908 



Herpes. 



spots remain for a time, namely until the liairs break off in the 

 center; in very rare cases these ring-shaped spots may be 

 brought about as the result of an early healing of the process 

 in the center (herpes tonsurans circinatus). Itching is generally 

 absent or quite insignificant. The disease often occurs in 

 enzootic extension, especially in foals on pasture, very rarely 

 in adult horses (de Does) (herpes contagieux des poulains of 

 Frojicli autliors). 



The second form of 

 herpes, which might l)e 

 designated as herpes 

 crustaceus or tricophy- 

 tia, and which is gener- 

 ally caused by the Trico- 

 pliyta megalospora, be- 

 gins with the occurrence 

 of similar nodular ele- 

 vations of the skin, with 

 slightly ruffled hair, as 

 in the previous form ; in 

 its further course it is 

 distinguished by the 

 gradual formation of ir- 

 regular r o u n d i s h or 

 oval, gray or grayish, 

 thick and soft scabs, 

 which may become as 

 large as 10 cm. and ad- 

 liere rather loosely to 

 tlie skin ; they mat the 

 dry and lusterless liair 

 together, are easily cast 

 ofT with the matted hair 

 in cleaning and leave 

 completely bald spots 

 behind. The surface of 

 the skin bared in this 

 manner then appears 

 either quite smooth, 

 somewhat moist and 

 still covered by some 

 hair-root stumps arising from the hair follicles, or a few little 

 vesicles or pustules may be recognized. Not infrequently one 

 observes little depressions with grayish bases on the moderately 

 swollen and reddened skin which have arisen as a result of sup- 

 puration of the hair follicles (herpes mentagrophytes). After the 

 crusts have become detached the slightly moist skin soon dries 

 and is covered for a time with light or slate gray or yellowish 

 scales ; through the occurrence of new scabs at the periphery and 

 the resulting faUing out of the hair, the ringworm spots gradual- 



Herpes on the head of a hor? 



