540 



DISEASES OF THE SKIN. 



nent; the adjacent skin is tumefied and swollen. The regions 

 which are first invaded remain pale for a long time ; they are smooth 

 or covered with a little epidermic furfur. 



3. In the horse. It is generally observed in the regions 

 upon which the harness is placed (withers, back, croup) and on 

 the flank ; it is rarely found on the head. The blotches, the 

 dimensions of which vary from that of a ten-cent piece to a silver 

 dollar, are round, more or less bare, and covered with furfur or 

 scabs. The hairs of the neighboring regions may be pulled out 

 with the slightest tractiou. Those which grow again in the centre 

 of the blotches are ordinarily of a darker color than the old ones. 



4. In sheep. It is generally located upon the neck, chesty 

 shoulders, and along the back. According to Brauer, the wool is 

 found to be packed and the skin is squamous or scabby. The 

 patients experience intense itching. At the beginning small tufts 

 appear above the surface of the fleece ; later, when they exist in 

 larger numbers, they give to it a slashed appearance. 



5. In poultry. In birds, depilating thrush is accompanied by 

 dropping of the feathers and a serious hyperemia of the derma in 

 the neighborhood of the papilla. 



Diagnosis. The objective symptoms of the disease enable us 

 to recognize it easily. The multiplicity and dissemination of the 

 blotches, the dropping out of the hairs toward their periphery,, 

 their amianthous epidermic productions, in the dog especially (lips, 

 cheeks, eyelids); itching being slight, or entirely wanting; lastly, the 

 contagiousness characterize it sufficiently. In doubtful cases mi- 

 croscopic recognition confirms the diagnosis : it is sufficient to pull 

 out a few hairs upon the periphery of the blotches, and make an 

 examination of their roots with an enlargement of 300 to 400 

 diameters ; we may also examine the scabs after having macerated 

 them in a solution of potash of 10 per cent. ; this method enables 

 us to isolate the pilous roots which are contained in them. The 

 fungus is also recognized by the microscope, because of the exist- 

 ence of the whitish membrane formed around the base of the hair. 

 In the dog, depilating thrush may be confounded with other derma- 

 toses ; it extends at times over the whole surface of the body and 

 offers great similarity to sarcoptic mange. The frequency of the 

 transmissibility of thrush to man and the very intense itching 

 which accompany mange are sufficient differential characters in 

 some cases. But, in a similar occurrence, the practitioner should 



