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Pyothorax in Cats

Posted July 01, 2014 in Cat Diseases & Conditions A-Z

What is pyothorax?
Pyothorax, which is a fancy way of saying that pus is in the chest cavity, is a life-threatening, severe infection that can be seen in both dogs and cats. While rare, it can be devastating, as it requires aggressive treatment (including chest tube placement, surgery, etc.). Pyothorax is different from pneumonia, as it is caused by abnormal infection in the thorax, not in the lungs themselves (versus bacterial pneumonia, which is an infection within the lung). Note that this doesn’t mean that there is pus in the lungs, but rather in the sterile space surrounding the lungs. As more and more pus accumulates in the pleural cavity (which is the space surrounding your lungs and heart), it compresses the lungs, making breathing more difficult. Also, the pus can result in septic shock, an overwhelming bacterial infection in the bloodstream.

Cats laying downPyothorax is seen more frequently in cats than dogs, and is due to an infection that progressed into the chest cavity. One study has shown that cats that come from multi-cat households are almost 4 times more likely to develop pyothorax than cats that live alone (this is likely due to fighting).1 Likewise, younger cats are often more likely to develop pyothorax than older cats.1 Cats that go outside and potentially fight with other cats are also at greater risk because a bite wound to the thorax can result in a pyothorax.

Symptoms of pyothorax
Unfortunately, clinical signs of pyothorax can be very subtle, so it’s important to be aware of signs of this problem in your cat. Signs of difficulty breathing make for an immediate trip to the emergency room – even if it’s in the middle of the night!
Signs of pyothorax in cats include:

  • Lethargy or not moving much
  • Drooling
  • Not eating/anorexia
  • Hiding in unusual places (e.g., under the bed, in the closet, etc.)
  • Warm to the touch
  • Fever
  • A slow heart rate1 or abnormally elevated heart rate
  • Vomiting
  • Dehydration
  • An increased respiratory rate > 40 breaths per minute (bpm) or constant panting
  • Seeming out of shape during a walk (e.g., exercise intolerance)
  • Hunched over in sternal
  • Open mouth breathing (unless it’s a stressful event like a car ride, this is always abnormal, as cats prefer to always breath through their nostrils)
  • Difficulty breathing
  • Blue-tinged gums (which indicates severe difficulty and possible death if not treated immediately)
  • Stretching the neck out to

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Justine has more than 18 years of experience in the veterinary industry and is a board-certified emergency critical care veterinary specialist and toxicologist as well as the CEO and founder of Vetgirl. She is also a founding member of IDEXX’s Pet Health Network team.