474 DISEASES OF THE HOKSE. 



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 mav serve to moderate 

 the violence. 



This affection ma}^ attack a wound on any part of the horse's body, 

 Avhile, 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- 



