Fungal Infections & Related Organisms in Cats

You mean there are more fungi in the world than felines?
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If your cat suffers from a fungal infection, there's a specific organism causing his misery. Treatment depends on what's necessary to get rid of that organism. Be careful around him—some feline fungal infections are just as happy to invade people. Rubber gloves are your friend when treating Kitty.


There's no actual worm in ringworm, an infection that easily spreads to humans. Instead, the responsible organism is a dermatophyte, one of several types of fungus that feed on skin or hair. Cats with ringworm lose hair on the head and front legs, the bald spots appearing as rings with red patches in the middle. Take your cat to the vet for an accurate diagnosis, but keep Kitty away from other pets in the meantime because the fungus is quite contagious. Your vet will prescribe a special shampoo that can kill the dermatophytes, and might prescribe medication for Kitty if the problem is severe. You'll probably have to shampoo every pet in your household to eradicate the problem.


If your cat's been sick or is getting on in years, the aspergillius fungi could take the opportunity to infect him. These fungi result from mold in the environment, both in your house and outside. Nasal aspergillosis infection is the most common type in felines. By the time your cat becomes symptomatic, the fungus has already started destroying his sinus bones. Your cat appears to suffer from a constantly runny nose, a thick discharge with a bad smell. If your vet prescribes antibiotics to clear up Kitty's nasal issues and nothing happens, she'll suspect aspergillosis. Systemic aspergillosis is far more serious—the fungus is in the process of destroying the bones in his body. While the prognosis for systemic aspergillosis isn't that good, especially as it usually affects cats with compromised immune systems, a treatment is available for the nasal variety. It requires anesthesia and infusion of a topical fungicide into the cat's nasal cavity. Several treatments may be necessary to get rid of the fungus once and for all.


If your cat ventures outdoors he's a candidate for cryptococcosis, an infection spread by pigeon droppings. Infection starts out as a nasal discharge and can proceed to far worse symptoms. While fairly rare in felines, cryptococcosis can become systemic, affecting every organ in his body. Immune-compromised cats, such as those with feline leukemia or the feline immunodeficiency virus, are far less likely to fight off the infection than a healthy cat. As with other fungal treatments, getting rid of it can be a long, involved process.

Other Fungal Infections

There are countless numbers of fungi in the world, so it's always possible some rare type could infect Kitty. Some fungi that affect felines, such as Blastomyces dermatitidis, grow only in specific areas. Blastomyces dermatitidis occurs in soils in the Mississippi River basin and the Great Lakes region, as does Histoplasmosis capsulatum, the cause of histoplasmosis. Coccidiomycosis, caused by Coccidiodes immitis, is found in the soils in dry regions from southern California to Texas. Symptoms of these infections mimic those of other, more common fungal diseases, but your vet should be familiar with the feline fungal infections in your region.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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