Pneumonia in Dogs and Cats: Signs to Recognize

Pneumonia — inflammation and infection of the lungs — can develop as a complication of an initially milder respiratory illness (like kennel cough progressing further than usual, particularly in puppies, seniors, or dogs with weakened immune systems), from inhaling foreign material like vomit or food (aspiration pneumonia), or less commonly, from a primary bacterial, viral, or fungal infection.

Symptoms include a productive, often moist-sounding cough, fever, lethargy, reduced appetite, and labored or rapid breathing as the infection affects lung function. In more advanced cases, breathing becomes visibly more effortful, and gums can take on a pale or bluish tinge as oxygen exchange is compromised. This progression from a milder cough to these more systemic signs is an important pattern to recognize, since it suggests an initial respiratory illness has worsened rather than improved.

Aspiration pneumonia deserves specific mention — it can occur after a pet vomits and inhales some of the contents, after difficulty swallowing, or in pets who've had recent sedation or anesthesia without full recovery of their normal swallowing reflexes. This type can develop relatively quickly and is worth watching for after any of these situations.

What to do: A worsening cough combined with fever, lethargy, reduced appetite, or any labored breathing warrants prompt veterinary attention — pneumonia typically requires antibiotic treatment and sometimes hospitalization for oxygen support and fluids, and doesn't resolve with home care alone. Don't wait for breathing to become severely labored before seeking treatment; earlier intervention leads to better outcomes.

If kennel cough seemed to be improving and then took a turn for the worse, that progression pattern is exactly what to watch for.