Pneumonia (Interstitial) in Dogs

Interstitial pneumonia is a serious lung disease similar to the pulmonary fibrosis that people get, and older West Highland White Terriers are the most often infected. In this disease, the lung tissue is replaced by scar tissue leaving the lungs with reduced ability to breathe properly. The cause of interstitial pneumonia is not known, but some experts believe that it is preceded by an injury to the lungs that did not heal properly. The scarring of the lungs from previous injury or illness makes the lungs less pliable and unable to function properly. Just like a scar that you get on your skin, the scar tissue is not as soft and flexible. Since pulmonary fibrosis is hereditary in people, some veterinary professionals think the same may be true for dogs. Unfortunately, this disease is almost always fatal within less than two years because there is no medication to do anything but treat the symptoms.

Interstitial pneumonia includes a group of pulmonary diseases that include the alveolar septa (the wall separating the oxygen sacs in the lung). One of the most common varieties of this disease is idiopathic pulmonary fibrosis, which is an incurable lung disease that affects the terrier more than any other breed, especially middle-aged West Highland White Terrier, but any breed of dog can contract interstitial pneumonia.

The symptoms of interstitial pneumonia depend on how far the disease has progressed. In the beginning of the illness, your dog may show no signs except for being tired and maybe depressed for several months before the infection really takes hold and spreads to the rest of the lungs. This disease commonly affects older dogs, so the symptoms may be ignored because they are thinking it is just old age. However, if your dog starts acting different in any way at any age, you should consult your veterinarian just to be sure because the sooner you start treatment, the better the chances of success.

• Fever
• Fast breathing
• Wheezing
• Coughing
• Shortness of breath
• Weight loss
• Depression
• Blue tint to skin and mucous membranes (mouth, eyelids, stomach)
• Inability to exercise for the regular amount of time
• Coughing up blood
• Runny nose and eyes

Although there is no real proven cause of interstitial pneumonia, some experts have their own ideas of where the disease came from. Some of these are:

• Hereditary (i.e. West Highland White Terrier, Cairn Terrier, Jack Russell Terrier)
• Exposure to toxic vapor, gas, or dust
• Reaction to certain medications
• Lung cancer
• Canine distemper virus
• Uremia

During the physical examination the veterinarian will usually find loud crackling in the lungs, fast (but weak) heartbeat, coughing, malaise, a fever, and possibly a heart murmur. Let the veterinarian know your dog’s history of previous ailments and injuries, vaccination records, symptoms you have noticed, and when the symptoms started. The veterinarian will check your dog’s weight, blood pressure, and heart rate.

The veterinarian will do some tests to rule out any other disorders and get a definite diagnosis. First, some of the basic tests will be done, such as urinalysis, fungal culture, complete blood count (CBC), blood chemical panel, and blood gas profile. Some of the most common tests for interstitial pneumonia are radiographs (x-rays) of the chest, bronchoscopy, bronchial lavage, echocardiograph (ECG), high resolution thoracic CT scan, and lung biopsy.

The treatment for interstitial pneumonia is mostly just supportive care because there is no medicine to cure the disease. Some of the medications your veterinarian may use to alleviate the symptoms are corticosteroids (i.e. prednisone), antibiotics, diuretics (i.e. hydrochlorothiazide to reduce fluid build-up, hormone therapy (i.e. sildenafil), and bronchodilators (i.e. theophylline). If your dog has a severe case of interstitial pneumonia and respiratory distress, the veterinarian will want to put him in the hospital to give oxygen therapy and an antimicrobial medicine (clindamycin) to reduce the chance of a bacterial infection.

Even with treatment, many dogs with interstitial pneumonia do not survive this disease because there is no cure. The average length of time of survival in a dog diagnosed with this disease is only 16-18 months. The sooner the treatment begins, the better the outcome, but this disease is usually fatal within two years even in a healthy dog. For an older dog or a dog with a compromised immune system, the time of survival is less than one year. For the best chance of survival for your pet, you should be sure to follow your veterinarian’s instructions and give your dog the medication as prescribed. It is also essential that you bring your dog back for a follow-up examination and continue visiting the veterinarian as directed.