Dermatophytosis in pigs is usually caused by Microsporum nanum. Lesions present as papular eruptions that enlarge to ringlike lesions with brown discoloration; these spread centrifugally (see image of dermatophytosis, pig). Lesions tend to be subclinical in adults, and dermatophytosis in swine is generally of little economic consequence. Zoonotic infections in farmworkers present as skin lesions.
Courtesy of Dr. Karen A. Moriello.
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 and Nannizzia gypsea (formerly M gypseum), and less commonly M canis.
Lesions in lambs are most often noticed on the head; however, 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 shearing with contaminated clippers. 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-limiting disease in otherwise healthy animals; however, treatment is used to shorten the disease course.
In large animals, it is cost-effective to isolate confirmed cases and treat 2–3 times a week with topical antifungal rinses such as enilconazole 1:50. 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.
