Fungal Pneumonia in Cats

Fungal pneumonia has a gradual onset, and the longer it is present the harder it is to eradicate. Bacterial infection may occur from the immune system being weakened from fighting the fungal pneumonia. In some advanced cases, systemic inflammatory response syndrome (SIRS) may develop. This can be deadly, as it spreads the infection to other organs and stops them from functioning. 

Pneumonia occurs when an infection causes the lungs to become inflamed. The alveoli (tiny sacs of air in the lungs) fill with pus and fluid. This makes breathing very difficult, and if left untreated can become life threatening. The alveoli are responsible for transporting oxygen from breathing into the bloodstream. If they are not functioning properly, the entire body of the cat becomes depleted of oxygen.

In the case of fungal pneumonia, fungal spores infiltrate the lungs and airways. This is also referred to as “mycotic pneumonia”. Cases of fungal pneumonia are rare in cats, but they do occur. An infection of the Cryptococcus fungus is the most commonly seen fungal infection in cats. There are a few other fungi that may cause pneumonia in cats. Cats with immune disorders are more prone to developing fungal pneumonia, as are younger cats and cats that are male (by 2 to 4 times). The infection affects the nasal cavity, irritating the lining of the nose and sinus. 

The first stages of fungal pneumonia carry almost no symptoms. The further progressed the infection is, the more symptoms that will manifest. Symptoms are as follows:

• Thick green/yellow nasal discharge
• Eye discharge
• Weight loss
• Dehydration
• Swollen lymph nodes
• Labored breathing
• Loud breathing
• Short wet cough
• Weakness
• Depression
• Fever
• Increased heart rate
• Bumps of lesions on the skin
• Lameness
• Dull fur coat
• Blepharospasm (squinting)
• Sudden blindness (in advanced cases)

While the cat’s own immune system is partly responsible for whether it will be susceptible to fungal pneumonia or not, geographic location is a heavy determinant of exposure to fungal spores. Different fungi live in different parts of the earth. All known causes are listed below.

• Spore inhalation from soil
• Interaction with bird droppings
• Genetic defects of the immune system
• Living near damp or wet habitats
• Feline immunodeficiency virus (FIV)
• Prednisone use
• Chemotherapy
• Certain cancers that affect the immune system

To make a proper diagnosis, your veterinarian will need the cat’s full medical history. A physical examination will be completed, including listening to the lungs with a stethoscope. The vet will check to see if the cat’s symptoms match those of fungal pneumonia. Often a correct diagnosis is made after a course of antibiotics proves to be ineffective, ruling out bacterial pneumonia. 

X-rays can show increased lung density, which will confirm the presence of pneumonia. Full blood work will be needed, including a complete blood count and a biochemical profile. An increase in white blood cells can indicate the presence of both cancer and/or fungal pneumonia. A lung aspiration may be done by sticking a needle into the lungs and collecting lung cells for microscopic evaluation. This can identify any fungi present. Testing for FIV should also occur. 

Appropriate treatment will depend on how severe fungal pneumonia has become. An earlier diagnosis has much more success than does a late one. 

Antifungal Medication 

In all cases of fungal pneumonia, an extensive prescription of antifungal medication will be needed. Medications of choice are generally itraconazole or fluconazole. Both are expensive, and the duration of treatment will last months after symptoms have disappeared. The cat is often kept in the clinic or hospital for the first 2-5 days to determine whether it is responding to medications or not. 

Supportive Care 

While the cat is hospitalized, it will need ongoing supportive care to promote healing and maintain comfort. This generally includes intravenous fluids to return the cat to proper hydration and nebulization to keep the airways moist. Oxygen supplementation may also be needed. If the cat does not respond to medication, supportive care will be maintained into palliative circumstances.

Surgery 

Surgery may be needed if the pneumonia has progressed to SIRS. If skin nodules or granulomas have developed, they may need to be surgically removed. If increased eye pressure has caused blindness, the entire eye may need removal. All surgeries require general anesthesia and carry extra risks, especially in a cat who is already weak. 

Antibiotics 

If a secondary bacterial infection is present, or if the cat has undergone surgery, antibiotics will be prescribed to rid the body of harmful bacteria. Prescriptions may last from 2 weeks to a month or longer. 

The cat will need to take antifungal medication for months on end to rid the body of infection. It should be noted that less than 70% of cats respond favorably to this medication. Some cats may clear the infection on their own, however, this is rare. Two weeks after hospital discharge, you will need to make a vet appointment for follow-up chest X-rays to confirm the pneumonia is resolving. At that time the cat will be reevaluated.

Clean any outdoor areas that may be collecting fecal material. Limit your cat’s outdoor access. Restrict all play and activity during the healing process. Give your cat a high-quality cat food with protein and lots of calories. You may also want to supplement your cat with liver enzymes. If blindness has occurred, it will be permanent. Relapse can happen up to one year after treatment has taken place.