Normal shedding. Shedding out of time; laminitis, dropsy, exudative
dermatitis, acariasis, ringworm, traumas, folliculitis. Debility,
excessive lactation, starvation, petechial fever, spoiled fodder.
Without apparent cause, alopecia areata, neurosis, micrococci, disease
of derma. Symptoms: general disorder has general shedding. Local
disorder extends from a centre. In horse with increased pigmentation.
Treatment: correct general causes, use hair stimulants, cantharides,
kerosene, tar, pilocarpin, mercuric chloride, cresol, iodine, balsam
of Peru, silver nitrate. Arsenic.
Acquired baldness is recorded in horse, cattle, sheep and dog.
_Causes._ The simple shedding of hair occurs physiologically in animals
with the change of season, and if anything interferes with the growth of
the new hair a transient baldness may ensue. If such shedding occurs
from any cause at the wrong season, before the new hair has started, the
baldness may be accentuated. Thus shedding may occur in some forms of
indigestion, in laminitis, in dropsical swelling of the limbs or ventral
aspect of the body, in dermatitis with an exudation which concretes
around the hairs and raises them out of their follicles, in mange, in
demodectic acariasis, in circinate ringworm, in traumas as on the elbows
of dogs, etc., from lying on them, and in inflammation of the hair
follicles from a variety of infections. It has been charged on general
debility in excessive lactation, in gestation, and in starvation, on
poisons in the blood as in petechial fever, and on musty or spoiled
fodders in bad seasons, or from low damp lands.
When in the absence of such appreciable causes it commences at one or
more points and gradually extends, and persists, it constitutes alopecia
areata. This has been attributed to a disorder of the cutaneous nerves
(tropho-neurosis), but the progressive advance of the disease, without
limitation to areas representing the distribution of given cutaneous
nerves, and the complete absence of other derangement of nerve function,
throw doubt on this conclusion. Another doctrine attributes it to a
microbe, but though micrococci and other organisms have been found, they
have not been proved to be constant nor to be absolutely causative of
the disease. Still another theory holds that it is a disease of the
derma and not of the hair at all, the evulsion of the hair following the
implication of the tissues around the follicles.
_Symptoms._ The baldness dependent on a general disorder occurs at once
over an extended area. That of ringworm, acariasis, and of the specific
alopecia areata, advances gradually and often slowly from a given point,
until it may include a large area. Röll has seen it extend from a few
points to nearly the whole body of the horse in a single year. In this,
as in other cases in horse and dog, the baldness was followed by a
considerable increase of the pigmentation of the skin.
_Treatment._ In cases that occur as the result of other diseases, the
rational treatment is to deal with these diseases, and then to stimulate
the growth of hair by some one or other of the known stimulants (dilute
tincture of cantharides, kerosene, tar water, solution of pilocarpin
hydrochlorate). In the more specific form, no treatment has been very
successful, yet the best results on the whole appear to have come from
local germicide applications. Mercuric chloride in alcohol and water (1
∶ 500); cresol 1, alcohol 20; tincture of iodine reduced to half its
strength by addition of alcohol; balsam of Peru 1, alcohol 5; nitrate of
silver 1, alcohol 15, serve as examples.
As general treatment arsenic has been employed, but with no very
encouraging results.