298 DISEASES OF THE SKIN 



similar to those found upon the lips, they are covered by a 

 thick, dry crust which when removed exposes a granulating 

 surface covered with pus. 



(6) Venereal Form. — ^In this form the external genital 

 organs of both males and females are involved. It may be 

 associated with the lip-and-leg form, but not infrequently 

 occurs independently. In males the skin of the sheath espe- 

 cially at its orifice is inflamed. The first symptom is the ap- 

 pearance of one or more light-yellow-colored centers, necrotic 

 areas, which appear at the junction of the skin and mucous 

 membrane of the prepuce. Soon there develops an ulcer 

 which usually extends outwardly over the skin rather than 

 inwardly over the mucous membrane. By coalescence the 

 whole swollen sheath may be covered with ulcer. Occasion- 

 ally the pendent portion of the prepuce may slough. In 

 wethers the penis is rarely if ever attacked. In bucks, how- 

 ever, the necrosis attacks the penis, which swells ("big 

 pizzle"), becomes ulcerous on its surface, and occasionally 

 gangrenous, the distal portion of the organ not unrarely 

 sloughing ofl^. 



In ewes the ulcerations occur in the skin and mucous 

 membrane of the vulva, the ventral surface of the tail, and 

 the perineal region. Occasionally the vagina may be 

 involved, leading to a discharge. 



(c) Foot-rot Form. — ^The foot-rot form involves at first the 

 interdigital spaces, the erosions usually making their first 

 appearance at the heel. The inflammation invades the hoof 

 matrix leading to the discharge of a thin ichor which has a 

 very characteristic, pungent, penetrating pdor. The foot-rot 

 form may attack any sheep in the herd irrespective of age or 

 sex. 



(d) Sore Mouth Form. — This form is seen in lambs during 

 the fall of the year. The symptoms are similar to those of 

 the lip form in older sheep. The lips of the lambs swell, 

 prehension of food becomes difficult, and the patient falls off 

 in flesh and remains stunted in growth. At the junction of 

 the mucous membrane and skin of the lips, nodules or 

 necrotic areas appear. By confluence large, diffuse, fissured 

 scabs form covering in some cases the whole muzzle. If 



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