing the larynx with sensa-
tion ; it also gives fibres to the crico-thyroid muscle, which,
according to some physiologists, are motor, and therefore
stimulate that muscle to contraction, but which, according
to Moeller, are trophic filaments, and are concerned in the
nutrition of all the laryngeal muscles.
, Stimulation of the superior laryngeal nerves is stated to
cause paralysis of the crico-thyroid muscles and slowing of
the respiration; but Moeller satisfied himself that the muscles
remained unaffected under such stimulus. However this
may be, it is certain that division of the nerves deprives the
larynx of sensibility; so that saliva and particles of food pass
through it into the trachea and lungs without causing reflex
contraction of the glottis, or coughing, and this leads to the
production of " traumatic pneumonia."

Experimental stimulation of the recurrent nerves pro-
duces spasm of the glottis, while section of them paralyses
all the muscles they supply. When stimulation is applied
to them, after the larynx has been exposed for observation,
the effect is very perceptible. As soon as the electrodes are
brought into contact with the central stump of the divided
nerve, or with the peripheral end of the vagus, the arytsenoid
cartilages begin to move convulsively; and by inserting the
finger into the lateral ventricle, one is soon convinced
of the energetic contraction of the lateral crico-ar3^tiEnoidei
^nd thyro-aryt^enoidei muscles, the crico-thyroid muscles
remaining passive. The glottis is narrowed, and at
every inspiration the vocal cords approximate con-
siderably, as do also the arytenoid cartilages, Avhile
during expiration they are separated from each other.
Hence the inspiration, especially in .young animals whose
glottis respiratoria is narrow, is difficult and noisy, while

Anatomy and Physiology of the Larynx. 95

expiration is easily effected. After a few days, however, the
animals experimented upon (carnivora) become tranquil,
respire with less effort, and the passive vibratory movements
of the vocal cords diminish. But even after a considerable
time, if the creatures are excited, they are seized with
severe dyspnoea, which disappears only when they have
become -quiet again.

In this condition, also, owing to paralysis of the laryngeal
muscles, foreign matters are likely to enter the trachea,
because of the paralysis rendering the initial stage in the act'
of swallowing more difficult in the oesophageal region.
Hence broncho-pneumonia may ensue.^

It is, therefore, a well-established fact that division of
both pneumogastric nerves, or their recurrent branches, is
often very quicldy followed by fatal results, especially in
young animals. But in old ones, section of the recurrent
is not generally fatal, and even that of both pneumogastric
nerves is not always so ; when it does occur, it only ensues
slowly. This difference is probably because the laryngeal
cartilages are very elastic in young creatures, and in yield-
ing permit the glottis to be closed by the excess of external
atmospheric pressure in inspiration, over that of the rarified
air within the trachea ; and though in expiration the glottis
returns to its original size, yet these animals will quickly die
of suffocation, unless tracheotomy be performed upon them.

In old animals, on the contrary, the rigidity and pro-
minence of the arytenoid cartilages prevents the glottis
from becoming completely closed by the atmospheric
pressure; for even when all the muscles are paralysed,
the posterior portion of the pars respiratoria remains openi
and through this sufficient air can be drawn so long as
the creatures remain tranquil. °

Schech's experiments on dogs, made in 1873,2 show that

2nVSn:;ol1 ftr- Human Physiology,"

96 Roaring in Horses,

after division of both dilator muscles, the vocal cords pass
beyond the ordinary position inwards, towards the middle
line, and lose the power of separating on inspiration. But
the full median position and continuous dyspnoea do not
immediately appear, and the power of narrowing the glottis,
as well as the vibratory function of the vocal cords, is undis.
turbed; so that the voice or bark remains intact. As a
rule, the operation was immediately followed by consider-
able dyspnoea, but this soon subsided; and Schech was of
opinion that it was the result of the constriction of the
glottis, which takes place at once after the operation, and
which, again, necessitates deeper and more frequent respira-
tions. In this way there arises a difference of tension in the
columns of air above and below the glottis, the vocal cords
approach each other still closer, and thus the entrance of
air is yet more impeded. The abatement of the dyspnoea
soon after the operation on animals is due, on the one hand,
to the fact that the respiration gradually becomes quieter,
and, on the other, because the creature soon becomes accus-
tomed to the hindrance in breathing ; though it is assumed
that the constrictors of the glottis never exert their power
suddenly, but only after a certain period. The dyspnoea
and stridulous inspiration make their appearance, however,
immediately the animal attempts any sudden and violent

exertion. ^ . r

Such is the function of respiration and its mechanism, so tar
as the larynx is concerned ; and it is necessary to bear these
details in memory while studying the pathology of Roaring,
and especially the part the recurrent nerve assumes m rela-
tion to its muscles. It is also necessary to remember that
conclusions arrived at from experiments on creatures other
than the horse cannot always be made apphcable to that
animal with certainty. Exner,i Mandelstamm."^ and others,
for instance, have maintained that in the distribution of the
recurrent nerve there are frequent individual variations.

2 " Monatschft. f iir Ohrenbeilkunde," December, 1884.

Anatomy and Physiology of the Larynx. 97

Exner, experimenting on rabbits, concludes that, while the
external thyro-arytseuoid muscle is supplied chiefly, if not
exclusively, by the inferior or recurrent laryngeal nerve,
the internal thyro-arytajnoid derives a large share of its
innervation from the superior laryngeal nerve. He also
demonstrated the existence of a third or median laryngeal
nerve in the rabbit and dog, which is believed to be of great
motor importance. He and Mandelstamm, in rabbits, and
Weinzweig in man, have found that sometimes the re-
current nerve of one side sends fibres to that of the oppo-
site side. But we agree with Moeller, that further investi-
gations are needed to ascertain whether these variations
occur in the horse, and if they can be taken into account in
explaining the graduated differences in the respiratory
sounds which constitute Koaring. It appears certain, at
any rate, that the differences observed by Exner with
respect to the innervation of the dilator muscles in rabbits
— section of the recurrent nerves at one time leading to
degeneration of these muscles, at another time having no
such result — are not observed in horses ; for section of
these nerves in them always brings about more or less pro-
nounced atrophy of the muscles, according to the duration
of their paralysis.

The movements in the horse's larynx during respiration
can be readily noted when that organ is opened, as in the
operation for Eoaring— the opening being made through
the middle crico-thyroid ligament, and also through the
cricoid cartilage and first tracheal ring if necessary. It will
then be seen that in gentle breathing the action of the
laryngeal muscles is slight, the arytcTnoid cartilages and
vocal cords moving very little, the natural tension of the
dilator muscles ensuring sufficient width of the glottis. In
deep, forcible respiration, however, these muscles are most
active in effecting dilatation of the upper and middle
portions of the larynx, by their traction on the arytenoid
cartilages, as already described. As has been pointed out,

7

98 Roaring in Horses.

in tlie horse the adductor muscles of the larynx appear to
•act primarily during swallowing, coughing, and neighing ;
■the first is demonstrated by touching the vocal cords at their
junction with the aryt£enoid cartilages, when there occurs a
regular swallowing movement, succeeded by deep inspira-
tion and a sharp pushing of these cartilages towards the
middle line of the cavity. This movement was observed
by Giinther some years ago, and it is a valuable criterium
as to the existence of paralysis ; as the cartilage on the
affected side remains immovable during the act.

In this way, we also obtain at the same time an insight
into the act of swallowing. When it takes place the
entire larynx is raised, and its adductor muscles almost
completely close the upper compartment, while the ary-
epiglottic folds, as well as strong folds of the mucous mem-
brane of the pharyngeal cavity, cover it. This mode of
closure was first described by Moeller, who observed it m
a horse from the larynx of which both aryt«inoid cartdages
had been removed ; and it serves to explain how swallowing
can be safely accomplished a few days after one or both
of these cartilages have been extirpated.

Moeller has also pointed out that the epiglottis is not
passive during deglutition, as it is pushed over the folds ot
mucous membrane which occlude the supra-glottic space.
If the hand is introduced into the pharynx, and an act of de-
glutition is induced by touching the larynx, the movement
of the epiglottis can be distinctly felt, and if attempts are
made to seize it, it slips away from the fingers _ If the finger
is inserted into the larynx when the horse is drinlmig, at the
moment of swallowing it is energetically squeezed between
the two arytjenoid cartilages; this movement can also be seen.

As the result of experiment and observation on the horse
then we may accept it as a fact that the larynx is innervated
chiefly through the pneumogastric or vagus nerve, and m
such a manner that the sensory and trophical filaments are
supplied by the superior laryngeal nerves, and the motor
filaments from the spinal accessory and recurrent nerves.

CHAPTER VII.

PATHOLOGY AND COUESE OF CHEONIC EOAEING.

After what has been described of the anatomy and
physiology of the horse's larynx in the last chapter, there
wiU be less difficulty in understanding the nature of the
morbid alterations which occasion those disturbances in
breathing that chiefly manifest themselves by Roaring.

It is now nearly three-quarters of a century since the
characteristic changes that are observed in the larynxes of
horses which had been affected with chronic Roarin^ durino-
life were first alluded to. But, then, as we have seen when
reviewmg the history of the infirmity, the notices of these
changes were only casual and rare; and, though the appear-
ances are extremely strikmg, and should have received
serious attention,yet but little importance seems to have been
assigned to them, and their significance was lost amid the
many conjectures indulged in as to what was really the
cause of the noisy, and oftentimes distressed, respiration

PercivalUn 1824, saw some of the more marked of these
changes exactly as we now see them. "Another and a not
very uncommon cause of Roaring," he says, "is a wasting
or, m some instances, a total absorption of one or more of
the small muscles of the larynx. I have lately examined a

horse of Mr. J y's-a remarkable instance of it In his

larynx, upon the near side, the crico-aryta^noideus" posticus
was very pale and shrunk to half its original size the
crico-aryt.noideus lateralis, the thyro-aryt^^noideus,' and
the aryt.noideus, were altogether colourless, and sclrce'y

7-2

IQQ Roaring in Horses.

recognisable as muscles; but their antagonists upon the
other side were unusually red and strong. Now these
muscles, contracting in pairs, are all employed m ddatmg
(sic) the glottis; but if one set act by themselves, this orihce
is not only distorted, but actually diminished in dimension,
in consequence of the aryta3noid of the opposite side being
drawn over it. Thus it is, then, that Bearing is produced.
But the cause of these changes were beyond his comprehen-
sion, and the conjectures of others he deemed unworthy ol

'^^bTalterations in the larynx of a horse which had been
a Roarer to a severe degree for some time, is smgularly
striking when compared with a healthy arynx, and its
appearance is shown in the frontispiece to this work. The
horse from which this larynx was obtained was known o
have suffered for a long time from Roaring, and g^'eatly
distressed when much exerted. It will be ^een that the
left dilator muscle (posterior crico- arytenoid) has dis-
appeared, its place being occupied by some fat and connec-
tive tissue, and that the arytenoid cartilage -^f^^
muscle elevates in inspiration is lower than its ffow while
the aryta^noideus muscle above it has only a few fibres ot
muscular tissue left. The epiglottis, m .^^^
depression of the aryta^noid cartilage, is slightly mclmed to
the le t side. The dilator, as well as the aryta^noideu
mLct on the right side, is l-^lthy. ^d ^^^^^^^^
developed than in an unaffected larynx. The other mus^^^^^
on the left side offered the same appearance of JegenexaUo-
as the aryta^noideus, with the exception of the ciico
hyroideus' which was quite healthy and f-^V'-J^^
muscle it will be remembered, being supplied with mo oi
mientf by the spinal accessory nerve, the wasted muscles
by the inferior laryngeal or recurrent nerve.

The deformity in the larynx, due to this ^vastmg o the
muscles on its 4 side, is perhaps sti 1 ^^^^
look into its cavity. In consequence of the depiessi

Pathology and Course of Chronic Roaring. 101

the arytenoid cartilage, and its taking an oblique direction
inwards, the supra-glottic cavity is asymmetrical in shape,
and, instead of being oval, has become comma-shaped, and
therefore greatly diminished in size. The processus vocalis
of the cartilage, as well as the vocal cord attached to it (and
which is now flaccid), share in the depression to a corre-
sponding degree ; not only so, but they are much nearer the
middle line of the cavity than those of the right side. As
a result of this, the pars vocalis, and to some extent the
pars respiratoria, is narrower than we find it in the healthy
larynx: showing that, even after death, if the dilator
muscles are not wasted, they still possess sufficient tension
to prevent the arytasnoid cartilages falling so deeply into the
cavity of the larynx, as when they are weak or atrophied.
As a rule, the lining membrane and vocal cords are healthy,
and the cartilages themselves may or may not be ossified ;
but this is quite independent of Roaring,

These are the principal alterations found on the left side of
the larynges of horses which have been affected with chronic
Roaring to a serious degree. In all the autopsies which I
have made of such horses, I have never found any other
changes, strange to say ; while Professor Goubaux, of the
Alfort Veterinary School, has dissected sixty-five horses
which had been Roarers, and Leblanc, of Paris, sixty-one,
and both have found all the larynges affected with left-
sided muscular atrophy. I have already mentioned" that
Glinther was of opinion that this uni-lateral atrophy is
the cause of 96 per cent, of the cases of Roaring, and
I am inclined to place it still higher.

When the muscles of the right side are also involved
(bi-lateral paralysis), very few cases of which are recorded as
occurrmg in the horse, then the atrophy is said to be not
so marked in them.

In very rare instances, there is found disease of one or more
of the cartilages (perichondritis), contraction of the whole
laryngeal cavity (due to inflammatory processes in the

1'02 ■ Roaring in Horses.

mucous and submucous tissues), polypi, and other altera-
tions mentioned in a preceding chapter. These conditions
the veterinary surgeon who determines on operation for
the removal of Roaring should be prepared for, though
they are so extremely unusual.

The gross appearances which I have described as char-
acteristic of the morbid changes found in the larynges of
horses which were Roarers, belong to an advanced stage.
In this the muscles of the left side, with the exception of
the one which has a different nerve-supply, are wasted, but
the dilator or abductor muscle shows this more markedly
than the constrictors.

At an early stage, before the Roaring is very pronounced
or continuous, the left dilator appears to be alone affected ;
its colour being paler— the paleness being in proportion
to the wasting of the muscle-substance, which leaves the
sheath of this more apparent— and its texture softer than
that of the right muscle.

In this condition, there is only weakness (^^aresis) of the
left dilator muscle. At a more advanced stage, this muscle
has lost much of its convexity, is softer and paler, and
there are yellowish streaks of fatty tissue among its fibres,
especially towards its inner border— fat granules or ceUs
having taken the place of the muscle-substance. The con-
strictors on the same side now begin to manifest a similar,
thouo-h less advanced, change, and the left arytaenoid carti-
lao-e is on a lower level than the right. In some instances,
the dilator muscle is unequally involved in atrophy, the
change being limited to one or more portions of its substance,
the outer border of the muscle being evidently the last to
undergo degeneration. The constrictors are certamly the
last to suffer seriously.

The degenerative process may cease at any stage, or pass
on rapidly to the final one, in which all the muscle-sub-
stance of the affected muscles has disappeared; while the
corresponding muscles of the right side appear to have

Pathology and Coursd of GhroniG Roaring. 103

become much augmented m size and deeper in colour, they;
having undergone a kind of compensatory hypertrophy in
the efforts to perform the work of their vanished fellows.

It may be remarked that the changes which the atrophied
muscles of the larynx undergo are simply those observed in
other muscles as a result of prolonged inactivity, especially
due to loss of nerve-stimulus {neuropathic origin of.
atrophy).

That the atrophy is owing to defection of the left recur-
rent nerve, and not to disease of the muscles themselves
{myopathic origin), is supported by the strongest evidence.
In the first place, if chronic Eoaring were occasioned by
myopathic paralysis, we should find proof of it in the
appearance of the muscles, and particularly if it were due
to inflammation in them ; one of the results of this would
be an increase of the fibril sheaths (perymisinm), such as is
observed in chronic myositis. And, in the second place, we
should not have the muscles of the left side of the larynx
alone involved in nearly every case of Roaring, and those on
the right side not only perfectly healthy, but unusually
developed.

In cases of long-existing chronic Roaring, the left recur-
rent nerve and its filaments have become so wasted, that
little is left of them except their sheath ; and this, even, is
so attenuated that a most careful dissection is required to
find it : a circumstance that has led some investigators to
the conclusion that the nerve was congenitally absent. Of
course, this is not the case. Like the muscles, this nerve
undergoes, after a certain time, such degenerative changes
as other nerves are liable to from various causes ; the nerve-
sheath, then the axis-cylinder, becoming atrophied and
altered, the white substance of Schwann being sometimes
increased ; this change is coincident with a lighter colour of
the nerve, and diminution in its circumference, until it is
completely wasted.

This impHcation of the nerve in the morbid changes has

104j

Roaring in Horses.

strangely escaped the investigation of veterinary writers
until lately. For instance, Williams asserts that " dissec-
tions, have failed to discover any change in the nerve-trunk
itself, although the animals dissected have been confirmed
Roarers for years previous to their death. In the form of
disease involving the laryngeal muscles, which commonly
causes Roaring, there is no change in the nerve itself."^

The effect of these anatomical changes on the respiratory
act will be examined when we come to inquire into the
immediate cause of Roaring.

Course of Roaring.

Considering Roaring to be produced by morbid conditions
having a neuropathic origin, we will now glance at its course,
anatomically and clinically.

The course of the defect— as every experienced veterinary
surgeon and horseman knows— varies within wide limits,
sometimes proceeding rapidly from an almost imperceptible
sifflement to a screaming sound, with urgent dyspncea on
the horse being subjected to only moderate exertion. In
other instances, it increases slowly until it reaches a certain
degree, and then remains stationary for a long time— per-
haps for years, varying only slightly and temporarHy,
according to the condition of the animal or surroundmg
circumstances. In rare cases, the noise, after continuing in
a more or less notable degree for some time, spontaneously
disappears, and the horse is again sound, so far as its breath-
ino- is concerned. Of this there are many instances, but
perhaps the most remarkable is that of the race-horse
Bric^antine, one of the best of what were, in their time,
called the "Buccaneerids"-a rather renowned family. Her
own trainer vouched for the fact, which was otherwise well
known, that the mare began her racing career m a very
promising manner as a two-year old, but ran badly at a
Principles and Practice of Veterinary Medicine," pp. 509, 510.

1 "

Pathology and Course of Chronic Roaring. ' 105

July meeting at Newmarket, when she was probably unwell.
Immediately afterwards she was discovered to be a Roarer,
and continued so until the end of the following spring;
when it was found that the noise was gradually diminish-
ing, and it ultimately disappeared altogether, until at last
she was as sound as on the day she was foaled. After this
she won the Oaks, Ascot Gold Cup, and Hurstbourne Cup,
easily.

In the first class of cases, the whole of the muscles of the
left side of the larynx (always excepting, of course, the
crico-thyroid) are usually involved throughout their entire
structure, and the process of degeneration goes on rapidly in
them. In the second class, these muscles are not wholly
affected, their innervation being only weakened or partially
suspended. For we may conclude, judging from the appear-
ances presented by the left abductor muscle and one or two
of the adductors, that individual fibres of the left recurrent
nerve have alone lost their conducting power, the remaining
fibres continuing to stimulate the portions of muscles to
which they send filaments. Consequently, a part of the
muscle may retain its irritability or contractile property,
while another part is paralysed. Cohen^ has remarked that
it is not known whether the double function of the recur-
rent nerve is due to innervation by a common centre, or
whether distinct centres preside over separate sets of fila-
ments ; while the influence which the pneumogastric nerve
may exercise upon abduction of the vocal cords as an
organic feature of the respiratory act, is a problem as yet
unsolved.

In the third and somewhat rare class of cases, there is
only temporary derangement of the function of the recur-
rent nerve ; the suspension or modification not being suffi-
ciently prolonged to allow serious atrophy of the muscles
to take place.

When the recurrent nerve becomes more or less incapable
1 "International Encyclopfedia of Surgery," p. 783.

IOG Roaring in Horses.

of stimulating the laryngeal muscles it supplies, apparently
the first of these to suffer in function is the dilator muscle.
This, failing to contract for want of stimulus, leaves its
arytasnoid cartilage and attached vocal cord more or less
immovable towards the middle of the glottis, and itself
undergoes those histological changes with which we are so
familiar, before the constrictor muscles, whose ofHce is not
nearly so important in respiration.

Clinically and experimentally, the evidence is strong
that such is the fact. Semon^ has shown that in all cases
of acute or chronic organic disease or injury of the nuclei
or trunks of the motor laryngeal nerves (spinal accessory,
pneumogastric, recurrent laryngeal), the abductor muscle
or muscles first feel the effects; whilst, on the other hand,
in cases of functional disorder, the adductors usually alone
suffer. That authority and Horsley,^ experimenting to-
gether, found that, in all classes of animals experimented
upon (monkeys, dogs, cats, rabbits), if the larynx was
excised immediately after death and its muscles indi-
vidually stimulated, the dilators (posterior crico-aryteenoids),
which are absolutely the largest of all the laryngeal muscles,
lose their electrical excitability long before the adductors.
This is, in all probability, due to the circumstance that the
two sets of muscles are histologically different, the dilators,
according to Griitzner and Simanowsky, belonging to the
class of Krause and Kanvier's red muscles, and the con-
strictors to the so-called white muscles.^

Onimus had already demonstrated that, after death, both
the extensor muscles and their nerves elsewhere lose theur
excitability before the flexors; and Kosenbach and Semon
compare the dilators of the glottis to extensor muscles.
Jeanselme and Lermoyez have found, on stimulatmg, withm
1 « Archives of Laryngology," 1881, No. 3 ; BerUn, Klin. Wochen-

"K'on't?' apparently Peripheral and Differential Action of Ether
upon the Laryngeal Muscles," London. 1886.
3 Jhicl, p. 5.

Pathology and Course of Chronic Roaring. 107

three-quarters of an hour after death, the laryngeal muscles
of people who had died from cholera, that no contractions
at all could be obtained of the dilators, while the thyro-
arytienoids responded well.

This difference in the physiological characteristics of the
constrictors and dilators of the larynx, is, in all likelihood,
related to the very important and constant activity of
function demanded from the latter.

For how long a period the dilator muscles of the larynx
of the horse may retain their vitality when- their nerves no
longer stimulate them, we have no exact knowledge. Bassi
found commencing atrophy, of the laryngeal muscles two
months after division of the recurrent nerves, in a horse.
Experiment has demonstrated that, after section of the
motor nerve of an ordinary striped muscle, there is in-
creased excitability for mechanical stimuli until about the
seventh week, when it gradually diminishes, until it is
altogether abolished towards the sixth to the seventh
month. Fatty degeneration begins in the second week after
section of the nerve, and goes on until there is complete
muscular atrophy.

In young horses, Koaring usually appears more suddenly
than in old ones, and has a tendency to become more
rapidly acute in them, the dyspnoea being also more severe.
This is no doubt owing to the difierence in the condition of
the laryngeal cartilages, as has been already mentioned when
treating of the physiology of the organ and the results of
division of the recurrent nerves. In what may be termed
really chronic cases, the afiection does not become modified
as the horse advances in years, but, on the contrary, has a
tendency to become more developed, for reasons which will
be given in the following chapter.

The condition of the horse, weather, food, and other
circumstances, influence the noise emitted in respiration,
no less than the dyspnoea. Horses so affected roar less when
in good working condition, than when '-soft" and fat.

108

Roaring in Horaea.

Damp weather, and especially if it is also cold, is unfavour-
able for such horses ; and an attack of catarrh or bronchitis,
if ever so slight, greatly aggravates the Koaring. The good
effects of abstention from water have often been noticed ;
and to relieve the distress consequent upon severe exertion,
it has been sometimes found advantageous to administer a
quantity of an oleaginous or lubricating fluid previously.
To diminish the breathing capacity, and so lessen the strain
on the larynx, the nostrils have also been partially occluded,
or bulky food has been given.

With regard to the latter treatment, Youatt gives an
amusing anecdote. He writes: "There are few hunts in
which there is not a Eoarer who acquits himself very
fairly in the field, and it has occasionally so happened that
the Roarer has been the very crack horse of the hunt ;
yet he must be ridden with judgment, and spared a little
when going uphill. There is a village in the West Riding
of Yorkshire, through which a band of smugglers used
frequently to pass in the dead of night. The horse of the
leader, and the best horse of the troop, and on which his
owner would bid defiance to all pursuit, was so rank a
Roarer that he could be heard at the distance of a quarter
of a mile. The clatter of all the rest scarcely made so much
noise as the roaring of the captain's horse. When this got
a little too bad, and he did not fear immediate pursuit, the
smuggler used to halt the troop at some convenient hayrick
on the roadside ; and, having suff'ered the animal to distend
his stomach with this dry food, as he was always ready
enough to do, he would remount and gallop on, and for a
whik the roaring was scarcely heard. I am not compelled
satisfactorily to account for this; but the loaded stomach
now pressing against the diaphragm, that muscle had
harder work to displace the stomach in the act of enlargmg
the chest and producing an act of inspiration, and accom-
plished it more slowly, and therefore, the air taking longer
time to rush by, the Roaring was diminished. I will not

Pathologij and Course of Chronic Roaring. 109

stop to calculate what must have been the increased labour
of the diaphragm in moving the loaded stomach, nor how
much sooner the horse must have been exhausted. This
did not enter into the owner's reckoning, and probably the
cruel application of whip and spur would deprive him of
the means of forming a proper calculation of it." ^

1 "Veterinary Lectures "— " The Veterinarian," 1833, p. 61.

CHAPTER Vill.

CAUSES OF CHRONIC ROARING.

The causes of Chronic Roaring may be considered as
" mechanical " and " pathological ;" the first being related
to the impediment in respiration which occasions the noise,
and the second to the morbid changes to which the impedi-
ment is due. We will study the causes in this order.

Mechanical Causes.

It has been already stated that the abnormal sound heard
in respiration is coincident with the act of inspiration — at
least it is loudest then ; for in advanced stages there is a
more or less audible noise also during expiration. The way
in which the noise or stridor is produced, and the parts
which produce it, has afforded matter for discussion for a
long time ; but remembering the physiology of respiration,
and the share the larynx takes in this function, there should
not be much doubt as to the origin of the noise.

We have seen that, during breathing, the arytsenoid carti-
lages, and the vocal cords attached to them, are moved out-
wards and upwards in inspiration, so as to widen the glottis
and allow the necessary volume of air to pass through to
the lungs, the degree of movement depending upon the
physiological requirements of the body. In tranquil respira-
tion the movement is only trifling, as the space existing
between the vocal cords (pars vocalis) and their movable
cartilages (pars respiratoria), when they are at rest in the
living animal, is almost sufficient for the admission of the

Causes of Chronic Roaring.

Ill

required amount of air. But in proportion as the need for
an increased supply of air becomes urgent, so the move-
ment of these parts is extended to afford more glottal space,
until, in forced and deep respiration, the glottis is dilated
to the utmost, by each arytasnoid cartilage being drawn by
its dilator muscle upwards and outwards, and the vocal
cord pulled close to the side of the thyroid cartilage; so that
the middle division formed by these in the organ has
almost entirely disappeared, and the lumen of the larynx
is nearly of the same dimensions throughout (Fig. 6). In-
spiration being accomplished, the cartilages fall downwards
and inwards, chiefly by the dilator muscles ceasing their
contraction (though they are never entirely relaxed during
life), and the natural elasticity of the cartilages and vocal
cords coming into play ; then they are in the passive posi>-
tion assumed in tranquil respiration, in which the glottal
opening is wider than when they are in what is termed their
" cadaveric position." Expiration now taking place, the air
expelled from the lungs easily pushes cartilages and cords
aside, in its course through the larynx towards the nasal
passages.

It will now be perceived what must happen when the
dilator muscles are weakened or paralysed, and the respira-
tion is increased. The vocal cords and arytf^noid cartilages
not being moved sufficiently out of the way of the inrushing
column of air, they form such an obstacle in the laryngeal
cavity as to allow only a portion to enter, and this is drawn
in with such force as to produce a noise, all the more shrill
the narrower the glottal space has become. It may be
observed that in man a similar condition is remarked ;
paralysis of the abductor muscles of the larynx is always
manifested by inspiratory stridor.

When the dilator muscle of only one side is affected — the
left, for example— then the stridulous breathing is not so
marked or distressing on exertion ; as the opening of the
glottis is wider, not only because the other dilator muscle is

112 Roaring in Horses.

healthy, but also because it is more energetically called into
action to compensate for the defectiveness of its fellow.

In commencing Roaring, or in those cases in which it
remains at a less advanced stage, and in which the muscle
is only slightly affected, the sound is probably produced by
the vocal cord alone ; the thin border of this, projecting into
the cavity of the larynx, meets the inspired air and pro-
duces the characteristic sound. But in more advanced
cases, when the muscle is feebler, or altogether paralysed,
then, during exertion, there can be no doubt that the ary-
tsenoid cartilage shares with the vocal cord in obstructing
the admission of air, and renders the noise louder and of a
different tone. When the muscle is completely wasted, both
vocal cord and cartilage assume and maintain the " cada-
veric position" when the horse is at rest ; but durmg severe
exertion they even pass beyond this, and still further
constrict the air-passage, diminishing it by more than one-
half. ,

This movement of these parts beyond the centre of the
cavity, is due to the pressure the air exerts upon them, and
also to the part played by the sac or ventricle on their
outer side. During inspiration, when the larynx is m a
healthy condition, this somewhat extensive sac is obli-
terated and its slit-like entrance shut ; but when the glottis
is closed, as during neighing, then it is inflated with
air to allow the vocal cord more liberty of movement for
vibration, and to act, with the upper laryngeal cavity, as a
resonator. In Roaring, from its flaccid condition, its elas-
ticity and its wide opening, it catches a portion of the air
which should pass into the trachea, and this inflates it to
a considerable degree, causing the vocal cord to be pushed
still further towards the opposite side (Fig. 7). At tne
same time, this movement of the cord downwards and
inwards also compels the arytienoid cartilage to which it is
attached to be drawn in the same direction, this action
being supplemented by the air also pressing down the upper

Causes of Chronic Roaring. 113

part of the cartilage itself, and so still further decreasing
the glottal space at the loars respiratoria, as well as at the
aditus. Consequently, the greater the volume of air enter-

FlG. 7. — YiEW OF THE LARYNX OF A HORSE AFFECTED WITH "ROAR-
ING, DURING EXTREME INSPIRATION, SHOWING THE DIFFERENCE
IN POSITION OF THE RIGHT AND LEFT ARYT/ENOID CARTILAGES
AND VOCAL CORDS.

cf, Epiglottis, hb, Arytsenoid cartilages, the right being pulled out-
wards and upwards, while the left (dark-shaded) is beyond the cada-
veric position, cc, Vocal cords : the right is drawn close to the side of
the larynx, while the left remains in the middle line, and diminishes
the aperture of the glottis, cl. ee, Ventricles of the larynx.

ing the pharjTix from the nasal passages, the less will pass
through the larynx, owing to its distending this pouch and

8

114. Rum-ing in Horses.

depressing and pushing inwards the vocal cord and arytfe-
noid cartilage ; at the same time that this encroachment
narrows, to a serious extent, the " portal of the breath of
Hfe" the upper division, or aditus, is corrcspondmgly
diminished in size by the passing forward of this cartilage
into its cavity. So that after a certain amount of weaken-
ing of the dilator muscle, and resulting protrusion of cord
and cartilage into the breathing space, the condition be-
comes yet more aggravated by the pressure exercised on
them by the air which should pass into the lungs, but
which drives against their upper surface instead. The more
frequently a horse affected with Roaring undergoes severe
exertion, so the more rapidly will the morbid displacements
of these parts become serious and permanent, and especially
if the animal is young-for then their softness allows
them to yield all the more readily to the pressure of the air.

In this way can the striking distortion observed m the
larynges of horses which have been for some time bad
Roarers be accounted for_; the atrophy of the dilator muscle
would not alone explain it. , -, • • ^

It will now be understood why limiting the admission ot
air at the nostrils during active exertion benefits, rather
than inconveniences, a horse which is a Roarer.

When the vocal cord does not advance to the middle ot
the larynx, but is only rather relaxed, it is thrown mto
coarse vibrations by the forced inspiration, and the horse
then "roars"; when still less advanced, and the cord is
more tense, he whistles-the constrictor muscles of he
same side probably acting, though feebly, m shortenmg the
cord But when cord and cartilage pass to or beyond the
median line, then on slight exertion the inspiration is noisy,
and when the exertion is increased, the sound becomes
painfully loud and shrill ; at the same time, the right dilator
muscle has to act in a continuous and spasmodic manner
to allow as much air as possible to reach the lungs, and
also to pass from them.

Causes of Chronic Roaring.

115

The noise heard in expiration in these cases is caused
by the air pushing past, and lifting to one side, the ob-
structing cord and cartilage.

It has been denied that the immobile vocal cord has
anything to do with the production of the noise in Roaring;
but that it must have a large share in this, might be inferred
from the anatomical and physiological facts which I have
given, as well as those of a pathological kind, derived from
observation of morbid conditions of the vocal cords in man
and animals.

The distension of the ventricle with air would alone pro-
duce noisy respiration. Falconio^ describes a case of sub-
mucous emphysema of this ventricle in a horse, through air
obtaining access to the cellular tissue ; this condition caused
a whistling sound in breathing. Such an accident may be
more frequent than might be supposed, judging from the
extreme rarity of the recorded instances ; as stalks of
fodder may readily wound the mucous membrane at this
part. Giinther reports the case of a horse in which the
ventricle was filled with pus, and which caused a noise in
breathing ; the sound disappeared when the pus escaped.
Moller had a similar case.

The difference in the dimensions of the air-passage
during deep inspiration in the healthy larynx, and in that
of a horse affected with Roaring, will be better realised, per-
haps, by comparing fig. 6 (p. 91) with fig. 7 (p. 113).

Pathological Causes.

Having considered the mechanical causes of Roariag, we
will now inquire into the pathological conditions which lead
to these impediments. .

Beginning with the fully ascertained fact, that debility or
atrophy of the left dilator muscle is the causa proxima of
chronic Roaring, the questions to be answered are : why

^ " Giornale di Anatomia, Fisiologia," etc., 1886.

8—2

IIQ Roaring in Horses.

the left side of the larynx should be in, it may be said,
every case alone involved ; and what occasions the muscle-
wasting ?

Here, again, we find much mystery and obscurity pre-
vailing.' " Why the change is greater on the left than the
right °side, is," says Williams, "one of those things for
which no more satisfactory explanation can be given than
why the ulcers of Glanders are oftener seen in the left than
in the right nostril."^ I am not aware that the ulcers of
Glanders are more frequently noticed on one side of the head
than the other— all my experience leading me to believe
that neither is particularly favoured in this respect But
why the left side of the larynx should be that which is
alone involved in chronic Roaring, there should be now no
difficulty whatever in comprehending. It is due entirely to
the difference in the course and relations of the left
recurrent nerve, and which I have been at some pams to
indicate in describing the innervation of the larynx, ihe
anatomical distinction between the right and left nerves was
shown to be remarkably great ; and it is upon the special
features observed in the detachment, situation, connections
and environment of the latter nerve, that we can account
for the side of the larynx it supplies with stimu us bemg
the one to suffer from the characteristic pathological
changes which occasion Roaring.

It has been shown that the right nerve is comparatively
short, being given off from the right vagus nerve imme-
diately after the latter enters the chest, m which it has
scarcely any relations or connections: whereas the left one
is detached from the left vagus nerve deep m the cavi y at
the base of the heart, and is connected and related with the
sac (pericardium) in which that organ is e^vebped^
the great arterial trunk springing from the heart with the
pleural membrane and its dependencies, with lymphat c
glands-intra- and extra-thoracic -and with gangha of the

1 Oj}. cit., p. 510.

Causes of Chronic Roarivg. 117

sympathetic system of nerves. But outside the chest there
is no difference between the right and left nerves, and up
to and on the larynx they have the same course, relations,
and distribution. Therefore it is to the thoracic differences
in the nerves that we must look for the exemption of one
side of the larynx, and implication of the other,

I have stated that chronic Roaring is a neuropathic
disease, its nervous origin being undeniable. If it were due
to any local inflammation or swelling in the region of the
larynx, we should doubtless find the right side as frequently
involved as the left, and the morbid changes presenting
other characters than those described. Absence of mobility
of the aryttenoid cartilages an-d vocal cords might doubtless
be due to paralysis -of the dilator muscles, from infiltration
of their fibres and nerve-filaments ; but this would be
obvious on post-mortem inspection.

In chronic Roaring there are no indications whatever of
such inflammatory action, and the fact that very many
cases occur without any inflammation being present in the
larynx or its neighbourhood, is sufficient to prove that we
must seek for the causes elsewhere, and ascribe them to
other influences. Attributing the wasting of the muscles
on the left side of the larynx to some imperfection in the
condition of the nerve distributed to them, and also accept-
ing as a fact the statement that such imperfection, even
when sHght, is more apt to affect the dilator than the con-
strictor muscles, it now remains to inquire what influences
render the left recurrent nerve defective. Here, however,
we come upon less certain ground, and must extend our
inquiry over a wide area, if we are to arrive at a satisfactory
conclusion.

The causes which will render a nerve incompetent to
perform its function in one part of the body will do so in
another, and the left recurrent nerve cannot prove an excep-
tion. Experimentally, it has been demonstrated that divi-
sion or ligation of the right recurrent nerve in its course

118

Roaring in Horses.

up the neck will give rise to precisely the same symptoms
and the same morbid alterations on the right side of
the larynx as when this is performed on the left nerve.
External injury, or alterations in the nerve-structure,
due to changes in its histological elements, will modify
or altogether abolish the conductibility of a nerve. Such
are in operation in the development of chronic Roar-
ing. Pressure upon, or disease of the nerve, in any part of
ics course, from its origin close to the heart up lo its arrival
at the larynx, will impair or destroy its function, and in
time alter its structure.

How is this pressure or disease brought about? Any
change affecting other organs or tissues in immediate
proximity to the nerve will affect it. Aneurism of the aorta,
tumours, inflammation or disease of any portion of the
pleura with which the nerve is in contact ; inflammation,
hypertrophy, and induration of the lymphatic glands in any
part of its course, or any other morbid conditions in which
it may be involved either directly or indirectly, will impair
its use either partially or wholly, temporarily or per-
manently.

Perhaps, of all causes, the pressure or disturbance exercised
by diseased intra-thoracic lymphatic glands— chiefly the
bronchial— is the mosb frequently observed. So long ago
as 1838, Ferguson, when examining the body of a horse
which had been a Roarer for a long time, found the left
recurrent nerve enveloped and compressed by a voluminous
indurated bronchial lymphatic gland, while the remainder
of the nerve between this gland and the larynx was quite
diff'erent to that on the opposite side, it being greatly
wasted and its fibres scarcely distinguishable. All the
laryngeal muscles which received filaments from it were so
completely atrophied, that it was difficult to perceive theu:
structures, while the glottal opening was twisted and the
borders of the arytenoid cartilage partly obstructed it.i

' The Veterinarian," 1838.

1 u

Causes uf Chronic Roaring. 119

In 1846, Lafosse related a case in which a horse at first
manifested Roaring at intervals, but soon became continu-
ously affected, and the dyspnoea finally became so serious that
the animal died asphyxiated. At the autopsy the bronchial
lymphatic glands were observed to be extremely enlarged,
brownish in colour, indurated, adherent to each other and
to the lungs, and containing pus at various points, while the
pneumogas trie nerves were compressed in them, and almost
confounded in their mass.^ Trasbot^ made many autopsies
of horses that had been Roarers, and invariably found that
the left recurrent nerve was surrounded by indurated,
enlarged, or in some other way altered, bronchial lymphatic
glands, or was compressed between them and the aorta, and
that it was atrophied from its entrance among them ; in
some instances it had almost disappeared, or was reduced
to a thin gray filament throughout its entire length up the
neck.

Other observers, among them being Dupuy, Bouley,
Colin, and Zundel, have noted similar implication of the
nerve in these thoracic glands ; and my own examinations
of horses which had been affected with Roaring have, in
the majority of instances, yielded results the same as those
of Trasbot. Bassi reported a case in which a horse was
destroyed because of this defect, and an examination
showed that the left recurrent nerve had been pressed upon
by an enlarged lymphatic gland near the twelfth tracheal
ring, and was only one-third its ordinary volume.

Bouley, so long ago as 1825, found this nerve compressed
and altered by engorgement of the pre-pectoral lymphatic
glands of horses so affected f and F. Giinther records an
instance of confirmed Roaring being caused by the left
thyroid gland compressing this nerve, and leading to wast-
ing of the laryngeal muscles on the same side. Professor

1 " Journal des Veterinaires du Midi," 1846.

- " Archives Y6terinaires," 1879.

^ " Recueil de Medecine Veltvinairea," 1825, p. 38.

120

Roaring in Horses.

Sowell, in dissecting the body of a horse which had been a
Roarer, found a bony tumour growing from the cervical
vertebra between the first ribs, which had exercised pressure
on the nerve.^

Many other instances of a similar kind could be given, in
which compression of the left recurrent nerve has produced
Roaring. In the days when bleeding was fashionable, it was
not at ail an infrequent consequence of inflammation of the
jugular vein, due to phlebotomy.

Goubaux was of opinion that harness horses wearing
small collars were liable to become affected, as the left
recurrent nerve is more superficial at the bottom of the
neck than the right one. This is not at all a likely cause,
however.

Some authorities, as K. Giinther, Franck, and others,
have favoured the view that the paralysis was related to the
course the left recurrent nerve pursues around the posterior
aorta ; the pulsations of this great artery are supposed to
strain the nerve and weaken its function. But it may be
pointed out that the relations between the artery and nerve
are the same in horses inhabiting countries in which Roar-
ing is unknown.

Martin^ supposed that during the development of the
body in youth, the neck becomes lengthened and the heart
pushed back, straining the left recurrent nerve and pressing
it at the aorta, and so impairing its function. In this way
it was attempted to account for the greater frequency of
Roaring in horses with long, thin necks ; and Ellenberger,
according to Moller, adopting this view, lays stress on the
high development of the arterial system and the absence of
fat in English thoroughbred horses, whereby the nerve is
but little protected at the aorta ; this exposes horses^ to
become Roarers when their condition is fine— as durmo
training. The influence of this arterial pressure ie

1 Percivall, op. cit., p. 253.

2 "Oesterreich. Monatsschrift," 1885.

Causes of GhroniG Roaring.

damaging the nerve at the aorta is supposed to be further
supported by the observation of Sussdorf, that the left
recurrent nerve shows a flattening, perceptible by means of
the microscope, where it passes between the aorta and
trachea.

But the objection I have offered above applies also here.
English horses, however much they may be liable to become
affected in their own climate, appear to lose this predisposi-
tion in warm dry climates, and yet we cannot believe that
the anatomical relations of arteries and nerves are altered
with the change of latitude, Arab horses in training (as
they often are in India) cannot differ much, anatomically,
from English horses ; and yet Rearing is all but unknown
among them. Besides, nerves are not inelastic cords, but
can be extended to a considerable extent without their
function being interfered with. In small animals, the
recurrent nerve may be raised as much as half an inch,
without any effect being produced on the laryngeal
muscles.

Notwithstanding these objections, however, there is
reason to suspect that there is some foundation for the
supposition in the case of very young thoroughbred race-
horses. The early age at which these animals — immature
as they are — begin to be treated as if fully mature ; their
stable management, feeding, training, and altogether very
unnatural existence, must severely test their organization ;
and it can scarcely be wondered at if the left recurrent
nerve, like all other organs and tissues, sometimes, or even
frequently, suffers overstraining and pressure, particularly
at the point where it lies in contact with the posterior
aorta. Fast racing at two and three years of age must
impose a very heavy task upon the heart and its large
vessels, at a time when they are only partially developed,
and their dilatation must be all the greater as their tissues
are soft and yielding. The posterior aorta, from the large
amount of blood it has to carry, must participate in the

122 Roaring in Horses.

undue blood-pressure attending such severe and abnormal
exertion, and become greatly distended— the greater pro-
portional increase in its circumference, and which Stahel
describes as " Spindelbildung," being probably in conse-
quence of a sudden change or twisting in its direction
during distension. This will impose a condition of alter-
nate extreme tension and relaxation on the nerve, which
must be highly unfavourable for its functions and histo-
logical arrangement in the almost embryonic state in Avhich
it yet is in such juvenile creatures. In the course of a very
few generations we can reasonably infer that, in families
which may perhaps have some anatomical peculiarity in the
disposition of this nerve in the chest, the weakness induced
in this way will become inherited— as other defects often
are; and the predisposition thus existing, Roaring is
developed when certain predisposing or exciting causes, be
they ever so shght, come into operation. Of course, this
line of reasoning can only apply to young race-horses, not
to other or adult horses.

Chronic Roaring not unfrequently follows certain diseases,
chiefly those in which the respiratory apparatus in the
chest is involved, and particularly those parts of this
apparatus which are more or less closely related to the left
recurrent lung. Pleurisy, inflammation of the right lung or
the pericardium, or of the lymphatic glands in the vicmity
of the nerve, are often followed by Roaring, from the exten-
sion of the inflammation to it, or the pressure exercised on
it by inflammatory products. In this way it is often a
sequel of influenza, and similar febrile disorders m which
the chest is affected. What are called " colds," which may
he bronchitis or pleuro-pneumonia, in addition to catarrh,
often have this result. The infectious fever known as
" Stran^^les," in which there is abscess formation m the
submaxillary lymphatic glands, is perhaps the most frequent
cause of Roaring met with among army horses, and prob-
ably also among others than these. The occurrence of this

Causes of Chronic Roaring.

defect after Strangles in all likelihood depends upon
whether the tracheal and bronchial glands— between which
and the submaxillary glands there is great sympathy— are
inflamed and swollen.

It has long been known that Roaring often follows the
above diseases, though its cause was not suspected. Sixty
years ago, Professor Sewell, of the Royal Veterinary College,
wrote, in reference to it : " When it takes place in colts that
have not been broken or regularly domesticated, it is
usually the result of severe cases of Strangles that have not
terminated favourably, but left a thickening, and often
chronic ulceration, of the mucous membrane lining the
larynx ; in others it is preceded by severe colds and sore
throats, producing similar lesions of structure. The latter
is frequently the cause in all kinds of horses, and in all
unhealthy seasons, in spring especially, the disease has its
origin." ^

The occurrence of Roaring in young horses which have
never done any severe work — in fact, no work at all — such
as army remounts, but which have suffered from Strangles
and fevers implicating the chest and its contents, militates
against the development theory of the defect, and also that
of nerve stretching by the posterior aorta.

Whether a high temperature will cause disturbance in
the function of the left recurrent nerve in horses unaccus-
tomed to it, cannot be decided ; but it is most probable that
there were, in the instances recorded of English horses be-
coming Roarers in hot climates, antecedent or collateral
causes in operation which were overlooked, but which were
more potent than this : such as fever on board ship, with
congestion of the lungs and pleurae, exhaustion, etc.
Spooner-Hart ascribes the cases of Roaring observed
among imported horses at Calcutta, to the elevated tem-
perature of the summer, which induces what he terms
" thermic fever." " A patient, after an attack of such high
1 " The Veterinarian," 1829, p. G8.

124 Roaring in Horses.

fever, is left with his nervous system permanently damaged,
and is never a horse again. ... His body temperature, even
when at rest, stands abnormally high, and on the smallest
exertion in the sun it rises quickly. He never cools down,
and stands and blows over his food in the stable— he is in
a state of chronic fever. A httle work in the sun, and he
falls, registering a very high temperature. A horse of this
class becomes a Roarer, and is of little use here."i

I have already alluded to English troop-horses becoming
Roarers in South Africa and Egypt. In the latter country
an extraordinary number became affected, but they were
exposed to various causes besides the thermic one. Of this
I might cite many instances, but content myself with giving
the following, furnished me by Veterinary Surgeon (First
Class) Case, Army Veterinary Department. He says :

« During the campaign of 1882, in Egypt, I served with
G Battery"^ B Brigade, Royal Horse Artillery, a corps I had
been with for two years. When we embarked, on August 2nd,
there was not a horse affected in its breathing in the ranks ;
but soon after landing many of the horses, more especiaUy
the draught ones, began to show symptoms of Roarmg.' This
began to appear during the latter part of our first march
from Ismailia, which place we left on August l7th, at
four o'clock in the afternoon, and continued marching until
five o'clock the next morning, when we halted for four
hours During the early part of the night we were subjected
to a fearful dust-storm, and the bank of the Fresh-water
Canal on which we were marching, was very rough going ;
so that at the time I attributed the Roaring to over-exhaus-
tion-the horses only just having landed, and bemg some-
what out of condition. On continuing, the march was more
distressing, as the direction lay across the desert, the guns
and waggons having to be pulled through deep sand. Ihe
Roarin? of many of the horses then became much more
perceptible, and could be heard at some distance. More
1 " The Veterinary Journal," vol. xxv., p. 4.

Causes of Chronic Roaring. 125

especially were the ammunition-waggon horses affected, and
they Avere quite unable to move their loads, which neces-
sitated the horses being taken from the other waggons to
assist. The waggons were then drawn alternately for about
half a mile, the horses returning for the remaining waggons.
This excessive exertion was continued throughout a dread-
fully hot day, with but little food, and without water for the
animals. The laboured and distressed breathing of these
horses could be heard a long way off" — in fact, it was quite
painful to witness their distress.

"The next morning we marched at two o'clock, but had to
leave three horses behind, their breathing being so bad it
was impossible to move them ; and two were still Roaring
badly, although they had been at rest for about five hours.
The road now was somewhat better, but the Roaring of the
horses had increased, and there were several fresh cases.
After arriving at Kassassin, where we stayed some days, the
horses picked up in condition ; but when we marched again,
I noticed the Roaring had not disappeared — in fact, many
more horses were affected. And after Tel-el-Kebir, on
September 13th, and during our march on Cairo, several
animals had to be destroyed, as the Roaring brought them
to a standstill, while others were left behind at villages in
charge of the sheiks, who afterwards brought them to us.

" On arriving at Cairo, out of the 210 horses embarked,
about 185 were with the Battery, including officers'
chargers; of which number 33 were Roarers, 13 'broken-
winded,' and several others more or less affected in their
breathing (Whistlers). Many of the affected horses after-
wards died of fever; some were destroyed from various
causes ; others were cast and sold ; and a few were sent to
the Mounted Military Police, and are now (1888) serving at
Cairo and Alexandria.

"After I arrived at Cairo (in 1886), I saw many cavalry
horses that had become Roarers during the campaign.
" The immediate cause I attributed to fever, contracted

126

Roaring in Horses.

either on board ship, or after landing— in the former case •
by the heat between decks, especially among those horses
that were in the lower hold, and by the emanations from
the excretions ; and in the latter by climatic causes, filthy
water, etc.— and which became aggravated by exhaustion.
In some cases the fever may have been so slight as to pass
unnoticed. I think in some horses, more especially the
draught ones, the Roaring might have been caused by the
muscles of the larynx becoming partially or wholly paralyzed
from over-exhaustion.

" I may mention that I brought to this country a half-
bred mare, perfectly sound in every respect. On the voyage
out she suffered from rather a severe attack of fever; she
was placed in the upper deck with other horses, the weather
being fine. The day we landed she met with an accident
which caused her to be left behind at the sick depot at
Ismailia. She remained there about seven weeks, arriving
at Cairo about the 1st of October. She soon after began to
show symptoms of Roaring ; at first it was shght, but it
fxradually increased. I took her home in March, 1883.
She never recovered, and when I left England, in March,
1886, she was still a bad Roarer. She was very high-
spirited, and the least excitement, even at a walk, caused
her to 'roar so badly that she could be heard at some
distance.

"Veterinary Surgeon Griffiths states that a large number
of the horses of the regiment (7th Dragoon Guards) he served
with in 1882 became Roarers soon after landing. He attri-
buted it to the excessive heat on board ship, the horses
perspiring a great deal ; and as the vessel changed her course
a sudden current of air would rush through the port-holes,
which he thinks, caused the horses to be chilled.

" He adds that one of his own horses commenced to roar
soon after it arrived in Egypt, and, by Janiiar^ roared so
badly that it could be heard a long way oft. He sent tlie
animal home in February, 1883. It was then a very bad

Causes of Chronic Ro<iring.

127

Roarer, and remained so during the winter, but in J uly of
the same year it was passed sound by a veterinary surgeon,
tbe noise having disappeared."

So far, then, there does not appear to be anything
mysterious in the constancy with which the immediate
cause of Roaring is found to be localised on the left side of
the larynx ; it is simply due to the fact that the left recur-
rent nerve in the chest is exposed to injurious influences
from which the right nerve is altogether exempt ; and that
these influences are many and diverse, we know full well.
When one or more of these influences act upon the nerve,
weakening of the muscles it supplies is ■ soon manifested ;
and the first muscle to be affected being the left dilator, a
noise in respiration becomes evident, tlirough imperfect
opening of the glottis. The rapidity with which the
inspiration becomes impeded, and the noise grows louder,
will depend upon the extent to which the conductibility of
the nerve is involved. Outside the chest, both nerves are
alike exposed to injury; but as it is indeed rare to find the
right side muscles of the larynx wasted, the risk of damage
in the region of the neck must be infinitely small.

1

CHAPTER IX.

PREVENTIVE AND CURATIVE TREATMENT OF CHRONIC

ROARING.

In view of the increasing prevalence of chronic Roaring, its
tendency to occur in the most valuable horses, and" the
serious and often rapid manner in which it leads to their
depreciation, only too frequently destroying their utility,
the necessity for adopting every means for preventing its
development, or, when it has become evident, removmg the
causes upon which it depends, need not be insisted upon.
In fact, there are perhaps no questions connected with the
production, improvement, and utilization of horses, which
demand more serious examination and solution than those
relating to the prevention of this defect, or its removal
when its existence has become manifest. They have aheady
enaao-ed the attention of veterinary surgeons and horsemen
for" a long period, and the time has now arrived when, on
account of the great interests involved, no less than on
behalf of the noble creature himself, they should be seriously
discussed, and measures suggested for dealing with them m
a practical and satisfactory manner.

These measures must be devised: (1) To the preven ion of
Roarino-, from a sanitary and medical point of v^ew ; (2) io
fhe emoval of the causes which give rise to it, either by
medi^or surgical treatment. We will deal with them m
this order.

1 PREVENTION, FROM A SANITARY PoiNT OF ViEW.

The prevention of chronic Roaring is of the utmost im-
portance, and should be the chief aim of those who have it

'Hi

'•WW

Preventive and Curative Treatment. 129

in their power to carry out the measures essential to this
end. They may be enumerated as follows : (a) Exclusion
of unsound horses for breeding purposes ; (&) Care in the
management of young horses ; (c) Hygienic management.

(a) Exclusion of Unsound Horses for Breeding Purposes,

Numerous and incontestable facts pointing to hereditary
predisposition as a potent factor in the genesis of Roaring,
it becomes imperative, in order to diminish its frequency,
to exclude from breeding, be they males or females, horses
which are already suffering from the defect. This is a
severe measure, knowing the high value of some horses, due
to their excellent qualities; but its urgent necessity is
obvious. Of course, this measure applies more especially to
animals in whose ancestors Roaring has been noted for two,
three, or more generations, and in which it has become
evident without any, or apparently a very slight, assignable
cause — especially at an early age. For it must be remem-
bered that the defect may arise from a number of what may
be termed " remote causes " — such as pleurisy, pneumonia,
pericarditis, congestion of the lungs or pleura, strangles,
etc. — without hereditary predisposition being present.
Whether such predisposition exists in a horse, we have no-
means of ascertaining, except by instituting inquiries into
his pedigree ; for this tendency, in all probability, consists in.
transmitted anatomical peculiarities, which form the causa
interna, and therefore undiscoverable agencies, in the origin,
of Roarino-.

(b) Care in the Management of Young Horses. -

I have already alluded to the abnormal precocity whick
is forced upon very young thoroughbred horses, as a likely
cause in predisposing them to Roaring ; and I think this
has been too much lost sight of, in accounting for the greater
and increasing prevalence of the defect among them. For

9

130 Roaring in Horses,

other breeds, as the coarser and heavier horses and ponies,
which are not so abused in their very juvenile days, and
are allowed to develop in a more natural manner, there is
no necessity to insist upon this predisposing cause being
abolished— as the defect is rare in them; but for the
thoroughbreds, upon which the perfecting of our speed-
horses must depend, such injurious, premature treatment as
they now receive merits earnest condemnation. Until a
horse has reached an advanced stage of development, its
organs and tissues cannot be subjected to severe wear
and strain with impunity, no matter how much that
development may be forced artificially. Growth may be
accelerated, but with it consoHdation is required to consti-
tute maturity— and this cannot be so easily controlled, or
hurriedly brought about. Nature cannot be coerced beyond
a certain degree without resenting the compulsion ; and to
exact exertion from a two-years-old horse as if he were a
four-years-old— no matter how he may be stimulated to
oTowth by hot stables and rich food— cannot be otherwise
than damaging to him, and especially to the organs of respira-
tion, circulation, and locomotion.

By deferring the training and racing of thoroughbreds
for a year or two, the predisposition to this and other
damao-ing defects would be immensely lessened, if not alto-
gethe? got rid of, and a more healthy and useful race of
horses ensured.

(c) Hygienic Management.
In cold, damp countries, and especially those in which
there are sudden falls and rises in temperature, in order to
maintain horses fit for labour, and indeed as an essential
element in their improvement, they must be protected from
the eftects of climate by lodging them in stables, and keeping
them comfortable. But unless much care is exercised m
this housing, harm is done, and a predisposition to disease
of the respiratory organs established. Badly-ventilated and

Preventive and Curative Treatment

over-heated stables are eminently prejudicial to the health of
horses, and it is in these that Ave find those fevers and dis-
orders prevailing which are so often followed by Koaring.
For none of the other domesticated animals is plenty of pure
dry air so essential, and it should be rather cool than hot.
If the horses must be kept warm during cold weather, then
this should be done by clothing the body, and, if need be, the
limbs. This treatment has been insisted upon by the most
experienced horsemen, who have not ceased to point out the
injury inflicted upon horses by hot, foul stables. Admiral
Rous, for instance, speaking of Roaring in race-horses, men-
tions the advantages of cool stables and fresh air, and says :
" I have no doubt that Roarers might be improved a stone
if they were trained from an open shed, sheltered from wet
and rain, keeping them warmly clothed, and always in the
open air."

The hygienic management which is best adapted to pre-
vent the occurrence of coughs, colds, fevers, pleurisies, pneu-
monias, and other affections of the air-passages and chest, is
that which will afford most security against the develop,
ment of Roaring, whether or not the predisposition to it be
present in horses. Everything should be done to prevent
their being attacked by Strangles — a very infectious disease,
spreading only by its infectious properties, and which, in
western countries at least, is so frequently followed by
Roaring. Indeed, so marked has this sequel been in
my experience among horses, that for some years, while I
was a regimental veterinary surgeon, I treated every case of
Strangles in such a way that, in my opinion, injury to the
left recurrent nerve was less likely to occur from pressure
upon it by enlai'ged bronchial lymphatic glands. This
treatment chiefly consisted in the administration of iodide
of potassium, or iodide of iron ; and I have reason to believe
that it was very successful.^

Food does not appear to have so much influence in pre-
1 " Veterinary Journal," vol. xiv., p. 93.

9—2

ft

132 Roaring in Horses.

disposing to the affection as is often imagined it has, and
there is no reason why it should, so long as it is not of a
toxic nature.

' 2. Medical and Surgical Treatment of Roaring.

What is called the " cure " of chronic Roaring, has formed
a very vexed subject in veterinary medicine, and has
engaged the earnest attention of the majority of dis-
tinguished- veterinarians. A detailed account of the
attempts made to get rid of the noise in respiration
would form a curious chapter in the history of perplexed
" cure-hunters."

Percivall, who knew little or nothing of the pathology ot
Roaring, in 1841 expressed the opinion that its successful
treatment was hopeless, especially in cases of long duration,
no matter what causes they might be due to. "Also
such as there appears any reason to believe hereditary, or
dependent upon an original malformation of parts. Cases
of distortion are equally irremediable when the distortion
has existed so long as to destroy the origmal form_ and
properties of parts, and in their place to have established
fresh ones. Such can only be benefited by the French
treatment, which consists in the performance of bron-
chotomy, or tracheotomy as they more properly call it.
They make a large aperture, and use a proportionaUy large
tube so constructed and adapted that the animal can not
only breathe through it, but do his work, and gallop with it

in his neck." . • j th.i^

From Percivall's time up to a quite recent period, little
has been done in the way of treatment for the defect and
that little has been, as a rule, of the most empirical kind :
due to the fact that the morbid conditions upon which
Roaring depends were unknown or not understood.

Attempts at removal of the defect have seldom been made,
even in the case of most valuable animals ; and for many

Preventive and Curative Treatment

years it has been rare indeed to hear of veterinary surgeons
undertaking the treatment of horses so affected, such being
regarded as hopeless, even at the very commencement of
the Roaring. Bhstering the throat, or applying the ferrum
candens over the larynx, has been the principal treatment ;
but even this appears to have been long given up.

Now that we understand the pathology of Roaring, we
are in a better position to adopt rational measures for what
we may term its " cure," and with much certainty of suc-
cessful results. In this respect, we may venture to hope
that veterinary surgeons will be more fortunate in the future
than surgeons; as laryngeal paralysis is always a serious
condition in man, because the disease which gives rise to
it is so frequently of a fatal character.

(a) Medical Treatment of Roaring.
■Medical treatment, it must be confessed, has not been
found very successful in the removal of Roaring, and the
reason for this is obvious. Atrophied muscle cannot be
regenerated, and if the left dilator of the larynx has wholly,
or even partially disappeared, its restoration is impos-
sible. It is only in cases in which the muscular tissue
though weak (paresis, simple atrophy), can be again
developed to its original condition, and the compressed or
damaged nerve brought to its normal state, that medical
treatment is likely to be beneficial. So long as it is mere
weakness, through feeble conduction in the recurrent nerve,
then the resources of therapeutics may be made available in
removing the Roaring.

If it is suspected that the thoracic lymphatic glan_ds are
the cause of nerve impotency, then the administration of pre-
parations of iodine — as iodide of potassium, iron, or mercury,
will probably prove of value. Percivall, long ago, suggested
the employment of iodine. After recommending bleeding,
purging, alterative medicines, and counter-irritation, he
remarks : " I know of nothing more that can be done by

134 Roaring in Horses.

way of treatment for Roaring, unless we choose to try
iodine ; it may either be given internally, or employed as an
ointment, or used in both ways. I have not yet myself had
an opportunity of making trial of it."i Trasbot has given
iodide of potassium with good results, and I have also em-
ployed it, alternately with arsenic (Fowler's solution), with
excellent effect in some cases in which Roaring was recent.
Zundel has tried this treatment, and lauds it highly

Strychnine, given internally, and also applied hypoder-
mically over the larynx, has been favourably spoken of by
several Continental veterinary surgeons. It has also been
employed to discover whether Roaring maybe really due to
paralysis of the abductor muscle, and whether the muscle
yet possesses any contractile power, by injecting it beneath
the skin over the left side of the larynx.

Electricity, in the form of Faradisation, I have employed m
two cases, which perfectly recovered.^ It was tried, in con-
junction with the administration of iodide of potassium,
alternated with Fowler's solution of arsenic, upon the Duke
of "Westminster's Ormonde, and it certainly appeared to
have the effect of preventing an increase of the noise, and
consequent distress in breathing of that grand race-horse.
It might be claimed, I think, that it assisted him to achieve
the victories of his final year on the turf; and it would, m
all probability, have kept him a successful horse durmg the
following year. For in Ormonde, when I first recom-

1 " Hippopathology," 1840, vol. ii., p. 53. . x i.

^ "Veterinary Journal," vol. xiv., p. 93. The same treatment
appears to be serviceable in our own species, when similarly affected.
Lennox Browne, for instance, gives the case of a lady who consulted
him for severe attacks of hoarseness and dyspncea. A careful examin-
ation led to the conclusion that there was congestion and paralysis ot
the left vocal cord, due to enlarged bronchial glands pressing on the
recurrent nerve. Under the influence of doses of iodide of iron as
well as external counter-irritation, the patient greatly improved.-
" The Throat and its Diseases." Second Edition, p. 478.

3 " Veterinary Journal," vols, xiv., p. 94 ; xxiv., p. 353.

Preventive and Curative Treatment.

135

mended this remedy, though the noise was somewhat loud,
there were indications that the dilator muscle was only weak,
and not wasted, and Faradisation was adopted in order to
strengthen it, or at least to prevent its degeneration ; while
the medicine was given with the view of restoring the func-
tion of the left recurrent nerve. The current was applied to
the nerve on its course in the jugular furrow, the battery
employed being specially constructed for this purpose

Fl(j. 8. — BATTERY CONSTRUCTED FOR THE TREATMENT OF ROARING.

(Fig. 8), and the application being made for some minutes,
in a mild degree, several times a day.

This treatment, however, demands patience and constant
attention for a considerable time ; it is, of course, of no per-
manent value if the nerve cannot be restored to its normal
condition, and is valueless if the dilator muscle has dis-
appeared entirely, or even partially.

(&) Surgical Treatment of Roaring.
The surgical treatment of Roaring was for many years
limited to applying the actual cautery to the skin over the
larynx, and blistering that part ; but this was found so

136

Roaring in Hwaes.

unsuccessful that it was generally given up, and the relief
of horses affected with the defect was considered hopeless,
except through the adoption of tracheotomy, and con-
stantly wearing a cannula in the opening made in the wind-
pipe— a palliative remedy introduced by French veterina-
rians early in this century.^

But this cannula-wearing is so objectionable in many
respects, that it was soon generally discontinued, and is now
only resorted to on rare occasions. It does not remove the
cause of Roaring, but is merely designed to circumvent it
by establishing an artificial breathing-opening below the
larynx and nearer the lungs. In connection with this
operation, Percivall, in speaking of bands of lymph causmg
the noise, alludes to another, — a kind of will-o'-the-wisp hunt

which is curious. "It is said-^for its truth I cannot

vouch — that, once upon a time, a veterinarian, in perform-
ing the operation of bronchotomy on a Roarer, had the
good luck to cut against one of these bands of lymph, and
so, like a prudent man, excised it, and thus fortuitously
achieved a cure on the horse which he had anticipated but
to relieve. The circumstance was eagerly caught at as
opening a new and successful field to experimenters, and the
windpipes of Roarers were most mercilessly slit open in
search of similar bands. Alas! so many disappointments
followed that the novel operation was abandoned." ^

1 A similar palliative to tracheotomy may be noticed here. To
diminish the volume of air passing to the larynx of Roarers during
exertion, and so to lessen the noise and distress, it has sometimes been
the custom to fasten a narrow strap over the nostrils, so as to prevent
these becoming too widely dilated. The strap is fixed to each side of
the branch of the bit, and is kept in position by another strap, also
attached on each side to the head-stall of the bridle. To the inner
surface of the nostril strap, immediately over each false nostril, is
sometimes fixed an oval pad. When applied, these pads press upon
the triangular spaces formed by the point of the nasal bones and the
upper jaw, and in this way they prevent distension of the false
nostrils, as well as limit the dimensions of the true nostrils.

2 " Hippopathology," vol. ii., p. 52.

Preventive and Curative Treatment. 137

So long ago as 1834, Gunther, of Hanover, from a care-
ful study of the alterations observed in the larynges of
affected horses, ventured to attempt relief to them by
operating directly or indirectly on the larynx, but without
success.i He and his son, K. Gunther, again instituted ex-
periments in 1845, upon affected and healthy horses, with the
view of testing the feasibility of removing the obstruction in
that organ, so as to allow the passage of a larger volume of air
through it. Operating through the trachea, at first both
vocal cords were removed in horses that roared, but the result
was negative. Then the vocal cord of the affected side was
extirpated, but the Roaring was not diminished, but rather
increased— owing, it is supposed, to the retraction caused
by cicatrization, which drew the ar3-tcenoid cartilage deeper
into the larynx. Trial was made of passing a seton through
the laryngeal sac, but this failed ; then the experiment was
made of removing the vocal cord and the laryngeal sac, as
it was believed that the latter also hindered the admission
of air ; but here, again, the success was nil. The entire
arytaenoid cartilage was then excised, but all the horses
died, through food and water passing into the trachea
and lungs. Better results, in some instances, followed
excision of the anterior part of the arytsenoid carti-
lages {processus vocalis) and its vocal cord, great im-
provement being noted ; but in other instances the defect
was aggravated, in consequence of cicatricial contrac-
tions. When very severely exerted, however, though the
horses roared, there were no signs of asphyxia. One
horse was rendered much worse, because of caries and dis-
tortion of the cartilage. Finally, they endeavoured to
bring about a firm adhesion between the inner surface of
the thyroid and the outer surface of the aryta^noid cartilage,
by excising the laryngeal sac, but leaving the vocal cord
intact. Here, again, the result was uncertain ; for while in

^ "Die Topographische Myologie des Pferdes," etc. Hanover, 1886.

138

Roaring in Horses.

some cases adhesion between the cartilages took place
sufficiently high to fix the arytienoid well back out of
the way, and consequently to prevent Roaring, in others
this union occurred too low or was incomplete, and the
horses remained roarers.

On the whole, the results obtained by the Professors
Glinther were unfavourable; and when Gerlach,^ of the
Berlin Veterinary School, was unsuccessful in effecting any
improvement in the condition of Roaring horses by partial
removal of the arytLenoid cartilage, operation for the defect
appeared to be generally condemned in Germany.

The distinguished Danish veterinarian, Stockfleth,^
director of the Copenhagen Veterinary School, who visited
Hanover in 1857, concluded that removal of the upper part
of the left arytsBuoid cartilage would prevent the noise in
inspiration, and experimented in this direction. He en-
deavoured to avoid injuring the left vocal cord (which he said
was difficult), as he considered it should be left entire, in
order to maintain the remains of the arytenoid cartilage in
situ. But he found that, though operation was limited
to the upper part of the cartilage, yet considerable swelling
ensued, owing to inflammation of the perichondrium ; the
glottal space was consequently much encroached upon, and
therefore the Roaring persisted. But when the healing
process took place without perichondritis and tumefaction,
the noise was no longer perceptible, and the horse was fit
for work. In Stockfleth's hands, however, the operation was
almost as uncertain as in those of the Gunthei's, and deaths
from asphyxia were not infrequent, while some of the horses
operated on were worse than before. He considered that
the operator must be twice favoured by fortune to be suc-
cessful : he must have removed sufficient of the arytjenoid
cartilage, without wounding the vocal cord or thyroid carti-

1 " Gerichtliche Thierheilkunde," 1862.
■ 2 "Handbuch des Thierarztlichen Ghirurgie." Translated from
Danish by C. Steffen, Leipzig, 1881, p. 263.

Preventive and Curative Treatment. 139

lao-e • and no orreat amount of connective-tissue tumefaction
should occur to fill up the glottis.

Professor Bassi, of the Turin Veterinary School, and a
few others, tried Stockfleth's method, and with the same
uncertain and, on the whole, unsatisfactory results.

The exceptional importance of the subject induced Pro-
fessor Moller,! of the Berlin Veterinary School, to take it up,
and to institute experiments with the same object, and
somewhat after the methods of Glinther and Stockfieth, in
1887. He tried extirpation of the left vocal cord, but
failed to remove the Roaring. Concluding that the noise
was caused by the inferior and posterior portions of the
aryteenoid cartilage, attempts were made to effect a cure by
fixing this cartilage. To accomplish this, three methods were
tried : 1. Opening the articulation between the arytsenoid
and cricoid cartilages, from the trachea, and separating part
of the connection between these ; this was unsuccessful. 2.
Dividing the left dilator muscle,hy making an opening on the
side of the neck, beneath the parotid gland, and through the
constrictor of the pharynx, with the idea that retraction and
cicatrization of the divided muscle would fix the arytsenoid
cartilage. This operation was also a failure, as might have
been expected, when we know that in the great majority of
cases there is little or no muscle left to operate upon. 3.
Fixing the arytsenoid to the cricoid cartilage, by attaching it
to the upper part of the thyroid cartilage by ligature, without
opening the trachea or larynx. Here, again, the result was
not satisfactory, for the Roaring continued. Moller then
decided to extirpate the arytsenoid cartilage, by intra-laryn-
geal operation f and in this he appears to have been pretty
successful, though he would probably have been more so had
he entirely removed it and the vocal cord ; but he claims to

1 " Das Kehlkopf-Pfeifen der Pferde," Stuttgart, 1888.

^ I was not aware that Professor Moller was performing this
operation until he kindly sent me a copy of his booklet immediately
after its publication, in August.

140

Roarmg in Horses.

have cured twenty-two of thirty Roarers operated upon.
Of the remaining eight, five were reUeved somewhat — one
of them having paralysis of both sides of the larynx, and,
consequently, both arytenoid cartilages were removed ; two
died from blood-poisoning (septikcbmia), or doubtful phleg-
monous laryngitis ; in another case there was a relapse in
ten months ; and the eighth, during recovery, had to be
destroyed because of a fractured limb.

In the cases in which a noise still remained, this was
much less than before, and thg breathing was so much
relieved that work could be performed. The result was
more favourable in cart than in riding horses.

For many years, Roaring in horses had received much of
my attention, and the practicability of its prevention and
cure by medical treatment has been tested for a long time. '
So long ago as 1878, the feasibility of successful operation
on the larynx for the removal of the obstruction to respir^
ation was suggested by an accident which happened to an
aged horse, in which the thyroid cartilage was fractured.
In attempting to remedy this injury, the cavity of the larynx
was exposed, and I was astonished at the impunity with
which its interior could be manipulated. Operations upon
the larynx of the horse were previously unkno\vn, I be-
lieve, in this country— at least, I can find no record^ of
them, and there seems to have been a dread of openmg
it; consequently, disease in it could not be observed
until after death, and if polypi or tumours were present
in it or in its immediate neighbourhood, there they
remained, notwithstanding the distress the horse may
have experienced. The revelation afforded by the accident
alluded to, induced me to attempt the removal of Roarmg
by the simplest and safest operation possible ; but, like those
who had preceded me in this business, though not then cog-
nisant of any except the Giinthers' attempts, the way had
to be felt, as all was novel and strange, so little bemg
known of the physiology of the horse's larynx, or of its

Preventive and Gwrative Treatment.

141

amenability to surgical treatment. The inadvisability of at-
tempting the removal of obstruction by lateral extra-laryngeal
operation was evident, for anatomical reasons ; also, because

Fig. 9.

Vertical antero-posterior section of the Horse's larynx, showing the
interior of the left side, and direction of incisions in the vocal cord
and arytenoid cartilage ; i to j, excision of vocal cord and processus
vocalis of the arytsenoid cartilage ; g to /;;, excision of inferior portion
of arytsenoid cartilage ; I g Ic, excision of upper part of arytasnoid
cartilage.

in this way one could not be certain that the Roaring was
really due to immobility of the left arytsenoid cartilage ; and,
lastly, because success was far less likely to be the result.

142 Roaring in Horses.

Removal of the obstruction was sought to be obtained
with as little mutilation as possible, and it was resolved to
proceed step by step until it was ascertained what, and how
much, it was necessary to excise in order to enable the
respiration to be carried on noiselessly and with ease.

The left vocal cord (Fig. 9, g) was extirpated through an
opening made in the middle crico-thyroid ligament, between
the wings of the thyroid cartilage. This was not found satis-
factory, so far as the noise was concerned, and the excision
was then extended to the anterior portion of the arytnenoid
cartilage {processus vocalis. Fig. 9, itoj, black dotted lines).
For about a month, two horses operated on in this manner
made no noise, but whether from being put to severe
exertion too soon, from exuberant granulations springing
up in the laryngeal wound, or from the remaining portion
of the aryt£enoid cartilage falling deeper into the acUus,
the Roaring reappeared, though the distress in breathing
was removed. A portion of the vocal cord and the greater
part of the arytajnoid cartilage (Fig. 9, /c to g, light clotted line),
were next removed ; but with no better results, so far as the
Roaring was concerned, the chief trouble being the extra-
ordinary tendency of the remaining cartilage to rapidly
throw out luxuriant granulations of great density, and
which occupied almost more space in the cavity than did
the parts that were removed. _

Next the upper portion of the cartilage was excised (J^ig.
9, I q k), but this also was unsatisfactory. , ^ ,

Then it was decided to excise the whole of the left
arytienoid cartilage; this, in causing close adhesion of the
vocal cord, and consequent obliteration of the aryngeal sac,
bv which the larynx would be completely cleared of the
obstruction, must, it was surmised, a^ow ample space for
a full volume of air ; while, no fragment of cartilage bemg
left troublesome granulations were not so likely to interrupt
the healing process. The experience gained m the previous
operations^howed that there could be little danger m this

Preventive and Curative Treatment.

143

one, notwithstanding Gllnther's misfortunes ; and that in-
jurious contraction from cicatrization was not hkely to
follow.

It was found, however, that the small opening through the
middle crico-thyroid ligament, though permitting easy access
to the interior of the larynx, would not allow extensive intra-
laryngeal operations to be easily performed ; the incision was
therefore carried through this ligament, the cricoid cartilage,
the crico-tracheal ligament, and, when necessary, one or more
rings of the trachea. By this larger opening, removal of the
left arytfenoid cartilage could he easily effected, its passive
condition during swallowing (caused by passing the finger or
a long probe up towards the epiglottis) or active respiration,
being previously ascertained through the wound. Not only
was this the case, but for a day or two after the operation,
when swallowing was imperfectly performed, it was observed
that any food or water that passed into the larynx escaped
by this dependent opening ; while the healing process could
be watched and regulated for as long as there was any
chance of excessive granulation, or other cause, rendering
the cure less certain.

The results were in some cases satisfactory, in others not
so ; and it was then discovered that, in the latter, the
persistence of the noise was due to the left vocal cord,
which, owing to cicatrisation of the wound not having
drawn it close to the thyroid cartilage, projected into the
larynx and caught the entering air. This was a practical
demonstration of the share this part takes in noise pro-
duction. Consequently, it was found necessary, in order to
ensure a more certain cure, to excise the vocal cord and
arytfenoid cartilage. This added very little to the operation
wound, as in removing the cord the incision was limited to
its fixed border, which is narrow, and the thyroid cartilage,
being lined by mucous membrane to the bottom of the
ventricle, was in no way endangered.

This perfected operation has had most encouraging

144

Roaring in Horses.

results, and so far as these go, it might be anticipated that
a very large percentage of horses affected with Roaring
may be rendered serviceable, and perform their work with-
out impediment in respiration.

In a few cases there may remain a slight " coarseness "
in the breathing for some time after . the operation, and the
noise may even be rather marked until the wound has
completely cicatrised, and the larynx has had time to ac-
commodate itself to the altered conditions.

A large number of troop and officers' horses have been
operated upon,under my direction, by Mr. F. Raymond, of the
Army Veterinary Department, and without a fatal case or
accident of any kind, notwithstanding that every horse was
thrown down and placed fully under the influence of chloro-
form for the operation ; besides having the interior of the
larynx frequently examined, and sometimes the wound
surface dressed, during the healing process. Of course, this
success depended upon the skill with which the horses were
treated, both during operation and subsequently ; care in
the administration of the chloroform ; expertness in surgical
manipulation, acquired by practice ; close attention to the
wounds for some days ; and the strict observance of sanitary
precautions.

Cicatrisation has generally taken place favourably and
rapidly, and without undue, if any, contraction of the mucous
membrane. The walls of the larynx (thyroid and cricoid
cartilages) being firm and unyielding, and the mucous mem-
brane being rather closely attached to them at the seat of
operation, contraction is not very probable. In some cases,
the granulations, being rather exuberant, required checkmg
or removal; but with the acquirement of expertness in
excising the arytenoid cartilage, and the adoption of certam
precautions, the wounds gave little trouble, and the heahng
process was generally rapid.

It may be mentioned that of all the horses prepared for
operation, only one was found with both arytenoid carti-

Preventive and Curative Treatment

lages alike movable when the larynx was opened ; showing
that the noise made in respiration was not due in this case
to laryngeal paralysis ; and also demonstrating the value of
operating in the larynx from the front.

A very old horse (sixteen years at least), an extreme
case of Roaring, was operated on ; but it was observed
that the right cartilage moved very feebly, and that the
cavity of the larynx appeared altogether constricted.
The operation did not afford much relief, and the animal
was consequently destroyed about three months afterwards
for examination. The left vocal cord, which had not been
excised, projected from the inner surface of the thyroid
cartilage, but there was no constriction from retraction of
mucous membrane ; the right dilator muscle was pale and
much degenerated in its middle portion, and its arytsenoid
cartilage and corresponding vocal cord consequently ob-
structed the lumen of the larynx. This might almost be
designated a case of bilateral paralysis.

It may be noted that, notwithstanding removal of the
arytsenoid cartilage and the vocal cord, the horse can
swallow, cough, neigh, sneeze, and perform expulsive acts
as if these were still present, and that the operation does
not appear to cause any inconvenience whatever to the
animal afterwards. In the course of a few months it is
very difficult to discover any traces of the operation in
the region of the neck.

10

CHAPTER X.

THE OPERATION FOR ROARING.

Having stated the results of operation for Roaring, so far
as they have been ascertained, it now remains to describe
(1) the operation itself, and (2) the after-treatment. It
is of course understood that the operation is intra-laryn-
geal, the larynx being opened from the front. This has
been found to be the simplest, safest, and most expeditious
operation, as well as the most certain in its results, of any
yet attempted for removing the obstruction to respiration.

1. Operation.

Apparatus and Instruments Necessary.— These con-
sist of:

■ 1. Hobbles for casting the horse.

2. Side-line, or piece of rope.

3. Twitch, which may be necessary to ensure quietude

before casting. , , r i

4 Chloroforming apparatus. Carlisle's chloroform bag
or muzzle (Fig. 10) is the best. This consists of a leather
bao- fitting closely over the nose, with an aperture at the
bottom, into which a tray slides. This tray is of tm, and
is furnished with a sponge covered by a perforated metal-
plate (A) The chloroform is poured upon the sponge when
the horse is cast, and the tray is slipped into the aperture
in the bag, which is then fastened on the horse's head
Between the perforated plate and the nose a few smaii

The Operation for Roaring. 147

round iron bars pass across the interior of the bag, to
support it and prevent the plate being damaged.

5. Buckets of water and two or three sponges. Some

r

Fig. 10.

small sponges, each securely fastened to a cane ten or
twelve inches long, are very useful.

6. Syringe to contain a pint or quart of water.

7, Strong ordinary forceps and scalpels (Fig. 11).

Fig. 11.

8. Bull-dog forceps.

9. Tracheal tampon-cannula (Fig. 12). This is a modi-
fication, by Moller, of Trendelenburg's cannula for tracheal
operations in man. It consists of a long tracheotomy tube,

10—2

148

Roaring in Horses.

with an indianibber bag surrounding its middle. This
bag is inttiitcd by an- india-rubber air-pump after the tube
has been, inserted in the trachea, and is useful in preventing

Fig. 12.

blood flowing into the bronchi during the horse's getting
up after the operation, and for half an hour subsequently.^
10. Razor-shaped knife, for excising the arytsenoid carti-
lao-e (Fig. 13). This knife, suggested by Moller, has the

AllNOLD a SOhfi LOMOON

Fm. 13.

end of the blade like that of a razor, and is consequently
safer than a scalpel. The blade is 3i inches, and the
handle 8 inches long.

r

ARiHQLb Ei SONS LONDON

Fjg. 14.

11 Bent knife, for removing the muscles from the out-
side of the arytsenoid cartilage (Fig. 14). The length of
the blade is 3 inches, and handle 4 inches.

The Operation for Roaring.

149

12. Hook, for seizing and raising the lower end of the
aryt£enoid cartilage (Fig. 15). This is 3^ inches in length,
the handle being 7 inches.

& .1 M 01. D ft S OH *: LOM

Fia. 15.

13. Special forceps, with toothed ends, to seize the body
of the arytJBnoid cartilage, and a catch at the handles to
fix the blades, and eyelets for the fingers (Fig. 16). The

length is 8 inches

ABNOUD ft SONS LONDON ' '^

Fig. 16.

14. Curved scissors, to cut through the mucous mem-
brane (Fig. 17). The length is 8| inches. ,

Fig. 17.

15. Two retractors, to keep the trachea open during
operation (Fig. 18). The^e are perhaps best made of strong
wire slightly flattened, double, and opened and bent, so as to

Fig. 18.

form an angular portion about 3 or 4 inches wide. The
length of the handle part may be 6 to 8 inches, that of the
bent portion about 2 inches.

150

Roaring in Horses.

%

16. Electric-lamp, to illuminate the interior of the
larynx. Mr. Raymond has introduced a most useful lamp
for this purpose (Fig. 19). It is bent at an angle within
about two inches of the end of the handle, and a shield
fits upon this part ; the front of the shield, being plated,
forms a reflector ; while the back is covered Avith vulcanite,
which, lying against the tissues, protects them. The
advantages of this lamp are the excellent light it throws
upwards into the larynx and pharynx ; it may remain in
the trachea for a long period without doing any injury,
while it hangs into it by its bend, and does not require to
be held by the hand.^

Fig. 19.

A bucket containing a ten per cent, solution of common
salt or borax should also be ready.

Operation.— The horse should be well fed for a day or
two before the operation, but have little or nothing to eat
or drink for some hours before being operated upon. In
the case of thoroughbred horses, Mr. Raymond thinks it
advantageous to administer four ounces of tincture of
opium in a pint of water half an hour before operating.
The hair must be removed closely from around the upper
part of the trachea and larynx before the horse is cast.

1 All the instruments and apparatus are naade by Arnold and Sons,
surgical instrument makers, West Smithfield, London.

The Operation for Roaring.

The animal is thrown down in the usual manner, on a
good bed of straw or moss litter. The cHo-lorm bag
is put on ; the tray having been previously removed from
it. the chloroform is uow poured over the sponge m t, and
it is inserted in its place in the bottom ot the bag. The
suitable state of narkosis having been mduced, and which
is promptly arrived at in from one to two or three mmutes
-beinc indicated by cessation of struggling, more tranquil
breathing, the appearance of the eye and the loss of sensa-
tion-the animal is placed on his back and mamtained there
by sacks filled with straw, placed close under each side of
the body. If there is a beam above, the hobble-rope may be
passed over it and held by one or two men; this mil
maintain the body in the dorsal position Or, with the
same object, a man may be placed on each side with an
arm round a fore leg. The neck and head are extended m
a Hne with the body, the head being placed on the vertex,
and kept steady by an assistant. The operator Peaces him-
self in a kneeling position on the off, or right, _side of the
body, if he be right-handed, beside the neck, with his back
to the shoulder and face towards the head.

He is now ready to operate, and for clearness of descrip-
tion the operation may be divided into three stages.

. The quantity of chloroform required to produce complete narkosis
does not vary much. For the great majority of horses o-^ ^ -^^^
ounces has sufficed.and a veryfew required two or ^-[-^^^^^^^''^^^
More than seventy horses have been chloroformed ^ ^^^^^^

Lousness, are important advantages to be f ^^^^^ ^« ^'^^
Carlisle's bag, while the after-effects are scarcely percepUble. By he
ordinary way of administering chloroform, a large q"^>^t^*y J
drt is required-as much, Sometimes, as eight or ten ounces, or even
lor' -the'inhalation often occupying half an hour, and recovery from
the effects is generally protracted.

152

Roaring in Hursea.

First Stage. — With a scalpel, an incision of from four to
six inches in length is made through the skin in the
middle lino of the larynx and trachea, opposite the posterior
border of the lower jaw, extending from the body of the
thyroid cartilage to the second or third tracheal ring. This
exposes the subscapulo-hyoid, sterno-hyoid, and sterno-
thyroid muscles, which are incised to the same extent, and
as close as possible at their line of junction {;r-a'ph4) in the
middle, the section being carried clean through to the
larynx and trachea. There is a variable amount of haimor-
rhage now to contend with ; this, if only oozing, may be
checked by sponging dry until blood has ceased to flow ;
and if from twigs of arteries or veins, these may be seized
and twisted, or ligatured.

Second Stage. — The middle cricoid-thyroid ligament,
cricoid cartilage, and one, two, or three tracheal rings are cut
through in a straight line, exposing the interior of the
larynx and trachea. If any blood-vessels are cut, these
should be taken up. A retractor (Fig. 18) is applied to
each side, and, these being pulled gently apart by an
assistant, there is ample space to manipulate in. The
convex lower border of the arytsenoid on each side can now
be seen, and if respiration is deep, that next the operator
(the right) will be observed to move actively from the side
towards the middle; while if the Roaring is due to paralysis
of the left dilator muscle, there is no movement in the
opposite cartilage. When the breathing is very tranquil,
which is often the case, the right cartilage moves almost
imperceptibly, and it is then necessary to ascertain whether
the left one is really immovable. This can be done by
passing the finger, or a long probe, up towards the
epiglottis, when swallowing will be excited, during which
act the right arytsenoid cartilage is energetically jerked
into the middle of the cavity; but the left one does not
stir, or only feebly, depending upon the degree of wasting
of the constrictor muscles on that side.

The Operation for Roaring. 153

Any blood that lodges in the trachea can be removed by
large or small (handled) sponges, which may be passed to
the operator by an assistant, who receives and washes
them. As the horse is now breathing through the wound,
the chloroform bag may be removed, being no longer
necessary.

Fig. 20.— Left-side Section of Larynx, showing the Parts
Excised in the Operation for Roaring.

It is always advisable to examine the interior of the
larynx carefully, in order to- ascertain its exact condition,
as there may be something more than an immovable
cartilage. For this purpose Raymond's lamp is invaluable.

The left arytsenoid cartilage may be excised by com-
mencing at the lower convex border (Fig. 20, '2), or at the

154

Roaring in Horaea.

upper part, where it meets the right cartilage (Fig. 20, 1).
If the last method is resolved on, then with the razor-shaped
knife (Fig. 13) a cut is made through the mucous membrane,
inter-aryttenoid ligament, and aryttunoid muscle, as close to
the margin of the cartilage as possible, beginning between
the cartilages of Santorini, downwards and then upwards to
the vocal process, at the insertion of the vocal cord (Fig.
20, 2). The hook (Fig. 15) is inserted into the vocal process,
which is raised, and the vocal cord is separated from the
cartilage by scissors ; then, with the bent knife (Fig. 14),
the muscles on the outside of the cartilage are cut, or
better, pushed from its surface as close as possible. The
hook is removed, and the body of the cartilage seized by
the rachet forceps (Fig. 16). With the curved scissors
(Fig. 17) the mucous membrane connecting the cartilage to
the vocal pouch is divided, cutting as close to the cartilage
as possible, so as to save the membrane. The arytenoid
cartilage is now free, except at its articulation with the
cricoid, and by means of the scalpel it may either be dis-
articulated or cut through at this point, care being taken
to leave no loose portions or shreds. The cartilage being
now only retained by the soft parts at the upper portion
(base of the arytsenoid cartilage), with scissors these are cut
through close to it, when it is altogether detached. ^

Care must be taken not to wound the other cartilages or
the pharyngeal mucous membrane, and to spare that mem-
brane in proximity to the arytenoid cartilage as much as
may be, removing only that which covers its surface and the
cartilage of Santorini.

The vocal cord is now removed close to its attachment
to the thyroid cartilage in front, and at its fixed border
(Fig. 20, 4). This can be done with scissors, a finger being
passed to the bottom of the ventricle to facilitate the
excision ; or the cord may be drawn from the side by a
hook inserted into it, so as to allow the scissors free play.
If the haemorrhage is troublesome, which it seldom is,

The Operation for Roaring. 1^5

the blood can be mopped out of the trachea by the
sponges ; it cannot pass down that tube, owing to the
.position of the neck. If necessary, the electric-lamp may
be employed to ascertain how the operation has been
performed, or even during the operation ; but after a little
experience this is not needed.

Third Stage.— The trachea is completely freed from
blood, and the tampon cannula introduced, the bag being
inflated after it has been properly passed into the trachea,
by means of the indiarubber pump ; the cannula is then
secured in position by a tape round the neck. It is only
required for about half an hour, until the haemorrhage has
ceased, as it will prevent blood passing into the lungs
while the horse is getting up, and for a short time after-
wards, respiration being carried on through the tube. It
ought not to be left in any longer, as it is liable to
injure the interior of the trachea. The blood is again
cleared out of the larynx, and one or two syringefuls
of the common salt or borax solution are injected mto
it and the pharynx. This washes out these cavities
and the sinuses of the head— a necessary precaution,
as putrefying blood in them sometimes gives rise to trouble-
some consequences. Swallowing should be induced by
touching the epiglottis, and then the horse may be turned
on his side, the lower margin of the wound being depressed
to allow the remaining blood and water to flow out. This
completes the operation.^

The horse is now allowed to recover from the chloroform,
and when ready he may be assisted to get up, care being

1 Though it has required some time to describe it, yet the operation
may be rapidly performed by an expert operator. I was present on
one occasion when Mr. Raymond went through the whole course of
operation in five minutes ; this embracing throwing the horse down,
giving the chloroform, opening the larynx and trachea, excising the
cartilage, and inserting and securing the cannula. The usual time he
'occupies is ten to fifteen minutes.

156

Roaring in Horses.

taken that the cannula is not displaced while doing so.
The wound is kept open by the finger for a short time,
to allow any blood to escape ; afterwards the blood is
cleaned away from and around the wound, the face and
nostrils sponged to refresh the animal, and the body
clothed and legs bandaged, if the weather is cold.

2. After-treatment.

When able to walk after the operation, the horse is led
quietly into a loose box which has no litter on the floor,
and the head-collar is removed. It is very necessary, in
order to ensure healthiness of the wound, that the box and
its surroundings be kept scrupulously clean, the drainage
beinof srood and the air sweet. The wound is to be left
open and undisturbed. Serosity and mucus will escape
from it for a short time after the bleeding has ceased, suc-
ceeded by slight purulent discharge as the healing process
goes on. The external wound is to be kept free from dis-
charge, and if flies are troublesome it may be dressed with
a weak solution of carbolic acid, or covered with a piece of
thin muslin, tied by tape around the neck.

The advantages of removing the cannula soon after the
operation lie chiefly in the injury it is likely to inflict in the
trachea if left there for a considerable period ; respiration
is not so easy with as without it ; while its accidental dis-
placement or obstruction might be serious.

Leaving the entire length of the external wound open is also
essential to success. Not only does tbis permit the horse
to breathe entirely through the aperture, and so obviates air
passing over the intra-laryngeal wound, but it also allows the
movements of the larynx to be greatly diminished, and
this still further promotes rapid and favourable healing;
while it renders inspection easy, and any needful dressing
of the interior can be effected. Another advantage is,
that the external wound, being immediately below the

The Operation for Roaring.

157

pharynx and larynx, any food or water which might chance
to pass into the latter a few days after the operation falls
directly through the opening, instead of finding its way
into the lungs.

For a few days, the horse does not seek to eat or drink
much. Indeed, it is better not to give food or water for
two or three days, as swallowing is not easy, and is, besides,
not favourable to the earlier stage of the healing process.
A small quantity of water may be allowed at first, being
offered in a bucket placed on the floor. Some of this may
escape through the external wound, but none passes down
the trachea. When water can be swallowed, sloppy mash
of bran and oatmeal may be given— still in a bucket on
the floor ; and in a day or two after, good soft hay.

It is advisable not to have any litter in the box, for
sanitary reasons, and also because the horse may eat it, if
it be straw ; while it may get into the wound and cause
trouble. In the course of a fortnight or three weeks, the
horse may be fed in the usual way on the ordinary diet.

The dangers to be apprehended are traumatic pneumonia,
pyemia, oedema of the larynx, and excessive granulation
and tumour formation at the seat of operation.

With regard to oedema, a certain amount of inflammatory
infiltration must take place after such an operation ; but it
ought not to cause inconvenience, and should in no way
embarrass the respiration, as it is present for only a short
time, and the laryngo-tracheal wound permits the free
admission of a sufficiency of air.

The intra-laryngeal wound need not be examined closely
until about the eighth day; though the external wound
should be cleaned frequently— twice or thrice a day— with
a soft sponge, and dressed with a mild antiseptic lotion. A
good criterium as to the condition of the internal wound
is afforded by that of the external one. If in the latter
the granulations are small and firm, then in the former
they will generally be found the same ; but if they are soft

158

Roaring in Horses.

and spongy externally, and form rapidly, then it may be
surmised they are in this condition in the larynx.

In order to examine the interior of the larynx — which
may be done in about a week after the operation — it is
safest and most satisfactory to put the horse in the dorsi-
cumbent position, as for the operation, though ansesthesia
is not necessary.

The electric lamp will prove useful in illuminating every
part, and the retractors are needed to give sufficient space
for scrutiny. A solid retractor (Fig. 21) does not injure the
external wound so much as the open one.

Fig. 21.

Granulations, if too luxuriant, may be cleaned from
mucus or pus by the small sponges with handles, and
swabbed with a solution of chloride of zinc (1 to 10), sul-
phate of zinc (1 to 60, or 2 grains to the ounce of water),
or corrosive sublimate solution (1 to 1,000) ; or touched
with solid nitrate of silver, securely held in a caustic-
holder with a long handle. In some cases there is no
need for this interference with the healing process, which
goes on favourably from beginning to end. In other
cases this dressing may be necessary more than once, and
may be repeated in the way indicated above ; while in some
instances tumours will appear, seemingly in spite of all pre-
cautions : though it must be admitted that, if the operation
is not well performed, and small pieces of cartilage, or shreds
of mucous or muscular tissue are left, they are likely to
spring from these. If they are discovered on examination
of the intra-laryngeal wound in a week after the operation,
they should be removed by means of scissors or the

The Operation for Roaring.

159

o-alvano-cautery, and the parts dressed with a mild caustic
or astringent solution. They rarely appear after the first
or second week.

When the internal wound is healing favourably, the
external one should be allowed to close ; this is effected
usually in three weeks. In about a month little trace is
left of the wound, and in two or three months it has to be
closely looked for. A head-collar may be worn when the ex-
ternal wound is nearly well, and then litter can be allowed.

The general health of the horse is rarely disturbed
after recovery from the immediate effects of the operation.
The temperature sometimes rises to 102° (Fahr.), but it has
never been noted beyond that point.

No instance of pneumonia, pysemia, or other serious
condition has been met with ; and if proper precautions
are adopted, there seems to be no reason why mishaps
should occur. If all has gone well, in a month or six
weeks after the operation walking exercise may be per-
mitted, and in another month trotting for a mile or two
. should be prescribed ; but severe exertion ought not to be
imposed for some time longer. Not only should cicatriza-
tion be allowed to become completed and consolidated in
the larynx, but that organ must be gradually allowed to
accommodate itself to the altered conditions in which it
has to perform its functions. In trotting, at first a noise
may be heard, but in time this diminishes, and usually
disappears.

If any harshness should remain in the respiration, there
is, notwithstanding, no distress exhibited, no matter how
severe the exertion may be.

When exercise is first begun, the horse sometimes coughs,
especially if the weather is cold ; but as the interior of the
larynx becomes less sensitive by complete healing of the
wound in it, this slight irritability disappears.

So far, the weather does not appear to exercise much
influence on the immediate results of the operation, which

160

Roar In;/ i n Horses.

has been performed in summer as well as in winter. The
great majority of the horses hitherto operated on have
been troopers — Cavalry, Artillery, and Transport ; all were
so seriously aft'ected as to be considered unfit for further
military service. Their ages varied from four to fourteen
years, and they were of all temperaments. With the ex-
ception that the operation was more difHcult in thick-
necked, coarse-bred horses, and the wounds were more
inclined to granulate too luxuriantly in them, there was
little difference noted in the whole of the cases.

THE END.

Baiimn, TindaU Jc Cox, 20 <fc 21, King William Street, Straitd.

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