Cryptococcosis

What Is Cryptococcosis?

Cryptococcosis is an infection caused by Cryptococcus fungi, mainly Cryptococcus neoformans and Cryptococcus gattii. These yeast-like organisms live in the environment, especially in soil enriched with bird droppings (pigeons in particular) and around certain trees such as eucalyptus. Pets usually become infected by breathing in spores, which then settle in the nose and sometimes spread to the skin, eyes, lymph nodes, or brain.

It is the most common systemic fungal infection in cats worldwide and is less common in dogs. In the US, C. gattii has been reported particularly in the Pacific Northwest. Cats that go outdoors may face more exposure, but indoor cats can be infected too. Like Valley Fever, it comes from the environment rather than from other animals.

Signs Owners Notice

In cats:

• Chronic sneezing and nasal discharge, sometimes bloody, from one or both nostrils
• A firm swelling over the bridge of the nose, or a fleshy lump in a nostril
• Noisy breathing or breathing through the mouth
• Skin lumps or sores, often on the head
• Enlarged lymph nodes under the jaw
• Eye changes such as dilated pupils or sudden blindness, or neurological signs like wobbliness or seizures

In dogs: infections are more likely to spread beyond the nose, so eye problems, behavior changes, head tilt, wobbliness, or seizures can be the first signs. Young adult dogs are most often affected.

Diagnosis and Treatment

A blood test that detects cryptococcal antigen is very useful and is also used to track treatment. Vets may confirm the infection by looking at a sample of nasal discharge or a lump under the microscope, by fungal culture, or by biopsy. Imaging such as CT may be used to assess the nose or brain.

• Oral antifungal medication, such as fluconazole or itraconazole, given for several months and often six months or longer
• Injectable antifungals, such as amphotericin B, for severe or brain-involving cases
• Surgery to remove a large nasal mass in some pets
• Repeat antigen tests to decide when it is safe to stop treatment
• Testing cats for FIV and FeLV, since a weakened immune system can complicate recovery; see our FIV guide

Prognosis and Cost Guidance

Pets with infection limited to the nose or skin generally have a good outlook with full treatment. Cases involving the brain or eyes are more serious and need more intensive care. Because treatment lasts months, the total cost in the US commonly reaches from several hundred to a few thousand dollars, depending on the medication, follow-up testing, and any imaging or surgery.

Practical Tips for US Pet Owners

• Give antifungal medication exactly as prescribed, and don’t stop early just because signs improve.
• Keep pets away from areas with heavy pigeon or bird droppings where possible.
• Ask your vet about liver monitoring during long courses of antifungals.
• Find general and specialty-referral practices through veterinary clinic listings.

Key Takeaways

• Cryptococcosis is an environmental fungal infection that usually starts in the nose.
• Cats are affected more often than dogs, and nasal swelling is a classic sign.
• Long courses of antifungal medication guided by antigen tests give most pets a good outcome.

FAQ

Is cryptococcosis contagious to people or other pets?
It is not normally spread from pet to pet or pet to person. People and animals are infected from the same environmental sources, so an infected pet is a reason to speak with your doctor only if someone in the home is immunocompromised.

How long does treatment take?
Usually several months, and sometimes a year or more, until antigen tests show the infection has cleared.

Can it come back?
Relapses can happen, especially if treatment stops too soon, so follow-up testing is important.