Pneumonia (Bacterial) in Dogs

4 min read

Pneumonia is a condition which refers to an inflammation of the lungs. Bacterial pneumonia, meanwhile, refers to an inflammation of the lungs in response to a disease-causing bacteria. This inflammation is characterized by an accumulation of inflammatory cells and fluid in the lungs, airways, and alveoli (the portion of the airways in which oxygen and carbon dioxide are exchanged).

Prognosis for bacterial pneumonia is generally good if properly treated. However, there are two secondary conditions that may result from bacterial pneumonia, and which are associated with increased fatalities: hypoxemia and sepsis. Hypoxemia refers to severely low levels of oxygen in the blood, while sepsis refers to a systemic infection with the presence of toxic, pus-forming bacteria in the dog's blood stream.

Bacterial pneumonia is relatively common in dogs. Sporting dogs, hounds, and larger mixed-breed dogs seem to be at greater risk for bacterial pneumonia than other breeds.

If you would like to learn more about how this condition affects cats, please visit this page in the PetMD health library. 

Symptoms and Types

Symptoms of bacterial pneumonia include cough, fever, difficulty breathing, lack of appetite and consequent weight loss, sluggishness, nasal discharge, dehydration, and rapid breathing. Intolerance to exercise due to breathing difficulties may also be apparent. Listening to the lungs with a stethoscope may reveal abnormal breathing sounds, a diagnostic process known as auscultation. Symptoms may include short rough snapping sounds known as crackles, and whistling sounds known as wheezes.


Causes of bacterial infection in the lungs may vary -- with no single bacterium being thought of as responsible for this condition. In dogs, the bacterial organisms Bordetella bronchiseptica and Streptococcus zooepidemicus are the primary bacterial causes of pneumonia. Additional types of bacteria, as well as anaerobic bacteria - which are capable of living and growing in the absence of oxygen, may also be to blame.

Some risk factors that may increase the risk of bacterial pneumonia include a pre-existing viral infection, difficulty swallowing, metabolic disorders, and regurgitation.


Bacterial pneumonia is just one cause of pulmonary dysfunction. Additional causes may include aspiration pneumonia, in which the lungs become inflamed due to inhalation of material, such as a foreign body, or vomit. The symptoms of bacterial and aspiration pneumonia may be similar, and diagnosis must properly determine between them in cases of pulmonary dysfunction.

If bacterial pneumonia is suspected, there are a number of diagnostic procedures that may be used for your dog. A tracheal wash may be performed to gather some of the material (fluids and cells) that lines the trachea for analysis. Because the bacteria cannot always be seen via microscope, any specimens taken should be cultured for further examination. Other tests may include visual imaging, specifically X-rays of the chest and lungs. Blood analysis, and urine analysis tests will also be conducted.


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