290 DISEASES OF THE SKIN 



Diagnosis. — A positive diagnosis can be made only with the 

 microscope. In sucking calves herpes attacks the skin around 

 the mouth. There appear round spots covered with yellowish 

 scabs made up of bran-like scales. 



Horses. — The favorite seats of herpes in the horse are the 

 head, back, shoulders, and croup. As a rule it assumes the 

 form of round, well-defined, bald spots the size of a 25-cent 

 piece. Usually there is no prm-itus. In rare instances a 

 herpes vesiculosus occurs on the sheath and inner surface of 

 the hind limbs, with the formation of scabs and crusts. 



Treatment. — ^The treatment depends somewhat on the 

 extent and form of the eruption. When feasible it is advis- 

 able to shear off the hair and soften up the crusts with green 

 soap. This may be followed by painting the areas with tinc- 

 ture of iodin or salicylic acid in alcohol (1 to 10). In horses 

 mercuric ointment is useful. In obstinate cases nitric acid 

 may be tried. However, most cases yield to treatment with 

 any disinfectant. One attack of herpes produces a certain 

 immunity against subsequent ones. 



FAVUS. 



Favus is a contagious skin disease common in man but 

 very rare in animals, caused by a fungus similar to the Tri- 

 chophyton tonsurans and called the Achorion Schoenleinii. It 

 forms round, thick scabs on the skin, which, being depressed 

 in their centers, are saucer- or shield-shaped. The scabs have 

 a sulphur-yellow color, especially toward the center. They 

 appear upon the head, abdomen, and feet of carnivora. In 

 fowls the comb and wattles are the favorite seats. The treat- 

 ment is the same as for herpes. 



CONTAGIOUS PUSTULOUS DERMATITIS. CONTAGIOUS 



ACNE. 



Deiinition. — Contagious pustulous dermatitis is a benign 

 pustular exanthema of horses which occurs in the regions of 

 the harness and saddle rests. 



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