Prevention of Microsporum canis infection in a cat challenge model

Abstract

Oral lufenuron is reportedly an effective treatment for some cats with existing dermatophytosis. We sought to determine if lufenuron, when used as a pre‐treatment prior to challenge exposure and infection, would prospectively protect against development of infection by direct application of Microsporum canis spores. Three groups (n = 6 per group) of juvenile cats were treated with either monthly oral lufenuron (30 or 133 mg kg−1) or placebo. After 2 months of treatment, kittens were challenged using 105Microsporum canis spores applied to the skin under occlusion. Cats were observed weekly, including: Wood’s lamp examination; scoring for scale/crust, erythema, induration; lesion size; and development of satellite lesions. Fungal cultures were performed biweekly. All cats became infected; the infections progressed, and then regressed, in a similar fashion in all groups. There were no consistent statistically significant differences in weekly infection scores throughout the study. Treated cats did not recover faster than untreated cats. We concluded that oral lufenuron at the dosing schedule and conditions used in this study did not prevent dermatophyte infection by direct topical challenge. Further studies are warranted to evaluate alternate dosing schedules, less severe challenge exposures, varying strains of M. canis, and other factors that may be present under field conditions. This study was funded by Novartis Animal Health.

Antifungal agents of use in animal health – practical applications

“…However, recent studies indicated that lufenuron at monthly doses of 30 or 133 mg/kg was unable to prevent dermatophyte infection by direct topical challenge (Moriello & Deboer, 2002) and oral doses of 100–140 mg/kg orally did not prevent dermatophyte infection by exposure to experimentally infected cats (Deboer & Moriello, 2002).…”

Treatment of dermatophytosis in dogs and cats: review of published studies

“…There are 17 studies that report on the efficacy of griseofulvin, itraconazole, terbinafine, or lufenuron alone or in combination with other therapies 20–22,26–39 …”

“…Chitin is a critical component of the outer cell wall of fungi and it possible drugs that disrupt chitin synthesis might also have antifungal activity. The use of lufenuron in the treatment of dermatophytosis has been described in several studies 35–38,43 . In 2000, a retrospective study suggested that lufenuron treatment was strongly associated with recovery in a large number of dogs and cats with a number of fungal infections, including dermatophyte infections 35 .…”

“…In cases where mycological cure was determined, the mean time to recovery was 34.7 days (range 12–90 days). There are two reports of controlled blinded studies evaluating the efficacy of lufenuron to prevent or alter the course of experimentally induced M. canis infections in cats 37,38 . In one study, lufenuron was used as a pretreatment prior to challenge exposure and infection 38 .…”

“…There are two reports of controlled blinded studies evaluating the efficacy of lufenuron to prevent or alter the course of experimentally induced M. canis infections in cats 37,38 . In one study, lufenuron was used as a pretreatment prior to challenge exposure and infection 38 . Two oral doses of lufenuron were evaluated (30 or 133 mg kg −1 ); after 2 months of pretreatment the kittens were challenged with infective M. canis spores.…”