Refractory Dermatophytosis in a Spitz Dog Successfully Managed with Posaconazole in India: A Case Report

Dermatophytosis is a superficial fungal skin disease of cats and dogs. The most common pathogen of small animals belongs to the genera Microsporum and Trichophyton. It is an important skin disease because it is contagious and can be transmitted to people. Refractory dermatophytosis has become an increasing concern in dermatological practice due to poor response to standard antifungal therapy. The condition is characterised by chronicity, recurrence or persistence despite adequate treatment. This study aimed to assess the clinical profile and therapeutic outcomes in patients with refractory dermatophytosis. An 8-year-old intact male Spitz dog weighing 10 kg, presented with persistent alopecia, scaling, erythema and pruritus despite multiple courses of systemic and topical antifungal agents. Diagnosis was confirmed by microscopic examination, culture and punch biopsy. Due to the lack of response to standard therapy, Posaconazole was initiated based on antifungal susceptibility testing (AFST); however, AFST is not routinely performed for dermatophytosis, although it may provide valuable guidance in refractory infections by identifying reduced susceptibility or resistance to commonly used antifungal agents. Marked clinical improvement was observed, with complete clinical and mycological cure achieved without adverse effects. This report highlights a case of refractory dermato-phytosis in which antifungal susceptibility testing guided the successful use of Posaconazole. The case highlights the diagnostic challenges associated with recurrent dermatophytosis and underscores the potential role of antifungal susceptibility-guided therapy in managing treatment-resistant infections. Hence, Posaconazole is a promising alternative antifungal agent for managing refractory dermatophytosis in dogs.