Randomized, non-inferiority clinical trial of three topical dermatophytosis treatments in shelter cats

Abstract

Objectives Topical treatments, along with systemic oral antifungals, are the mainstay of infection and environmental control for cats with dermatophytosis in animal shelters. This study aimed to provide realistic expectations of the performance of three commonly used topical treatments to help shelters minimize the length of stay and optimize feline welfare. Methods A prospective, randomized, semi-blinded clinical trial compared treatment success and time to cure for miconazole chlorhexidine (MC) and hydrogen peroxide (HP) shampoos vs lime sulfur (LS) using a non-inferiority model. Cats with Microsporum canis were enrolled at four US animal shelters, treated with oral itraconazole and randomized into three topical treatment groups. Treatment success was defined as mycological cure by 7 weeks, while inferiority was defined as requiring more than 1 additional week to achieve cure. Results A total of 76 cats were enrolled. LS significantly outperformed both alternatives in cure by 7 weeks. Time to cure analysis showed significant differences between LS (mean 27 days, range 7–45) vs MC (37, 14–62) ( P = 0.04) and LS vs HP (36, 11–65) ( P = 0.06). Although alternative products took significantly longer to cure, confidence intervals (CIs) around the difference of means included the inferiority margin: LS vs MC (9.66, 95% CI 0.7–18.5) and LS vs HP (8.54, 95% CI 0.44–16.6). Therefore, inferiority of the alternative products was suggestive but inconclusive. After controlling for confounders, a Cox proportional hazards analysis confirmed significantly poorer performance of MC ( P = 0.003) and HP ( P = 0.032) vs LS. Younger age also significantly prolonged treatment ( P = 0.039), while intake type, co-housing and low body condition score did not. Shelter staff ratings showed no differences between products in terms of treatment unpleasantness, difficulty or cat reactions. Conclusions and relevance In this study, LS outperformed HP and MC in treating cats with M canis . Younger cats took a longer time to achieve cure. If shelters or practitioners wish to use an alternative topical treatment to LS, then HP should be considered.