474 DISEASES OF THE HORSE. 
ERYSIPELAS. 
This is a specific contagious disease, characterized by spreading, 
dropsical inflammation of the skin and subcutaneous tissues, attended 
with general fever. It differs from most specific diseases in the ab- 
sence of a definite period of incubation, a regular course and duration, 
and a conferring of immunity on the subject after recovery. On the 
contrary, one attack of erysipelas predisposes to another, partly, 
doubtless, by the loss of tone and vitality in the affected tissues, but 
also, perhaps, because of the survival of the infecting germ, 
* Cause.—It is no longer to be doubted that the microbes found in the 
inflammatory product are the true cause of erysipelas, as by their 
means the disease can be successfully transferred from man to animals 
and from one animal to another. This transition may be direct or 
through the medium of infected buildings or other articles. Yet from 
the varying severity of erysipelas in different outbreaks and localities 
it has been surmised that various different microbes are operative in 
this disease, and a perfect knowledge of them might perhaps enable 
us to divide erysipelas into two or more distinct affections. At pres- 
ent we must recognize it as a specific inflammation due to a bacterial 
poison and closely allied to septicemia. Erysipelas was formerly 
known as surgical when it spread from a wound (through which the 
germ had gained access) and medical, or idiopathic, when it started 
independently of any recognizable lesion. Depending as it does, 
however, upon a germ distinct from the body, the disease must be 
looked upon as such, no matter by what channel the germ found an 
entrance. Erysipelas which follows a wound is usually much more 
violent than the other form, the difference being doubtless partly due 
to the lowered vitality of the wounded tissues and to the oxidation 
and septic changes which are invited on the raw, exposed surface. 
As apparently idiopathic cases may be due to infection through bites 
of insects, the small amount of poison inserted may serve to moderate 
the violence. 
This affection may attack a wound on any part of the horse’s body, 
while, apart from wounds, it is most frequent about the head and the 
hind limbs. It is to be distinguished from ordinary inflammations 
by its gradual extension from the point first attacked, by the abun- 
dant liquid exudation into the affected part, by the tension of the skin 
over the affected part, by its soft, boggy feeling, allowing it to be 
deeply indented by the finger, by the abrupt line of limitation be- 
tween the diseased and the healthy skin, the former descending sud- 
denly to the healthy level instead of shading off slowly toward it, by 
the tendency of the inflammation to extend deeply into the subjacent 
tissues and into the muscles and other structures, by the great ten- 
dency to death and sloughing of portions of skin and of the struc- 
