«s
NORTH DAKOTA AGRICULTURAL EXPERIMENT STATION
(DEPARTMENT OF VETERINARY SCIENCE)
Swamp Fever
in Horses
By L. VanEs, E. D. Harris
and A. F. Schalk
BULLETIN 94
FARGO, N. D., SEPTEMBER 1911
UNIVERSITY OF CALIFORNIA
MEDICAL CENTER LIBRARY
SAN FRANCISCO
Gift of the
A. W. Hewlett Estate
!
North Dakota Agricultural College
GOVERNMENT AGRICULTURAL
EXPERIMENT STATION
OF NORTH DAKOTA
BULLETIN NUMBER 94
Swamp Fever in Horses
By L. Van Es, E. D. Harris and A. F. Schalk
Any farmer, teacher, or student in the State may have this Bulletin mailed
to his address, free of charge, upon application.
FARGO. NORTH DAKOTA, U. S. A.
SEPTEMBER, 1911
BOARD OF TRUSTEES
CLARK W. KBLLEY, President; Devils Lake, N. D.
GEORGE H. HOLLISTER, Fargo, N. D.
H. D. MACK, Dickey, N. D.
C. E. NUGENT, Fargo, N. D.
PETER ELLIOTT, Fargo, N. D.
FRANK SANFORD, Valley City, N. I).
JOHN DONELLY, Grafton, N. D.
W. A. JTODEE, Secretary, Agricultural College.
W. P. PORTERFIELD, Treasurer, Pargo, N. Dak.
STATION STAFF
.1. II. WORST, LL. D., Director.
E. F. LADD, B. 8., Chemist.
C. B. WALDRON, B. S., Horticulturist and Entomologist.
II. !.. BOLLEY, M. S., Botanist and Plant Pathologist.
J. II. SHEPPERD, M. S. A., Agriculturist and Vice-Director.
L. VAN ES, M. D., V. S., Veterinarian.
W. B. BELL, Ph. D., Assistant Botanist (Plant Survey).
W. B. RICHARDS, B. S. A., Assistant Agriculturist (Animal Hus-
bandry).
ADOLPH ZIEPLE, Ph. C, B. S., Assistant Chemist (Drugs).
W. F. SUDRO, B. S., Assistant Chemist (Beverages).
R. E. REMINGTON, B. S., Assistant Chemist (Foods).
W. L. STOCKHAM, M. S., Assistant Chemist (Illuminants) .
.1. W. ENCE, A. M., Assistant Chemist (Soils).
H. L. WHITE, M. A., Assistant Chemist (Cereals).
H. F. BERGMAN, B. S., Assistant Botanist (Mycology).
R. ('. DONEGHUE, M. S., Assistant Agriculturist (Soils).
O. \Y. DYNES, B. S., Assistant Agriculturist (Poultry).
E. M. DOLVE, B. S., Assistant Agriculturist (Engineering).
E. D. HARRIS, D. V. M., Assistant Veterinarian.
A. F. SCHALK, D. V. M., Assistant Veterinarian.
A. McMEANS, Assistant Horticulturist.
ADELE SHEPPERD, Assistant Chemist (Waters).
E. B. PUTT, B. S., Assistant Chemist (Beverages).
M. L. DOLT, Ph. D., Assistant Chemist (libres).
L. W. SARGENT, A. B., Assistant Chemist.
C. V. KENNEDY, Farm Foreman.
W. A. YODER, Secretary.
SUPERINTENDENTS OF SUB-STATIONS
O. A. THOMPSON, Edgelev.
L. R. WALDRON, Dickinson.
E. G. SCHOLLANDER, Williston.
E. D. STEWART, Langdon.
W. R. PORTER, Superintendent of Demonstration Farms.
\
SWAMP FEVER IN HORSES
(From Department of Veterinary Science.)
By L. VAN ES, E. D. HARRIS and A. F. SCHALK
For some years past a peculiar disease of horses, widely
known under the name of swamp-fever, has engaged the
attention of veterinarians and horse owners of various sec-
tions of the Northwest. Also in our own state, the disease
has occasioned considerable damage and in order to obtain
some definite knowledge on the subject, this department
has been entrusted with a systematic investigation of the
disease. Other institutions and persons also have been en-
gaged in research work on the disease and it may not be
amiss to sum up the results of the investigations as well
as the more important features of the disease as we meet
it in the field.
It is uncertain when and where the disease first began to
attract attention. According to Torrance (12)> veterinarians
settling in the Province of Manitoba during the years 1881-
1882 soon had their attention called to it and to the fact that
the disease was at first confined to the country bordering the
Red River. From here it seems to have spread over a
large area of Manitoba and into some parts of the North-
west territories.
A disease, of which it is fair to suppose that it is iden-
tical with "swamp-fever" is described by Watson (6)> who
writing in 1896, states that the disorder first made its ap-
pearance in the vicinity of Eau Claire in the State of Wis-
consin some seven or eight years before. Since then it had
continued its distribution covering an area with a radius
of about one hundred miles.
125080
258
In 1899 Taylor (7) describes the Manitoba disease, but
it was not until 1902 that a full scientific description of the
disease was offered by Torrance ((J)-
In addition to the published reports of Torrance (9lL L5"
21-28-54), Rutherford (">■ Ballah <31>. Charlton <33>. Acres
<48>. McGilvray (64>- and Todd and Wolbach (75> contri-
buted to the Canadian literature on the subject.
From Minnesota the disease is mentioned by Brimhall,
Wesbrook and Bracken (10) in 1903 and by Beebe (18) in
1905.
From Nebraska, the disease is described by Peters (26)
in 1906; from North Dakota by Van Es (37-68> in 1907 and
1910; from Texas by Francis and Marsteller (42) in 1908;
from Nevada by .Mack (53-51-65-73) jn 1909 and 1910; from
Louisiana by Flower (57) in 1909; from Wyoming and Col-
orado by Whitehouse (56) in 1909; from Oklahoma, Kansas
and Missouri by Kinsley (6372) in 1910; from Washington
by Thatcher (71) in 191-0 and from the delta country of the
Mississippi and Arkansas by Norton (82) in 1911.
General descriptions of the disease were published by
Mohler (46-52-53-66) in 1908, 1909, and 1910.
Darling (58) writing from the Panama Canal Zone, also
makes mention of the disease clinically corresponding to the
swamp-fever of the United States.
While it is by no means certain that there is always
described under the name of ''swamp-fever" one and the
same disease, there is sufficient evidence to show that we have
among the horses of a large area of the continent, a disease,
which has thus far only received purely local attention.
On the European continent also there seems to exist
a disease, which is exceedingly similar to ours (at least for
so far as that of the Red River Valley is concerned) and
probably identical to it.
The disease has been described by various French
writers since 1843. In more recent times something like
our swamp-fever was observed in 1883 by Zschokke (1) in
Switzerland; in 1886 by Frohner (2) in southern Germany;
259
in 1890 by Osteriag (3) in Berlin; in 1901 by Kopke id) in
the vicinity of Metz; in 1904 by Jarmatz (14) among the
farm horses of Lorraine and by Vallee and Carre (16) in
various sections of France; in 1906 by Beghin (22) near
Florennes in Belgium; in 1906 and 1908 by Ries (27"47> in
Luxemburg; in 1907 by Brickman <32) in Sweden and by
Charon (34) near Sainte Menehoulde ; in 1907 by Ostertag
<35) in the vicinity of Trier; in 1908 by Friedrich <44> in
Kur-Hessen; and, in 1909 by Hutyra and Marek (69) in
Hungary.
It is not quite certain that the American disease is iden-
tical to the one described, but there are very strong indica-
tions that it is.
The name under which the disease is most widely known
in this country plainly indicates that it is most prevalent
in low, marshy sections or during wet seasons. ' Torrance
states that the worst infected districts are notably those
in.! rest to sea-level and during wet seasons the losses there
are very great. In a later report (15) he points out that the
ebb of the disease in Manitoba, which had a dry summer,
appears to coincide with an increase in the Northwest ter-
ritories, where the season was unusually wet, a fact which
lends support to the theory of swamp-infection as the main
source of the disease.
In the investigation of the disease in Minnesota by Brim-
hall. Wesbrook and Bracken (10)- two distinct foci of distri-
bution came under observation. In one focus, the same
geologic formation generally prevails. The soil is a heavy
black loam, while the country is markedly flat and there
is but little natural drainage. Bogs and small lakes and
ponds are very apt to form, wherever flowing wells are
present. Wherever the land is a little lower than the sur-
rounding country, water will stand on it for a considerable
time each year or there may be an abundant growth of
swamp-grass. The second focus of the disease did not show
the same uniformity in geologic features and topography,
2G0
nor was the disease as generally prevalent as was the case
in the other focus. The country is rolling, with an exception-
ally light sandy soil, in many places well wooded. In neither
of the two districts could low places be excluded, although
the observers failed to find conclusive evidence of the relation
between those circumstances and the occurrence of swamp-
fever.
Rutherford (n> states that the disease is most prevalent
in a low lying swampy country. Peters <26) found the dis-
ease on marshy pastures during wet seasons. Francis and
Marsteller <42') describe the disease as occuring in the flal
coast region of their state. Acres (48> found the disease
only on low-lying and swampy pastures where the water
becomes stagnant during the hot months of the year. Moh-
ler (5266) finds that the disease is most prevalent in low-
lying and badly drained sections of the country and con-
siders the drainage of infected pastures indicated, as a
preventative measure. According to him the disease has
been found in altitudes as high as 7,500 feet on marshy
pastures during wet seasons. Kinsley (63) observed that
the wet seasons seemed to increase the prevalence of the
disease, which, however, is as liable to be found on high
land as on low.
In the description by European observers, the relations
of the disease with low, marshy pastures is not emphasized,
although Brickman (32> describes it as most frequent in wet
regions. Ries (47) states the farms situated in wooded
regions have especially been affected.
For so far as our own observations go, it would seem
that most of our eases come from the lower sections of the
country, although many reports indicate that the disease
may occur on high and dry land, where deficient drainage
could not possibly be an etiologic factor.
Most of the cases of swamp-fever occur during the
months of summer and early fall. Torrance (9> finds that
261
the cases usually make their appearance in the month of
June and increase in frequency until September and October,
while Brimhall, Wesbrook and Bracken (10) state that they
were not prepared to make a definite statement in relation
to the time of the year when infection takes place, but that
it appeared that the cases seemed to begin in the early sum-
mer months and to increase in number during the months
of July, and August. Rutherford (11) speaking of the dis-
ease in Canada, states that it is the most common in the late
summer and early autumn, but that a few fresh cases come
under observation between December and the latter part of
July. In the outbreak described by Mack (50) the disease
appeared during the summer of 1906. It abated during cold
weather but only to reappear with equal fatality during the
following summer, but a year hence there were but few
sporadic cases. Mohler (52) found that the disease makes
its appearance in June and increases in frequency until
October. The observations of Kinsley (63) show that swamp-
fever is most prevalent in the summer months, the initial
attack usually occurring during July, August or September.
Among the European data on the disease, we find that
the outbreak described by Kopke (8) also occurred during
the latter part of the summer and autumn, while Ries (47)
confirms an estivo-autumn recrudescence of the malady ob-
served before.
The foregoing observations are fully in accord with
the usual occurrence of swamp-fever as it is met with in
North Dakota. The great majority of our cases show up
for the first time during the months of August and Septem-
ber, and it is probable that cases which occur during the
winter contracted the disease during the preceding summer
or autumn.
It is difficult to undertake to place an estimate on the
economic importance of the disease. While we cannot ex-
press losses in money values, there seems to be no question
as to the serious nature the disease may assume. Ruther-
262
ford (11) reports that in some oi* the Canadian districts the
mortality is simply appalling and that settlers were ruined
by the loss of their horses. Todd and Wolbach (75) writing
aoout the Canadian disease state that one farmer lost fourteen
horses in four years and that another near Winnipeg lost
forty in the same length of time. A firm of contractors work-
ing on a railroad near Edmonton in 1908 had seventeen
losses from swamp-fever in a herd of twenty-eight hoises.
They also quote a statement made by the animal insurance
companies to the etfect that seventy per cent of the death
claims for horses made in Manitoba are on account of swamp-
fever. In other parts of the country, the disease is entirely
unknown, while in a few sections sporadic cases occur from
time to time. In one of the Red River Valley counties of
North Dakota, where the disease has been prevalent for
8 to 10 years, thirteen farms with a total horse population
of 242 head sustained a loss of 98 head or about 40.5 per cent
during the year 1908. On another farm in the same district,
twenty-four horses succombed to the disease within four
years and the loss forced the owner to close out his busi-
ness. Numerous instances of this sort are recorded for the
different ''swamp-fever" districts, and fairly indicate the
havoc of which the disease is capable. Those figures also
point to the serious possibilities in case the disease should
become more generally distributed. We should not pass by
"swamp-fever" figures, however, without a word of caution
against their acceptance at their face value.
It is probable that only those cases of the disease which
go on to the chronic anemic stage are diagnosed as such and
that the more acute forms of it are never properly identi-
fied. On the other hand, there is a strong tendency on the
part of veterinarians and horse owners, to regard any
chronic disease accompanied by anemia as swamp-feverr
while in not a few instances anything more or less difficult
in diagnosis or in which a diagnosis at the spur of the mom-
ent is impossible is being charged to the disease under
consideration.
263
In the light of our present knowledge of the disease,
swam^-fever may be defined as a specific septicemia of the
horse species, due to the presence and vital activity of virus,
which thus far has been demonstrated only in an ultra-
microscopic form and characterized by a more or less in-
termittent fever and albuminuria, accompanied or not ac-
companied by a progressive anemia.
Various views have been advanced in regard to the
etiology of "swamp-fever." Zschokke (1) writing about an
anemic disease of horses, as seen in Switzerland, was led to
think that the disease was caused by an agent similar to
that of malaria. Frohner (2) also points to the proba-
bility of some infection as an etiologic factor, and in sup-
port of such a possibility, he mentions the simultaneous
sickening of several animals in one stable, the sudden feb-
rile attacks in the beginning and the malaria-like exacer-
bations and remissions of the fever during the further
course of the disease.
On the other hand Watson (6) expresses himself, that
there is no doubt but that it is caused by a vegetable poison
taken into the system through the mouth. Kopke (8) be-
lieves that the disease described by him is one of infection,
although he was led to doubt, because it happened frequently
that horses exposed to infection did not become sick at all.
In the first description by Torrance (9) he states that
the question of contagion was not settled. He had kept
fever cases in the most intin>ate contact with healthy horses
without observing transmission of the disease, while his in-
oculation experiments had up to the time of writing proved
negative. He also states that there appeared to be reasons to
think, that paludisra plays an etiologic part, basing this
opinion upon the prevalence of the disease in low-lying dis-
tricts. In another article. Torrance (12) expresses himself
as certain that the disease is not identical with surra and
mentions a large bacillus, non-motile, spore-forming and
264 '
Gram staining as having a possible connection with the dis-
ease. Later, the same author f21> "thought" that he saw
several round bodies in the erythrocytes which occurred
either singly or arranged in groups of four. Still later Tor-
rance (28) reports that in his investigation a point was
reached at which it seemd reasonable to exclude trypano-
soma or plasmodia from the possible causes of the disease.
In a publication of still later date, Torrance (54) reports a
case in support of the view that a disease closely simulating
swamp-fever in its clinical manifestations, may be accom-
panied or caused by the presence of large numbers of worms
belonging to two closely allied species (Sclerostomum tet-
racanthum et armatum). The suggestion of a hemolytic
agent, that may originate in the intestinal tract by bac-
terial activity is made by Torrance (21)-
In the investigations in Minnesota by Brimhall, Wes-
brook, and Bracken (10)> the possibility of horses of the
infected districts drinking from pools, marshes or lakes
could not be excluded, while attention is called to the pos-
sible part played by insects or arachnoids as factors in
"aiding saprophytic development of parasitic bacteria," as
well as to the overworked condition of horses and their
irregular food supply as influencing their resistance power
to infection. The same investigators made very ex-
haustive bacteriologic studies with the material at their
disposal and report that a small, non-motile, ovoid bacil-
lus, which they named B. equisepticus, was present in prac-
tically all cases. It was further found that B. equisepticus
was highly virulent to rabbits, pigeons, sparrows, while
calves were less susceptible. Dogs and swine appeared to
be resistant. Horses succumbed to the infection and "at
autopsy, the findings wrere practically those met with in
clinical cases of acute swamp-fever."
Other experiments were also carried on with an organ-
ism spoken of as B. pyrogenes equinus as well as with the
toxines of both organisms mentioned. The authors men-
tioned, further state that an etiologic relationship between
265
B. equisepticus and the disease/ 'swamp-fever" would there-
fore seem to be a safe deduction from the autopsy findings
in clinical cases and the experimental inoculations.
Jarmatz (14) is of the opinion that the disease begins
early in life, during the first months even and attributes it
especially to the results of in-breeding, which is very much
in vogue in the section of Lorraine, where he made his obser-
vations. Insufficient nutrition also shares in the production
of the disease.
Bacteria were isolated from most cases by Beebe (18)
but his experiments did not seem to establish a causative
relationship of those micro-organisms to the disease. In the
same report, the author mentions the case of a horse con-
tracting the disease after having been driven with a prob-
able case of " swamp-fever. "
Peters (26) made cultures from spleen, blood, kidneys,
and urine, but those cultures inoculated into smaller ani-
mals failed to infect. His autopsies showed a large number
of worms "known as tetraeanthum" and he seems to lean
to the theory that intestinal parasites may be etiologic fac-
tors.
Kies (27) deems the theory that intestinal helminths
exercise a preponderating influence to be quite supportable
and calls attention to the fact that he once made the state-
ment that he accused the larvae of Gastrophilus to play a
part in the propagation of pernicious anemia, either by being
the carrier of infection, by opening up a port of entrance
or by causing a general weakening of the resistance power.
Ries thinks that the frequent occurrence of the disease on
isolated farms situated in wooded regions supports his
theory.
Ballah <31> injected some cavia with "swamp-fever"
blood and the animals promptly became sick. It was proven,
however, that those results could be attributed to a strep-
. tococcus, which occurred in the blood of a horse as a second-
ary infection. This author was induced by certain changes
found in the liver to study this organ more closely for the
266
presence of micro-organisms, and in the course of this in-
vestigation he found certain liver-cell inclusions, which he
believed to the protozoa and probably the specific cause
of the disease. Those bodies were found by Ballah in over
50 per cent of the cases examined, but they were absent
in all specimens of normal liver from horses or other ani-
mals.
Charlton (33) injected several laboratory animals with
material from swamp-fever cases. After two weeks, some of
the cats showed a slight rise in temperature and appeared
somewhat ill. The fever was irregular and although the
animals ate well, they failed to thrive and had an unhealthy
appearance. One of the cats developed a well denned edema
all along the belly about five weeks after injection. The
edema lasted about two months, when it disappeared, the
animal afterward remaining in good health. Two of the
smaller cats died about three months after injection, but
horses injected with the blood of the sick cats remained
in good health. Specific organisms were not found.
Brickman (32) in cases, in many respects similar to the
pernicious form of anemia in France, claims to have found
parasites resembling those of malaria in the blood corpus-
cles.
Van Es (37) was able to isolate several bacterial species
from the blood of "swTamp-fever" cases and his observations
on the damage done by certain helminths may be an indica-
tion as to how the micro-organisms found their way into
the general circulation. There was no evidence adduced,
however, that the conditions found bore an etiologic relation
to the disease under investigation.
Hundreds of blood examinations were made by Francis
and Marsteller (42) but none of them revealed the presence
of blood parasites. Cultures from the blood on various
media also led to negative results. In a later report the
same authors (81) described an experiment on the possibility
of transmission of infectious anemia through the agency of
267
Fig. 1. A field case, No. 921, about one month before death.
Fig. 2. The same horse as shown in Fig. 1 about one week before
death. Note the marked edematous swellings of brisket, lower
part of chest and abdomen, the sheath and the right hind leg.
268
Boophilus annulatus, but in the one ease tried the results
were negative.
Mack (50) isolated various bacteria but their relation-
ship to the disease under consideration was not positively
demonstrated, neither did he find evidence of direct con-
tagion.
The invariable presence of parasitic aneurism in all the
cases subjected to autopsy by Whitehouse (5G) led him to
look with considerable suspicion upon this fact.
Trypanosoma were found by Darling (58) in the blood
of an American gelding and a number of mules in the Pan-
ama Canal Zone. These animals were suffering from a dis-
ease which corresponds clinically with the descriptions of
"swamp-fever" published in this country. The readiness
with which Darling infected a great assortment of various
animal species with his trypanosoma renders-the identity of
the Panama disease with our swamp-fever rather question-
able, however. His inoculations with filtered blood did not
permit of definite conclusions and hence the reports of fur-
ther experiments by this investigator will be looked forward
to with considerable interest.
Kinsley (63> reports the instance of a farm, which has
been infected for twelve or fourteen years and on which
horses were lost with the disease every year, while on a
neighboring farm not more than sixty rods away, there
never was a case. On another farm five horses were lost
during the winter and a pony placed in the same stable for
three or four weeks during the following summer became
affected and died. On the other hand, several instances
were, observed in which one of the horses of a certain team
had become infected and the other remained normal, and
this, in spite of the fact, that the animals were watered
from the same pail, and fed in the same trough. Colts ap-
pear to suck from infected mares with impunity, while in
other instances sucking colts become affected, although the
mares remain healthy. Horses and mules seem equally
susceptible, while the age of the animals seems to have no
269
more influence on susceptibility than the breeds to which
the animals belong.
It is probable that Torrance (12> was the first to actually
transmit the disease by direct infection, although from his
report it does not appear that he clearly recognized the
fact. In 1902 this investigator observed a rise of temperature
in a horse injected with swamp-fever blood on the 12th day
after injection and he merely holds it for probable that the
animal had become infected. This horse had two more sub-
sequent rises of temperature at intervals of 10 to 12 days,
but without any clinical symptoms of the disease.
The first serious attempt to clear up the etiology of the
disease was made by Vallee and Carre (16-17-19-23-86) amj
they succeeded in doing so to a remarkable extent, at least,
for so far as the European disease was concerned. While
the infectious nature of the disease had been suspected for
some lime, they definitely settled the question of trans-
milting the disease to a healthy animal by the injection of
blood from a diseased one. In their first communication
Vallee and Carre (16) relate that in their first experimental
subject, the disease ran its course, identical to the natural
disease in 57 days and how the blood count dropped from
the normal 7,800,000 to 2,800,000 on the day of death. The
autopsy revealed the ordinary lesions of anemia, namely
extreme muscular emaciation, subcutaneous, sub-serous, ami
peri-ganglionic edema, enlargement of the spleen, liver cir-
rhosis and hemorrhages of the bone-marrow. Bacteriolo^ic
research was not rewarded with positive resulls and a
search for piroplasma or trypanosoma also failed to disclose
those parasites. On the supposition that the etiologic factor
of the disease might belong to the invisible viruses, Vallee
and Carre made a mixture of 500 c. c. of blood serum coming
from a sick animal with 200 c. c. of physiologic salt solution
ami added to it a culture of an extremely virulent ovine
pasteurella. This mixture was passed through a special
filter bougie and the opalescent liquid passing through the
filter was injected in doses of 20 c. c. into the veins of some
270
rabbits and into the peritoneum of cavia, which animals
remained healthy. This experiment showed the efficiency
of the filter. Next the investigators injected 500 c. c. of the
filtered liquid into a healthy horse and found that after a
lapse of a certain period of incubation the animal presented
symptoms of an absolutely typic anemia. It was thus fairly
well established that the etiologic factor in the disease is a
so-called ultra-microscopic organism.
Somewhat later Vallee and Carre (17) completed their
previous report and state that it is easy to maintain the
virus by successive passages through the horse, the vir-
ulence increasing. They also found that the anemia in
reality only constitutes one of the forms of an infectious
disease, which often reveals itself under an entirely different
aspect. In fact, three types of the disease may be recognized
and Vallee and Carre emphasize that those three types un-
questionably belong to one and the same affection as. they
are experimentally reversible. They also infected the ass
and showed that virulent blood loses nothing of its vir-
ulence by being diluted five times and by being filtered
either through a Berkefeld filter or through Chamberland
bougies F or B. In the same series of experiments, Vallee
and Carre also proved that the disease is transmissible by the
digestive tract, as a horse fed on 20 c. c. of virulent blood
promptly contracted the disease. Note is also made of the
fact that horses which were apparently absolutely cured
of the chronic form of the disease still retained their full
infective powers and hence Vallee and Carre express the
opinion that the presence of such virus-carriers constitutes
in infected regions a great obstacle to the extermination
of the disease by prophylactic measures.
Carre and Vallee (19Mn a later report cite an instance
which tends to show the infectiveness of the urine of an
apparently recovered case. Continuing their studies Carre
and Vallee <23) found that the quantity of virulent blood
injected into a healthy experimental animal had no influence
upon the course of the disease.
271
Cattle, sheep, goats, dogs, rabbits, cavias, mice and
white rats proved to be refractive to infection.
Carre and Vallee report that the virus is destroyed by
heating to 58° C. for one hour, but that drying in vacuum
at room temperature does not alter its virulence. The dried
material from 1 c. c. of virulent blood kept for ten days
and then inoculated into a vigorous horse, kills the same in
thirty days, but after storing this substance for seven
months, it is no longer disease producing.
The authors metioned, further report that the keeping
of virus outside of the body seems to rob it gradually of
its virulence, but that putrefaction did not seem to disturb
the vitality of the virus.
Carre and Vallee are of the opinion that the natural
mode of transmission of the disease takes place by food
stuffs and drinking water soiled by virulent urine and prob-
ably also the feces, but they did not succeed in establishing
any relationship between blood sucking animals and the
distribution of the disease.
The results of the experiments of Vallee and Carre
relating to the ultra-microscopic nature of the virus have
since been confirmed by various investigators, Charon (84)>
Ostertag <35>. Francis and Marsteller (42-81>- ITempel (49)'
Mack <5°). Mohler <52-G6)- Van Es <68> ; Todd and Wolbach
<75) transmitted the disease by intra-peritoneal injection.
In the experiments of Ostertag (35)- attempts to trans-
mit the disease by means of the saliva failed, but he suc-
ceeded to bring about infection with 20 c. c. of blood serum
of an acute case, after it had been kept on ice for seven
weeks.
Hempel (49) reports that virulent material which was
stored on ice for some time and given by the mouth in
small quantities was not capable of producing the slightest
reaction, although it produced, a typical infection when
given subcutaneously in one-fourth of the dose used in the
feeding experiments. Material from a case in the dormant
stage of the disease, when given intravenously in doses of
272
120 c. c. produced a slight form of the disease and when
given per os in a dose 2y2 times as great, a one day fever
period was observed after 21 days incubation. Given intra-
venously or subcutaneously, small amounts of virulent blood
will produce infection, but larger quantities are required
if infection per os is to be produced.
The question of a transmission of the disease by con-
tagion has not received much attention, but the Few data on
record seem to indicate that this means of transmission is
not an easy one.
Melvin (70) reports the experimental exposure of a
healthy horse, which was quartered in a stall adjacent to one
containing a sick horse for seven months and which Failed
to transmit the disease.
Francis and Marsteller (81) kept a susceptible pony
continually exposed to swamp-fever infection for more than
two years by intimately associating it with infected animals
in a small pasture, without the experimental pony becoming
infected.
In our own experiments with the disease as it occurs
in the Red River Valley, the results obtained by Vallee and
Carre were practically repeated.
During the latter part of 1907, we injected an apparently
healthy horse intravenously with 8 c. c. of blood from a
typical chronic field case and the injection was followed
some eight days later by the initial fever attack, which we
have since learned to recognize as evidence of positive in-
fection. Since that time, we have succeeded in transmitting
the disease by means of filtered (sterile as far as cultures are
eoncerned) diluted serum.
In our hands, not only the disease was transmitted by
subcutaneous or intravenous injections or virulent blood,
but we also produced infection by giving capsules filled
with virulent blood by the mouth. In addition, we found
Dial, urine either injected subcutaneously or given by the
mouth is capable of transmitting the virus.
273
For so far as our investigations go, it does not appear
that the virus is eliminated by the bowels. The subcutaneous
injection of 100 c. c. of an extract of faeces from a virulent
horse into a susceptible horse was not followed by any re-
action. In another case four liters of a similar extract in
which 1790 G. of faeces from a virulent case were used and
which were introduced into the stomach by means of a
stomach tube failed to bring forth any noticeable results.
The latter experiment was repeated with larger quan-
tities of extract made with faeces from another case, using
a different experimental horse, with the same results. The
susceptibility of the experimental horses used was proven
by their subsequent infection when injected with virulent
blood.
From the various experiments quoted, it seems safe to
conclude that the disease is due to an ultra-microscopic virus
and that this is the primary factor to be considered in the
problem. The experiments have eliminated poisonous plants
as a factor, and the readiness by which a virus can be caused
to make several passages in unbroken succession also sets
aside the etiologic importance of intoxication by intestinal
helminths. There can be no question as to the possibility
of intestinal worms in producing outbreaks of anemic dis-
ease, and in the study of such diseases, their presence should
not be neglected, but in the disease under consideration, they
cannot be regarded as primary factors.
The importance of certain helminths as producers of
anemia and as instruments of opening the way for bacterial
invasion is strongly pointed out by the publications of Glage
^24> and of Weinberg <38-39>-
For the time being, the demonstration of ultra-micro-
scopic virus must not be accepted as final, and the search for
blood micro-parasites should not be discontinued. We may
readily conceive the possibility that in the metamorphosis
of a micro-parasite there may occur a stage, during which
the forms become filter passers.
274
The nature of the virus was not further investigated
by the writers, with the exception of its behavior toward
freezing temperatures.
The following observations were made :
'A quantity of virulent blood was exposed to freezing
for 24 hours during which the minimum temperatures re-
corded was 10° F. The blood was permitted to thaw at
room temperature and 240 c. c. were injected subcutaneousl y
into an experimental horse with the result that the animal
sickened on the ninth day and died on the fifteenth day
after injection.
Another quantity of blood was exposed to freezing, the
prevailing temperatures being indicated by the following
table :
Date
Maximum
Minimum
Date
Maximum
Minimum
Temp. F.
Temp. F.
Temp. F.
Temp. F.
Jan. 3
-10
-26
Jan.
20
17
0
Jan. 4
16
-22
Jan.
21
14
-15
Jan. 5
0
-14
Jan.
22
3
-13
Jan. 6
3
- 7
Jan.
2.;
2
-12
Jan. 7
15
-14
Jan.
24
24
0
Jan. 8
15
-13
Jan.
25
28
- 1
Jan. 9
9
- 9
Jan.
26
27
11
Jan. 10
31
-14
Jan.
27
11
3
Jan. 11
-15
-23
Jan.
28
5
13
Jan. 12
0
-23
Jan.
29
33
3
Jan. 13
0
-22
Jan.
30
16
-13
Jan. 14
-11
-22
Jan.
31
23
- 9
Jan. 15
- 2
-19
Feb.
1
24
7
Jan. 16
- 3
-20
Feb.
2
23
-16
Jan. 17
8
-10
Feb.
3
10
-16
Jan. 18
8
- 7
Feb.
4
11
-14
Jan. 19
22
0
On the fifteenth day of exposure, a quantity of this
blood was thawed and 240 c. c. of it injected into an experi-
mental horse. This horse developed fever after an incubation
period of forty-nine days and died eight days later.
275
A similar quantity of this blood was injected into another
experimental case after it had been exposed for thirty days
with the result that the animal developed fever on the 45th
day, dying 6 days later.
From the above observation it would seem that if severe
freezing has any effect at all on the virulence of the blood,
it merely consists of lengthening the incubation period. Be-
fore concluding definitely on this point, however, further
research will be required, especially in view of the unusually
long period of incubation.
In certain cases of pernicious anemia of man, the presence of
peculiar bodies were found by I'crlcs ^5). He proposes the name
of anemia-bodies for them and describes them as elongated, elliptical,
very thin and narrow, flexible, colorless, and highly refractive leaflets.
Perles failed to either stain or cultivate them, nor could he find them
in cases of secondary anemia, llocfer (62> apparently found certain
protozoa in a case of severe anemia eight days after the be,gimiing
of sickness, but the question whether or not they constituted an
etiologic factor could not be decided.
The transmission of "swamp-fever" to other animals
seems to be denied by most authors. Carre and Vallee (23)
tried to infect other animals, but without positive results.
Ostertag (35) reports that in the district where he studied
the disease, a transmission to other domestic animals had
never been observed and attempts to transmit the disease
artificially also resulted negatively. Man had not been known
to contract the disease, although many persons constantly
cared for infected horses and even consumed their meat.
Francis and Marsteller (42) failed to obtain positive evidence
of infection after injecting cattle, sheep, goats, pigs and dogs
with virulent blood. Charlton (33) observed that injection
with virulent "swamp-fever" blood into cats wras followed by
illness, but the blood of the cats so affected proved to be in-
occuous to horses. Mack (73) in his latest publication states
that in the Nevada disease there is no evidence that it is
276
contagious and that while there is every clinical indication,
that it is a specific infectious disease, he must have more
conclusive evidence than his experiments have \<i afforded
before one is warranted in pronouncing it such. At the
time, however, he would venture no opinion as to the ideiil it y
or non-identity of the Nevada disease with the affections
reported from other sections. Todd and Wolbach <75> in-
jected with swamp-fever virus four cavias, two mice, nine
rats, two rabbits, ten dogs, two kittens and one sheep and
no symptoms which could be attributed to swamp-fever fol-
lowed in any of the animals experimented with.
In our own work, a similar condition was experienced.
A number of cavias were injected with virulent blood and
several among them showed a rise of temperature after a few
days, while still later some of the animals died. The blood
of the sick pigs injected into a healthy horse, however, ab-
solutely failed to cause any reaction.
The occurrence of anemic diseases among live stock
other than the horse is generally well known, but as far as
we know, nothing like swamp-fever has ever been observed,
unless the case reported by Trincas (29) in the dog pertains
to a similar disease. In this case the author demonstrated
that anemia in the dog may be due to an ultra-microscopic
virus.
The anatomic changes met with in swamp-fever are
rarely of a striking character. They include degenerative
changes in the various parenchyma, petechia?, ecchymoses,
especially about the serous membranes and endocardium,
edematous conditions, certain changes in the lymphnodes
and the bone marrow. The changes noted indicate a more
general intoxication or septicemia than that the disease
stamps a peculiar feature upon a certain organ or sets of
organs. In the interpretation of the various lesions found,
277
Fig. 3. A non-anemic field case No. 1032.
Fig. 4. Experimental horse No. 636, 33 months after original infection.
278
it should be borne in mind that in all probability secondary
infections and influences also bear a large share in their
production and that it is not always possible to determine
which lesions to charge to the specific agent of "swamp-
fever" and which are to be credited to other determining
factors. For the purpose of presenting the pathologic an-
atomy of swamp-fever as fully as the importance of the
subject demands, it seems wise to quote from the descrip-
tions of various observers in addition to mentioning our
own findings.
Taylor (7) found the blood of the carcass darker and
more fluid that normal. Numerous petechias and hemor-
rhagic spots were visible in the fasciae ol* dorsal and lumbar
muscles. Both heart cavities were thickly spotted with
black hemorrhagic areas. The intestinal surfaces were
also studded with petechia}. The mesenteric lymphnodes
were black as if filled with dark blood. The spleen Mas
considerably enlarged. The kidneys showed nephritis
(interstitial). The muscles showed hemorrhages both in
the perimysium and between the fibres themselves. Taylor
states that numerous black bodies scattered throughout the
lungs are "the most striking features."
In the experience of Kopke (8) the carcasses dead with
the disease were highly emaciated, hide-bound, and present-
ed a dull, rough coat. The mucosae were perfectly anemic
and the eye-balls were sunk deeply into the orbits. The
subcutaneous veins appeared almost bloodless and the sub-
cutis of the thorax, belly, prepuce, and the hind legs were
markedly edematous. The musculature, which immediately
after exposure, had a pale red color, assumed a character-
istic reddish yellow, almost orange red tint after an ex-
posure to the air for a few hours. The mesocolon showed
numerous hemorrhages of the size of a pea to that of a
hazelnut. The mesenteric lymphnodes were two or three
times their normal size on account of the edematous swell-
ing. The mucosa of the intestines showed petechia? in two
of the cases. In the third case, the mucosa was thickened.
279
this thickening being firm, and more of a fibrous connective
tissue nature than edematous. Liver and spleen were nor-
mal in size, the former showing a slight parenchymatous
cloudiness. The markedly enlarged kidneys appeared pale
red and were so friable that their entirety could scarcely
be preserved, when they were taken out of their capsule.
Their parenchyma was cloudy. The heart was always con-
siderably enlarged and the myocardium degenerated to a
high degree so that it presented a pale-grey-red color and a
parboiled appearance. In the ventricles, especially about
the column* carnae, extensive endocardial hemorrhages
could be demonstrated.
Torrance (9) describes anemaciated state of the car-
cass with a most remarkable absence of adipose. The tis-
sues were blanched. The blood is often firmly clotted in
all the vessels, the clot having the appearance of yellow
jelly. The abdominal viscera are normal in color but fre-
quently studded with petechia? on the serous surface. The
spleen is generally much enlarged, reaching in some cases
a weight of six pounds, while its surface appearance is
normal. The liver is not much changed in appearance, but
is sometimes studded with flakes of lymph. The kidneys,
not infrequently, show evidence of chronic nephritis. A few
petechia? may be noted on the surface of the lungs. The
heart is generally enlarged, sometimes much hypertrophied,
reaching in one case a weight of twelve pounds and four-
teen ounces. The pericardium is frequently studded with
petechia? and the pericardial fluid in some cases is greatly
increased. Spinal cord and brain are found to be in a
normal condition.
Brimhall, Wesbrook, and Bracken (10) report sharply
defined edemata in the regions of the chest, the abdomen
and the limbs. In some cases there was evidence to show
that such subcutaneous edematous areas became purulent
later on. Conditions of this kind were met with between
the pectoral muscles and those of the legs. They were also
seen in the mediastinum and in the auriculo-ventricular
280
groove in advanced cases. The deeper Layers of the skin
and the subcutaneous connective (issue showed in nearly
all cases hemorrhages, varying in size from petechia* bo
irregular spots, two or three inches in diameter. Such
hemorrhages were also found between and in muscles, fas-
ciae, synoviae, lymphnodes, serous membranes and the heart.
The lungs were sometimes stippled with red spots, showing
through the pleura, while at other times irregular areas
of hemorrhage occurred which completely filled several con-
tiguous lobules. The spleen as a rule was found to be spotted
with irregular red blotches and in certain instances well
marked and extensive infarcts were to be seen. In a Jew
instances the organ seemed almost entirely devoid of hem-
orrhages. The changes shown by the kidneys varied and
included petechias, large hemorrhages under the capsule and
parenchymatous nephritis. Hemorrhagic areas were quite
frequently seen in the mesenteries and the walls of the
stomach and intestines. In some cases they were several
inches in diameter. Often they were sub-peritoneal, but
in a number of instances they involved the entire intestinal
wall. While the authors found it impossible to ascertain
accurately at what stage of the disease hemorrhages are
most likely to occur, it would appear that they were more
common in advanced cases, when the blood changes were
most marked. Abscesses were frequent in the Minnesota
cases and the inflammation of the serous surfaces was so
common as to be recorded as characteristic of the disease.
The heart was enlarged, in many cases showing numerous
hemorrhagic patches underneath the endocardium or epi-
cardium and occasionally involving the whole thickness of
the heart wall. Frequently there was an increase in the
pericardial fluid and very occasionally a sero-fibrinous peri-
carditis was present. In some instances, white depressed
areas, irregular in shape and size probably indicated the
seat of old hemorrhages and infarcts. Histologic examin-
ation showed that in those areas the heart muscle fibers
are replaced by connective tissue. The lymphnodes are
2S1
frequently swollen and infiltrated with a gelatinous exu-
date. In all cases lymphnodes could be found in which
marked hemorrhages could be demonstrated and the whole
structure was often found to be hemorrhagically infiltrated.
The liver usually was increased in size and congested and
when peritonitis was marked flakes of lymph covered its
surface. The liver tissue was frequently softened, light in
color, giving evidence of parenchymatous changes. Branches
of the portal vein were quite frequently found to contain
whitish thrombi. Cirrhosis was met with twice. The blad-
der often showed hemorrhages in its wall, sometimes in-
volving the whole thickness and the areas being some inches
in diameter.
In the cases studied by Carre and Vallee (23)- the lesions
varied according to the evolution of the disease and were
especially associated with the blood, the heart, the spleen,
the lymphnodes, and the bone-marrow. In addition there
were changes in the kidneys, liver, intestines and edemata
of various parts. The lymphnodes in acute and sub-acute
cases and also in the chronic cases during an acute exacer-
bation will show congestion, even hemorrhages, especially
those of the mesentery and the spleen. In the cases dead
with exhaustion, the nodes will show a simple edematous
enlargement, while at the same time they are surrounded
by a yellow edematous mass. The spleen is nearly always
enlarged, doubled or tripled in volume. There is no soften-
ing, on the contrary there is thickening, the organ being
lumpy in the middle and seems to have gained in consis-
tency. On section the pulp is paler than usual and the
splenic bodies are hypertrophic, granular and grayish. In
acute cases, the capsule is speckled by ecchymoses. The
bone-marrow most generally presents extremely marked
alterations in all the patients. The lesions are particularly
intense in the femurs of which the marrow is transformed
for a great part of its height in a veritable bloody, brick-
red or blackish mush and in consistency resembles foetal
marrow. The histologic examination reveals the special
282
characters of the latter, like it dors m all the known anemic
conditions. Changes of the heart are exceedingly common.
In the acute type it is speckled over by multiple ecchymo
sub-pericardial and sub-endocardial. The myocardium is
marked by numerous hemorrhagic foci, triangular in shape
and of several square centimeters in area. One may observe
a valvular endocarditis, this being best described by com-
paring theirs to the aspect of an eschar dor to a weak
caustic. In the chronic cases the myocardium is disco] >red,
marked by the remains of hemorrhages, pink or greyish in
color and one sees occasionally a slighl valvular edema and
atheromatous lesions of the aorta. The liver is generally
enlarged, of a washed yellow color, sometimes stippled with
fine white specks or it presents the typic aspeel of the liver
of cardiac insufficiency. The liver tissue is more friable
and can be readily torn. The kidneys are pale, discolored
in the chronic types, hemorrhagic in the acute forms. The
capsule can be readily stripped. Sometimes we meet with
well rounded pin-head abscesses in the cortical portion and
which project under the capsule of the organ. The intestines
are normal in the chronic cases, but in the acute ones on the
contrary they are speckled with multiple sub-serous hem-
orrhages. The mucosa is the seat of a more or less intense
congestion, while the muscular coat may present the same
features. The lesions are generally quite extensive in the
large intestines, which are sometimes entirely hemorrhagic
but in the small intestines the lesions are more discreet.
The lungs were always normal with the exception of a
few sub-serous petechia?.
Charon (34) notes the following changes seen during
the autopsy of a natural case; emaciation, absence of a
subcutaneous edema, the presence of three or four liters
of a lemon-colored serous fluid in the peritoneum. The
lymphnodes, the superficial ones, as well as those of the
viscera, are enlarged, infiltrated, juicy, showing on the cut
surface numerous hemorrhagic foci. There was an absence
of internal fat, the liver in normal color, but with its cap-
233
side thickened. The spleen is nearly three times its normal
size and weighs 2100 grammes. The kidneys have a sclerous
aspect from periphery to center. The cortical portion is
discolored, the medulla is pale. A section of the bones
reveals the marrow to be altered in its entirity, foetal and
hemorrhagic. The endocardium is a little thickened. The
same author also gives an account of the autopsy of an
experimental case. lie states that the cadaver is poor.
There is no subcutaneous edema. The muscles have a normal
color and there is no exudate in the body cavities. The
lymphnodes of the groin, spleen, kidneys are very much
enlarged and those of the spleen show numerous small hem-
orrhagic foci. There is a wasting of the internal fat. The
liver has a normal color and Glisson's capsule is thickened.
The spleen is triple the normal size, weighing 2600 grammes.
The kidneys are slightly discolored. A section of the femur
shows a hemorrhagic focus 10 c. m. in width and 1 c. m.
in thickness. There is foetal marrow of the consistency
of vaseline. The lie rt presents a hemorrhagic area of the
right ventricle extending for 2 m. m. into the myocardium.
The autopsies made by Francis and Marsteller (42) re-
vealed extreme emaciation, some edematous swellings along
the lower part of the body and usually some bed sores.
The muscles w^ere pale and the blood watery. Peteehiae were
noted on the heart and pericardium, while some enlargement
of the heart was observed. There was a marked enlarge-
ment of the spleen, the organ ranging in weight from four
to eight pounds. The digestive apparatus was normal, while
kidneys and liver showed no conspicuous changes. Aside
from the lesions found in the blood, heart and spleen, the
authors were at a loss to account for the death of the
animals.
Hutyra and Marek (69) state that the anatomic changes
are those of an acute or chronic septicemia and are quite
variable according to the duration of the disease. The
spleen of horses, which died during an attack of the dis-
ease or during an acute exacerbation is considerable en-
284
larged. Its capsule is tense, marked by hemorrhages, while
the pulp is black red, projecting from the on! curface,
mushy or even liquified. Sometimes there are found in 1 1n-
otherwise normal spleen, several large projecting, uneven
areas, corresponding to very dark red softened foci. The
slower the course of the disease, the slighter the changes
in the spleen. In very protracted cases, the enlargemenl
is often completely absent. For so far as the corresponding
organs show hemorrhagic changes, the lymphnodes of the
body show acute enlargement and a hemorrhagic condition.
In chronic cases, the lymphnodes may not be altered or be
at the most somewhat edematous. Sub-serons hemorrhages
are a common finding but in the chronic cases they become
inconspicuous. They are especially soon in connection with
the caecum and the colon, bnt in ;i less marked condition
also in other parts of the peritoneum. Ecchymoses are
always seen under ths capsule of the liver which is more or
less, in some cases, even considerably, enlarged. The in-
testinal mucosa shows either isolated, round hemorrhages
or there is a diffuse hemorrhagic condition with a bloody
consistency of the intestinal contents. The heart with the
exception of that in the very chronic cases, reveals snb-
peri, sub-endo, or intramyocardial hemorrhages. The kid-
neys show hemorrhagic areas only in the aeute eases and
the same is seen in the lungs. Parenchymatous degeneration
of kidneys, myocardium, and liver is always present, Hem-
orrhagic areas in the urinary bladder are not rare. The
bone-marrow shows conspicuous and constant changes.
Especially in the femur and the humerus, the yellow marrow
is partly or entirely changed into a dark brown red or black
red mass. In the cases of a more chronic course, only
several circumscribed hemorrhages in the fatty marrow are
shown. The latter may appear to be normal, while in chronie
and acute cases, the red marrow in the extremities is apt
to show a red discoloration. The same is seen in the mar-
row of the vertebra?, ribs. etc.
The most frequent lesions met by Mack (50) are hem-
285
orrhagic areas in various organs, but most constant in con-
nection with the intestinal canal. In some instances various
lymphnodes were found to be edematous and hyperasmic,
in others they were normal. The bone-marrow was found
to be altered. Especially that of the humerus and femur
showed a color darker than normal, with red areas in var-
ious parts. Histologically various changes were encountered,
but nothing of a striking, characteristic nature. The presence
of the petechias and ecchymoses in many of the viscera was
a notable feature of one of the autopsies, but those changes
were absent in the other. The lymphnodes were either nor-
mal or hyperasmic or edematous. Parenchymatous degener-
ation was present in the kidueys and liver.
Mohler (GG) reports that animals dead with the disease
air very emaciated and anemic. There is a marked absence
of adipose. Subcutaneous and intermuscular edema and hem-
orrhages are frequently observed, although the absence of
gross lesions is remarkable in many cases. Mohler regards
the petechias of the heart as the most predominating and
most constant lesion. The organ is usually enlarged. In
some cases the lungs may be studded with petechias, while
rous exudate may be present in the thorax. The peri-
cardial fluid is also generally increased. Peritonitis and a
hemorrhagic condition of the intestine may be encountered.
The liver is generally normal, although sometimes it presents
a few areas of degeneration. The spleen, at times, is found
to be enlarged and covered by petechias. The kidneys may
appear normal or anemic and flaccid, while under the mic-
roscope they usually show a chronic parenchymatous degen-
eration. The lymphnodes may be enlarged and hemorrhagic.
Melvin <7°) expresses the opinion that in a broad gen-
eral way, it may be said that the blood is the real seat of
the trouble, and that any pathologic changes observed in
the circulatory system or in the viscera are dependent on
this rather than that the lesions in the circulatory system
are primary. This author further states that the atrophy
and weakening of the muscles of the hind quarters, causing
Fig. 5. Experimental hd 37, 25 months after original infection.
Fig. 6. Experimental horse No. 6£8, '23 months nfter original infection.
287
the consequent staggering gait undoubtedly are the result
of metabolic disturbances, which are inherent in the blood
rather than in the muscles themselves.
Todd and Wolbach T" found in one case that the mar-
row of the long bones was fatty and that it did not contain
blood forming cells.
In order to permit a comparison between the autopsy
findings of the observers mentioned and those made at the
North Dakota Experiment Station, we hereby submit some
notes referring to the latter. Those notes only refer to
such field cases of which the infectiousness was proven by
the fact that their blood conferred the disease to normal
horses and to the findings in connection with those experi-
mental cases.
No. 562. (Field case taken from an outbreak near Har-
wood, N. D.) At the time of death this animal was greatly
emaciated and after the removal of the skin the lack of adi-
pose and the pallor of the muscle tissues were much in evi-
dence. There was a slight yellow tinge noticeable, in connec-
tion with the subcutaneous connective tissues. The periton-
eum showed evidence of a chronic inflammatory process by
the numerous fine threads of fibrinous exudate and slight ad-
hesions. Those lesions are found on the parietal as well as on
the visceral portion, but perhaps more marked in connection
with the latter although at this time it is not thought that
there exists any connection between those peritoneal lesions
and "swamp-fever." They are probably the result of para-
sitic migrations.
The spleen is considerably enlarged (weight 5 lbs. 12
oz.). Its peritoneal covering is thickened over its entire
surface, which is covered with an organized fibrinous exu-
date. The splenic lymphnodes are enlarged. The spleen
substance is of a little more solid consistency than is found
under normal conditions, but does not otherwise present
any marked features. Microscopically the spleen structures
do not present noticeable changes. The liver, aside from
288
being somewhat resistant to the knife, in its macroscopic
aspect does not differ from the normal. Microtome sections
of this organ reveal an apparently recenl leucocyte infil-
tration of the interstitium. In several lobules, however,
the round cells can also be seen between the cells of the
parenchyma and around the vena centralis. Pigment de-
posits are common through the sections. The porta] lymph-
nodes are hemorrhagically infiltrated and exceedingly fri-
able. They contain considerable deposits of a brownish yellow
pigment. The intestines show no marked changes. The
caecum contains a number of nematodes. A vermilions
aneurism is present on the anterior mesenteric artery. The
aneurism is quite large and extensive and shows evidence
of a chronic existence. It contains a few embryos of
Sclerostomum. The kidneys arc of normal size but pale
upon section. The histologic examination of those organs
shows in many instances a beginning of the thickening of
Bowman's capsule, the glomerulus frequently occupying all
the available space. The structure of the glomerulus is
generally intact but here and there degenerative changes
have taken place and between the debris leucocytes may be
seen. The epithelium of the tubules is fairly intact, where-
ever it is not encroached upon by interstitial changes. Inter-
stitial round cell infiltration is confined to certain limited
areas. It is limited in extent and at no place is any evidence
of induration noticed. The arterial walls are somewhat
thickened. The lungs are normal in appearance with the
exception of a pneumonia focus of about 15 c. m. diameter
situated in the anterior portion of the right lung. The
solidification seems to follow the larger bronchioles and
presents numerous hemorrhagic infiltrations. The histologic
picture is that of a broncho-pneumonia, which here and there
shows evidence of indurative changes. In most of the sec-
t;ons the alveolar walls can scarcely be recognized, owing
to the dense masses of leucocytes. They also fill the bron-
chioles, which in many places seem to have become atrophic
or obliterated. In many of the vessels thrombi are present,
289 .
while near the periphery of the inflamed area hemorrhagic
extravasation also fills the 'pulmonary alveoli. Unfortunate
circumstances prevented the examination of the heart of
this case.
No. 6-iO. (Field case obtained from the neighborhood
of Christine, N. D.) The cavader is very thin, the muscles are
of normal color. The heart is normal in appearance but mic-
roscopically shows wry slight evidence of granular degen-
eration and interstitial myocarditis which changes appear to
be in their incipiency. The lungs are well contracted, pre-
senting a few parasitic nodules under the pleura. There are
also a few dark areas under the same membrane apparently
due to a localized hyperemia giving rise to a somewhat mot-
tled appearance of the regions involved. Several of the
Lymphnodes along the colon are enlarged and hyperemic.
The intestines themselves are normal in appearance and
contain a few specimens of Sclerostomum e<piinum. The
liver is somewhat enlarged, dark in color and has its surface
covered by fibrinous threads. Sections of this organ show
parenchymatous degeneration, and interstitial hepatitis.
Many lobules are infiltrated more or less with leucocytes
and in some instances those cells are grouped in the form
of small, round, narrowly circumscribed areas. There is
a moderate degree of siderosis. The spleen is enlarged and
shows numerous petechia' on its surface. Microscopically,
the trabecule seem thickened, while a considerable amount
of pigment is in evidence. The kidneys are normal in
appearance, and under the microscope, their parenchyma
is fairly intact and interstitial round cell infiltration, al-
though present, is insignificant in extent. The vessel walls
are slightly thickened.
No. 635. (An experimental case infected by an in-
jection of blood from No. 640.) The cavader is ema-
ciated and • there is a great reduction of adipose.
The skeletal muscles have a normal color. There is
a general peritonitis with a fibrinous exudate. The colon
and caecum are hyperemic. The mucosa of the colon is
intensely inflamed or hemorrhagically infiltrated and a large
290
quantity of hemorrhagic exudate is found in the Lumen of
the gut. Sections of the wall show it to be densely packed
with leucocytes and blood debris, while numerous small
necrotic areas are noted in the sub-mucosa. The floating
colon is stippled with petechia?. The omentum is densely
inflamed. A small parasitic aneurism is noted in the an-
terior mesenteric artery and contains a few worm embryos.
The liver is enlarged, hyperemic, very friable and histologi-
cally presents evidence of a considerable amounl of fresh
interstitial leucocyte infiltration. Many round cells are seen
within the lobules. There is a moderate degree of siderosis.
The spleen is about six times its normal size, its pulp very
dark and soft. Sections of the organ show blood engorge-
ment and a great amount of siderosis. The trabecular are
not changed. The lungs are poorly contracted with a slight
fibrinous exudate on the pleura and the heart is soft, flabby,
par-boiled in appearance, but has its microscopic structures
fairly well preserved. The kidneys are soft, friable and
richly interspersed with miliary abscesses. A purulent pye-
litis is in evidence. Microscopically, there is a considerable
amount of interstitial nephritis, with here and there areas
of dense acute inflammation (miliary abscesses). Bowman's
capsule is considerably thickened. The epithelium is gen-
erally intact when not encroached upon by extratubular
changes. The tubules themselves contain a small amount
of granular debris, but there is no evidence of tube casts.
No. 744. (An experimental case infected by means
of the blood of experimental case No. 636.) The well
developed adipose presents a yellow tinge. The ab-
dominal cavity contains about one-half liter of fluid.
The peritoneum is bluish white in color, smooth, shiny and
transparent. In the liver the lobules present a more than
usual distinct demarcation, its capsule is tense and its bor-
ders rounded and of a light blue color. The spleen is appar-
ently normal. The capsule of the kidney is tense and the
tissue friable. Stomach and intestines as well as their con-
tents present nothing abnormal. The left lung is pink in
291
color and slightly emphysematous on ventral border. The
right lung is dark blue in color and somewhat edematous.
The heart tissue is quite firm but of a pale color.
No. 855. (An experimental case infected by means
of the blood of experimental case No. 636.) The
carcass is very thin and there is a lack of subcut-
aneous, sub-mucous, sub-serous, and omental fat. The
peritoneum is n<>nn;i] and contains a small quantity of fluid.
The kidneys and pancreas are apparently normal, but the
former show upon microscopic examination, a few, very
slight and probably recent interstitial round cell infiltra-
tions. The glomeruli are somewhat congested and a few
tubules contain hyaline casts. The bladder contains about
a quart of normal urine and has a normal mucosa. The
external surface of the spleen presents evidence of a slight
adhesive peritonitis, and shows numerous 'ecchymoses con-
tiued to its capsule. The Liver aside of a pronounced ad-
hesive peritonitis on its surface, has a normal appearance.
The stomach contains about ten "hots" but is otherwise
normal. The small intestines are normal. The mucosa of
the caecum showed a number of 'Sclerostoma, also three
nodules (parasites) between the serous and muscular coats.
The first and second sections of the large colon showed
myriads of small round worms (probably S. tetracanthum)
mixed with the contents. The third section showed several
ulcers in the mucous coat, which were of a probable para-
sitic origin. The different lobes of the lungs contained
numerous small nodules principally underneath the pleura,
but few were scattered through the lung tissue. The pleura
is normal. The heart has a normal appearance and does
not show any microscopic lesions. All lymphnodes examined
are normal. Bone-marrow changes are pronounced espe-
cially in the femurs. The proximal cancellated bone tissue
is densely hyperemic and a good part of the fat marrow
shows a change to lymphoid structure.
No. 857. (An experimental case infected by means
of the blood of experimental case No. 636.) The car-
292
cass is poor, has very little adipose, but the muscles
are normal in color. The small intestines and float-
ing colon are normal, but the mucosa of caecum and Large
colon is inflamed over a considerable area. Sclerostomy
are present but not in Large uumbers. The spleen is normal
but shows slight siderosis. The naked eye appearance of
the kidneys is normal with the exception of small calcareous
deposits being present in the medulla just outside the pel-
vis. Microscopically the kidneys show some capillary en-
gorgement and areas of interstitial nephritis, but the paren-
chyma is fairly intact. In the region of the diaphragm and
liver there is evidence of a considerable chronic peritonitis
in the shape of numerous adhesions. Otherwise the gross
appearance of the Liver is normal. Microscopically the
organ shows interstitial and intralobular round cell infiltra-
tion and some parenchymatous degeneration. The bone-
marrow especially that of the femur shows areas of a dark
red discoloration, the remainder being pale and very fatty.
No. 867. (An experimental case infected by means
of the blood from experimental case No. 636.) The
subcuta contains a yellowish, gelatinous substance, es-
pecially well marked on ventral portion of abdominal
wall. There is marked evidence of an old adhesive peri-
tonitis, both parietal and visceral. There is no excess of
peritoneal fluid. The spleen is slightly enlarged and shows
numerous hemorrhagic pin-head areas beneath capsule. Mic-
roscopically there is marked siderosis and slight hem-
orrhagic engorgement. Splenic lymphnodes are slightly hem-
orrhagic. The small intestines show a distinct, acute enter-
itis throughout, with the exception of the first ten feet
of the jejunum. The bladder is devoid of urine, but con-
tains a couple ounces of yellowish, brown, sandy sediment.
There is also evidence of a slight, cystitis. The kidneys con-
tain a mucoid deposit, closely adherent to the pelvis, other-
wise they appear to be normal to the naked eye. Sections,
however, reveal pronounced interstitial lesions but the par-
enchyma is well preserved. The large and floating colons
293
are normal but the mucosa of the caecum presents slight
petechia? Dear the apex. The stomach contains a small
amount of ingesta and presents a well marked gastritis.
The visceral Lymphnodes show a slight hemorrhagic con-
dition. The liver has a normal size. Its capsule shows
well developed fibrinous appendages, some penetrating into
the liver structure. The border of right lobe shows a con-
siderable hemorrhage. Histologically, this organ shows an
interstitial hepatitis, well marked and of recent origin.
There is a slight siderosis and the parenchyma is fairly in-
tact. Both Layers of the pleura show adhesive pleuritis.
The lungs arc collapsed, the right one showing hypostasis.
The bronchial and mediastinal lymphnodes are hemorrhagic.
The pericardia] sack contains about oOO e. c. of a yellowish,
red fluid. It is slightly adherent to the diaphragm. The
myocardium shows small petechias, while there are very
marked ones on the endocardium. The bicuspid valve has a
marked hemorrhagic area extending throughout the entire
valve. Microscopically the myocardium shows a beginning
of brown atrophy with here and there a slight evidence of
interstitial myocarditis. The n arrow of the proximal ex-
tremity of the left femur is dark vri] in color, the marrow
cavities being filled with an abundance of dark red pulp.
The marrow of the distal extremity is pale, the pulp appar-
ently being replaced by a fatty debris. The place normally
occupied by the yellow marrow shows a large area of hem-
orrhagically infiltrated tissue. This dark red part shows
an arrangement in foci. Each such focus is surrounded
by a bright red zone, which is somewhat separated by an
intervening light colored strip from the dark red structures.
Of the right femur the upper extremity is like that of the
left, while the lower also resembles the corresponding part
of the left hone.
No. 902. (An experimental ease infected by means
of blood from experimental case No. 855.) The cav-
ader is thin. The peritoneum shows a slight yel-
low tinge and is quite pale. The spleen is normal in size,
294
but shows numerous slight, sub-capsular hemorrhages. The
borders are slightly rounded and the organ shows a rather
tense appearance. Splenic lymphnodes are somewhal edema-
tous and enlarged. The liver is normal in size and appear-
ance with slight adhesions to the diaphragm. The small
intestines appear to be normal with the exception of several
ecchymotic areas on the mucosa. The large colon presents
a normal appearance. Its contents show several specimens
of Sclerostomum equinum. There are numerous ecchymotic
spots in the region where the parasites are found. Several
small nodular enlargements were to be seen in the mucosa.
The caecum contained a markedly hemorrhagic area. The
kidneys are apparently normal. The bladder contained about
500 c. c. of a straw-colored viscid urine. Its mucosa is
slightly congested in the ventral portion. The heart muscle
is quite firm and has a good color. The left ventricle presents
a slight ecchjmiosis of the endocardium. A small hem-
orrhagic area is found on the auriculo-ventricular valve.
The lungs show no changes and collapsed completely when
the thorax was opened. The bone-marrow shows but very
few hyperplastic areas.
No. 903. (An experimental case infected by means
of the blood of experimental case No. 873.) The gen-
eral condition of the carcass is good and all adiposa
are well developed. The peritoneum shows pronounced
visceral adhesions, especially on liver and spleen; the
peritoneal fluid is normal. The right kidney is appar-
ently normal; the left one is considerably congested (ante-
mortem). The bladder is normal and contains 200 c. c. urine of
an orange-yellow tinge (S. G. 1046, neutral reaction, con-
tains a trace of alb.umen). The spleen is normal, with the
exception of the adhesions noted above. The splenic lymph-
nodes are enlarged and hemorrhagic. The liver presents
no changes, aside of the adhesions previously mentioned.
The mucosa of the small intestines presents numerous fresh
hemorrhagic areas and that of the caecum, a few small ulcers,
evidently of a parasitic origin. The first division of the
295
large colon contained a great number of helminths (Scleros-
toma). The apparently normal stomach contained a few
"bots." Lungs and pleura are normal. No changes are
seen in connection with the heart, but a few projecting cal-
careous concretions are attached to the intima of the common
aorta just behind the valves.
Nearly all the visceral and body lymphnodes were
slightly enlarged and hemorrhagic. Hyperplasia of the mar-
row is seen in the femurs and humeri while the proximal
cancellated structures either are hemorrhagic or marked by
small dark areas.
■No. 64:2. (A field case purchased in the vicinity of
Fargo, N. D.) There is an almost complete absence of subcut-
aneous fat. The musculature, although reduced in volume
was normal in color. The lymphnodes lying on the caecum are
enlarged and surrounded by hemorrhagic areas. The meso-
colic lymphnodes are enlarged and soft, but the mesenteric
nodes are not involved. In the caecum there are a few para-
sites (Sclerostoma) and at certain places the mucosa is
ecchymotic, while near the apex, there are quite a few
parasitic nodulos in the mucosa. The kidneys are slightly
enlarged, soft, pale and friable, but sections taken from
those organs show a slight degree of interstitial involvement,
a shrinking of the glomeruli and an intact epithelium.
The spleen is normal in size, thin and flabby. Cutting through
the organ, it seemed as if the spleen pulp was reduced, while
the connective tissue elements were more conspicuous. The
liver is normal in appearance. The lungs are poorly con-
tracted, while the right anterior lobe is somewhat emphy-
sematous. The heart was pale and soft, and its cavities filled
with ante-mortem clots. The peritoneum showed evidence
of chronic inflammation with an organized fibrinous exu-
date, more especially near the diaphragm. The anterior
and posterior mesenteric arteries showed small aneurisms.
In the bladder was found a small quantity of urine (S. G.
1025, acid in reaction and free from albumen).
No. 639. (An experimental case infected by means
296
of blood from experimental ease No. 637.) There
is a reduction in adipose. The muscles, are generally
of normal color. The spleen is about twice the nor-
mal size, shows some infarcts and microscopically, reveals
a moderate degree of siderosis. The kidneys are paler than
normal and the naked eye appearance leads one to think
of parenchymatous degeneration. Microtome sections, in-
deed, reveal the presence of a naked congestion of the
medullary vessels. There is a very marked interstitial
nephritis, accompanied by shrinkage and degenerative
changes of the glomeruli, with thickening of the capsule.
In a few of the convoluted tubules there are some signs of
parenchymatous impairment and many of the straight tub-
ules contain casts. Tn the liver interstitial inflammation
is marked and a greal number of Lew ocytes have infiltrated
into the lobules. Siderosis is apparent throughoul and tin4
parenchyma shows some slight fatty changes. The large
colon shows a few sub-peritoneal nodules, while a few speci-
mens of Sclerostonum equinum are contained within. The
anterior mesenteric artery shows a large verminous aneur-
ism. The lungs are well contracted and normal, with the
exception of a small area of solidification which has a soften-
ed area in the center. The heart looks normal, but microscop-
ically a very slight degree of interstitial myocarditis can
be detected. The mucosa of the nasal septum presents a
large, gangrenous area. This ulcertation was apparently
due to a deep necrosis and extending clear through the sep-
tum involves the mucosa of both sides to the same extent
and in the manner that the affected mucous surfaces were
directly opposite one another. A large eschar is still intact
in the ulcer and represents the gangrenous mucosae and
cartilage. The edges of the ulcer were rather smooth and
at places occupied by a softened mucosa, apparently becom-
ing gangrenous by continuity. There is nothing to indicate
malleus and a conscientiously carried out bacteriologic re-
search confirms this statement. The sub-maxillary lymph-
297
nodes were somewhat enlarged, but neither softened or pur-
ulent.
No. 743. (An experimental case infected by means
of the blood from experimental case No. 638.) The
lungs are inflated and show numerous slight adhes-
ions between the pleural layers. There is no liquid exudate
in the cavity. The anterior half of the lungs are filled with
solidified foci, the cephalic lobe being entirely solid. The
ventral border also solid to a width of about two inches.
The ventral border of the posterior lobe also contains many
solidified foci and presents numerous ecchymoses beneath
the pleura. Along the ventral border of the posterior lobe
there are numerous small oecrotic areas. The pericardium
contains about one liter of a straw-colored exudate. The
right side of the heart shows marked ecchymoses and the
auricle contains a Large ante-mortem clot, which extends
into the ventricle. The left side shows no changes. Sections
of the heart reveal a general cloudy change of the myocar-
dium. The liver has a weight of twenty pounds, is somewhat
congested and firmly adherent to the diaphragm. The pos-
terior surface was likewise somewhat adherent to the
stomach, which organ showed a corresponding inflammation
on the external surface, hot its mucosa showed no lesions.
Liver sections showed a well advanced parenchymatous
degeneration and some siderosis. The intestines show noth-
ing abnormal. The kidneys and bladder appear to be normal,
although sections of the former show slight interstitial
changes throughout. There is a small degree of arterial
thickening, while the glomeruli are enlarged filling out the
entire capsule. A very slight degree of parenchymatous
damage may be mentioned. The spleen is quite flaccid, shows
some#necrotic areas and a moderate degree of siderosis.
No. 723. (An experimental case infected by means
of the blood of experimental case No. 638.) The
cavader is poor, but not emaciated, the muscles have
a normal color. The spleen has a weight of four
pounds, six ounces, and shows small hemorrhages under the
298
capsule. Heart, kidney, liver, intestines and Lymphnodes
are normal in appearance. The marrow of radius and tibia
is pale, deficient in coloring and is quite i"atty. The same
conditions prevail in the lower extremity of the humerus
and femur, but the upper extremity of the femur is lightly
red. The cancellated tissue of the proximal extremity of tie
humerus has a mottled appearance.
No. 816. (An experimental case infected by means of the
simultaneous injection of the blood from experimental Cfl
Nos. 637 and 638.) The subcutaneous connective tissues are
poor in adipose, lemon-colored, while the musculature has a
salmon color. All the mucosae are blanched. The lungs are in-
flated and show petechias on pleura. The bronchial and me-
diastinal lymphnodes are normal with the exception of a cer-
tain degree of anthracosis. The heart has a par-boiled appear-
ance with pronounced ecchymosis of the endocardium of
the left ventricle. The kidneys are of normal size, but
show dark spots on surface and their substance is rather
friable. The large intestines show very numerous petechia-,
which are also visible through the mucosa. The liver is nor-
mal in size and shows a fibrinous exudate on the surface.
The spleen is slightly enlarged and has a few petechias on
the surface. Petechias are also seen on small intestines,
mesentery and bladder. In the upper end of the femurs, the
bone-marrow is red for a considerable proportion and this
red marrow is sharply demarcated from the yellow parts.
The marrow of the lowTer part is of a yellowish-white color
and edematous. The humeri and tibiae have a marrow like
that seen in the lower part of the femur, but in that of the
lower part of the radii, there is still a pink color present,
although it is very pale.
No. 920. (A field case purchased in the vicinity of Kelso,
N. D.) The carcass was poor but not emaciated. The quan-
tity of adipose is small. The peritoneum is apparently nor-
mal and contains about one liter of peritoneal fluid. Pancreas
and kidneys are normal in appearance. The bladder looks
normal and contains about 200 c. c. of amber-colored urine
299
(S. G. 1015, reaction strongly acid, albumen present). The
spleen is of natural appearance but the splenic lymphnodes
were enlarged, showing a hemorrhagic lymph-adenitis. The
liver is enlarged to one and one-half the normal size, show-
ing a marked adhesive peritonitis and pronounced siderosis.
Under the microscope, the interstitial changes prove to be
pronounced, there are granular changes in the parenchyma,
while pigment deposits are seen throughout the sections.
The portal lymphnodes are enlarged and hemorrhagic. There
is a well denned verminous aneurism on the anterior mesen-
teric artery. The small intestines contained a small quantity
of semi-fluid ingesta, through which were scattered about
a dozen specimens of Ascaris megalocephala. The caecum
and large colon contained a large quantity of semi-fluid
ingesta. The caecal mucosa showed a few specimens of
Sclerostoma. The floating colon is normal to the naked
eye. The mesenteric lymphnodes were greatly enlarged
and hemorrhagic. The normal stomach contains about six
large "bots" and about a dozen smaller ones. The gastric
lymphnodes present the same features as the mesenteric
ones. The parietal pleura shows a well marked ecchymosis,
the result of a pleuro-pneumonia. Both lungs show a well
marked lobar pneumonia, the left being very extensive, tak-
ing in the entire ventral half. The pulmonary artery showed
a marked thrombus. The bronchial and mediastinal lymph-
nodes are enlarged and hemorrhagic. The pericar-
dial sac contained about one quart of fluid. There is Sube-
picardial ecchymosis. The myocardium is pale, flabby, and
apparently degenerated. Subendocardial ecchymosis is in
evidence. The right heart is filled with an ante-mortem
clot. The marrow changes are the same as in the other cases ;
there is hyperplasia of the fat marrow and hemorrhagic
areas are noted in the other parts of the bone.
No. 930. (An experimental case infected by means
of the blood from experimental case No. 919.) The
cavader is thin and presents a scant amount of sub-
cutaneous, sub-serous, sub-mucous, and omental fat. The
300
peritoneum is apparently normal with the slight exception
of some adhesions of the viscera. Liver, spleen and kidneys
are seemingly normal. The bladder contained about one
liter of lemon-colored urine and has a normal mucosa. 1 I Irine -
S. G. 1030, reaction neutral, albumen presenl . The stomach
and small and large intestines are normal. There is a colony
of "bots" in the stomach and the Large intestines contain
contain a few Sclerostoma. Lungs and pleura are both normal.
The heart presents slighl subendocardial petechia- and ecchy-
moses, bul is otherwise normal. The lvmphnodes are appar-
ently normal with the exception of the mesenteric ones,
which are slightly edematous. The marrow of the hones
shows some hemorrhagic infiltration and a few well defined
hemorrhagic areas.
No. 921. (Field case purchased in the vicinity of Shelly,
Minn.) The carcass is thin and shows a marked edema of the
sheath, the lower abdominal and thoracic walls, between the
fore legs and on the inner side of the thighs. The adiposa
are reduced in volume and the subcuta shows a slight lemon
color. The fairly well developed musculature suggests a
lemon color. The peritoneum presents numerous fibrinous
adhesions to the viscera and contains about one liter of a
dark thin hemorrhagic fluid. The stomach is normal ; there
are not "hots" and the gastric lvmphnodes are normal also.
The small intestines offer no changes, but their lvmphnodes
are hemorrhagic. The large intestines are normal throughout.
The heart is enlarged, flabby, and has a par-boiled appear-
ance. There was about one liter of dark hemorrhagic fluid
in the pericardial sac. There are subendocardial petechia?
near the eolumnae carnae of the left side and the auricles
are filled with large chicken-fat clots. The kidneys are
normal in size, but very pale, probably the seat of a con-
siderable parenchymatous change. The renal lvmphnodes
are enlarged. The liver shows a post-mortem change, but
is normal in size. The spleen is slightly enlarged and shows
petechias under its capsule. The bladder contains about one
liter of urine (S. G. 1012, and acid reaction and contains a
30]
trace of albumen). The upper pari of the bone-marrow of
the femur is of a deep hemorrhagic \-in\. The marrow cavity
contains fat marrow to one-half of its capacity, while the
other half contains a hyperplastic red marrow. The extrem-
ities of the humeri are extremely pale and here and there
show small hemorrhagic areas. The fat marrow also shows
a few hyperplastic areas. In the tibiae and radii, a uniform
lemon color is observed.
No. 924! I An experimental case infected by means of the
blood of field ease \o. (.)'2] . | The car case is in fairly good con-
dition. The pannicnlns adiposis is well developed and sub-
mucous, SUb-serOUS, and omental fat is not materially reduced.
The peritoneum, with the exception of some slight adhesions
between liver and diaphragm, is normal throughout. The
kidneys are both congested and the bladder contained about
two liters of urine | S. (J. 1020, ueutral reaction, containing
;i trace of albumen). The liver has a normal appearance
as well as the spleen. In the small intestines there are
diffusely spreading hemorrhages, the duodenum showing a,
decided congestion. In the ea-cum and large colon, the
mucosa is almost a continuous hemorrhagic mass and the
vessels of the sub-iiuicosa are heavily injected. With the
exception of a few subendocardial petechia', the heart is
normal for so far as naked appearances go. 'fhe Lungs and
pleura are normal. There is marked hyperplasia of tin;
bone-marrow of the femurs, but in the other bones, this
COndil ion is less marked.
No. 934. (An experimental case infected by menus
of the urine of experimental case \o. {.)2A.) The
cadaver is in fair condition, although there is but a
slight amount of subcutaneous, sub-mucous,' sub-serous and
omental fat. The kidneys are slightly enlarged and show
slight capsular and parenchymatous hemorrhages. The
bladder contains about 500 c. c. of urine (S. G. 1021, reaction
sharply acid, contains a considerable amount of albumen).
The spleen is considerably enlarged and the pulp showed a
blackberry jam-like color and consistency. The liver is
302
slightly enlarged and wholly free from adhesions. The
mucosa of the stomach showed marked ecchymoses. With the
exception of a couple of parasitic nodules, 1 ae small intestines
are apparently normal. The large intestines present a few
parasitic ulcers to which a pair of specimens of Sclerostoma
were attached. The lungs were normal. The heart shows
subpericardial ecchymoses, myocardial hemorrhages and the
endocardium in all compartments of the heart is covered by
hemorrhagic areas. Most of the visceral lymphnodes and
especially those of the spleen are enlarged and slightly
hemorrhagic. The bone-marrow changes in this ease are
slight and consist principally of the presence of small hem-
orrhagic acreas.
Reviewing our findings made at autopsies and those
reported by other investigators, it would seem that none
of the lesions are such as deserve to be regarded as pathog-
nomic. There are no changes which unmistakably bear the
brand of identity. Almost any of the changes met with may
be found in association with other diseases and in them-
selves are of but little diagnostic value, and hence they can
only be used diagnostically as a certain link in a chain of
evidence furnished by clinical, epidemiologic and experi-
mental data. The features deserving the most attention
are no doubt the petechiae and ecchymoses of certain struc-
tures, lymphnode involvement, interstitial and parenchy-
matous lesions of certain important viscera, albuminuria, and
the alteration of bone-marrow and the blood. We have
refrained from discussing the latter in connection with the
pathologic anatomy of the disease, preferring to do so when
dealing with the clinical features of the disease. It is pos-
sible that the bone-marrow lesions constitute a valuable
aid in the post-mortem diagnosis of the disease, but in view
of the fact, that we know, comparatively so little of bone-
marrow changes in connection with other diseases of the
horse, or even under varying normal conditions, we would
rather suspend judgment relating to their diagnostic value
303
until the matter has been looked into more fully. The
writers contemplate making some observations in regard
to marrow changes in various conditions and hope' to be
prepared to place a proper value on those seen in "swamp-
fever" in the course of the coming year.
Studying the clinical manifestations of the disease, we
meet with a more or less constant series of symptoms, which
are somewhat characteristic. Taylor <7> speaks of "swamp-
fever" as an intermittent fever somewhat analogous to surra
and characterized by anemia. The one case described by
him has a slight attack of fever, was rested up and appeared
at one time to have recovered. When driven, however, it
appeared so sluggish, that it staggered when led into the
Btable. In addition to the staggering gait, the animal showed
signs of laminitis. The weakness of the hind quarters
remained a prominent feature in this case, but the appetite
showed but little impairment. The animal soon commenced
to lose flesh, the abdomen became tucked up. Taylor also
speaks of a discrepancy existing between the height of tem-
perature elevation and the increase in the number of pulse
beats and regards it as "one very diagnostic symptom."
In Taylor's case the mucosa became paler than normal,
baving a yellowish tinge, which became more evident as the
disease advanced. The animal improved and relapsed
several times.
The patients observed by Kopke (8) stood with their
heads down in the manger and showed a rather capricious
appetite. The conjunctiva was conspicuously pale without
showing any yellow tinge. In the beginning of the disease,
the pulse was relatively strong, but more frequent than
normal (50-60 p. m.). The most pronounced symptom was
the high body temperature which in nearly all cases was
elevated from the beginning. (105.5°-106.7°F.). In the
further course of the disease, the fever remained almost
constant for eight to fourteen days. The heart function
decreased in force, the pulse becoming weaker and its fre-
304
quency ranging from eighty to one hundred beats per
minute. At the same time the pallor of the conjunctiva
became more marked. In the cases running a favorable
course, the temperature receded gradually to normal in from
six to eight days, and the animals made a complete recovery
in from two to three weeks. In the more severe cases also.
the temperature came down in Prom teD to fourteen days.
but only to 102.2° K. to 101.1 F. The patients then became
more lively, but the pallor of the mucosa and the cardiac
weakness persisted and after an apparent, im provement of
from ten to fourteen days, another febrile attack with the
usual accompaniments had to he sustained. This would
happen three or four times within two or three months.
During this time, the animals would lose considerable tlesh.
hi many cases a severe diarrhea would set in. During the
last stages of the disease, the animals would sway con-
siderably with their hind parts and could no longer maintain
themselves in the standing posture. As an accompaniment
of the complete anemia of the mucosa and a high degree
of cardiac weakness, marked edema of the dependant parts
of the body would make ils appearance and the animals,
after an illness lasting from four to eight weeks, would
succumb in a very emaciated condition.
As described by Torrance ,:" the disease is essentially
a fever of the remittent type characterized by progressive
anemia, gradual emaciation in spite of a good appetite,
edema, weakness and loss of power in the hind legs. Weak-
ness is the earliest symptom, which is closely followed by
uncertainty in the movements of the hind legs, which causes
the animals body to sway the hind quarters. The appetite
continues normally or is even increased. The pulse gradually
assumes a greater frequency, running from 50 to 70 beats
per minute and presenting a peculiar thrill as if the vessel
were only partly filled. The temperature ascends to 103° F.
or higher and shows considerable irregularity. The animal
now becomes too ill for work and may receive some form of
treatment, In spite of apparent improvements, which how-
305
ever, are only temporary, the animal becomes thinner, the
mucosa becomes pallid on account of the profound anemia,
while the edema of the dependant parts of the body makes
its appearance. The pulse becomes more rapi,d and weak
and the heart action labored. The skin is dirty and greasy
to the touch and the animal has polyuria. Torrance also
met sometimes with more acute cases in which the symptoms
are presented in a more aggravated form and the animal
dies in two or three weeks. The red blood count of Tor-
rance's cases went as low as two millions. The corpuscles
retain their form well and this author never witnessed
marked poikilocytosis, although there has generally been
seen a small proportion of megalocytes and microcytes.
There was a marked increase in the clotting properties. In
one or two acute rases, Torrance observed, what appeared
to be debris of red corpuscles floating in the plasma. The
granules were formless, irregular in size and had no power
of motion.
Brimhall, Wesbrook and Bracken (10) write that in the
Minnesota disease the onset was insiduous, but once devel-
oped, it was accompanied by a general weakness, slowly
progressive, loss of flesh, periods of fever, followed by times
of apyrexia, gradual emaciation, staring coat, a ravenous
appetite, and sometimes by polyuria, as the most prominent
symptoms.
The following symptoms are described by Rutherford
(11) as the most prominent: progressive emaciation, ede-
matous swellings of the dependant parts of the body, pro-
gressive pallor of the visible mucosa on which petechia? may
be occasionally seen. The peculiar soft, flat pulse is regarded
as almost diagnostic, while the periodic rise and fall of the
body temperature, ranging from normal to 105° F. is regard-
ed as the most important of all symptoms. The appetite,
while capricious, generally remains good until near the last.
Lack of muscular control is common in the more advanced
cases, but Rutherford ascribes this more particularly to the
306
general weakness. Polyuria is frequently seen in the latter
stages.
The tea cases reported by Beghin (22) all commenced
by losing then- appetite, then they became dull and still
later they acted as if paralyzed. All animals sustained a
considerable loss of flesh. They showed swelling under the
chest and belly, while in the geldings the sheath became
swollen also. The fatal cases went on to the extreme emacia-
tion. The one case actually seen and examined by this
author himself was very poor in flesh, hide-bound, with a
staring coat and stood with its head down. The appetite
was diminished and irregular. The mucosa are pale. The
pulse is small and very much accelerated. The artery is
soft, but the beats are regular in spite of those changes.
There is a slight edema under the chest and the heart beats
violently. A marked systolic murmur can be detected. The
respiration is more frequent than normal, but there is neither
cough nor discharge. The temperature is 103° F. and
weakness is a marked feature, the animal having difficulty
in moving the hind legs.
The fundamental observations made by Carre and Vallee
(23) deserve to be quoted quite fully. Their investigations
led them to recognize three clinical forms of the disease;
namely, the acute, subacute, and chronic types.
The acute type sets in suddenly. The animals become
soft and lazy when at work. The least effort at pulling
or speed causes the animals to blow or in some cases even
to fall down. The appetite fails and the food is taken
slowly. The conjunctiva is injected, edematous, yellowish
with a red ground-color. Petechias of a translucent aspect
are frequently observed. They are pink red, brownish or
purplish in color and from 10-20 m. m. in diameter. A flow
of tears is quite often seen. The temperature rises to 104°,
105°, sometimes even to 107.5° and generally keeps up
until the end. The animals hold the head in a fixed posi-
tion, the nostrils are dilated, and the facies reminds one of
tetanus. Evidence of enteritis with diarrhea makes its
307
appearance. The faeces are often reddish in color and would
lead one to believe that they contain blood, if the spectro-
scopic examination were not negative in its results. In
certain cases, however, the faeces are streaked with blood.
No respiratory disturbances are encountered. The pulse
is soft, quite frequent (60-90 beats per minute). The car-
diac sounds are accentuated. Marked edema is not encoun-
tered, only a simple swelling of dependant parts. The urine
is abundant, generally deep in color and always containing
albumen. In certain cases the albumen amounted to 14
grammes per liter. As a general thing urine does not con-
tain blood corpuscles or hemogoblin, but granular and epi-
thelial casts may be present.
The animals sway or take the position of a foundered
horse. Movements are painful and the wabbling gait is a
marked feature. Getting up is difficult, there being present
a clear paresis of the hind quarters. There is a progressive
emaciation and the extreme weakness and paresis of the hind
quarters may be expressed by incontinence of urine. The
coat is staring and the hairs of the mane and tail can be
pulled out with extreme ease. Pregnant mares commonly
abort. In this form of the disease, the course ranges from
five to fifteen days, more often about eight days.
In this acute type, the changes of the blood are but
little pronounced. There are no signs of anemia. Never-
theless, the blood coagulates but slowly. There is a rapid
separation of the corpuscles, which have a brownish red
tinge and which agglutinate, massing themselves in small
agglomerations floating in a highly colored plasma, which
frequently is -opalescent.
The subacute type presents the same features as the
acute one, but they are more or less attenuated and differ-,
ently associated. Clear cut remissions are a distinguishing
symptom of this form, a remission, which, when anemia
does not happen to become apparent, would lead one to
accept a real recovery from the disease. Carre and Vallee
even saw cases which went along for eight months without
308
presenting fever. Such recoveries, however, are more appar-
ent than real, as the urine still shows albumen upon analysis
and the conjunctiva is edematous. Blood examination re-
veals a marked anemia. The slightest work causes the ani-
mals to blow, while the heart beats become fast. The ani-
mals sweat abundantly and sometimes drop in an exhausted
condition. In this form the duration of the disease varies
very greatly, ranging from a few weeks to several months.
The chronic type is characterized by the symptoms of
an extreme anemia. The patients become soft, lazy, the
appetite indifferent and capricious, the coat rough and star-
ing, while the hair of tail and mane can be pulled out with
ease. The mucosa are pale and the temperature is most
frequently normal ; there are intermittent attacks of fever,
but they are not frequent. The animals are soft and weak.
The pulse is soft, frequent, unequal and the artery is flabby.
Sometimes a transitory diarrhea is observed. Edema of
the dependant parts is seen and the gait is wabbly, stumb-
ling, and arising is difficult. The urine is abundant and
more often contains albumen. The anemia is progressive,
the blood coagulating poorly, forming a soft small clot.
Sometimes, even it is difficult to check hemorrhage in pa-
tients. After more or less frequent remissions the animals
die, either in one of the exacerbations or succumb to the
final stage of anemia.
Changes in the blood are never absent and pertain to
both plasma and formed elements. The plasma is but very
little coagulable, it is over-colored, of a deep yellow or
greenish tint, very often dichroic, especially so in the acute
cases and during the acute exacerbations of the chronic
cases. The erythrocytes are friable and readily agglutin-
ated. They are irregular in size. They are poor in hemo-
globin and fragile. Crenation is very commonly found. The
red corpuscles, after being stained with the basic aniline
dyes enclose a body comparable in shape and color to a
piroplasma.
The red cell count varies according to the type of the
309
disease and the time of the examination. In the acute form,
when the signs of anemia are masked by other symptoms,
there already is a notable reduction in the number of cells.
From the tenth or fifteenth day, the cells fall from one and
a half million to two millions below the normal figure (about
seven millions). At the time of death in the acute cases,
the count only runs to four millions, in the subacute cases
about two to two and a half million, and in the chronic
cases the count will range from two to four millions, accord-
ing to the condition of the patient. In some cases it will
fall to one million. The leucocyte count does not show
great deviations, there commonly being a slight leucopenia.
As seen in Nebraska by Peters (26) the disease is ini-
tiated by a recurrent fever, which is followed by weakness.
The mucosa of mouth and eyes become very pale. A stag-
gering gait is noticed as the disease progresses. The appe-
tite is retained but the emaciation is progressive. The
temperature becomes higher, ranging between 103° F. and
106° F. Temporary improvements were observed. Diseased
horses usually live from two to three weeks, although Peters
mentions some eases, which lived three months. Edema of
the dependant parts of the body and petechia' on the mucosa
wm-e observed. Polyuria is spoken of as a symptom of a
serious condition. The blood count in field cases amounted
to 1,800,000 to 2,000,000 ml cells per cubic m. m.
Ries ,-T) does not regard the clinical picture as absolute-
ly uniform. In certain subjects the disease runs its course
without fever. The appetite is retained or diminished, while
the strength becomes reduced. There is shortness of breath
and tin1 animals break out in sweat. Along with the presence
of those conditions the anemia already is quite evident; the
mucosa1 are pale, white, and the pulse is weak, thready,
while the heart sounds have acquired a metallic ring.
In other cases no alarm is taken before the appearance
of the edema of the abdomen and the limbs. This form is
especially seen during summer and early fall and on farms
where there is a short supply of oats. In another form of
310
the disease, albuminuria is seen, aside from a notable increase
in the rate of respiration and a fever which fluctuates
around 104° P. This albuminuria may be pronounced and
exhausting in some cases, while in others the albumen only
occurs in traces. The animals continue to eal but waste, as
it were, before one's eyes. The mucosa are nol yet blanched
but become paler. The eyes present a peculiar aspect, they
are bright, feverish with the bulbs retracted, the eyelids
participating in this movement. In the advanced stages,
the patients move about with difficulty, sway to and fro,
and threaten to fall. The limbs become edematous as well
as the lower parts of the body. The horse no longer lies
down, but when he does so in Prom five to ten days, he goes
down for good.
The symptoms named by ('baron <34) are a rather sudden
loss of flesh, softness when being moved, Bwaying of the
hind quarters, a pale yellow color of the conjunctiva, muffled
heart sounds, arterial depression, venous pulse, a well
marked reduction of the blood cells and an irregular but
rather high temperature. The appetite, at first capricious,
becomes better, the animal eating abundantly. The hair
coat was not bad and the conjunctiva yellowish, but neither
infiltrated nor oily. In Charon's case there was no edema
of the sheath, the abdomen, the chest or the hind limbs. At
no time was there polyuria or albuminuria.
Ostertag (35) elicited the following description of some
cases from an owner, who in the space of five years has lost
some twenty horses with the disease. The first phenomena
noticed was a knuckling of the hind legs, while in the course
of eight days, the animals would be tired and unfit for work.
They would lose flesh rapidly and in a high degree. The
mucosae would be yellowish-white and periodically the pa-
tients would show a high fever. A few animals also presented
edematous swellings of the lower part of the chest and the
sheath.
Among the most conspicuous symptoms, Francis and
Marsteller (42> mention: progressive emaciation without any
311
apparent cause, polyuria and a peculiar weakness of the
hind quarters, which has given the disease the local name
of ''loin distemper." There are periodic attacks of fever
lasting several days to a week or more; the temperature
ranging from 103° F. to 107° P., and being followed by a
drop to sub-normal, ranging from 95° F. to 98° F. There
are remissions in the course of the disease, even apparent
recoveries. The mucosas are very pale, often of a yellowish
or rusty color, while petechia' may be. observed on the con-
junctiva as well as a dribbling of a bloody serum from the
nostrils and anus. The skin becomes dirty, the eyes are
sunken and there is a dribbling of urine with relaxation of
the sphincters. Notwithstanding all this, the animals will
cat ravenously until the last. The authors did not observe
any nervous disturbances. They found anemia to be present.
Some of the erythrocytes being abnormally large, while
others were small. Nucleated cells were but rarely encounter-
ed.
Hutyra and Marek (69) recognize two forms of the dis-
ease. The acute form is ushered in by well marked signs
of sickness. There is a pronounced dullness and general
weakness, so that the animals easily tire and even fall
during exertion. The weakness is most plainly seen in the
hind quarters. Fever is simultaneously observed. This
reaches its maximum height in from two or three days
(1(U°-107°F.). It may remain constant until death or resume
a resistant character. The pulse frequency is increased to
60-90 beats per minute, while it becomes weaker and softer,
the heart impact being increased in strength. The conjunc-
tiva is somewhat puffy, diffusely red in color, with a yellow
tinge and on which irregular hemorrhagic areas are not
rarely seen. The nasal mucosa also is reddened and shows
petechias, especially on the lateral wall of the nasal cavity.
Not infrequently, this is accompanied by a scant serous,
Sometimes reddish nasal discharge. A cough is sometimes
noticed. There frequently is diarrhea, the dung sometimes
being tinged with blood. Urine is frequently voided and
312
contains albumen, of which the quantity may amount to
J. 5%, as well as granular and epithelial casts. The appetite
is suppressed from the beginning. A progressive Joss of
flesh, whieh may make such a headway, that in a few days
the animals lose from one-fourth to one-third of their body
weight. Slight edematous swellings of the dependant parts
of the body were only rarely observed. The coagulability
of the blood is lessened, the serum appears dark yellow or
even somewhat greenish and dichroic. The number of ery-
throcytes lessens the duration of the disease. The duration
of the acute eases ranges from 5-15 days, but may be extend-
ed to from three to four weeks.
Hutyra and Marek's chronic form of the disease is char-
acterized by periodic attacks of fever and evidence of
anemia. The occurrence of albuminuria is not constant and
when present during the febrile attacks it is only slight.
In this form edematous swellings are not rare. Nutrition
is reduced from the beginning or remains satisfactory in
those cases whieh are marked by a slow progress of the dis-
ease. Loss of flesh occurs sooner or later. The duration
of this form of the disease extends from one to several
months and may drag even over a few years.
Mack (50) speaks of acute, subacute and chronic
types of the disease and states that they are not separated
by a hard and fast line. The acute type comes on suddenly.
There is an initial dullness, followed by prostration and high
fever. Heart action is more powerful and frequent than
normal and is accompanied by venous regurgitation. The
conjunctiva is injected, yellowish and deep red. Loss of
nerve and muscle force becomes remarkable as the disease
progresses. Emaciation is rapid. The temperature although
variable is high (105°-107° F.) with frequent irregular re-
missions. Cardiac impact is conspicuously increased, but
in a few cases the heart is weak. The pulse is rapid, soft
and compressible. Edema of the dependant parts of the
body and enlargements of the lymphnodes are seen, but not
constant in its occurrence. A blood stained, watery fluid
313
frequently drops slowly from the nostrils. The faeces are
often streaked with blood. Exertion provokes dyspnoea and
palpitation of the heart. In eases lasting more than five or
seven days there is a reduction in the hemoglobin, as well
as in the corpuscles of the blood, but otherwise those changes
appear to be insignificant. The number of leucocytes gen-
erally remains about normal.
The subacute type, spoken of by Mack, resembles the
acute, but may be more insiduous in its onset. Its course
ranges from a few weeks to several months and is marked
by periods of apparent convalescence and subsequent exacer-
bations of the disease. A high, irregularly remittent, fever,
a progressive anemia, a rapid emaciation, prostration, car-
diac weakness and edema are characteristic features of this
type of tlie disease. While the temperature may rise as high
in this type as it dues in the acute one, the periods of remis-
sion are Longer. It rarely reaches the normal point and a
greater irregularity is encountered. Locomotor, respiratory
and cardiac difficulties become pronounced and are aggra-
vated by exertion. Respiration may become labored. A
venous pulse is noticed and the arterial pulse is soft and
compressible. The Lymphnodes may show enlargement. Dur-
ing the periods of high fever, the appetite may be interfered
with, but otherwise it is keen enough.
In the chronic type the duration is longer. There are
occasional slight febrile attacks, a weakened heart, jugular
pulse and more or less loss of flesh and energy. Anemia
is not marked until the later stages. In spite of temporary
improvements a fatal issue is almost certain.
Whitehouse (56) recognizes several types of the disease.
Those of the anemia type will run a very slow indefinite
course. There will be a slight and gradual loss of flesh,
with a staggering or swaying gait. The mucosa are pale.
A constant and voracious appetite is invariable in this type
and is accompanied by considerable thirst. There is gen-
erally a slight rise of temperature, but not over 103.5° F.
The pulse runs from 50-70 beats per minute. As the disease
314
advances, polyuria develops. The various symptoms grad-
ually increase, the duration of the disease covering from
three weeks to six months, the animal wasting away to a
perfect skeleton.
Another type is mentioned by Whitehouse as the ede-
matous one. It closely resembles the anemic one and is very
nearly as common. Dropsical swellings appear early in the
disease, beginning with a small pad a1 the brisket and a
slight enlargement of the extremity of the sheath. These
edemata, may increase to a great, size ;m<l the skin covering
them may exude serum. The legs may swell, but do not often
do so. Temperatures up to 104.5° F. are occasionally wit-
nessed...
A different type is the one showing intermittent fever.
In this type the initial temperature may suddenly run up to
107° F. After three days of illness the norma] may again be
reached. Twenty-one days later there is a repetition of the
occurrence and after twenty-one days more another attack
occurs.' Whitehouse observed two such cases, one completely
recovering after a third attack, and the other one succomb-
ing, while the third attack was in progress. This author also
speaks of the bronchial type and calls it puzzling. His
observations on this type are limited. The cases which he
saw were only very slightly wanting in flesh and "appeared
like animals left with a bronchial thickening after influenza."
A fulminating type is mentioned by Whitehouse.
In a more recent Canadian publication, McGilvray (64)
dwells upon the tendency to apply the name of "swamp-
fever" rather promiscuously to a considerable variety of
horse diseases. He recognizes three typical entities, which
are more often covered by the name of swamp-fever and
calls them : I. Swamp-fever ; II. Typhomalarial fever ;
and, III. Low fever. No. I is characterized by its insiduous
and chronic course, remittent fever, pronounced anemia,
associated with a steady, progressive emaciation, in spite of
a well maintained and frequently voracious appetite. No.
II is an acute or subacute affection of horses characterized
315
by its sudden onset. There is an extremely high initial tem-
perature, marked injection of the visible mucosae, which later
become icteric. There always is a marked disturbance of
circulatory functions and extensive edema of dependant
parts. A critical polyuria and diarrhea precede dissolution.
No. Ill is distinguished by slight elevation of temperature,
usually maintained, marked unthriftiness, lassitude and in-
capacity for work. The visible mucosae are congested and
frequently icteric. The appetite is capricious. Edema of
the sheath is noticed. Polyuria is always more or less in
evidence. The bowel function is irregular, the faeces fre-
quently being coated with a slimy mucus.
Mohler (52> describes the disease as characterized by
a progressive, pernicious anemia, by remittent fever, polyuria
and gradual emaciation, in spite of a voracious appetite.
This stage is followed closely by a staggering gait, swaying,
uncertain gait, the hind legs being most affected. Weakness
and tenderness in the loins are also mentioned. The pulse
increases in rapidity and may run as high as 70 beats per
minute, although weak, stringy and intermittent. The tem-
perature may rise to 103° F. or higher, remaining high for
several days and then dropping to rise again at irregular
intervals. Toward the end of the disease, the temperature
occasionally remains persistently high. Temporary improve-
ments are noticed. Albumen appears in the urine in the
advanced stages. Mohler occasionally observed a slow drip-
ping of blood-tinged serum from the nostrils as a result of
the oozing of thin blood from the mucosa.
Our own observations tend to show that fever is per-
haps the most constant symptom mentioned in connection
with the disease. It is always more or less irregularly
remittent or intermittent in the field cases, the range of tem-
perature commonly lying between 101° F. and 104° F. To-
wards the last it may have a tendency to be more constant,
although this feature is not to be depended on as of constant
occurrence.
:i\6
In the experimental cases, il is the first of all symptoms
and in quite a number of cases about the only one sufficiently
pronounced to have a diagnostic meaning. Inmost of those
cases it makes its appearance after periods of incubation
varying from 6-21 days, according to the method of infection
practiced. After intraven n s injection, for example, the in-
cubation period will be found to be shortened when the
same virus' is used. It will be somewhal Longer after sub-
cutaneous injection, while when the virus be given by the
mouth, it will be still more prolonged. In general the period
of incubation is longer when mine is used for infecting pur-
poses than when blood is employed. It. is, of course, not
possible to fix the period of incubation definitely as varia-
tions in the virulence of blood and virus and the suscept-
ibility of the experimental horse used are factors over which
we have no control or which cannot be estimated. In the
greater number of our eases we have found that when using
fresh blood as a virus and injecting it subcutaneously in
quantities of 60-120 c. c. we may expect the initial tem-
perature rise in from 12 to 14 days. In such cases it some-
times happens, that the temperature rises to about 105.5° F.
and then again drops down to normal for 12-24 hours, after
which there is a steady increase in temperature, which
reaches its height in from 2-4 days. The maximum tem-
perature will usually amount to from 104°-107.5° F., but
will not long remain so, as in a day or two, it will gradually
go down either to normal or nearly so. This initial attack
in most cases will last from four to ten days. In a few
cases, the remission or intermission is of but short duration
and is followed immediately by periods of more or less fever
of indefinite duration. Such cases may run an acute course
and carry an abnormal temperature until they die, while in
other cases the fever may recede gradually after having
lasted for several days. In most of our cases, the first
months of infection witness a number of well defined fever
exacerbations, separated by remissions and intermissions. At
first they are apt to succeed in rather rapid succession, but
317
as time goes on they become divided over greater periods.
In the further course of the disease, as induced by experi-.
mental infection, there will he noticed periodic rises often
.•liter rather markedly regular intervals (See chart of No.
636), varying from 30-60 days. In some of the cases this
feature kept up for two years, although the fever periods
occurred at greater intervals after the first year. In other
cjiscs the temperature phenomena did not reappear after a
year, while the virulence of the blood persisted for much
longer.
The pulse rate is often influenced by the temperature
and to some extent the curves show some parallelism. In
anemic* field cases of lung standing the pulse is soft and
thready, conveying the idea of swishing through the pal-
pating linger. In more vigorous experimental cases, the
pulse is more voluminous and but for the increased fre-
quency docs not differ much from the normal. Towards the
fatal termination, the pulse becomes smaller, weaker and at
hist imperceptible. In all cases, with the possible exception
of the more vigorous experimental <-;ises, during the fever
intermissions, the frequency of the pulse ranges between
55 and 65 beats per minute and may even reach from 90-
loo, or even mote towards the final issue.
During the latter stages of the disease are changes of
cardiac origin noticed. The impact is increased in force and
nay be accompanied by a churning sound, wdien pericardial
exudate be present. An anemic bruit has been heard in some
old field cases but is not a constant feature.
Xo respiratory changes have been noticed, which could
be attributed to specific changes. In one of our field cases
there wTas a concurrent pneumonia, with the ordinary symp-
toms of respiratory distress. In some cases there, of course,
are respiratory disturbances incidental to cardiac or general
weakness. In one of our cases there was a foul smelling
nasal discharge due to extensive necrosis of the septum nasi.
During the febrile attacks dullness is a noticeable fea-
ture. The animals will stand with heads down into the
318
manger or will hang back on their halters, as if wishing to
support themselves in thai way. In not a few of the cases,
however, the fever exacerbations are not accompanied by
any marked features and the rise of temperature and a little
higher respiratory frequency arc the only symptoms present-
ed.
Under the conditions just mentioned, the appetite is
usually reduced or entirely suspended. An idea prevails
that in "swamp-fever" a normal or even an abnormally in-
creased appetite is a constant feature. This is no1 so, as we
have seen in many cases of the disease and especially during
the febrile periods, that the appetite shows the same irreg-
ularities that it does in other febrile diseases. It is, how-
ever, true that in many of the chronic and anemic eases, a
voracious appetite is a notable phenomenon and as such cases
are probably the only ones usually diagnosed, we cannot
wonder that an increased appetite is so often mentioned as
something characteristic of the disease.
Weakness and lack of muscle tone is a prominent symp-
tom in the anemic cases and even in the cases running the
course without anemia, it is not infrequently a marked fea-
ture. The animals readily tire and blow, when exercised,
they will knuckle over and stumble when moving and they
present a well marked swaying, wabbling motion with the
hind quarters, which seems to be the principal seat of mus-
cular weakness.
Loss of flesh usually accompanies the febrile attacks
and in quite a number it is progressive, the animals reaching
a stage of extreme emaciation. Affected animals will fre-
quently present a dull, staring coat, while the condition
known as hide-bound .usually prevails whenever emaciation
is present. In other cases the state of nutrition improves
during the non-febrile intervals, but when anemia becomes
a feature, emaciation becomes a more or less constant phe-
nomenon.
Edema of the dependant parts of the body, such as the
lower thoracic and abdominal wall, the sheath, the limbs, is
319
a common feature. It is more commonly seen toward the
latter stages of the anemic cases, when it is due to the blood
changes, combined with cardiac and probably also renal
insufficiency. We have also observed marked edema, how-
ever, in the acute experimental cases, in which anemia was
not a feature and in which the blood count even ran higher,
than what is usually considered normal.
Anemia was certainly a more or less marked symptom
in all but one of the field cases which have thus far come
to our attention. The visible mucosae are pale, even blanched^
and the blood count will reveal a sub-normal number of red
cells, usually ranging between two and four millions, al-
though in one of our field cases, the count amounted to less
than a million. In the experimental cases, anemia is by no
means a constant feature, in fact, it was only in a few cases
that artificial infection expressed itself by a marked anemia
and several of the cases went to a fatal termination, with
a normal blood count or even with a number of erythrocytes
considerably above normal. The hemoglobin percentage is
often reduced and this reduction is frequently greater than
the degree of anemia would indicate.
Not uncommonly the blood clots but slowly and occas-
ionally separation of clot and serum is imperfect. In such
instances, the cellular constituents of the blood have time to
settle to the bottom of the vessel before the entire contents
are changed into a rather soft coagulum. The serum fre-
quently shows a high color, sometimes a greenish cast.
Occasionally there is a tendency on the part of the ery-
throcytes to clump together, so that the thorough mixing
preparatory to counting becomes either difficult or impos-
sible.
The changes in the corpuscles are not very marked. The
erythrocytes are somewhat fainter in the anemic cases and
may in the same blood, show a more or less conspicuous varia-
tion in size. Crenation is not uncommon, but typical rouleau
formation is not often seen. A slight poikilocytosis has been
observed in one or two cases only, but in none of the cases
320
examined by this department were nucleated erythrocytes
found. As far as our cases go, the blood always contains the
specific virus of the disease, but a search for visible parasites
which could possibly be associated with its causation always
resulted negatively. In some of our cases bacteria were found
in the blood, but there was no constancy as to the species
nor were there indications that they were anything beyond
mere accidental intruders.
The blood may be highly virulent in the absence of all
other symptoms or phenomena. We know this virulence to
exist for not less than thirty-five months in an experiment-
ally infected case, and further investigations will probably
reveal the fact that it is retained for a much longer period.
We do not believe that in all of the cases of this character
the blood remains permanently virulent as there are some
indications that warrant the belief that after a long time its
virulence becomes less and finally disappears. Our investi-
gations, however, have not yet advanced far enough to per-
mit of a definite statement in this regard.
Albuminuria is frequently seen in cases of "swamp-
fever," both in the field and experiment cases. It is not
a constant accompaniment of the disease ; sometimes it will
be in evidence in a given case, while a little later, it may
have completely disappeared. At no time have we found
the amounts of albumen, mentioned by European authors.
In a few cases there was a sharp and well defined albumen
reaction, but in the greater number, only traces were pre-
sent. Only in one case were we able to find tube casts in the
urine.
Polyuria is occasionally seen and especially towards the
latter stages of the anemic field cases.
The chronic cases usually die from general exhaustion,
supplemented by cardiac weakness, while in the more acute
cases, the immediate cause of death is not explained by the
lesions found after death.
In some of the latter types of cases, we found that death
could be attributed to thrombosis of the pulmonary vessels,
321
while in others no anatomic changes explained the exitus
lethalis. Here we probably had to deal with a true intoxi-
cation and subsequent interference with the more essential
parenchyma.
When we carefully analyze the clinical features pre-
sented by our cases, we will be struck by the regular presence
of anemia in the field cases and its rather uncommon occur-
rence in the cases in which the disease was experimentally
transmitted. The blood of field cases never failed to induce
infection into the experimental horses and from them it could
be passed into other horses again with almost unbroken reg-
ularity and often with fatal results and yet in no case were
the symptoms of the original field case fully duplicated.
Were it not for the fact that this was regularly the
case in all experiments involving six field cases from dif-
ferent sources of origin, we might be warranted in believing
that the original infection had not been transmitted, but
that some other virus had accidentally interfered with our
work. The repetition of our observations, and the findings
during the autopsy, however, would preclude such a con-
clusion. It may be suspected that in our experimental cases
certain contributory causes are not in operation. Such cases
are well fed, housed and not exposed to the wear and tear
incidental to hard farm work, while in our field cases the
opposite is not uncommonly the case. We will not deny the
influence of the factors mentioned, but the fact that many of
our experimental cases, in spite of the complete absence of
anemia, terminate fatally, seems to indicate that the virus
introduced is capable of producing fatal disease without any
contributory cause cooperating in the process.
In an endeavor to explain this peculiar finding another
theory may be advanced, namely, that the anemic cases, are
the only ones which are diagnosed as " swamp-fever" and
that perhaps they only constitute a certain fraction of all
swamp-fever cases. The clinical observations made on our
non-anemic experimental cases, convince us that, had they
32'2
occurred under actual field conditions, they would either
have escaped attention altogether or would not have been
diagnosed as swamp-fever.
In just this type of cases, we would never suspect the
disease, if we did not know that they were artificially in-
fected, as the symptoms presented are so extremely indefinite
as to most commonly preclude a clear cut diagnosis. We
lean, therefore, more or less to the opinion that the anemia
so commonly associated with the disease is by no means a
constant occurrence and that we will have to reconcile our-
selves to the idea of non-anemic swamp-fever cases, in other
words that in only a certain number of the cases anemia
is a feature. We have a similar instance in the case of car-
cinoma in man. There, anemic conditions under certain
circumstances are considered sufficient to warrant the sus-
picion of cancer, in fact, cancer is frequently accompanied
by anemia. Yet many cancer cases exist, continue and die
without anemia being a feature.
Unfortunately, we have no reliable field data, covering
this point, but we may mention the fact that often, when
making inquiry regarding swamp-fever outbreaks, informers
will tell us something like this: "Yes, we lost quite a few
horses, but only a few died with swamp-fever, as the others
that died were sick only a few days and it takes swamp-
fever much longer to kill a horse.' '
We are in hopes to carry our experimental work into
the field during the coming season and then this point will
be more thoroughly looked into.
If the above opinion be correct, it seems that the diag-
nosis offers greater difficulties than was heretofore supposed.
Most authors seem to regard the diagnosis of "swamp-fever' '
as something easily accomplished, and but little space is
devoted to its discussion.
Kopke <8> mentions "Brust-seuche" (infectious pneu-
monia), febrile gastro-enteritis and pernicious anemia as of
importance in the differential diagnosis, while Torrance (9)
323
regards the dragging gait, the good appetite, accompanying
loss of flesh, anemia and the peculiar thrilling pulse as diag-
nostic evidence. Peters (26) does not consider the diagnosis
to be very difficult during the later stages of the disease.
He considers the anemia and progressive emaciation, com-
bined with the good appetite, as good grounds for a diag-
nosis. Hempel (49) moving along more rational lines experi-
ments with a view of determining the existence of the dis-
ease by the complement fixation method, but his results ap-
pear to indicate that this method cannot be relied upon to
become an aiding factor in the diagnosis. Hutyra and
Marek (69) take into consideration influenza catarrhalis,
anthrax, enzootic spinal paralysis, piro-plasmosis, Scleros-
tomiasis and simple anemia when dealing with the differen-
tial diagnosis of the disease. To Mack (50) the correct diag-
nosis of swamp-fever does not appear to be without its
problems, at least, he speaks of the difficulty of differentiating
this disease from other conditions accompanied by anemia.
In this differential diagnosis, he attaches some importance
to the relative increase of lymphocytes and the correspond-
ing decrease in the polynuclear cells of the blood. He also
lays stress on the value of eosinophilia as an evidence of
helminthiasis. The acceleration of respiratory and cardiac
activity after exercise is also looked upon by Mack as a
valuable aid in the diagnosis. Mohler (52)> on the other hand,
stales that the diagnosis is not difficult and he regards the
symptoms, usually met with in swamp-fever cases as suffi-
ciently characteristic to warrant a diagnosis. Kinsley (63)>
when making the diagnosis is guided by the presence of a
high temperature, anemic pulse, anemic cardiac murmur,
jugular pulse, petechia? on or a muddy appearance of the
conjunctiva, relaxation of the sphincters, enlargement of the
sub-maxillary lymphnodes and general depression. To this
he adds that locality and history must be given due credit
and asserts that "blood inoculation is the only positive
method of diagnosis in this disease." According to a Prus-
sian source (55) "infectious anemia" may be suspected when
324
there are observed : dullness, a bad state of nutrition, pale
and pinkish white mucosae, reduction in the erythrocyte con-
tents of the blood, increase in the pulse frequency (especially
marked after exercise). To those phenomena there may be
added, fever, subcutaneous edema and albuminuria. In one
of the cases studied by Todd and Wolbach (75)> the animal
when first examined appeared healthy, the blood count
amounting to 6,500,000 erythrocytes, which in the course of
three months rose to 8,500,000 and the authors add that,
were it not for the distinct rises of temperature which fol-
lowed in the horse which was inoculated with the blood
from the case, it would be permissible to question whether
it were ever infected with swamp-fever. The same authors
record a blood examination in a horse four months after
inoculation and which was down and unable to rise and yet
the count revealed 10,640,000 red corpuscles and 29,500 leu-
cocytes per cubic m. m., while the hemoglobin amounted to
115 per cent.
If "swamp-fever" under natural conditions only occurr-
ed in the form of the anemic disease, which we had occasion
to describe in a former paragraph, the problem of diagnosis
would become simplified to a remarkable extent. But even
then a clear cut definite diagnosis, such as is possible in so
many of our infectious diseases, would often be impossible
if we had to depend on objective symptoms alone. Accept-
ing the experimental evidence of the existance of a non-
anemic form of the disease, and especially with reference
to what may be called non-clinical infection carriers, we find
that the task of correctly diagnosing the disease is not only
highly difficult, but more frequently even absolutely impos-
sible with the means and knowledge now at our command.
In fact, for so far as our observations go, we have come to
recognize in the problem of the diagnosis, the most difficult
phase in our investigations. It is true that for purposes of ex-
periment, we have recourse to the inoculation of a healthy
horse, but this method of diagnosis can only find a very limit-
325
ed application in actual every day practice. The absence of an
absolutely reliable method of diagnosis, aside of offering
an enormous obstacle, also places a great part of field and
experimental data in the doubtful column. Every so often
we learn of a certain line of treatment, for example, which
proved to be beneficial in "swamp-fever" or even ''cured"
cases of the disease, but before accepting those statements
at their face value we may well question, what evidence is
there of an absolutely correct diagnosis and if the diagnosis
were correct by what method was the cure proven?
Under the existing difficulty of diagnosis, a greater part
of the evidence on swamp-fever becomes worthless and under
these conditions we have come to accept only such evidence
as can be supported by actual inoculation tests.
In spite of unreliable objective symptoms, a diagnosis
is howrever, often possible, especially in the anemic type of
the disease. Aside of the ascertaining of the various symp-
toms mentioned above, an inquiry into the circumstances
surrounding or preceding the case under observation, is im-
perative if we wish to be guided toward correct conclusions.
An anemic fever case, with occasional albuminuria, edema,
a swaying gait is in itself sufficient to arouse suspicion, but
when this evidence is supplemented by a history of several,
previous cases of the same nature and this all in a locality
reported to be a swamp-fever center, it becomes quite safe to
make a swamp-fever diagnosis. Such supplementary evidence,
may and would also aid in arriving at a plausible conclusion
in the face of indefinite non-anemic illness, marked by remit-
tent or intermittent fever, even 'if an unimpeachable diag-
nosis cannot be obtained. The question of picking out from
an infected herd, the non-clinical infection carriers, how-
ever, important, is as yet very difficult. Unless we resort to
inoculation experiments, we could only offer one suggestion
and that is to record the daily temperature for long con-
secutive periods. Such cases, the great majority of them at
least, will sooner or later show their typic febrile exacer-
bations and this at least would be an indication of some
32G
practical value. However, it must not be forgotten that in
some of the cases of this type, no fever reaction occurs and
that if it does occur, that we are not in position to definitely
attribute it to swamp-fever infection. Here possibly, th€
demonstration of albuminuria may help out, although this
condition could very well occur in other infections.
After carefully considering our evidence in the light
of our present knowledge, we must conclude, that with the
exception of the diagnosis of the anemic cases, with a history
of infection, we are not able to promptly recognize the dis-
ease. We maintain, therefore, that in the matter of diag-
nosis, investigators have as yet to solve, perhaps the principal
problem of the disease.
Abderhalden and Frei (G7^ and Abderhalden and Buchal
(74) report a series of experiments, which tend to show that
the blood serum of horses infected with pernicious anemia
exerts a marked inhibitory action upon the hemolysis in-
duced by saponin. As the reaction was not studied in case
of other febrile diseases, our judgment of the practical value
of this reaction must as yet be suspended, but at any rate the
findings of the authors mentioned should stimulate further
investigation.
In view of the difficulty of correctly diagnosing "swamp-
fever" in all its forms, the data on the prognosis must also
be accepted with a considerable amount of caution and it
seems probable that the information available principally
pertains to the anemic cases. Of the sixteen cases observed
by Kopke (8) nine terminated fatally and of those one colt
died on the fourth day of sickness. In the cases running
a favorable course, the temperature gradually receded to
normal in from six to eight days, and Kopke states that they
made a complete recovery. Torrance (9) says that the dur-
ation of the disease extends over two or three months, but
that in some more aggravated forms, the animals die in from
two to three weeks. Torrance considers the prognosis as
327
being very unfavorable and places the mortality figure be-
tween 50 and 100 per cent. In the opinion of this author,
a small part of the cases recover when treatment is begun
early and when the erythrocyte destruction has not exceeded
a certain limit. In the report of Brimhall, Wesbrook and
Bracken (10) the unfavorable prognosis and the futility of
medicinal treatment are dwelled upon. They estimate the
mortality of the cases at 80 per cent. In Rutherford's (11)
experience recoveries are very rare. He says that apparent
recoveries are sometimes noted, but a sudden relapse is not
uncommon in such cases. Jarmatz (14) places the mortality
at about 10-15 per cent if suitable treatment is begun
soon after recognition. Ostertag (35) states that re-
covery from the typical disease is exceptional and re-
quires a long time. Hutyra and Marek <69> inform us
that recovery seems to be a rare exception and that if it
takes place at all, it may only be apparent. Mack <50> places
the mortality figure as probably well above 90 per cent of
the cases. In Mohler's (52) description of the disease, the
mortality is rated at 75 per cent or even higher. He states
that recovery takes place only when treatment is begun early
or when the animal has a long convalscent period, but fol-
lows this up with the statement that the treatment of the
disease "has so far been far from satisfactory." Kinsley
(63) advises a guarded prognosis, although he gives the
opinion that if the veterinary directions were followed the
mortality would not be over 25 per cent.
It is, of course, impossible to construct mortality statis-
tics from the cases, field and experimental, that came under
observation of the writers, as in a number of cases the cause
of death was open to question while in not a few instances,
the animals, although infected, were not permitted to live
long enough for the disease to run a natural course.
The following table gives a review of the fate of our
cases :
328
Still alive
Died or killed
in moribund
state
[nfected but
killed in fair
condition
Cases
resistant
to infection
Remarks
Among those there are
live of which the cause
of death is doubtful
One of those was de
stroyed on account of
bone tract me
In a disease in which the diagnosis is manifestly beset
by so many difficulties, most data on prognosis can only be
accepted with suspicion as to their accuracy. In the type
of the disease, that is commonly diagnosed as "swamp-
fever," we are safe in expecting an unfavorable termination,
and in placing the mortality percentage as ranging between
90 and 100 per cent. Kecoveries have often been reported
but such reports mean but little if they are not substantiated
by positive proof that the blood of such cases is no longer
virulent. In a disease of infection and evidently transmiss-
able, recovery should not only be meant to include restora-
tion to health, but also that the case under consideration
has ceased to be dangerous as a virus carrier.
There are indications, that recoveries may be more com-
mon among the non-anemic forms of the disease, but it also
seems that recovery only takes place after a very long
period, marked by indefinite febrile attacks and their accom-
paniments. As such cases, however, are actively infective
during all this long time, it seems that a fatal termination
after a brief illness, would be more economic than the actual
recovery from the disease. It should not be overlooked,
however, that a number of the non-anemic cases die early in
this disease (See chart of No. 934), but we have not a suffi-
cient amount of data at our disposal to warrant the naming
of a definite death rate for this type of cases or for the
disease as a whole.
329
As a general rule the presence of anemia, edema, emacia-
tion, weakness, albuminuria and polyuria must be looked
upon as bad omens. In the acute non-anemic cases, con-
tinued fever even if more or less remittent in type, or fever
exacerbations following one another in rapid succession
point toward a short duration and fatal termination. In
those cases also we must look with apprehension upon a con-
tinued albuminuria and the presence of edematous swellings
of the dependant parts of the body.
On the whole, the disease in all its forms will justi-
fy a rather unfavorable prognosis.
It is not a surprising feature that in so fatal and so
damaging a disease as "swamp-fever" or as some authors
prefer to call it "infectious anemia" numerous attempts
have been made to save the animals affected by various
methods of treatment. Kopke (8) directed his efforts so as
to secure a proper diet and disinfection of the intestinal
canal, while aside of this he aimed to reduce the fever and
to sustain the heart functions. Torrance (9) tried the use
of quinine, arsenic, iron, mercury, Crede's silver, various
potassium salts, without discovering any line of treatment
which was uniformly successful. According to Rutherford
(11), the long continued use of arsenic, as recommended in
surra by Lingard in India, combined with mineral and
vegetable tonics and a change to high, dry grounds has
perhaps been more satisfactory than any treatment yet tried.
In a later report by Torrance (12) mention is made of thera-
peutic experiments with salol and that recovery followed
in one of the cases, while the other case was lost by accident.
From a subsequent report (15) it would appear that the
recovery mentioned was only an apparent one.
Jarmatz (14> obtained the best results with white arsenic
in quantities of 15 grains per day, supplementing this treat-
ment by a highly nutritious diet. He mentions claret as to
be of service also.
Hies (27) uses the following treatment in his "infectious
330
anemia" cases; viz., assimilable food, hygienic care and sur-
roundings, stimulants, febrifuges, tonics, blood builders.
When fever is present 15 grammes of quinine sulphate are
given at one dose, while at each meal a bottle of claret is
administered and a few liters of cold water are injected
per rectum about three or four times per day. Against the
albuminuria, which is a usual accompaniment, Kies usee
a milk diet. In the morning ten liters of sweet cold milk,
are given and immediately after some crushed or whole
oats with a little bran. To this starchy ration the author
adds, morning and evening, a spoonful of cooking salt and
the same quantity of phosphorated oil (1:300). At evening
the patient is watered, with water containing iron prepared
by permitting water acidulated with 30-40 grammes of hy-
drochloric acid to act on rusty iron. When the disease
reached the stage where the test tube revealed a clot which
only was one-fifth of the total quantity, two patients, show-
ing voluminous sub-ventral edema received morning and
evening eight liters of physiologic salt solution until from
80-100 liters were thus given, but notwithstanding a slight
improvement, after the first injections at least, death was
not prevented.
Ostertag (35) relates an experiment with atoxyl as a
therapeutic agent. The subcutaneous administration of doses
of 10 and 15 c. c. of a ten per cent solution of atoxyl
was followed by a marked improvement in the clinical ap-
pearance of two cases, although notwithstanding this appar-
ent improvement, the hemoglobin percentage and red blood
cell count showed a reduction.
Friedrich (44> reports that iron and arsenic preparations
were given with unsatisfactory results. Apparently better
results were obtained by the use of bicarbonate of potash,
but Friedrich expresses the fear that the improvement ob-
tained is only a temporary one, in view of the remittent
character of the chronic form of the disease.
In a later publication Ries (47) mentions a trial with
atoxyl and concludes that it is both harmless and useless.
331
His best results were obtained with infusion of salt solution.
A strenuous therapeutic activity is displayed by Acres
<48) who used, either in combination or separate, liquor
cresol, strychnine, potassium-chlorate, anti-febrine, ferric-
sulphate and nux vomica. He also tried quinine sulphate,
potassium iodide, resublimed iodine, arsenic, hydrochloric
acid and "other drugs," but obtained the best results from
the anti-febrine treatment. He qualifies this statement, how-
ever, by saying: "The animal, however, is generally sub-
ject to several relapses, which none of the drugs above
mentioned seem to prevent." Acres winds up by trying
antistreptococcic serum and states that his results were so
encouraging that "it would be worth while giving this
serum a thorough test."
Hempel (49) also experimented with atoxyl as a thera-
peutic agent. It was given in doses ranging from 0.5 G.-
4 G., by gradual increase. Apparently the atoxyl treatment
resulted in a marked improvement of the cases, although
the blood of a horse thus treated was still infectious after
it had received 26 G. in the course of about six weeks.
Hutyra and Marek (69) state that thus far no medicinal
treatment of promise has been found, but make mention of
the fact that certain arsenic preparations, at least in certain
cases, seem to have a favorable influence.
Kinsley (63) gives a first place to absolute rest in the
stable because "sunshine has a decided injurious effect upon
the diseased animals." Cold baths and enemata to reduce
the temperature in the acute type, while stimulants and the
use of arsenic are relied upon for the rest. He states that
this line of treatment continued from 4-6 weeks apparently
completely destroys the causative agent of the disease, at
least, the animals recover.
Mohler <66> seems to approve of the use of certain drugs
but he regards the results treating the disease as far from
satisfactory.
Van Es (68) thinks that in a therapeutic effort, iron and
332
arsenic, perhaps are best indicated, but that even with them
no marked results can be anticipated.
Francis and Marsteller (81; made some therapeutic ex-
periments with quinine, trypan-blue, trypan-red and atoxyl.
The results of the latter three drugs were either doubtful
or negative, but the authors speak of some encouragement
from the use of quinine. It may, however, be mentioned
that the case in which quinine was used, was under observa-
tion only for a short period afterward, and that the virulence
of its blood was not tested after the treatment.
Whitehouse (83) used trypan-blue, giving only one in-
jection of three grains dissolved in 200 c. c. of sterile cold
water or physiologic solution, and expresses the opinion
that in one of his cases recovery was due to the trypan-blue
treatment. The results of the treatment apparently were
not verified by experimental evidence.
From the above it would seem that the present status
of swamp-fever therapy is as yet deplorably inefficient, and
that in the way of treatment, we have nothing that promises
to be specifically useful. In the absence of such a treat-
ment, we will have to confine ourselves to meeting the symp-
toms as they arise, if we consider it worth while to do any-
thing at all. Antipyretic treatment, medicinal or otherwise
may be employed during the febrile periods, while in the
anemic cases the use of the arsenic and iron may be tried.
At one time it appeared that we obtained good results by
giving six grains of arsenic, mixed with one drachm of the
carbonate of iron on the feed morning and evening, and
continued for a month at a time, but as neither our diag-
nosis nor the results of our treatment were verified by
means of inoculation experiments, this evidence will have
to be rejected as insufficient. As long as the horse owners
are bound to demand medicine, to be swallowed by their sick
horses, the arsenic-iron combination can perhaps not readily
be improved upon, at least, it will in many cases prevent
the use of irrational or freak remedies.
333
Whatever treatment be undertaken, it should be supple-
mented by the use of proper food and water and by placing
the patient in hygienic surroundings.
A beginning has been made with some therapeutic ex-
periments, which we hope to continue as the proper material
for it becomes available.
The first trials concerned a preparation, most widely
known as trypan-blue and which had gained some repu-
tation abroad as being of use in certain diseases of infection
caused by protozoa. The firm of Meister Lucius und Briin-
ing, Hoechst A. M., Germany, was so kind as to place a
liberal quantity of trypan-blue at our disposal and the fol-
lowing experiments were tried with it.
Experimental horse No. 855, shortly after its initial
fever was given an intravenous injection of three grammes
trypan-blue in 250 c. c. physiologic salt solution and the
injection repeated every other day until six injections in
all were given. There was apparently no constitutional
disturbances caused by the injections. The mucosa became
of a dense, ashy blue color, after the first injection and this
blue was still apparent some six weeks after the last injec-
tion. During the three and one-half months which the ani-
mal was permitted to live, there were no fever exacerbations,
although on a few occasions the temperature ranged between
101° P., and 102° F. When 48 hours after the third trypan-
blue injection the blood of this case was drawn it still proved
to be virulent.
A subcutaneous injection, of 60 c. c. of this blood made
after the last dose of typan-blue into experimental horse
873, caused this animal to become infected, showing the
initial fever between the 10th and 21st days after inocula-
tion. Immediately after the first febrile period and during
part of the second one, this animal received seven intraven-
ous injections of 3 grammes of trypan-blue in 250 c. c. of
physiologic salt solution, and sustained the injections very
well. The mucosa and the urine became quite blue but other-
wise, there were no ill effects attributed to the drug. Up-
334
to-date this animal's temperature has not been above 102.5°
F., although the animal, while not anemic, looked unthrifty
most of the time. When this horse's blood, however, was
fed to experimental horse No. 903, it again produced posi-
tive infection.
While we hope to resume the experiments with trypan-
blue, it would appear from the above experiments that it
cannot be relied upon to destroy swamp-fever virus in vivo.
The one experiment, systematically made with atoxyl,
resulted similarly.
Again using experimental horse No. 873, the following
subcutaneous injections with a 10 per cent solution of atoxyl
in physiologic salt solution were made:
Date
Am
Oil
nt
Date
Amount
9-23-10
10
C.
c.
10- 8-10
40 c. c.
9-24-10
10
c.
c.
10- 9-10
40 c. c.
9-25-10
10
c.
c.
10-10-10
50 c. c.
9-26-10
15
c.
c.
10-11-10
40 c. c.
9-27-10
15
c.
c.
10-12-10
40 c. c.
9-28-10
-.15
c.
c.
10-13-10
30 c. c.
9-29-10
20
c.
c.
10-14-10
30 c. c.
9-30-10
20
c.
c.
10-15-10
25 c. c.
10- 1-10
20
c.
c.
10-16-10
25 c. c.
10- 2-10
25
c.
c.
10-17-10 ...
20 c. c.
10- 3-10
25
c.
c.
10-18-10.
20 c. c.
10- 4-10
25
c.
c.
10-19-10
15 c. c.
10- 5-10
- 30
c.
c.
10-20-10...
15 c. c.
10- 6-10
30
c.
c.
10-21-10
10 c. c.
10- 7-10
30
c.
c.
10-22-10
10 c. c.
After the tenth injection there was a slight attack of
colic but otherwise nothing out of the ordinary was ob-
served. During the injection period the animal lost flesh
a little, but no evidence that the atoxyl had anything to
do with it could be detected.
During the month of treatment this animal thus received
71 grammes of atoxyl and yet, when a week after the last
dose, this animal's blood was drawn and injected into experi-
335
mental horse No. 939, it produced disease after an incubation
of ten days.
An as yet incomplete experiment with the use of quinine
may be reported at this time, because the results thus far
obtained already, indicate more or less what is to be ex-
pected when the returns will be complete.
Experimental horse No. 638 was given a series of in-
travenous injections of the hydrochloride of quinine, dis-
solved in physiologic salt solution, according to the following
schedule :
6-22
1.0
500
6-24
1.5
500
6-26
1.5
500
6-28
2.0
500
6-30
2.0
65D
7- 2
2.5
650
7- 4
3.0
650
7- 6
3.5
650
7- 8
4.0
650
7-10
5.0
750
7-12
7.0
900
7-14
8.0
900
7-17
7-19
7-21
7-24
7-26
7-28
7-31
9.0
10.0
11.0
1000
1200
1350
12.0 I 1500
Slight tremors of Tensor fasciae latae.
Tremors well marked.
Tremors still more marked. An increase
in pulse frequency of 5 beats per minute.
Tremors involved more muscular regions
of hind quarters.
Tremors same as before. Increase in
pulse rate 15 p. m.
Subject restless; tremors extending to
abdominal muscles. Pulse increase 20
p. m.
Tremors general. Subject sways while
moving. Pulse increase 30 p. m.
Symptoms of 7-24-11 duplicate but more
intense. Pulse increase 45 p. m.
Muscular phenomena same as before.
Marked muscular incoordination. Sub-
ject staggered. Pulse increase 65 p. m.
the tenth and fifteenth day after the last
638 sustained a typical fever exacerbation,
while experimental horse No. 1068, which was injected with
a quantity of serum drawn from No. 638, immediately be-
fore the quinine injection of 7-17-11 developed fever 24
days after inoculation.
Another experimental horse was injected with blood of
No. 638 one week after the latter had received its last quinine
injection, but as the usual incubation period has not yet
13.0
14.0
15.0
1750
2000
2250
Between
injection No.
336
terminated the evidence expected from this case cannot
at this time be incorporated in our report.
The indications at this time thus, very strongly point
that but little is to be expected from the use of medicines
in the management of this disease. Like in the case of most
diseases of infection, we will have to direct our attention
more particularly to possible means of prevention.
Torrance (15) advised farmers through the agricultural
press to avoid pasturing their horses and to water them
only from wells and this advice has had a good effect in
diminishing the number of cases and reducing the loss.
Carre and Vallee (19) formulated the following rules
of prevention: 1. Isolate or still better destroy the sick
animals, or at least, gather up and disinfect their liquid
and solid ejecta. 2. Do not offer to drink, in infected
regions, to healthy subjects anything but spring water or
water which was previously boiled. 3. Never to place a
horse coming from a suspected district, among healthy ani-
mals, without being certain beforehand that the urine does
not contain albumen.
Ries (27) who, as will be remembered suspects "bots"
of having an etiologic relationship to the disease, recom-
mends thorough grooming and in particular the removal
of the eggs of Gastrophilus and the early treatment with
bisulphide of carbon on farms where the disease breaks out
or where there is reason to suspect the presence of bots in
the stomach.
In the opinion of Ostertag (35> it is primarily necessary
in order to guard against the introduction of the disease,
to exercise increased care in the purchase of new horses.
Furthermore, new horses should be kept completely separ-
ated from the other occupants of a stable and all, oppor-
tunities of infection by means of contaminating the water or
food supply should be carefully eliminated. He also insists
on a water supply of unquestionable purity. Those preven-
tative measures are recommended to be kept up for three
337
months in view of the insiduous nature of the disease. When
the disease appears in a stable, the affected animal is to be
immediately segregated and the stable is to subjected to a
thorough disinfection under veterinary supervision. Imper-
vious stable floors are regarded as imperative in thorough
disinfection. Manure from infected animals will be ren-
dered innoxious by keeping it packed for one month in
quantities of at least one cubic meter (1 meter equals 40
inches) . Ostertag further recommends that the attention of
horse owners be directed to this disease and that they be
cautioned to be careful in making new purchases.
Beghin (22) recommends segregation of cases, disin-
fection of the stable and harness, as well as general hy-
gienic measures.
The prophylaxis outlined by Hutyra and Marek (69)
includes the prevention of the introduction of any horses,
which are in a poor, anemic and weak condition, and of
which the cardiac frequency increases markedly on slight
provocation and which have albuminuria. In infected dis-
tricts new purchases should be segregated for three months.
For infected stables, isolation of the diseased horses and
thorough stable disinfection are recommended.
Mohler (52) proposes segregation of healthy from sick
horses, and thorough disinfection of premises and utensils.
Van Es (68) outlines a plan of prevention and mentions
separation of healthy and diseased animals, and where this
is not possible, the destruction of the diseased ones. The
elimination of animals suspected of being "infection car-
riers" is also spoken of as well as thorough stable disin-
fection. On the suspicion that biting insects may be instru-
mental in the transmission, he also recommends that horses
be protected against pests of this type. In conclusion, he
recommends that "swamp-fever" be included among the
quarantinable diseases.
As a transmissible disease, swamp-fever, must in the
first place be dealt with like we deal with any other in-
338
fectious disease. If we are to confine this disease to its
present centers of infection, it will be necessary to exercise
some supervision over the horse traffic in and from the
infected districts. In fact, it would seem wise to suspend
all movements of horses from an infected region, at least,
for a certain time of the year, say from July to December,
as evidently most of the actual transmissions take place
during that time.
Animals showing such symptoms, as would warrant the
suspicion of swamp-fever, certainly should not be moved
from place to place, even after they have made apparent
recovery, because of the now well established fact that such
cases will remain actively infective for a long period.
Especially important is care on the part of farmers,
having healthy stock, when introducing recently purchased
horses into the stable. Owners of non-infected stables with-
in the sections where the disease is prevalent, would do
better to make their purchases outside of the district than
within it, if they are in need of new horse stock.
Complete segregation of animals having the disease or
suspected of having it must be carried out rigidly and the
best way to do this is to leave the infected animals where
they are and remove the horses, which are still in good
health. Better still would it be to destroy the actual cases.
In the great majority of instances such animals die anyway
and the longer they are kept the more liable will they be
to infect other stock.
When once the disease has made its appearance among
a certain lot of horses and the apparent cases of the disease
eliminated by destruction or otherwise, the possibility of
infection still lurking about in the body of some horse which
does not show symptoms becomes a serious problem and
here we feel most acutely the imperfection of our knowledge
of this disease. The results of our own investigations, as
well as those of Vallee and Carre (17), Ostertag (35), and
Francis and Marsteller <42> clearly indicate that such cases
will have to be reckoned with. As yet we have no clear
339
cut practical method by which such ''infection carriers"
or rather "infection distributors" may be detected. The
best we can do under the circumstances is to keep track of
the body temperature of all the horses in the stable, on the
principle, that many of those so-called occult cases will from
time to time show the typical transitory fever mentioned
in another paragraph. In addition, we may examine the
urine from time to time for the presence of albumen. Cases
showing the characteristic temperature rise or albuminuria
must be isolated on the ground of presenting symptoms,
warranting the suspicion of swamp-fever.
Under all circumstances connected with real or sus-
pected cases of the disease, thorough stable disinfection
must be rigidly carried out. This must not be done in a
perfunctory manner because much may depend on it.
In infected districts, damp, swampy or marshy pastures
should either be avoided for horse stock or thoroughly
drained. It is here where probably most of our infections
occur, through the contamination of the foliage and water
pools by the urine of swamp-fever cases and "infection
carriers." It is also advisable to prevent horses from using
the water found in ditches or pools of such pastures and
instead the water supply should be derived from wells, pro-
tected against the contamination by surface drainage or
seepage. The drinking troughs in which the water is offered
should be well above the ground, so as to reduce the danger
of contamiuation with body ejecta to a minimum. At the
same time, the formation of small pools around troughs
should be prevented, by providing a sufficient drain for
the waste water. Undrained pastures which are unfit for
horse stock may be safely used for other animals, for so
far at least as "swamp-fever" is concerned. While probably
most of our cases originate from pasture infection, there is
plenty of evidence to show that stable infection also takes
place and with that possibility in view, the stable should
receive considerable attention in a .hygienic way.
Remembering that we have absolute proof that the cause
340
of the disease leaves the body of the infected animal by
means of the urine, we can readily see how this substance
may find its way into the well if it be sunk immediately
under the stable. This is a practice prevalent on many farms
and constitutes a source of great danger in this, as well
as in many other diseases.
There is really but one condition under which a stable
or barn-well can be permitted and that is when the stable
is provided with a good concrete floor and when stable
drainage is conveyed away from the building by an ade-
quate arrangement.
We wish to call the attention of the farmers of fever
infected districts, especially to these facts, as we feel certain
that on many farms the disease can be brought to a stand-
still by paying attention to them. The common wooden stable
floor, with its space full of inequity under it, explains the
presence of many of our most stubborn diseases.
The constant presence of the specific virus in the blood
and the well known part played by biting insects in the
dissemination of other diseases seem to warrant us to include
the protection of our horses against those pests and the erad-
ication of them among the preventative measures.
It is but natural, that when dealing with an infectious
disease, some attention should have been paid to the possi-
bility of immunity as a factor including a promise of prac-
tical application. Owing to a rather recent solution of the
etiology of the disease, nothing definite on swamp-fever has
been thus far published.
Carre and Vallee (23) make mention of the fact that
certain apparently recovered cases sustain large doses of
virulent material without experiencing any grave disturb-
ances, while they state that a beginning was made by them
on some immunity experiments, which are to be made the
subject of a future publication. Hempel (49), however, after
experimenting in order to decide if horses which had appar-
ently recovered from the disease had acquired an active
341
immunity or not, found that such was not the case and that
such animals seemed to be still susceptible to a second in-
fection. Mohler (23) speaks of investigations being in pro-
gress with a view of producing a serum or vaccine for immun-
izing purposes. Melvin (70) concludes that natural immunity
against swamp-fever does exist in some horses and that this
immunity may be increased by repeated injections of viru-
lent serum from which contaminations have been removed
or by means of defibrinated blood.
Our own data on the question of immunity in "swamp-
fever" are very scant. There are some indications that some
of the experimental horses, which may have become mere
non-clinical infection carriers or which perhaps have entirely
recovered, are able to withstand large doses of virulent
blood with impunity but our researches in that direction
have scarcely advanced to the point, where it would be pru-
dent to even think of conclusions. However, as a matter
of illustration, the career of some of our cases may here
be briefly summarized.
Experimental horse No. 637 was injected with a quantity
of blood from field case No. 642 on August 11, 1908. As a
result the animal sickened showing several marked febrile
reactions between that and the latter part of November fol-
lowing. From then on to May 1909, the temperature re-
mained practically normal. On March 20, April 13, May 14,
May 30, and June 15, the animal received injections of viru-
lent blood, from different animals, which were increased from
20 c. c. to 1100 c. c. After May the general run of temper-
ature became a little higher but no sharp exacerbation took
place until October 25, 1909, when the temperature rose to
103° F., and although no further injections were made for
the time being, there were several distinct febrile attacks
between that date and October 4, 1910, when a large quantity
of virulent blood was injected. This was followed by an
indefinite slight transitory reaction on October 12 and Nov-
ember 15, while a subsequent injection of a large quantity
342
of virulent field blood on December 10, L910, provoked sharp
reactions on December 17, 1910, and February 2, 1911.
Encouraged by the fact that blood i'rom No. 637 on
June 15, 1909 failed to produce disease, the writers were
induced to test its possible immunizing properties. This
was done by the simultaneous injection of the blood of No.
637 and that of some other animal known to be virulent.
Acting on this plan experimental horse No. 729 was on
July 13, 1909 injected with 50 c. c. of virulent blood from
No. 638 and 500 c. c. of blood from No. 637. The horse was
found to be dead on the following morning. Experimental
horse No. 788 was used for a similar simultaneous injection
on July 15, 1909, and succombed after a febrile period of
eight days.
The experiment repeated on experimental horse No. 804
resulted fatally in five days, while experimental horse No.
811 lived only three days after injection.
Repeating the experiment in experimental horse No. 816
the results were again fatal in 25 days. In this case a marked
anemia (2,500,000 red cells,) was observed two days before
death.
From those observations it was evident that the com-
bination of the blood of Nos. 637 and 638 had to be dis-
carded as a base for immunity experiments.
It should, however, be observed that the experiment re-
peated on experimental horse No. 859 about one year later
did not provoke any visible results. The horse experimented
on had shown a high relative or perhaps absolute immunity
to previous injections, which may in a measure account for
his surviving.
Experimental horse No. 638 was inoculated with a di-
luted virus, passed through a Pasteur Chamberland filter
on 10-7-08, and showed several febrile periods, the curves
showing their apices on the following dates : 10-18-08, 10-25-
08, 12-10-08, 1-16-09, 3-4-09, 5-14-09, 10-18-09. Since that
time the animal has shown only twice a very transitory
rise of temperature, at no time exceeding 102.5° F. Be-
343
tween fever attacks and even after the last marked rise
of 10-18-09, the animal has been a picture of health and
vigor. Although No. 618 showed severe illness and great
depression during several of Its fever attacks, there never
was the least evidence of anemia; in fact, the blood. count
always showed a higher figure than what is usually con-
sidered to be the normal standard for the horse.
However, in spite of what from a clinical standpoint
may be considered a complete recovery, this animal's blood
was still virulent on 5-20-10 to experimental horse No. 879,
.ill hough the incubation period, longer than usual, (22 days)
may perhaps be considered as an indication of attenuation.
This animal was injected with virulent blood according
to the following table :
Date Blood C. C.
7-15-10. 636 60
8-15-10 873 120
9-20-10 921 240
11- 1-10 919 550
The last injection was followed by a marked rise of
temperature beginning 24 days after the injection.
The blood of No. 638 was still virulent on 5-3-11.
Among our experimental horses we found three ani-
mals which were naturally resistant to the infection.
Summarizing the results of our investigations, the
writers feel warranted in submitting the following conclu-
sions :
I. Swamp-fever is a disease of infection, transmissible
by subcutaneous and intravenous injection and by ingestion
through the alimentary canal.
344
II. The virus producing the disease is contained in the
blood and urine of affected ;i ni in ;i Is. bn1 it is absent •from the
faeces.
III. The virus has thus far been demonstrated onlj in
an ultra-microscopic form.
IV. The virus is resistant to the severe freezing weather
of our more northern climates.
V. While not denying the possible transmission of the
disease to healthy animals by means of insects and para-
sites, animals contract the disease naturally by the ingestion
of food and water, contaminated by the mine of an infected
horse.
VI. The disease is essentially a septicemia, anatomically
marked by sub-serous and sub-endocardial hemorrhages in
the more acute forms, by occasional involvement of the
lymphnodes and spleen, by degenerative changes in the
parenchyma of heart, liver, and kidneys, and probably
also by certain alterations in the bone-marrow of the long
bones of the limbs.
VII. The chief and most constant manifestations of
the disease are fever and albuminuria. The former is re-
mittent or intermittent, not uncommonly at more or less
regular intervals, while the latter is transitory and fre-
quently synchronous with the febrile exacerbations.
VIII. Many cases of swamp-fever terminate fatally
without a marked reduction in the red blood cells, a fact
denying the popular conception of "swamp-fever" being
primarily an anemia.
IX. The blood of an animal may remain virulent for
as long as thirty-five months after the initial infection, with-
out the infected horse manifesting any clinical evidence of
the fact.
345
X. Such non-clinical infection carriers probably play
an important part in the establishment of more or less per-
manent centers of infection.
XI. Both trypan-blue and atoxyl are worthless in the
treatment of the disease.
XII. In the light of our present knowledge we have to
depend upon such prophylactic measures as the destruction
of diseased animals, segregation of suspects, care in intro-
ducing new horses into the stable, the safe-guarding of food
and water supply from urine contamination, pasture drain-
age and stable disinfection.
346
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1909.
57. Flower. Report of the Louisiana State Live Stock Sanitary
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state Association of Live Stock Sanitary Boards, p. 162. Chicago
1909.
58. Darling. Correspondence. American Veterinary Review. Vol.
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62. Hoefer. Ueber ein unbekanntes Protozoon im menschlichen
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Jena 1910.
63. Kinsley. Equine infectious anaemia. Proceedings of the Ameri-
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64. McGilvray. Rarer forms of fever in Horses. Proceedings of
the Veterinary Association of Manitoba 1910, p. 23. Winnipeg.
65. Mack. A fatal anaemic disease among horses. Proceedings of
the American Veterinary Medical Association 1910. Philadelphia.
66. Mohler. Infectious anaemia. 25th Annual Report of the Bureau
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350
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70. Melvin. Swamp-fever of Horses. Report of the Chief of the
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73. Mack. Equine anemia investigations in Nevada. Report of the
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351
EXPLANATION AND KEY TO PLATES TV, Y, AND VI.
Plates IV, V, and VI indicate the various transmissions swamp-
fever infection in the course of the research work done at the Veter-
inary Department of the North Dakota Agricultural College. The
black figures indicate cases in which infection was positively trans-
mitted, the white ones, the cases in which transmission failed and
the pinto horses, in which results of infection were of a doubtful
nature.
No. 562. A field case from the vicinity of Harwood, N. D.
No. 577. Experimental horse infected by means of intravenous in-
jection of 8 c. c. of blood from No. 562.
No. 635. Experimental horse infected by means of a subcutaneous
injection of 100 c. c. of blood from No. 640.
No. 636. Experimental horse infected by means of subcutaneous
injection of 100 c. c. of blood from No. 635. Is still alive 35
months after injection.
No. 637. An experimental horse infected by means of a subcutaneous
injection of 100 c. c. of blood from No. 642.
No. 638. An experimental horse infected by means of an intravenous
injection of a filtered mixture of 100 c. c. of serum of No. 639
and 700 c. c. of physiologic salt solution.
No. 639. An experimental horse infected by means of a subcutaneous
injection of 100 c. c. of blood from No. 637.
No. 640. A field case from the vicinity of Christine, N. D.
No. 642. A field case from the vicinity of Fargo, N. D.
No. 723. An experimental horse infected by means of an intravenous
injection of a filtered mixture containing 100 c. c. of serum of
No. 638, and 700 c. c. of physiologic salt solution.
No. 727. An experimental horse resisting infection with 500 c. c.
of blood from No. 638 given subcutaneously.
No. 729. An experimental horse, suddenly dying after an injection
of 50 c. c. of blood from No. 638 and 500 c. c. of blood from
No. 637.
No. 743. An experimental horse, infected by means of a subcutaneous
injection of 50 c. c. of blood of No. 638 and after having
resisted a similar injection of 130 c. c. of blood from No. 637.
No. 744. An experimental horse, infected by means of a subcutaneous
injection of 50 c. c. of blood serum from No. 636.
No. 788. An experimental horse, suddenly dying after an injection
of 50 c. c. of blood serum from No. 638 and 500 c. c. of blood
from No. 637.
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352
No. 804. An experimental horse dying six days after an injection
of 50 c. c. of blood from No. 638 and 500 c. c. of blood from
No. 637.
No. 811. An experimental horse dying three days after an injection
of 50 c. c. of blood from No. 638 and 500 c. c. of blood from
No. 637.
No. 816. An experimental horse infected by means of an injection
with 50 c. c. blood from No. 638 and 500 c. c. of blood from
No. 637.
No. 855. Experimental horse infected by means of a subcutaneous
injection of 60 c. c. blood serum from No. 636, after having
failed to react upon an injection of 100 c. c. of urine from the
same source.
No. 856. An experimental horse, giving a doubtful reaction upon
a subcutaneous injection of 60 c. c. of blood from No. 857.
No. 857. Experimental horse, infected by means of a subcutaneoui
injection of 60 c. c. of blood serum from No. 636, after having
failed to react upon an injection of 100 c. c. filtered extract
of faeces from the same source.
No. 859. Experimental horse, which has failed to react upon a
subcutaneous injection of 60 c. c. of blood taken from No. 636,
upon a subcutaneous injection of 60 c. c. taken from No. 873,
upon a subcutaneous injection of blood taken from No. 637, upon
a subcutaneous injection of 60 c. c. of serum from No. 638, and
60 c. c. of serum from No. 637, and upon an intravenous injection
of 600 c. c. of blood from No. 919, but which showed an atypic
reaction when injected with blood from No. 933.
No. 867. Experimental horse, infected by means of a subcutaneous
injection of blood from No. 636, after having failed to react
upon a similar injection with the blood of No. 638.
No. 873. An experimental horse, infected by means of a subcutaneous
injection of 60 c. c. of blood from No. 855.
No. 879. An experimental horse, infected by means of a subcutaneous
injection of 60 c. c. of blood from No. 638.
No. 902. An experimental horse, infected by means of a subcutaneous
injection of 120 c. c. of blood from No. 855.
No. 903. Experimental horse infected by a daily dose of 50 c. c. of
blood from No. 873, given by the mouth in capsules for ten
days. Previous to this, this animal resisted a similar treatment
with daily doses of 25 c. c. of blood from No. 636.
No. 919. An experimental horse infected by means of a subcutaneous
injection of 120 c. c. of blood from No. 920.
No. 920. A field case from the vicinity of Kelso, N. D.
No. 921. A field case from the vicinity of Shelly, Minn.
353
No. 924. An experimental horse infected by means of a subcutaneous
injection of 120 c. c. of blood of No. 921.
No. 930. An experimental horse infected by means of a subcutaneous
injection of 120 c. c. of blood taken from No. 919.
No. 933. An experimental horse infected by means of a subcutaneous
injection with 240 c. c. of urine from No. 921.
No. 934. An experimental horse infected by means of giving 2000
c. c. of urine from No. 924 by the mouth.
No. 938. An experimental horse, which failed to react upon a sub-
cutaneous injection with 60 c. c. of blood serum from No. 921.
No. 939. An experimental horse infected by means of a subcutaneous
injection of 240 c. c. of blood from No. 873.
No. 944. An experimental horse, infected by means of a subcutaneous
injection with 200 c. c. of blood from No. 934.
No. 953. Experimental horse, which resisted an injection of 250
c. c. of blood taken from No. 933.
No. 960. Experimental horse infected by means of a subcutaneous
injection of 240 c. c. of blood taken from No. 873.
No. 967. Experimental horse infected by means of a subcutaneous
injection of blood from No. 873.
No. 969. Experimental horse infected by means of a subcutaneous
injection of blood from No. 919.
No. 976. Experimental horse infected by means of a subcutaneous
injection of blood from No. 919.
No. 977. Experimental horse infected by means of a subcutaneous
injection of blood from No. 636.
No. 979. Experimental horse infected by means of a subcutaneous
injection of blood from No. 919.
No. 995. Experimental horse infected by means of a subcutaneous
injection of blood from No. 976.
No. 1015. Experimental horse infected by means of blood from No.
638.
No. 1017. Experimental horse showing a doubtful reaction after an
injection with blood of No. 859.
No. 1022. Experimental horse which failed to become infected by
the blood of No. 979, but which showed a doubtful reaction
after being injected with blood of No. 859.
No. 1030. Experimental horse infected by means of blood from
No. 638.
No. 1032. A chronic field case obtained from the vicinity of Neche,
N. D.
No. 1033. An experimental horse infected by means of the blood
of No. 1032.
No. 1056. An experimental horse infected by means of the blood
of No. 636.
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