Antifungal Resistance in Animal Medicine: Current State and Future Challenges

The emergence of resistance to antifungal drugs, and in particular to the azoles, is causing great concern in the scientific community. However, the actual impact of antifungal resistance on animal health and the farming system is mostly unknown, as animal mycoses have traditionally received much less attention than those affecting humans, and in vitro antifungal susceptibility testing of animal isolates is still uncommon. In this chapter, we briefly review the main characteristics of antifungal therapy in the veterinary setting and the current knowledge on antifungal resistance of some major animal pathogenic fungi, including yeasts such as Candida spp., Cryptococcus gattii, and Malassezia pachydermatis, and the filamentous fungus Aspergillus fumigatus. In addition, we discuss some issues that should be addressed in order to optimize antifungal therapies in animal medicine and minimize the impact caused by resistant strains, including the species-level identification of pathogenic fungi, the establishment of meaningful breakpoints for antifungal resistance of veterinary isolates, and the reduction of the environmental impact of antifungal use. We conclude that veterinarians and other animal health professionals should take action to demand more resources for improving the monitoring of antifungal resistances in veterinary clinics and animal facilities worldwide.