Pulmonary Fibrosis in Dogs: Signs, Diagnosis & Care

Understanding Pulmonary Fibrosis in Dogs

Pulmonary fibrosis (PF) is a progressive, irreversible scarring of the lung tissue that makes the lungs stiff and hampers oxygen transfer. In dogs the condition is often idiopathic—no clear cause can be identified—but it follows a predictable pattern of gradual decline.

Which Dogs Are Most at Risk?

PF most commonly affects older small‑to‑medium dogs, with a striking predisposition for terrier breeds, especially West Highland White Terriers (WHWTs). These dogs are often overweight and may have concurrent chronic bronchitis, which can mask early signs of lung scarring.

Early and Late Clinical Signs to Watch For

Subtle early clues

• Exercise intolerance – lagging on walks or tiring quickly.
• Increased resting respiratory rate (tachypnea) that seems “normal” for the dog.
• Shortness of breath that becomes more obvious during excitement, heat, or after mild exertion.
• A dry, non‑productive cough that may be very mild or absent.

Signs that indicate progression

• Open‑mouth breathing or panting at rest.
• Visible “Velcro‑like” crackles on lung auscultation (often ventrally).
• Cyanotic gums or tongue during activity—an emergency sign of low blood oxygen.
• Lethargy, weakness, reduced appetite, and weight loss.

How Pulmonary Fibrosis Is Diagnosed

Diagnosis is a multi‑step process that combines history, physical exam, and advanced imaging.

1. History and Physical Examination

Veterinarians look for a chronic, slowly worsening pattern of breathing difficulty and listen for the characteristic crackles.

2. Thoracic Radiographs (Chest X‑rays)

Baseline X‑rays typically reveal a diffuse interstitial pattern with increased lung density, helping to rule out focal pneumonia or masses.

3. High‑Resolution Computed Tomography (HR‑CT)

HR‑CT is the gold‑standard imaging tool, showing:

• Ground‑glass opacities
• Traction bronchiectasis
• Honeycombing in advanced disease

4. Oxygenation Testing

Arterial blood gases or pulse oximetry demonstrate impaired oxygen exchange and help gauge disease severity.

5. Bronchoscopy & Bronchoalveolar Lavage (BAL)

These procedures are used primarily to exclude infections, chronic bronchitis, or neoplasia.

6. Lung Biopsy (When Feasible)

Histopathology is the only definitive test, but because anesthesia risk is high in compromised lungs, many clinicians rely on a presumptive diagnosis based on imaging and exclusion of other conditions.

7. Cardiac Evaluation

Echocardiography is essential to rule out primary heart disease and to detect pulmonary hypertension (PHT), which occurs in up to 40 % of dogs with idiopathic PF.

Key Differentials to Exclude

• Congestive heart failure (pulmonary edema)
• Chronic bronchitis
• Pneumonia or other infectious respiratory disease
• Heartworm disease
• Pulmonary neoplasia
• Pulmonary thromboembolism
• Parasitic lung disease or eosinophilic pneumonia

Prognosis and Natural Course

PF is incurable and inevitably progressive. Median survival after diagnosis in WHWTs is typically 12–18 months, although some dogs remain stable for several months with appropriate care. The rate of decline varies widely, making individualized monitoring crucial.

Medical Management: What Can Help

Core Supportive Strategies

• Supplemental oxygen during crises or in advanced disease—via cage, nasal cannula, or home concentrator.
• Sildenafil for pulmonary hypertension to improve exercise tolerance.
• Bronchodilators (e.g., theophylline) when concurrent airway disease is present.
• Corticosteroids—used cautiously; they may help an inflammatory component but do not reverse scarring.
• Antibiotics only if a secondary infection is documented.
• Cough suppressants for distressing non‑productive coughs, used judiciously.
• Weight management—maintain a lean body condition to reduce respiratory workload.

Investigational Approaches

Human antifibrotic drugs (pirfenidone, nintedanib) are not yet standard in veterinary medicine; any use would be experimental and specialist‑guided.

At‑Home Management to Maximize Quality of Life

Environmental Adjustments

• Keep the home cool, well‑ventilated, and low in humidity.
• Avoid smoke, aerosols, strong cleaners, dust, and scented candles.
• Minimize stairs and jumping to reduce exertion spikes.

Exercise & Activity

• Replace long walks with short, frequent outings at the dog’s own pace.
• Consider stroller‑assisted walks or sniff walks for severely limited dogs.
• Stop activity immediately if breathing effort spikes, gums turn blue, or the dog refuses to move.

Nutrition & Weight

• Provide a highly palatable, energy‑dense diet; feed small, frequent meals if appetite wanes.
• Aim for a lean but not underweight body condition to lower oxygen demand.

Monitoring at Home

Track the resting respiratory rate (RRR) while the dog is asleep or very relaxed. A consistent rise above the baseline (or >30–35 breaths/min at rest) warrants veterinary re‑evaluation. Also watch for new cough, increased panting, collapse, or reduced interest in food and play.

Stress Management

Excitement raises oxygen consumption. Maintain predictable routines, provide a quiet safe space, and discuss mild anxiolytics with your vet for situations like car rides or clinic visits.

Working With Your Veterinary Team

Optimal care is a partnership:

• General practitioner – coordinates day‑to‑day treatment, monitors progression, adjusts medications.
• Internal medicine specialist or cardiologist – performs advanced diagnostics (HR‑CT, bronchoscopy, echocardiography) and manages pulmonary hypertension.

Typical follow‑up includes re‑checks every 3–6 months, repeat imaging as needed, and periodic echocardiography if PHT is present.

Planning for End‑Stage Disease and Humane Endpoints

When breathing difficulty occurs at rest despite oxygen and medication, or when cyanotic episodes become frequent, quality of life may be compromised. Discuss in advance with your vet:

• When to initiate home oxygen therapy.
• Use of palliative drugs (e.g., low‑dose opioids) to ease “air hunger.”
• Specific signs that will prompt a decision for euthanasia to prevent prolonged suffering.

Key Takeaways for Dog Owners

• PF is a chronic, progressive lung‑scarring disease, especially common in older terriers and WHWTs.
• Early recognition of subtle signs—exercise intolerance, faster resting breathing, a dry cough—can give more time for supportive care.
• Diagnosis relies on a combination of history, chest X‑rays, high‑resolution CT, oxygen testing, and exclusion of other diseases; lung biopsy is definitive but rarely required.
• No cure exists; treatment focuses on symptom relief, managing pulmonary hypertension, and maintaining comfort.
• Thoughtful home management—environment control, gentle activity, weight optimization, and vigilant monitoring—significantly improves day‑to‑day quality of life.
• Regular communication with a veterinary team helps tailor therapy, track progression, and plan humane end‑of‑life care when needed.