Treatment of shelter cats with oral terbinafine and concurrent lime sulphur rinses

Background Dermatophytosis is an important contagious and infectious skin disease in an animal shelter. Itraconazole is the commonly used systemic antifungal drug, but it is expensive in some countries and, at times, difficult to obtain. Terbinafine is a fungicidal allylamine with documented in vitro and in vivo efficacy against M icrosporum canis in pet cats and in cats with experimental infections. Hypothesis/Objectives To describe the use of oral terbinafine for the treatment of M . canis dermatophytosis in shelter cats. Methods The response to treatment of 85 shelter cats with naturally occurring M . canis dermatophytosis was monitored by examination, weekly toothbrush fungal cultures and the number of colony‐forming units on fungal culture plates. Cats were treated with either 14 ( n  = 21) or 21 days ( n  = 64) of terbinafine per os (p.o.) along with concurrent twice weekly lime sulphur rinses and daily environmental disinfection. Results Cats treated with 14 days of terbinafine p.o. showed an initial response to therapy but by week 6 had relapsed and required rescue therapy with a course of itraconazole (10 mg/kg p.o.) to obtain a cure. Cats treated with 21 days of terbinafine p.o. showed a response to treatment similar to published reports using itraconazole p.o. for 21 days. The mean and median number of days to mycological cure was 22.70 (range 13–39). Terbinafine was well tolerated. None of the cats developed oral lesions postgrooming of lime sulphur rinses. Clinical significance Where itraconazole is not available, substitution with terbinafine in established protocols may allow shelters to treat cats that otherwise would go untreated.