538 



DISEASES OF THE SKIN. 



blotches ; at other times the morbid process becomes weakened;, and 

 then disappears from the centre while at the same time it pro- 

 gresses at the periphery (circinated herpes). The disease may in- 

 vade the greater part of the surface of the body and occasion an 

 almost general dropping of the hair. When examining the fallen 

 or pulled hairs with the microscope, the conidia (spores) and mycelia 

 mentioued above are found in them. 



The integument of the affected surfaces is altered in various 

 degrees — at times it is not at all inflamed ; upon the thick and 

 resisting skin of the horse we find only an augmentation of the 

 epidermic desquamation, an abundant ashy-gray or slaty, amian- 

 thous furfur [herpes tonsurans maculosus) ; upon the fine skin we 

 observe at the beginning some hyperemia and a slight tumefaction 

 of the diseased spots ; later vesicles become developed (herpes ton- 

 surans vesioulosus), which soon burst and dry up, forming thick 

 scabs. In the adult ox these scabs, the color of which is variable, 

 are of the consistence of leather. In the calf, where they appear 

 in a grayish-white color, similar to that of dough, they are deeply 

 slit. Their constitution depends also upon the character of the 

 fleece ; they are thick when the hair itself is abundant, while they 

 are very thin upon the regions where the hair is sparse ; in the ox 

 they acquire a thickness of one centimetre. After their falling out 

 the suppurating surfaces which they covered often heal by them- 

 selves. The following are, briefly expressed, the clinical characters 

 of thrush in our different species : 



1. In the ox. Gerlach has outlined an excellent description 

 of it. We find upon the head and shoulders, more rarely upon the 

 whole surface of the body, isolated or in groups, spots which are 

 distinctly limited and are salient upon the surface of the skin ; at 

 times they are denuded of hair and covered with furfur or whitish- 

 gray, amianthous scabs, at other times they are covered with erected 

 hair ; they may reach the size of a saucer and become confluent. 

 During its extreme periods — at the start, and when a cure is pro- 

 duced — the disease produces slight itching. Upon the black skin 

 the scabs are thick and are of a grayish tint ; upon the discolored 

 integument they are thinner and of a yellowish shade. Upon these 

 we find a viscous purulent liquid, and we observe small suppura- 

 tive dimples ir the derma, which are formed by the dilated, sup- 

 purating follicles which are deprived of their hair. The cure is 

 ordinarily produced by a sub-crustaceous cicatrization. When the 



