What To Know About Aspiration Pneumonia In Pets

October 2, 2025

Pneumonia is a common respiratory condition that can affect both dogs and cats — as such, it’s important for pet owners to know the signs that their furry friend may have developed an infection.

This includes aspiration pneumonia, which is a special type of pneumonia that can happen when bacteria and contents from the gastrointestinal system accidentally end up in the lungs.

Dr. Lance Wheeler, an emergency care specialist at the Texas A&M Small Animal Teaching Hospital, lays out the causes of aspiration pneumonia and what pet owners need to know.

1. Pneumonia Is Caused By Infection

Pneumonia is an infection of the lungs, most commonly caused by bacteria, though viruses, parasites, and fungi may also play a role. 

Bacterial pneumonias are usually diagnosed based on the patient’s history, physical examination, and chest X-ray findings as either infectious or aspiration pneumonia. 

“Infectious pneumonia occurs when the body’s defenses are overwhelmed by inhaled (air-borne) pathogens, such as Bordetella bronchiseptica, one of the main bacteria responsible for kennel cough,” Wheeler said. 

“In contrast, aspiration pneumonia develops when bacteria gain access to the lungs and infects the alveoli, which are the small air sacs inside the lungs,” he said. “Most cases in pets occur when the animal accidentally inhales stomach acid or other gastrointestinal contents that are contaminated with oral bacteria after an animal vomits, which allows bacteria from the mouth to get into the lungs.”

2. Some Pets Are More At Risk Than Others

While any pet could develop aspiration pneumonia after an instance of vomiting, some animals are more at risk than others. 

“Both dogs and cats can develop aspiration pneumonia, but it occurs much more commonly in dogs,” Wheeler said. “Dogs with laryngeal paralysis — a condition where certain throat muscles  slowly lose function over time — are more susceptible to choking on food or vomiting, which can lead to aspiration pneumonia.”

Being anesthetized for any condition also carries a small risk of aspiration pneumonia.

“Although the risk of developing pneumonia after sedation or anesthesia is low — regardless of whether a breathing tube is used — it is still a potential complication we discuss with every pet owner,” Wheeler said. “This applies even to minor procedures unrelated to the respiratory or gastrointestinal systems.” 

Animals with weakened immune systems — whether due to very young or old age, certain medications, or underlying illnesses — are less able to fight off inhaled or aspirated bacteria, making them more susceptible to infection. If an infection develops, animals with weakened immune systems are also at a higher risk for developing a more severe case.

3. Signs To Watch For

Dogs and cats with very mild aspiration pneumonia may show no symptoms — something Wheeler compares to “walking pneumonia” in people — or they may develop vague signs such as reduced appetite, mild lethargy, or a reluctance to engage in normal activities.

“For example, they may be less interested in following their owner around the house or playing with a favorite toy,” Wheeler said. 

In more serious cases of aspiration pneumonia, pets may show signs such as:

• Getting tired or short of breath with very little activity 
• Breathing faster or harder, even while resting or 
• Developing a cough. 

If you notice any of these changes in your pet, it’s important to have them examined by your veterinarian.

“When we’re considering aspiration pneumonia, the patient’s history is usually the first clue that points us in that direction,” Wheeler said. “If an animal has a history of vomiting or regurgitation, recent sedation or anesthesia, or conditions like laryngeal paralysis, we begin to consider aspiration pneumonia as a possible cause of their symptoms. When aspiration is the trigger, signs of pneumonia can appear right after waking up from anesthesia or sometimes not until more than a week later.”

While an occasional cough can be normal in healthy dogs and cats, frequent, daily coughing or heavy breathing is a warning sign that your pet should be seen by a veterinarian. 

If aspiration pneumonia is suspected, veterinarians will often check for signs such as fever, low oxygen levels in the blood, changes in white blood cell counts, and patchy areas in the lungs visible on ultrasound or chest X-rays.

“Coughing after vomiting can sometimes mean the lungs were irritated by inhaled stomach acid,” Wheeler said. “That doesn’t always indicate a bacterial infection. We use your pet’s  physical exam and diagnostic testing to help determine whether the cause is aspiration pneumonia, kennel cough, or another condition.” 

4. Treatment For Aspiration Pneumonia

Once the cause has been identified, most patients with aspiration pneumonia will undergo a course of antibiotics, since pneumonia is caused by a bacterial infection. Occasionally, the infection may be severe enough to merit hospitalization and oxygen support.

“It really depends on the severity of the aspiration, the strength of the patient’s immune system, and how advanced the infection is,” Wheeler said. “Some dogs may do well with just antibiotics and can go home the same day, while others — especially older pets or those with other health problems — may need more intensive care.” 

5. Most Pets Recover 

The good news is that most pets recover from aspiration pneumonia, especially if they are younger and in good health overall.

“Catching the infection early is also important for recovery,” Wheeler said. “This allows veterinarians to treat the infection before it becomes more serious. That’s why it’s so important that owners take their pets to the vet if they notice a change.”

Whether aspiration pneumonia causes long-term problems depends on the underlying reason for the aspiration. 

“If aspiration pneumonia occurs under anesthesia, pets usually recover without lasting effects once the infection has resolved,” Wheeler said. “However, if the aspiration is due to a persistent issue — such as laryngeal paralysis — there is a much higher risk of recurrence. In these cases, diagnostics or treatments may be recommended not only to address the pneumonia itself but also to identify and manage the cause of the aspiration.”

Pet Talk is a service of the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University. Stories can be viewed on the web at vetmed.tamu.edu/news/pet-talk. Suggestions for future topics may be directed to vmbs-editor@tamu.edu.

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