Cryptococcosis is the most common systemic fungal infection in cats, caused by inhaling spores of Cryptococcus neoformans or C. gattii — both found in pigeon droppings and soil. Cats typically show nasal polyps, chronic sneezing, and facial swelling before neurological signs appear. Treatment with antifungal drugs can be curative if started early.
Last reviewed: June 2026
What Is Cryptococcosis in Cats?
Cryptococcosis is a fungal infection caused by Cryptococcus neoformans and the related species C. gattii. Cats acquire infection by inhaling the microscopic yeast-phase spores from contaminated environments — particularly soil enriched with pigeon or other bird droppings, eucalyptus trees (C. gattii), and decaying organic matter.
Once inhaled, Cryptococcus establishes itself first in the nasal passages and sinuses, then can spread to the skin, eyes, lymph nodes, and central nervous system (CNS). Cats are uniquely susceptible — they are the most commonly affected domestic species, with reported infection rates substantially higher than in dogs. Cats without known immune suppression can develop cryptococcosis, though FIV-positive and FeLV-positive cats are at significantly higher risk.
Among systemic fungal infections in cats in North America, Cryptococcus is the single most frequently diagnosed pathogen in most regional surveys. Early disease confined to the nasal cavity is highly responsive to antifungal therapy; CNS extension carries a more guarded prognosis.
Signs of Cryptococcosis in Cats
Signs depend on which organs are involved:
Nasal / upper respiratory (most common, early stage):
- Firm, flesh-colored nasal polyp or swelling on the bridge of the nose ("Roman nose" deformity)
- Chronic, unilateral or bilateral sneezing
- Mucopurulent nasal discharge — often unresponsive to antibiotics
- Facial deformity from granulomatous tissue expanding through the nasal bones
Skin:
- Firm or fluctuant subcutaneous nodules, especially on the head and neck
- Ulcerated skin lesions that won't heal
Neurological (late stage / CNS spread):
- Seizures
- Head tilt, circling, ataxia
- Sudden blindness (optic nerve/retinal involvement)
- Behavior changes, dementia-like signs, vocalization
Ocular:
- Uveitis, retinal detachment, dilated unresponsive pupils
Approximately 40–50% of cats with cryptococcosis have nasal involvement at presentation; neurological signs occur in roughly 20–25% and carry the worst prognosis for recovery.
Diagnosis
Your vet will suspect cryptococcosis based on a chronic non-responsive nasal or skin presentation, especially in an outdoor cat or one in a pigeon-populated area. Definitive tests include:
- Serum cryptococcal antigen test (LCAT/CRAG titer) — highly sensitive and specific; a positive titer confirms active infection and is used to monitor treatment response over time
- Cytology — fine needle aspirate of nasal polyp, skin nodule, or lymph node reveals the organism's distinctive thick capsule (clear halo on India ink or Romanowsky stains)
- CSF analysis — if neurological signs are present
- MRI/CT of the head — maps nasal, paranasal sinus, and CNS involvement before treatment planning
- Fungal culture — confirms species and allows antifungal sensitivity testing
Retroviral testing (FIV/FeLV) is recommended at diagnosis because immune status influences treatment intensity and prognosis. The AAFP Feline Retrovirus Guidelines (2020) recommend that any cat presenting with an unusual opportunistic infection be screened for retroviral disease (AAFP Feline Retrovirus Guidelines, 2020).
Treatment
Cryptococcosis requires long-term antifungal treatment — weeks to months, not days. Standard protocols include:
- Fluconazole — oral; first choice for nasal and cutaneous forms; good CNS penetration; well-tolerated in cats. Typically dosed at 50–100 mg/cat twice daily. Duration: minimum 4–6 months, until CRAG titer is negative or at a stable low level.
- Itraconazole — oral; alternative if fluconazole fails; less CNS penetration
- Amphotericin B — IV; reserved for severe CNS disease or azole failures; nephrotoxic, requires hospitalization
- Flucytosine — used in combination with amphotericin B for severe CNS disease
Treatment response is monitored with serial CRAG titers every 4–6 weeks; a falling titer indicates response. Most cats with nasal disease achieve clinical cure. CNS disease responds more slowly and relapses after drug withdrawal are common.
As described in Ettinger's Textbook of Veterinary Internal Medicine, indoor cats recovering from cryptococcosis should remain on antifungals until two consecutive CRAG titers are negative at least 4 weeks apart.
When to See a Vet
Call your vet today if:
- Your cat has a firm swelling or lump on or around the nose that has been growing
- Chronic sneezing or nasal discharge has not responded to antibiotics
- You notice your cat's face has developed a new asymmetric bulge
Go to the ER immediately if:
- Your cat is having seizures
- Your cat suddenly goes blind or has a head tilt and is falling over
- Your cat is unresponsive or extremely lethargic
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Frequently Asked Questions
Can I catch cryptococcosis from my cat? The risk is very low. You would need to inhale spores from the same environmental source, not from your cat directly. Cryptococcus is not spread cat-to-human through saliva or touch under normal circumstances. Immunocompromised people (HIV, organ transplant recipients, chemotherapy patients) should take extra precautions and consult their physician if their cat is diagnosed.
How much does cryptococcosis treatment cost in cats? Diagnosis (CRAG titer, cytology, imaging) typically runs $300–800. Fluconazole is relatively affordable — approximately $1–3 per tablet depending on formulation, totaling roughly $100–400 for a 4–6 month course at cat-sized doses. CNS disease requiring amphotericin B hospitalization can cost $1,500–4,000 for initial stabilization. Long-term monitoring (repeat CRAG titers every 1–2 months) adds $50–100 per visit.
Is cryptococcosis curable in cats? Yes — nasal and cutaneous forms are highly treatable and most cats achieve long-term remission or cure with appropriate antifungal therapy. CNS involvement carries a more guarded prognosis, and some cats relapse after treatment is stopped, requiring lifelong low-dose maintenance.
How long does treatment take? A minimum of 4–6 months of continuous antifungal therapy is typically required. Stopping too soon leads to relapse. The CRAG antigen titer is used as a guide — treatment continues until the titer is undetectable or very low and the cat is clinically normal.
Does my other cat need testing if one cat has cryptococcosis? Cat-to-cat transmission does not occur. Other cats in the household would only be at risk if they were exposed to the same environmental source of spores. Environmental testing (of soil, pigeon roosts) and checking other outdoor cats for symptoms is reasonable, but automatic testing of asymptomatic housemates is not routinely required.
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