Cryptococcosis is an infection caused by a yeast-like fungus called Cryptococcus. It is the most common deep (systemic) fungal infection reported in cats [1]. In most cats it starts in the nose, and it can also reach the skin, the eyes and the central nervous system, which is the brain and spinal cord [1].
If your cat has a swelling over the bridge of the nose, lumps in the skin or a runny nose that does not clear, see your vet. If your cat has a seizure, see your vet now.
Where the fungus lives
One type of the fungus is found around the world and lives in old, weathered bird droppings, pigeon droppings above all, and in rotting plant matter inside hollow trees [1]. A second type is tied to trees and tree bark and is found mainly in warm regions, including parts of the western United States, British Columbia, Australia and Latin America [1].
Vets think most cats pick it up by breathing it in. The fungus settles in the nose first and can then spread to nearby areas or through the blood [1]. Cats of any age, sex or breed can get it [1]. Dogs can get it too, though less often. For fungal infections of the nose in dogs, see fungal nose infections in dogs.
Nose signs
About 8 in 10 affected cats have nose signs [1]. These can include:
- sneezing and snuffling [1];
- discharge from one or both nostrils that may be clear, thick and cloudy, or bloody [1];
- a firm or soft swelling under the skin over the bridge of the nose [1];
- a pink, polyp-like growth inside the nostril, which means a fleshy lump [1].
Swollen glands under the jaw are also common [1].
Skin signs
Roughly 40 to 50 in 100 affected cats have skin or under-the-skin changes [1]. You may see nodules, which are firm lumps, as well as pockets of pus that do not feel hot, tracts that leak fluid, and open sores [1]. A lump can break open and leave a raw, sore patch, for example on the nose or forehead [1]. Other problems, such as other fungal infections and skin cancer, can look similar, so a vet needs to check [1].
Signs beyond the skin
Brain and eye signs are less common in cats, seen in about 15 to 25 in 100 cases [1]. Eye changes, such as a wide pupil, often mean the infection has reached the brain [1]. Watch for changes in behaviour, wobbliness, seizures or poor sight. Weight loss can also happen [1].
How vets diagnose it
Your vet may take a sample from the nose discharge, a lump or a sore and look at it under a microscope, where the fungus is often easy to see [1]. A biopsy, a fungal culture and a blood test for the fungus can also help [1]. The blood test can be negative when only the skin is affected, and vets also use it to track how a cat responds to treatment [1].
Treatment
Your vet will advise on treatment for your cat. Treatment usually lasts a long time, and your vet may repeat tests before deciding when to stop [1]. The outlook is usually good when only the nose or skin is affected, and poorer when the brain is involved [1].
At home, as directed by a vet:
- do not give your cat human or leftover medicines unless your vet says so;
- do not stop or change any medicine without talking to your vet;
- give any treatment exactly as your vet prescribes, for as long as your vet says;
- go back for any recheck your vet books.
When to see your vet
See your vet if your cat has:
- a firm or soft swelling over the bridge of the nose [1];
- sneezing, or nasal discharge that does not clear [1];
- a growth in the nostril [1];
- lumps in the skin, leaking tracts or open sores [1];
- changes in behaviour, wobbliness or eye changes [1];
- any lump, sore or nose change you are unsure about.
See your vet now if your cat has a seizure.
The bottom line
Cryptococcosis is a fungal infection that can affect a cat’s nose, and it can also cause lumps and sores in the skin. Only a vet can find the cause with lab tests.
This article is for general information only and does not replace advice from your veterinarian. If your cat has a swelling over the nose or lumps in the skin, see your vet.
Sources
- Torres SMF. 4.5 Systemic Mycosis: Cryptococcosis, Small Animals. In: Small and Large Animal Dermatology Handbook, Vol. 1. University of Minnesota, 2025. CC BY 4.0. https://open.lib.umn.edu/animaldermatology/chapter/systemic-mycosis-cryptococcosis-small-and-large-animals/