Aspiration pneumonia is a serious chest infection caused by the presence of inhaled alien material in the lungs.
In dogs, this doesn’t have to be something dramatic, like a stick or grass awn. It can be the dog’s own saliva if he breathes in at the wrong moment, or inhaled stomach acid in a vomiting animal.
However, rest assured that the body has sophisticated defense mechanisms to stop exactly this from happening, and a fit, strong animal is unlikely to get aspiration pneumonia.
The most obvious symptoms are a cough and labored breathing that come on quickly. You may notice the dog’s chest wall moving more rapidly than usual, even at rest, and sometimes it is such an effort to breathe that the dog uses his tummy muscles.
In addition, the dog may look as though he’s doing poorly and loses interest in food, doesn’t want to move and prefers to lie down, breathing through his mouth.
Sometimes the chest symptoms are preceded by another illness, such as repeated vomiting.
These signs are quite general — but because of the potentially serious nature of aspiration pneumonia, if you suspect your pet has a chest problem, please get him checked by a veterinarian.
The immediate cause of aspiration pneumonia is the presence of a solid or liquid in the airway. But how did it get there?
- The most common reason is the animal breathes in at the wrong moment and sucks fluid down into his lungs. This is more likely if the dog has an anatomical abnormality such as a megaesophagus (a condition where the gullet lacks tone, allowing food and fluid to pool in the esophagus).
- Sometimes active dogs can inhale a grass awn when running through long grass. If this migrates all the way down into the lungs, it sets up a focus of infection. Likewise, a vomiting dog may be particularly unlucky and inhale some of his own vomit into his lungs. This is particularly worrying because stomach acid can cause serious damage to the lung tissue.
- A third cause is overenthusiastic syringe feeding. When a pet is ill, it is sometimes necessary to syringe small volumes of water or food into his mouth. If the food is forced in too quickly, it can flood the mouth and some may be sucked down into the lungs.
Large volumes of fluid filling the lungs are akin to the dog drowning. Likewise, a small volume of fluid may not cause an immediate problem; the lung may wall off the area to protect itself — but this can manifest in later life as scar tissue within the lung.
Any investigation must be done with care because these animals are usually weak.
If the dog is breathing heavily, a conscious chest X-ray gives useful information about the pattern within the lungs, which can suggest aspiration pneumonia. Your veterinarian will handle the dog as gently as possible so as not to further distress his breathing.
Blood tests can identify signs associated with inflammation or infection. If the dog is strong enough, then a procedure called bronchoalveolar lavage can provide a sample of cells for culture to pinpoint which antibiotic will kill the infection.
This involves putting a narrowing tube down the patient’s windpipe, flushing with saline and then sucking the sample back up. Not all animals will be well enough for this, and therefore your vet may start broad spectrum antibiosis anyway.
Time is of the essence; the swifter infection is brought under control, the better the likely outcome. Thus, antibiotics should be started before lab results come back.
A dog with aspiration pneumonia has difficulty breathing, and so bed rest, and possibly even an oxygen tent, can help.
Don’t let your dog lie in one position for hours on end. This allows fluid to dangerously pool in the lower lung. A sick dog having difficulty breathing should be rolled onto his opposite side every 2 hours.
If your dog has a preexisting condition that makes it difficult to swallow, such as megaesophagus, then feeding him with his forequarters raised above head height gets gravity to help the food to go down.
While syringe feeding, press the plunger slowly, making sure your pet swallows fully each time. Any animal that develops labored breathing should be taken to a vet for an urgent examination.
- “Aspiration pneumonia: treatment with pulmonary vasodilators.” Broe, Toung, Permutt & Cameron. Surgery 943(1): 95–99.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 2, 2015.