Fungal Diseases and Therapy in Dogs

Fungi may cause a wide variety of diseases from localized infections to fatal disseminated diseases in animals and humans. Fungal diseases have increased in importance over the last few decades and cause significant morbidity and mortality in dogs. Fungal infections may be confined to the surface of the body or may become systemic infection characterized by entry of the fungus into the dog and subsequent spread to various tissues of the body. Fungal infections are largely acquired via inhalation, ingestion, or through the skin. Some fungal diseases in the dogs are zoonotic, and the dogs can be responsible for transmission of these agents to the owner. Diagnosis of fungal infections in the dogs is challenging due to some limitations including the lack of specific signs and symptoms in the early stage of infection, diminishing number of clinical mycologists, cost, and lack of fast and accurate diagnostic tests. Early diagnosis of fungal infection is critical for effective treatment and reduces morbidity, mortality, and treatment cost. Chemotherapy is generally used for the treatment of fungal diseases. Antifungal drugs licensed for systematic use in dogs have been limited to a few agents and are often expensive and highly toxic to the dogs. Thus, limited therapeutic options exist for systemic form. Therapy with these drugs is often more prolonged than antibacterial therapy. The aim of this chapter is to review the most common fungal infections in dogs, including aspergillosis, dermatophytosis, blastomycosis, histoplasmosis, rhinosporidiosis, sporotrichosis, geotrichosis, and phaeohyphomycosis, and antifungal agents currently available for therapy.