CONDITION

Idiopathic Pulmonary Fibrosis in West Highland White Terriers

Idiopathic pulmonary fibrosis is a progressive condition in which the delicate tissue of the lungs becomes thickened and scarred over time, making it harder for oxygen to pass into the bloodstream. In West Highland White Terriers, this pattern appears more frequently than in other breeds, though the underlying trigger remains unknown. The scarring tends to be gradual and irreversible. Owners often notice a cough that persists over weeks or months, sometimes accompanied by faster breathing or reduced stamina during walks. The signs can be subtle at first and may be mistaken for other respiratory conditions. Some dogs show these changes in middle age, while others remain unaffected until later in life. This page explores what signs may be observed, what is understood about the changes occurring in the lung tissue, how the condition is investigated through imaging and other tests, and what approaches exist to manage symptoms and slow progression. The course varies between individuals, and the information here is intended to support understanding rather than predict what will happen in a particular dog.

Why this matters now

This condition tends to be recognised in older West Highland White Terriers, with age at diagnosis typically cited between eight and thirteen years, commonly ten years or more, though onset as early as two to three years has rarely been reported. The breed carries a much higher risk than others, suggesting a genetic component that has not yet been fully mapped. There is no clear link to environmental exposures, infection, or lifestyle, and many affected dogs have lived in varied circumstances.

The scarring accumulates slowly, often over months to years, and does not reverse. Some dogs show steady, gradual worsening of breathing effort and exercise tolerance, while others may plateau for a time before further decline. The rate of change varies widely between individuals, and it is not possible to predict the trajectory reliably from early findings alone.

Signals & patterns

Early signals

Persistent dry cough

A cough that continues for weeks without obvious cause, often described as harsh or hacking, and not typically productive of mucus. It may be more noticeable after excitement, exercise, or when the dog is resting at night.

Slightly faster breathing at rest

The breathing rate when the dog is calm may be a little higher than before, or the chest may appear to move more noticeably. This change can be subtle and may only become apparent when comparing the dog's behaviour over time.

Reduced stamina on walks

The dog may tire more quickly than usual, stop to rest more often, or choose shorter routes. The change is often gradual enough that it can be attributed to ageing or weather until it becomes more pronounced.

Occasional wheezing or crackling sounds

Fine crackling noises may be audible when listening closely to the chest, particularly after exertion. These sounds reflect stiffness in the lung tissue and the way air moves through scarred areas.

Later signals

Laboured breathing with minimal effort

The dog may breathe more rapidly or with visible effort even when lying down or moving around the house. The chest wall may show an exaggerated rise and fall, and the dog may adopt a posture that makes breathing easier, such as standing with the elbows out.

Bluish tinge to gums or tongue

In more advanced stages, the mucous membranes may take on a greyish or bluish colour, particularly after activity, reflecting reduced oxygen levels in the blood. This change is not always obvious in all lighting conditions.

Weight loss despite normal appetite

The increased effort of breathing can raise the body's energy demands, and some dogs lose condition even when eating well. Muscle mass over the spine and hips may become more prominent.

Click to read about the biological mechanisms

How this is usually investigated

Investigation usually begins with a history of when the breathing changes were first noticed and what patterns have emerged since, followed by a physical examination to listen to the lungs and assess breathing rate and effort. Because the signs can overlap with other respiratory conditions—heart disease, chronic bronchitis, infection—imaging and sometimes further tests are used to build a clearer picture. The approach tends to be stepwise, with each finding helping to narrow or widen the list of possibilities.

Physical examination

Purpose: Listening to the chest with a stethoscope often reveals crackles—short, dry sounds heard at the end of a breath—that occur when scarred lung tissue reopens during inhalation. Breathing rate and effort at rest can also be noted.
Considerations: Crackles are not unique to pulmonary fibrosis and can be heard in other lung conditions, including fluid accumulation or pneumonia. The examination provides clues but rarely confirms the diagnosis on its own.

Thoracic radiography

Purpose: Chest X-rays may show a pattern of increased density in the lower and central parts of the lungs, often described as a reticular or nodular appearance, which reflects the thickened, scarred tissue. The heart silhouette and larger airways can also be assessed to look for other contributing conditions.
Considerations: Early fibrosis can be subtle on radiographs, and mild changes may be overlooked or mistaken for ageing. The pattern is not always specific, so findings are interpreted alongside the history and examination.

High-resolution computed tomography

Purpose: CT scanning provides detailed cross-sectional images of the lung tissue and can reveal the distribution and extent of fibrosis with much greater clarity than radiographs. Characteristic patterns include ground-glass opacity, honeycombing, and traction bronchiectasis in the caudal lung lobes.
Considerations: The scan requires general anaesthesia in most dogs and is not available at all veterinary facilities. It is often considered when the diagnosis remains uncertain or when detailed mapping of the changes is needed.

Arterial blood gas analysis

Purpose: Measuring oxygen and carbon dioxide levels in a sample of arterial blood can show whether gas exchange is impaired, which tends to worsen as fibrosis progresses. A low oxygen level at rest or after mild exertion supports the presence of significant lung disease.
Considerations: The test requires a small arterial puncture, which some dogs tolerate without sedation and others do not. It reflects function at a single point in time and does not distinguish between different causes of impaired gas exchange.

Bronchoalveolar lavage and cytology

Purpose: Passing a flexible scope into the airways and washing a small volume of sterile fluid into a segment of lung, then retrieving it for analysis, can reveal inflammatory cells, infection, or abnormal tissue fragments. It is sometimes performed to rule out other conditions rather than to confirm fibrosis directly.
Considerations: The procedure requires general anaesthesia and carries a small risk of triggering coughing or transient worsening of breathing. Findings can be non-specific, and a normal lavage does not exclude fibrosis if it is present in areas not sampled.

Options & trade-offs

Management is directed at slowing the progression of scarring where possible, easing the work of breathing, and maintaining quality of life as the condition evolves. No single approach reverses the fibrosis, so strategies are usually combined and adjusted over time according to how the individual dog responds. What feels manageable varies between households, and the balance between intervention and observation shifts as signs change.

Corticosteroids

Drugs such as prednisolone are used to dampen the inflammatory and immune-driven components of the scarring process, with the aim of slowing further fibrosis. Doses are typically started at a moderate level and then adjusted downward to find the lowest amount that appears to stabilise signs. Some dogs show a reduction in coughing or breathing effort within weeks, while others show little change.

Trade-offs: Long-term use can lead to increased thirst, urination, appetite, and weight gain, as well as a higher risk of infections or other steroid-related effects. The benefits in pulmonary fibrosis are variable, and not all dogs tolerate the side effects well enough to continue.

Immunosuppressive drugs

Medications such as azathioprine or ciclosporin may be used alongside or instead of corticosteroids to target the immune pathways thought to drive fibrosis. The intention is to reduce the overactive repair response without relying solely on steroids. Response is unpredictable, and some dogs stabilise while others continue to decline.

Trade-offs: These drugs require regular blood monitoring to watch for bone marrow suppression, liver changes, or other adverse effects. Cost can be a consideration, and the time to see any benefit may be several weeks or longer.

Antifibrotic agents

Pirfenidone is a drug used in human idiopathic pulmonary fibrosis to slow the deposition of scar tissue, and it has been explored in dogs with this condition. The mechanism is not fully understood but appears to involve modulation of the signals that promote collagen production. Evidence in dogs is limited, and availability varies.

Trade-offs: The drug is not licensed for veterinary use in many regions and may need to be sourced through human pharmacies, which affects cost and accessibility. Gastrointestinal upset and sun sensitivity have been reported in people, though data in dogs is sparse.

Oxygen supplementation

Providing oxygen-enriched air through a mask, nasal prongs, or an oxygen cage can ease breathing effort and improve oxygen levels in dogs whose fibrosis has progressed to the point where resting oxygen saturation is low. It is used intermittently at home in some cases or continuously in others.

Trade-offs: Home oxygen systems require equipment rental or purchase, space for a concentrator or cylinder, and a dog willing to tolerate the delivery method. The benefit is symptomatic rather than disease-modifying, and not all owners find it practical in the long term.

Environmental and activity adjustments

Reducing exposure to airborne irritants such as smoke, dust, aerosols, or strong cleaning products may lessen airway irritation and coughing. Moderating exercise to a level the dog can sustain without laboured breathing, and avoiding heat or humidity that increases respiratory effort, can improve day-to-day comfort.

Trade-offs: These changes are generally low-risk and low-cost, but their impact on disease progression is uncertain. Some dogs show clearer improvement than others, and the approach depends on the owner's ability to control the home environment.

Common misconceptions

Misconception:

"A persistent cough in a Westie is usually just a sign of old age or a minor irritation that will pass on its own."

Reality:

While many older dogs develop a cough for benign reasons, a cough that persists for weeks or is accompanied by faster breathing or reduced exercise tolerance in a West Highland White Terrier warrants investigation. The breed's predisposition to pulmonary fibrosis means that chronic respiratory signs can reflect progressive lung changes rather than a self-limiting problem.

Misconception:

"If imaging shows fibrosis, there is nothing that can be done and the decline will be rapid in all cases."

Reality:

The rate of progression varies widely between individuals, and some dogs remain stable for months or even years with or without treatment. Management strategies exist that may slow scarring, ease symptoms, and maintain quality of life, though responses differ and no approach guarantees a particular outcome.

Misconception:

"Pulmonary fibrosis in Westies is caused by exposure to something in the home environment, such as cleaning products or air fresheners."

Reality:

The condition is termed idiopathic because no consistent environmental, infectious, or lifestyle trigger has been identified, despite affected dogs living in widely varied settings. The higher incidence in the breed points toward a genetic predisposition rather than an external cause that owners could have avoided.

Related conditions

Chronic Bronchitis in Dogs

Chronic bronchitis in dogs shares the pattern of persistent airway inflammation and coughing, though the underlying process differs—bronchitis involves the larger airways rather than the deeper lung tissue. In some cases, distinguishing between the two may require imaging or more detailed investigation.

Pulmonary Hypertension

Pulmonary hypertension can develop as a consequence of progressive lung scarring, as the thickened tissue and reduced oxygen exchange place increased strain on the blood vessels supplying the lungs. This added pressure may, over time, begin to affect the right side of the heart.

Eosinophilic Bronchopneumopathy

Eosinophilic bronchopneumopathy can present with similar signs—cough, increased breathing effort, and changes visible on imaging—though the underlying cause involves immune cell accumulation rather than progressive scarring. Distinguishing between the two often requires examination of cells or tissue from the airways or lungs.

Congestive Heart Failure in Dogs

Congestive heart failure may develop in dogs with advanced pulmonary fibrosis if the ongoing strain on the pulmonary circulation and right heart becomes sufficient to impair the heart's ability to move blood efficiently. Both conditions can present with coughing and reduced exercise tolerance, though the underlying drivers differ.

Aspiration Pneumonia

Aspiration pneumonia can occasionally be considered in the differential when investigating a persistent cough and abnormal lung imaging, particularly if there is a history of regurgitation or difficulty swallowing. The pattern of inflammation differs, and aspiration typically has a more acute onset.

Understanding how pulmonary fibrosis may progress in an individual dog can involve periodic reassessment of breathing patterns, exercise tolerance, and oxygen levels over time. The broader context of metabolic health in older dogs, including how the heart responds to changes in lung function and how appetite and weight may shift with treatment, can inform the adjustments made along the way. Conversations at routine appointments about what signs feel manageable and what might prompt a change in approach can help shape the course ahead.