Pulmonary Fibrosis in Dogs

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A yellow lab getting his lungs checked by a veterinarian
Dr. Erica Irish author of pulmonary fibrosis in dogs

When your dog is having trouble breathing, it can be frightening, especially if you find yourself in a situation when your pup is experiencing acute respiratory distress. Almost overnight, you may notice your dog panting excessively, and he is unable to enjoy food and walks outside because he is simply unable to catch his breath!

If your pet is having trouble breathing, it is considered a medical emergency. Your vet will work to evaluate your dog’s heart and lungs because these are the two biggest systems responsible for the ability to breathe. 

There are numerous diseases that can causedyspnea (trouble breathing), but there are other disorders that may be considered less often. One such disorder is known as pulmonary fibrosis.


What is Pulmonary Fibrosis in Dogs?

The termpulmonary indicates the lungs, andfibrosisrefers to the thickening and scarring of connective tissue in certain disease processes. In pulmonary fibrosis, the lungs become thickened and stiff, making them physically unable to transfer oxygen into your dog’s blood vessels. This is a chronic and progressive disease that starts out mild but then worsens over time, making it difficult to recognize in the early stages.


Causes of Pulmonary Fibrosis in Dogs

There are various causes of pulmonary fibrosis in dogs and even in humans. Chronic inflammatory conditions gradually contribute to thickening and scarring of the lungs, and environmental factors such as cigarette smoke and dust can exacerbate it. There is also a genetic component in certain dog breeds:

  • West Highland White Terriers (Westies)
  • Jack Russell, Scottish, and Cairn Terriers
  • Yorkshire Terriers, Bichon Frise, and Shih Tzu dogs

Lung diseases such as pneumonia and chronic obstructive pulmonary disease (COPD, aka chronic bronchitis) can cause pulmonary fibrosis. Other lower airway diseases such as asthma can also cause chronic inflammation, and tracheal collapse, which is a symptom of brachycephalic syndrome in Pugs and English Bulldogs, is another contributor. The build-up of fluid in or around the lungs from congestive heart failure will eventually result in fibrotic lung tissue and contribute to end-stage respiratory failure.


Symptoms of Pulmonary Fibrosis in Dogs

Symptoms can appear subtle at first due to the amount of time it takes for scar tissue to form in the lungs. You may notice that your pup is panting a little more than normal, or it may seem like he has to exert abdominal effort in order to catch his breath.

Healthy dogs can return to normal respiratory rates quickly after exercise, but any dog who is breathing more than 60 breaths per minute while at rest should be evaluated by your veterinarian. For dogs who have heart disease, respiratory rates higher than 48 breaths per minute are a cause for concern.

Over time, your dog may avoid exercise altogether, and he will develop a cough. When they overexert themselves or find themselves in stressful situations, you may see his tongue start to turn a bluish or purplish color. This is calledcyanosis and it occurs because your dog’s red blood cells aren’t carrying enough oxygen. Dogs in this state can also faint or collapse, a condition known assyncope.

When your veterinarian listens to your dog’s lungs, she should hear clear lung sounds in all lung fields as your dog inhales and exhales. Dogs with pulmonary fibrosis will have harsh crackle sounds. Diagnostics such as blood work, x-rays, and heart ultrasound (echocardiogram) can help to rule out causes for this. In some situations, advanced diagnostics such as bronchoscopy, CT scan, and lung tissue biopsy will be necessary for a more definitive diagnosis.


Treatment

Unfortunately, there is no way to reverse pulmonary fibrosis once it has developed. Treatments are targeted at keeping your pup comfortable and helping to manage their airways. Anti-inflammatory drugs can help with pain and discomfort while bronchodilator medications such as theophylline can help to open up your dog’s airways. Cough suppressants can also provide some relief, and in cases of concurrent pulmonary hypertension, your vet may prescribe a phosphodiesterase-5 inhibitor like sildenafil.

Lung transplants are performed in human medicine but are not typically performed in veterinary medicine. Veterinary colleges like the University of Minnesota are working on genetic studies to find out more about why certain breeds are affected more than others. Once a dog has been diagnosed with pulmonary fibrosis, they have a life expectancy of two to eighteen months, perhaps a little longer in some cases where detection is early.


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Key Takeaways of Pulmonary Fibrosis in Dogs

Pulmonary fibrosis results in chronic scarring and thickening of your dog’s lungs. It can be tricky to diagnose in its early stages, and there is no way to prevent it entirely or to fully treat it. Therapy is focused on addressing underlying contributing factors such as lower airway disease and heart disease, and medications like cough suppressants, bronchodilators, and anti-inflammatories can provide some relief. If you suspect that your dog is having trouble breathing, this is considered a medical emergency, and you should contact your veterinarian for a same-day appointment.


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Meet The Author 

Dr. Erica Irish

Erica has worked in the veterinary field since 2006, starting out as a veterinary technician before graduating from the UF College of Veterinary Medicine in 2013. As a general practitioner in an animal hospital, she has many interests and is especially interested in dermatology, cardiology, internal and integrative medicine