Dermatophytosis caused by Microsporum canis is a common complaint of cats and kittens entering North American shelters1. Topical treatment in shelters destroys fungal spores on the hair shafts of infected cats, a critical component of therapy, and is essential to preventing transmission, especially to human caretakers2. Both cost and treatment duration are significant concerns in animal shelters, since these influence the ability of the shelter to care for other animals. Currently, the most cost-effective and efficient protocols involve oral antifungal medications and application of lime sulfur (LS). Lime sulfur has a noxious odor, corrodes equipment, is not available in Canada, and is generally unpleasant to cats receiving treatment and the human caretakers applying it. All this has the potential to reduce a shelter cat's quality of life and affect human and cat compliance.

Two alternative treatments have shown promising sporicidal effects in vitro. Within one treatment, miconazole/chlorhexidine (MC) treatments showed sporicidal activity on cat hair1–3, and extremely dilute protocols using this medication have been tested in shelter cats.8 Another alternative treatment, accelerated hydrogen peroxide (AHP), has been shown to have sporicidal effects as a disinfectant and in vitro2,4 but has not been tested in vivo. This randomized, blinded prospective clinical trial will investigate whether application of MC or AHP are inferior to LS as measured by time to mycological cure using fungal culture in shelter cats receiving oral itraconazole, and by cure rate (treatment failure for alternatives to LS defined by fungal growth on the 7- week culture).