906 Herpes. 



remains, or the liair breaks off in the hair follicle, and perhaps 

 outside of the follicle. If the hairs persist somewhat longer they 

 split and become brittle by the action of the penetrating fungi. 

 The exudation in the epidermis, upon the surface of the skin 

 and the proliferation of epidermis cells are always rather active, 

 consequently little vesicles or mostly only crusts and scabs 

 form, which mat the hairs that still remain on the skin together 

 (scabby herpes, herpes tons, crustaceus). Itching is almost 

 always present in this form. 



When herpes in any form heals, it happens now and then 

 that the process remains stationary for a long time at the 

 periphery after healing in the center, or after healing of the 

 diseased area a fresh outbreak occurs some time later at its 

 periphery (herpes circinatus). 



An essential characteristic of all the forms of herpes is the 

 IDeripheral spread in ring form, but the extension at the 

 periphery only continues a certain and relatively short time, 

 in consequence of which even in untreated herpes the aifected 

 spot ' only attains a small extension and then heals sponta- 

 neously. 



Gerlach seeks to explain the cause of the spontaneous cessation of the periph- 

 eral growth of herpes in such a manner that the healthy skin at the boundary 

 of the ring-worm is covered with a strong layer of scales and is jjrotected thereby 

 from the implantation of fungous spores, v. Barensprung claims on the other hand 

 that the cause lies solely in the destruction of the hair by the fungus, whereby the 

 nutrition is wasted, as it were, by its own action. 



Symptoms. The period of incubation of herpes tonsurans 

 usually varies between 8 to 30 days (Gerlach, Hable, Schin- 

 delka), yet at times the first symptoms may arise within the 

 first week (Puscli, R. Frolmer). 



The clinical picture shows a great many variations, as may 

 be concluded from the pathogenesis of herpes. On what parts 

 of the body the ringworm arises, depends exclusively upon 

 which part of the body comes in contact with an affected animal 

 or with objects which contain the ring-^vorm fungi. Since the 

 mode of life as well as the conditions of work and of care of the 

 animals are of influence in this respect, it follows that in certain 

 species of animals certain parts of the body will be affected 

 preferably. 



(a) Herpes in the Horse. 



Favorite localizations of the disease are the shoulders, the 

 sides of the chest, and the flanks, also the croup and the back, 

 sometimes the saddle region (in saddle horses), the neck and 

 the head, while the lower belly, the sheath and the limbs are 

 attacked only rarely; the foretop and mane region as well as the 

 tail are hardly ever affected. Only Pecus & Sabouraud saw, 

 during an enzootic, in a few horses, herpetic disease of the skin 

 of the upper part of the mane and tail, which w^as accompanied 



