Pulmonary fibrosis in dogs: symptoms, tests and treatment

Overview

Idiopathic pulmonary fibrosis is a chronic, progressive disease of the tissue between the lung's air sacs. Canine idiopathic pulmonary fibrosis is abbreviated to CIPF. Connective tissue accumulates particularly in the walls of the air sacs. The disease can eventually lead to respiratory failure.

Not all diseases that cause lung scarring in dogs are the same condition. In other breeds especially, the cause of fibrosing lung disease needs separate investigation. Other lung and heart diseases can cause similar symptoms even in Westies. There is no known cure for the idiopathic form.

An owner questionnaire conducted in 2018 collected information on 542 Westies. Of these, 29.7% were classified as having pulmonary fibrosis based on owners' reports. This is not a prevalence measured across the whole breed population.

Causes

Fibrosis is a repair response following tissue damage. In the idiopathic form, the original trigger is unknown. Collagen and other extracellular material accumulate abnormally within the normal lung architecture. This alters the structure of the lung tissue.

Damage to the cells lining the air sacs and abnormal healing are key mechanisms under investigation. The tissue contains collagen-producing fibroblasts and myofibroblasts. In Westies, scarring may be both uniform and more pronounced in some areas. The canine disease does not share all the tissue features of human idiopathic pulmonary fibrosis.

A combination of inherited susceptibility and environmental factors is suspected. Microaspiration, where small amounts of stomach contents enter the airways, is one possible predisposing factor. No association with canine herpesvirus infection has been demonstrated. Fibrosis caused by a known injury is distinguished from disease of unknown cause.

Risk factors

The most commonly affected breed is the West Highland White Terrier. Other breeds can be affected, but their fibrosing lung disease may differ. Median age at diagnosis ranges from eight to 13 years across patient groups. The disease has also been diagnosed in Westies as young as three.

No clear difference in susceptibility between males and females has been found. In a survey published in 2026, median age at diagnosis was 11.6 years. The middle half of diagnosis ages fell between 9.1 and 13.3 years. Having an affected close relative was associated with a greater likelihood of disease.

Not all older Westies develop apparent pulmonary fibrosis. A questionnaire-based comparison found no statistically significant association between passive smoking and CIPF.

Typical symptoms

Typical signs you may notice at home include:

• A persistent dry cough.

• Reduced exercise tolerance and tiring on walks.

• Faster breathing than usual.

• Breathing with strong use of the abdominal muscles.

• Breathlessness or difficulty breathing comfortably at rest.

• In severe disease, bluish mucous membranes or fainting.

Symptoms usually develop slowly, and the dog may initially seem normal. Symptoms have often been present for 8–13 months before diagnosis. Not every affected dog coughs. A dog can appear bright even when blood oxygen levels are already low.

In the owner survey, coughing was reported in 117 of 148 dogs with symptom descriptions, or 79%. Breathlessness was reported in 80 of 148 dogs, or 54%. Reduced exercise tolerance was reported in 68 of 148, or 45.9%. Fainting was reported in 16 of 148, or 10.8%.

In the same survey, bluish mucous membranes were reported in seven of 148 dogs, or 4.7%.

Complications and consequences

Reduced oxygen transfer in the lungs can lead to chronic oxygen deficiency. Pulmonary hypertension is a common additional problem. Echocardiographic findings consistent with it have been found in around 20–60% of affected Westies. Its symptoms can resemble those caused by fibrosis itself.

Respiratory function can deteriorate suddenly even during slowly progressive disease. Bacterial pneumonia is one possible cause of sudden deterioration. If no other cause is found, this may be an acute exacerbation of fibrosis. The outlook for such an exacerbation is poor.

In long-term follow-up, median survival from diagnosis was 11 months, ranging from zero to 40 months. Median survival from the first symptoms was 32 months, ranging from two to 51 months. In the 2026 survey, median survival from diagnosis in 153 affected dogs was 1.0 years. The middle half of survival times in this group fell between 0.32 and 2.0 years.

Of the survey's 153 patients, 84, or 54.9%, had died by the time of the response. Fifty-five dogs, or 36%, were alive. Outcomes were missing for 14 dogs, or 9.1%. Of the 84 deaths, 65, or 77.4%, were attributed to pulmonary fibrosis.

Diagnosis at the vet

Symptoms and breathing sounds guide investigations

Diagnosis draws together the history, clinical examination and imaging. Other respiratory diseases are excluded at the same time. Crackles resembling the sound of Velcro being pulled apart may be heard over the lungs. These can be difficult to hear in a dog breathing shallowly.

Crackles are not unique to pulmonary fibrosis. In the survey, abnormal crackles were reported in 120 of 138 dogs, or 87%. Routine blood count and biochemistry results may be normal. These tests look for other causes of reduced exercise tolerance.

CIPF itself does not usually increase CRP. Faecal samples may be examined to exclude lung parasites. Echocardiography assesses concurrent pulmonary hypertension.

CT shows structure; blood gases assess oxygen transfer

X-rays may show increased lung tissue density, but this is not specific to fibrosis. They also look for other diseases, such as lung tumours. High-resolution computed tomography, or HRCT, shows lung tissue changes better than X-rays. A common CT finding is a ground-glass appearance in the lungs.

CT can also show a mosaic pattern of increased density. Traction bronchiectasis and honeycomb changes occur less often. X-ray changes do not reliably reflect disease progression. Arterial blood gas analysis measures lung function and the severity of impaired oxygenation.

Repeated blood gas measurements can monitor changes in oxygenation. Standard oxygen saturation measurement can give misleading results in an awake Westie. The vet may use a six-minute walk test to monitor exercise tolerance. The walk test does not confirm fibrosis.

In a comparison, affected Westies walked a median distance of 398 metres, ranging from 273 to 519 metres. Healthy older Westies walked a median of 492 metres, ranging from 420 to 568 metres. The result is interpreted as a measure of function alongside other investigations.

The benefits of sampling are weighed against procedural risks

Bronchoscopy and a lavage sample may be needed to investigate another disease or infection. Bronchoscopy requires general anaesthesia. The patient's general condition and severity of oxygen deficiency affect procedural safety. Inflammatory changes in lavage fluid are not specific to fibrosis.

A definitive tissue diagnosis comes from histological examination of lung tissue. However, lung biopsy is rarely performed in a living dog because it is invasive. Clinical information, imaging, laboratory tests and pathology are assessed together.

Treatment

Treatment eases symptoms and manages additional problems

There is no known treatment that reverses advanced lung scarring. Treatment aims to relieve respiratory symptoms and manage additional diseases. If a treatable cause of tissue damage is identified, it influences treatment choice. The vet plans medication according to the dog's findings.

A corticosteroid may reduce coughing in some dogs. However, a clear long-term improvement in arterial blood oxygenation has not been demonstrated with this treatment. Cough relief may reflect treatment of concurrent bronchial disease. Depending on the circumstances, a corticosteroid may be given orally or as an inhaled medicine.

Theophylline can be used for symptomatic treatment. It mildly dilates the bronchi. It may also promote mucus clearance from the airways. Its effects include increasing the diaphragm's ability to contract.

Concurrent pulmonary hypertension may be treated with medication that dilates the pulmonary blood vessels. Sildenafil is one medicine used for this purpose. Its selection is based on findings consistent with pulmonary hypertension. Treating pulmonary hypertension does not remove scarred lung tissue.

Pirfenidone and nintedanib are antifibrotic medicines used in humans. Information on pirfenidone's safety in canine CIPF is insufficient. Nintedanib has caused serious gastrointestinal adverse effects in canine toxicity studies. Research has not confirmed a benefit of cold laser therapy for canine pulmonary fibrosis.

Sudden worsening of breathing requires reassessment

During sudden deterioration, any bacterial pneumonia is treated as appropriate. Intermittent oxygen therapy may be suitable for some patients. A dog needing bronchoscopy may receive supplemental oxygen before, during and after the procedure.

Normal daily walks can continue within the dog's capabilities. Exercise is not continued through signs of exhaustion. Repeated measurements of oxygenation and function also help assess disease progression.

Prevention

There is no established practical way to prevent idiopathic pulmonary fibrosis. Regular grooming salon visits have been associated with a greater likelihood of CIPF being diagnosed. Exposure to inhaled grooming products is one possible explanation. Detangling sprays, fragrances, disinfectants and talc dust have been suspected as possible exposures.

Another explanation may be earlier recognition of respiratory symptoms at grooming salons. A home containing asbestos has been associated with a greater risk of death in affected dogs. A causal link between grooming visits or housing and fibrosis has not been established.

Important for dog owners

A healthy dog's usual breathing rate is around 12–30 breaths per minute. Breathing at rest is usually slower and deeper than during exercise. Take a dog with breathing difficulties to an emergency vet quickly and calmly. A cool car may ease breathing during the journey.

Record changes in resting breathing rate, the amount of coughing and how walks are going. Take a short video of abnormal breathing to show the vet. Also mention regurgitation, symptoms of other diseases and current medicines.

A dog can adapt to slowly developing oxygen deficiency and still appear reasonably well. A bright appearance alone therefore does not reliably reflect the lungs' ability to transfer oxygen. A sudden increase in symptoms may be caused by a treatable additional disease.

Agree monitoring goals with the vet and whom to contact if breathing worsens. Watch whether your dog can sleep, eat and move without constant distress. Assess quality of life through familiar everyday activities.

Frequently asked questions

Can pulmonary fibrosis occur without coughing?

Yes, not all affected dogs cough. Symptoms may include reduced exercise tolerance or faster breathing than usual. A dog can appear bright despite low blood oxygen levels. Diagnosis requires symptoms and investigation findings to be assessed together.

Do only Westies develop pulmonary fibrosis?

Idiopathic pulmonary fibrosis is diagnosed particularly often in West Highland White Terriers. Dogs of other breeds can also develop lung fibrosis. Their disease may not be the same as Westie CIPF. Any underlying cause of tissue damage influences treatment planning.

Can medication cure pulmonary fibrosis?

There is no established treatment that restores lungs scarred by end-stage disease to normal. However, medication can be used to try to reduce symptoms and manage additional problems. A corticosteroid may ease coughing in some dogs. Concurrent pulmonary hypertension can be addressed separately in treatment. Less coughing does not automatically mean better oxygenation.

Why is a CT scan suggested rather than just X-rays?

CT shows lung tissue changes in greater detail than ordinary X-rays. X-ray findings are not specific to fibrosis. Imaging is assessed alongside the history, examination findings and exclusion of other diseases. When needed, the vet assesses blood oxygenation through arterial blood gas analysis.

How long can a dog live after diagnosis?

In one long-term follow-up, median survival was 11 months from diagnosis. In the 2026 owner survey, the corresponding median for 153 affected dogs was 1.0 years. The course of disease in an individual dog is difficult to predict. The outlook for an acute exacerbation is usually poor.