The condition known as pneumonia refers to an infection of the lungs. Many infectious organisms, ranging from bacterium, viruses, fungi and even parasites, can cause cat pneumonia, and some of pneumonia's clinical signs may include vomiting, hiding and much more. However, while cat pneumonia signs can be quite alarming and serious, most cats do recover once they receive proper medical attention. Read on to learn more about how pneumonia affects cats and what you can do to help.
What Is Pneumonia in Cats?
Pneumonia in cats is defined as inflammation of the lungs, usually caused by infectious agents. It is a serious condition in which the air sacs fill with pus and other liquid, causing the patient to have difficulty breathing. Pneumonia can manifest in one or multiple lung lobes, depending on the underlying cause, and the portions of lung affected may help give your veterinarian clues as to how the pneumonia developed.
Cat Pneumonia Signs
An important factor to take into consideration about cat pneumonia is that it usually follows an upper respiratory infection. Prompt veterinary intervention will help to prevent a mild upper respiratory infection (sneezing, runny eyes and nose) from progressing into the lower respiratory tract, where it becomes pneumonia. Clinical signs may include:

- Discharge from the nose (mucus, pus or blood)
- Dry cough
- Productive coughing that may include mucus or blood
- Rapid, shallow breathing
- Labored or difficult breathing, shortness of breath
- Lethargy
- Shaking or tremors
- Vomiting
- Hiding
- Decreased appetite
- Decreased elimination habits
- Signs of pain associated with breathing in or out
- Grunting or rattling noises associated with breathing
- Increased aggression
Pneumonia in cats is more prevalent in both young kittens and older cats. Unlike the seasonal flu resulting in pneumonia in people, it does not follow a seasonal pattern in cats. Patients with an unhealthy body condition score (both overweight and underweight cats) may be more likely to develop the condition.
Because some infectious agents that cause cat pneumonia are spread from cat to cat, either by coughing or through direct contact with the infected cat's saliva or mucus, cats in multicat households, outdoor cats and cats living in rescue groups are at higher risk to develop pneumonia. Additionally, if a viral infection has weakened a patient's immune system, bacteria may begin to grow in the lung, adding a second infection to the original one.
Diagnosing Pneumonia in Cats
Bloodwork and x-rays of your cat's lungs will be needed to diagnose pneumonia. This blood work typically includes checking your cat for heartworm disease, which doesn't technically cause pneumonia but presents with very similar signs and is an important disease to rule out. Although uncommon, there are also other types of parasites that can infect cat lungs that your vet will only be able to identify by looking at a stool sample. In cases where basic tests aren't revealing a clear answer, your vet may consider looking at a sample of fluid from your cat's lungs under a microscope to look for evidence of bacteria, fungus or parasites. They may even decide that a referral is necessary, like to a specialist to visually inspect the lungs and collect samples with a specialized video camera while your cat is under anesthesia.