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Demodectie
MANGE
in Cattle

Photomicrograph of Demodex folliculorum bovis.

Demodectic mange in cattle is caused by a cigar-
shaped, sluggish mite* about one-fiftieth inch long.
It lives in the hair follicles of an animal’s skin and
causes lesions, or nodules, that appear as deep pits or
holes in the tanned hide. Each year, this damage costs
U. S. cattle owners an estimated $5,000,000.

Although demodectic mange is an old disease found
in every class of livestock and in man, we know little
about its transmission, treatment, control, or life his-
tory. The disease has not been transmitted by artificial
or experimental means. The possibility of prenatal in-
fection has been suggested but not proved. In dogs,
the organism has been found internally.

Appearance of Lesions

Demodectic mange in cattle causes nodules usually
in the neck, shoulders, and brisket. They range from
the size of a match head to that of a hazelnut. They
are caused by the formation of pus that accompanies
the mite. A single nodule may contain 20,000 or more
mites. All stages of development, from eggs to adults,
occur in one nodule.

Except in advanced cases there are no marked
changes in the animal’s hair coat, and ordinarily you
cannot see the lesions until you part the hair. You can
feel the nodules by passing your hand over the ani-
mal’s body with your fingers pressed firmly against
the skin.

Demodectic mange may spread quickly, and the
nodules may appear nearly everywhere in the animal’s
skin. It may spread slowly, and the number and size
of the nodules may show little change for several years.

* Demodex folliculorum bovis.

The nodules usually are firm. In advanced cases
several may unite to form a small abscess. If such an
abscess breaks and discharges its contents over the
surrounding hair and skin, the condition looks like
common scab.

Diagnosis

If you think one of your cows has demodectic
mange, have your veterinarian examine it.

The nodules contain a creamy white material of
cheesy consistency. Usually the veterinarian will lance
the nodule to obtain this material for examination.
He can find the mite easily by pressing the contents of
one or more nodules between two glass slides and ex-
amining it under a low-power microscope.

Control

Although demodectic mange does not spread rapidly
to other members of the herd, you should isolate ani-
mals infested by the mites.

Demodectic mange in cattle does not respond to any
treatment we know. The usual cattle scab dips and
sprays appear to slow progress of the disease. If the
nodules are small, they will cause no perceptible in-
jury and you may ignore them.

Sometimes bacterial infection causes open demodex
nodules to abscess. You may treat such abscesses with
local antiseptics if they continue to discharge. Use
light pressure to squeeze out accumulated pus and
flush it away with warm, soapy water. Then, gently
swab the abscess as deeply as you can; apply tincture
of iodine with a small piece of sterile absorbent cotton
tightly wrapped around the end of a toothpick.