Yeasts are one-cell, usually rounded fungi that reproduce by budding. Fungal infections in dogs and cats usually affect the skin, hair and claw. Cats with thyroid gland disease, flea bite hypersensitivity, and those undergoing prolonged drug therapy may be predisposed to yeast infections. Some yeast, such as Candidaspecies, are normal inhabitants of the respiratory, gastrointestinal, and urinary tracts and only become pathogenic in cases of prolonged usage of antibiotics and immunosuppressive therapy 2.
Malassezia pachydermitis is one species of yeast implicated in Malassezia dermatitis itchy skin condition both in cats and dogs. In cats, Malassezia dermatitis is often associated with inflammation of the ear otitis externa), diabetes mellitus, feline acne, FIV, lymphoid tissue cancer, and certain skin diseases. 1 Malassezia dermatitis is also associated with seborrheic dermatitis. Feline Malassezia dermatitis is usually treated by systemic antifungal drugs like ketoconazole and itraconazole 3.
Cryptococcus neophormans is a yeast that causes infections in cats most often. It is found in pigeon excrements and bark and leaves of certain species of Eucalyptus trees. It is especially common in the southeast and southwest United States. Cats get infected by inhaling airborne organisms. Not all cats exposed to Cryptococcus neophormans become infected, but those with a weakened immune system are at greater risk. Infected cats develop tumor-like masses in the lungs, nose, eyes, and skin. Recently, Cryptococcus albidus species has been identified as a potential feline pathogen capable of causing systemic yeast infections which may result in paralysis and death 4. An infection with Cryptococcus magnus can cause bone and lymph node tumors 5.