Management of endemic Microsporum canis dermatophytosis in an open admission shelter: a field study

Abstract

Endemic Microsporum canis dermatophytosis was identified in a large, open admission, private, no-kill shelter that admitted >1200 cats per year. Fungal culture (FC) screening revealed that 166/210 (79%) and 38/99 (38%) cats in the non-public and public area were culture positive, respectively. However, pending screening FC results, the 99 cats in the public area were treated with once-weekly lime sulfur rinses and monitored with once-weekly FC. Cats in the non-public area were not treated. When FC results were available, cats were separated into low-risk (n = 61) and high-risk (n = 38) groups based upon the presence or absence of skin lesions. Low-risk cats continued to receive once-weekly topical lime sulfur and rapidly achieved culture-negative status. High-risk cats were divided into two groups based upon the number of colony-forming units/plate (low or high). All 38 cats were treated with twice-weekly lime sulfur and oral terbinafine and within 6–7 weeks only 5/38 cats were still FC-positive. These cats were moved to a separate room. Dermatophytosis was eradicated within 5 months; eradication was prolonged owing to reintroduction of disease into the remaining room of cats under treatment from three kittens returning from foster care. Continued admissions and adoptions were possible by the institution of intake procedures that specifically included careful Wood’s lamp examination to identify high-risk cats and use of a ‘clean break strategy’.