Pneumonia (Interstitial) in Dogs

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Interstitial Pneumonia in Dogs

Pneumonia refers to an inflammation in the lungs, while interstitial pneumonia refers to a form of pneumonia in which the inflammation occurs in the walls of the alveoli (the air cells of the lungs), or in the interstitium (the spaces between the tissue cells of the alveoli). The alveoli are cellular components of the airway where oxygen and carbon dioxide are exchanged.

Interstitial pneumonia can occur in both cats and dogs, with some breeds being more susceptible than others. For example, the West Highland White Terrier and Bull Terrier are believed to be more susceptible to interstitial lung disease, which can lead to secondary interstitial pneumonia. Miniature Dachshunds are most susceptible to infection by Pneumocystis carinii, a parasite transitional between the stages of fungus and protozoa that causes the lung disease pneumocystosis.

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

Symptoms and Types


Symptoms vary depending on the severity of the disease. Some symptoms that may appear include rapid breathing (tachypnea), coughing, difficulty breathing (dyspnea), mild fever, and discharge from the eyes. Exposure to toxic elements, for example, may also result in gastrointestinal signs, such as vomiting, diarrhea, and a decreased amount of urine production.


There is a wide range of conditions that can lead to interstitial pneumonia in dogs. Bronchiolitis obliterans organizing pneumonia, a congenital (birth) defect, is characterized by inflamed airways and surrounding tissues, and increased odds of interstitial pneumonia.

Other causes include lung cancer, and metabolic disorders such as uremia, in which excess levels of urea and other nitrogenous waste products, which normally are excreted through the urine, appear in the blood.

Exposure to toxic elements through inhalation of dust, gas, or vapor, are also suspect in the diagnosis of causative factors.


There are a wide variety of diagnostic procedures that can be used if symptoms related to interstitial pneumonia appear, including a urine analysis, blood tests, x-ray imaging of the pleural cavity (the area between the chest wall and lungs), and an electrocardiography (ECG) test, used for measuring the electrical impulses of the heart, and for the detection of irregular heart rhythms related to increased pressure on the lungs.

Two more diagnostic procedures that are common when pneumonia is suspected are a tracheal wash, which involves a collection of the fluids and substances lining the trachea (the respiratory airway through which air is transported), and a bronchoscopy, by which a small tube with a tiny camera attached is inserted into the mouth and led into the bronchial airway so that a visual inspection can be made.

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