Pneumonia in Cats: Causes, Symptoms and Treatment

Last Updated on July 1, 2021 by Julia Wilson

What is pneumonia?

Pneumonia is an infectious/inflammatory disorder of the lung parenchyma. The lungs are filled with thousands of tiny bronchi, which end in smaller sacs known as alveoli which contain tiny blood vessels. Oxygen is added to the blood and carbon dioxide removed via the alveoli. Pneumonia causes these alveoli to fill with pus and fluids which affect the lung’s ability to exchange gases.

How do cats become infected with pneumonia?

  • Bacterial – Many types of bacteria can cause pneumonia in cats including Streptococcus, Chlamydia felis, Yersinia Pestis (the bacteria responsible for pneumonic plague), Pasteurella multocida, Staphylococcus, Bordetella and more. Often it develops secondary to a viral infection or aspiration. This type of bacteria may develop as a secondary to a viral infection when the cat’s natural defences are already weakened. It is also possible for bacterial pneumonia to originate from elsewhere in the body.
  • Viral – Upper respiratory infections are common in cats, particularly kittens and stressed cats in crowded environments (such as shelters). Feline calicivirus and herpesvirus are the most common causes. Inflammation in the lungs can lead to secondary bacterial infection. FIV and FeLV both lead to a decreased immune system, which can increase the incidence of pneumonia due to infectious agents.
  • Fungal – Mycotic (fungal pneumonia) infections are relatively rare in cats. Cryptococcosis, blastomycosis, aspergillosis and histoplasmosis. Once again, a cat with FIV or FeLV may be at higher risk due to their weakened immune system which allows for infection to take hold.
  • Parasitic – This form of pneumonia is rare in cats and almost always occurs in either young kittens or immunocompromised cats. Parasites that can cause pneumonia include lungworm, toxoplasmosis, liver flukes, roundworms.
  • Aspiration – Inhalation of gastric contents during vomiting or administration of medications. Cats are particularly vulnerable to aspiration pneumonia when given mineral oils to treat hairballs or have a recent history of general anesthesia. Cats who are chronic vomiters and cats with a cleft palate are also at greater risk of developing aspiration pneumonia. Inhalation of a foreign substance such as a grass awn can lead to inflammation of the lungs as well as a bacterial infection.

Symptoms of pneumonia in cats?

The most common symptom of pneumonia is a moist cough and dyspnea (difficulty breathing).

Other symptoms include:

There may be additional symptoms relating to the underlying cause if one is present. For example, draining skin lesions and ocular manifestations in cats who have systemic fungal infections.

Not all cats with pneumonia will display respiratory signs.

How is pneumonia diagnosed?

Your veterinarian will perform a complete physical examination of your cat and obtain a medical history from you. He will listen to the chest with a stethoscope which will reveal increased and harsh lung sounds. Symptoms may be acute or chronic depending on the underlying cause.

Diagnostic workup:

  • Baseline tests Biochemical profile, complete blood count, and urinalysis. Increased white blood cells are common with bacterial and fungal pneumonia. Cats with FIV may have anemia, decreased white blood cells and lymphocytes. These tests can also give your veterinarian a picture of your cat’s overall health before commencing treatment.
  • Lung aspiration – A needle is pushed through the chest into the lungs, and lung cells are aspirated into the syringe. These cells are then studied under a microscope for the presence of infectious organisms.
  • Tracheal wash – This is performed to obtain cells from the trachea which can be cultured to analyse and determine the particular organism involved.
  • Chest x-ray – This will confirm that your cat has pneumonia and look for inhaled foreign objects (if one is suspected).
  • Blood gas evaluation – To measure the levels of oxygen in the cat’s blood.

As well as diagnosing pneumonia, your veterinarian will want to look for an underlying cause:

  • Fecal examination to look for the presence of parasites.
  • Blood tests to check for FIV, FeLV, toxoplasmosis.
  • Nasal or eye discharge culture to check for Y. pestis (in affected areas).

How is pneumonia treated in cats?

Your cat may have to stay at in the hospital for treatment if he is severely ill, milder cases may be treated at home. Treatment will depend on the cause of pneumonia and may include:

  • Antibiotics to treat a bacterial infection or toxoplasmosis. Selection is based on bacterial culture and sensitivity. Mycotic (fungal) pneumonia typically requires long-term (2+ months) with systemic anti-fungal medication.
  • Supportive care such as a nebuliser or oxygen therapy if the cat is experiencing breathing difficulty.
  • Fluid therapy to correct dehydration.
  • Nutritional support if the cat is not eating. This may include strong-smelling food, appetite stimulants or a feeding tube.

As well as treating pneumonia, addressing the underlying cause will be necessary:

  • Anti-parasitic medications to treat worms and flukes.
  • Supportive care and where necessary anti-virals to treat cat flu.
  • Bronchoscopy to remove a foreign object.
  • Surgery to correct a cleft palate.

Home care

  • Confine to a small area or a large dog crate and restrict exercise during recovery.
  • Always follow your veterinarian’s instructions and give all medications as prescribed. Your cat will need to have a follow-up appointment and repeat chest x-rays.

What is the prognosis?

Prognosis depends on the underlying cause; prompt medical care has a more favourable outcome.


  • Keep your cat up to date on his vaccinations.
  • Have your cats desexed, FIV and FeLV are spread via sexual intercourse and bites, nasal secretions (FeLV)?
  • Don’t let your cat roam and hunt. Hunting cats are at greater risk of catching parasitic infections.
  • Don’t force liquids or foods into your cat; this exposes them to aspiration pneumonia.
  • Bottle feed kittens with their tummy facing the floor, do not hold them on their backs as we would feed a human baby.