Dermatophytosis in Pigs, Sheep, and Goats
Dermatophytosis in pigs is usually caused by Microsporum nanum. Lesions present as papular eruptions that enlarge to ring-like lesions with brown discoloration; these spread centrifugally. Lesions are fairly asymptomatic in adults, and dermatophytosis in swine is generally of little economic consequence. Zoonotic infections in farm workers present as skin lesions.
Dermatophytosis is a common, troublesome problem in show lambs but is otherwise uncommon in production flocks of sheep and goats. The most common pathogens are Trichophyton spp, M gypseum, and less commonly M canis.
Lesions in lambs are most often noticed on the head, but widespread lesions under the wool may be apparent when lambs are sheared for show, or they may develop later as a consequence of microtrauma from contaminated clippers from shearing. Infected lambs should not be issued certificates for transport to show until the infection is resolved. Systemic antifungal drugs are cost prohibitive in large animals. Dermatophytosis is a self-curing disease in otherwise healthy animals. Treatment is used to shorten the course of the disease. In large animals, it is cost effective to isolate confirmed cases and treat with topical antifungal rinses such as enilconazole 1:50 two to three times a week. Lime sulfur 1:16 can be used but will discolor the wool temporarily. It is important to drench the coat and ensure thorough application to hairs and skin. Clipping lesioned areas will help debulk the lesions. Infections take 4–8 weeks to resolve, which may mean that clinical resolution will not occur in time for a show.