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Browse our veterinary-reviewed Dog and Cat Illness Guide to learn more about pet health. Always talk to your veterinarian if you have a concern about your pet's symptoms or health.
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Feline Pyothorax

Pyothorax is a bacterial infection that causes pus to build up in the chest cavity (the space between the lungs and the ribs). Usually, the chest cavity has the lungs and a small amount of liquid for lubrication. If fluid fills up the entire space, the lungs cannot expand, and your cat will have difficulty breathing. Pyothorax is fatal if left untreated.


After any one of these causes, bacteria will enter the chest cavity, resulting in inflammation. Soon the entire space fills with pus.



To diagnose your cat with pyothorax, your veterinarian may perform the following:


You must treat pyothorax aggressively. Other, inexpensive treatments will usually not be effective. Treatment consists of:

When the pus has cleared and your cat's appetite returns, your veterinarian will remove the tubes and send you home with antibiotics. It is crucial to follow your veterinarian's instructions about the medication. Relapse is possible if the infection is not entirely cleared.


Although it is not necessarily practical, most veterinarians agree the best preventative measure is refraining from participating in activities that may result in one of the common causes.


Without proper treatment, pyothorax is fatal. Treatment may be expensive but generally has a high success rate.

The prognosis depends on the severity of the cause. If a severe disease does not cause pyothorax, your cat will have a better chance of healing completely.

Medically Reviewed by Sara Ochoa, DVM

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