Fungal Infection (Cryptococcosis) in Cats

Key Takeaways

Cryptococcosis in cats is a systemic fungal disease affecting the skin, respiratory tract, eyes, and central nervous system (CNS) as well as adjacent tissues in some cases. Cryptococcus is a yeast-like fungus found in soil and decaying matter contaminated with bird droppings worldwide, and can survive for years in the environment.

• Cats often become infected with Cryptococcus by inhalation, but ingestion and wound contamination are also possible

• Symptoms depend upon the organs affected, and include swelling over the bridge of the nose, sneezing, difficulty breathing, skin lesions, changes in gait, ocular lesions, and seizures

• Diagnosis uses specific antigen tests and tissue cytology

• Treatment is long-term antifungal medication

• The prognosis is generally good with treatment, but cats with CNS involvement have a guarded prognosis

A Closer Look: What is Cryptococcosis in Cats?

The Cryptococcus fungus is a species which can be found worldwide. It thrives in soils and vegetation and can survive for years in a dormant state. Soils and vegetation contaminated with bird droppings are its ideal growth environment and it especially thrives when the droppings are from pigeons.

Cryptococcosis is not common, although it is the most common systemic fungal infection in cats. Early intervention is important to treatment success. Prognosis is generally good with prompt treatment.

Risk Factors

Risk factors include living within 10 km of a logging site or large area of soil disruption, and immunosuppression, such as cats undergoing steroid therapy. FIV and FeLV, while immunosuppressive diseases, are not proven to be predisposing factors, but will affect the length of treatment.

As cryptococcosis is a systemic infection, the fungus may be present and cause disease in several body and organ systems. Some other symptoms that may be noted depend on the localization of the infection and include: 

Cutaneous (skin) lesions found mostly on the head and neck, but can be anywhere on the body

• Papules/nodules (bumps)

• Ulcers

• Abscesses

Central nervous system (CNS) signs

• Seizures

• Paresis (partial paralysis)

• Ataxia (uncoordinated gait)

• Depression, behavior changes

• Blindness (bumping into objects)

• Hyperesthesia (extreme sensitivity to touch)

Ocular symptoms

• Eye discharge

• Blindness (bumping into objects)

• Cloudiness of the eyes

• Dilated pupils

Possible Causes

The cause of cryptococcosis in cats is exposure and infection by the fungal organism Cryptococcus, present in the soil. Not all cats exposed develop disease.

Main Symptoms

Symptoms will depend on which body system(s) are affected. In the sinonasal form, which is the most common in cats, a hallmark sign is a characteristic swelling over the bridge of the nose. There may be ulceration or draining tracts associated with this lesion. Other common signs include 

• Nasal discharge (may be clear, thick and yellow, or even bloody; unilateral or bilateral)

• Noisy breathing

• Sneezing

• Difficulty breathing

• Open-mouth breathing

Testing and Diagnosis

Cats with cryptococcosis may need stabilization with anti-seizure medications, analgesia, IV fluids, oxygen therapy, and/or anti-nausea medications. Diagnosis requires a full physical exam, blood work, and diagnostic imaging (x-ray, CT, MRI). Further tests that may be required are cerebrospinal fluid analysis, cytology, or biopsy of affected tissues.

Steps to Recovery

Treatment is at least 6 months in length and uses antifungal drugs. Cats also require routine blood work to monitor for side effects of medication. Relapse is also possible, further complicating treatment. 

Generally, treatment for at least 6 months is effective. In some cases with CNS involvement, the prognosis may be guarded, especially if the cat shows signs of altered mentation. CNS cases may require lifelong medication and monitoring.

Prevention

There is no specific prevention for cryptococcosis in cats, other than to avoid contaminated areas. Keeping cats indoors helps to minimize chances of infection. Cryptococcosis in cats is not contagious to other animals or to humans.

Is Cryptococcosis Common in Cats?

Cryptococcosis is an uncommon disease, but is the most common systemic fungal infection in cats. Cats are the most commonly affected species, and are 5 times more likely to develop this disease than are dogs.

Typical Treatment

• Antifungal medications (systemic)

• Anti-seizure medications

• IV fluids

• Pain medications

• Anti-nausea medications