Your older dog has developed a cough that just won't go away. Or he's lost weight without trying, or seems to run out of breath faster on walks than he used to. These signs are easy to write off as "just getting old" but sometimes they point to something growing in the lungs or airways.

Key Takeaways

• The respiratory system can host several types of tumours — in the nose and sinuses, the larynx and trachea, and the lungs themselves.
• Primary lung tumours (starting in the lung) are rare in dogs, but tumours that spread to the lungs from elsewhere in the body are much more common.
• Most primary lung tumours are diagnosed in dogs around 10 to 12 years old, and over 80% turn out to be malignant.
• A chronic cough, weight loss, lethargy, and laboured breathing are the most common signs — but 25% of dogs with a lung tumour show no signs at all.
• Diagnosis relies on chest X-rays and a tissue biopsy for a definitive answer; CT scans can catch tumours too small to see on X-ray.
• Treatment and outlook depend heavily on tumour type, location, and whether it has spread — early detection makes a real difference.

Tumours of the Nose and Sinuses

Nasal and sinus tumours account for about 1 to 2% of all canine tumours, slightly more common in older, male dogs, with an average diagnosis age of 9.5 to 10 years. According to the Merck Veterinary Manual, virtually all of these are malignant in dogs. Long-nosed and medium-nosed breeds appear to carry higher risk than short-nosed (brachycephalic) breeds. These tumours tend to invade surrounding tissue aggressively but are less likely to spread elsewhere in the body when they do, the lymph nodes, lungs, and brain are the most common sites.

Signs to watch for include chronic nasal discharge containing mucus, pus, or blood usually starting on one side before becoming two-sided along with sneezing, nosebleeds, or snoring. As the tumour grows, it can cause visible facial deformity, and if it extends behind the eyes, protruding eyeballs, excess tearing, or corneal inflammation. Left untreated, survival is typically only 3 to 5 months from diagnosis, which makes early treatment meaningful.

Diagnosis relies on nasal X-rays or, preferably, a CT scan, which shows nasal cavity detail far better than X-rays and helps distinguish a tumour from other causes of chronic discharge. A biopsy confirms the diagnosis. Treatment surgery, drug therapy, radiation, or some combination offers a better outlook the earlier it starts.

Tumours of the Larynx and Trachea

These are rare in dogs. The most common signs of laryngeal tumours include laboured breathing when inhaling or after exercise, high-pitched noisy breathing, a change in bark or loss of voice, and coughing. Tracheal tumours cause a similar picture coughing, laboured breathing, and noisy breathing with coughing up blood being uncommon. How laboured the breathing gets usually tracks with how much of the windpipe is obstructed.

Diagnosis often comes from history and exam findings, ruling out other causes of airway obstruction or coughing, and confirming with an endoscope view or X-rays plus biopsy. Surgical removal is the main treatment, with some tumour types also responding to radiation.

Primary Lung Tumours

Tumours that start in the lung itself are rare in dogs, though they've become more frequently diagnosed over the last 20 years likely reflecting longer lifespans, better detection, and possibly rising environmental exposure to cancer-causing agents. Most are diagnosed at an average age of 10 to 12, affecting all breeds and both sexes roughly equally. More than 80% of primary lung tumours in dogs are malignant, and they can spread to other parts of the lungs, lymph nodes, bones, and the brain.

Signs vary depending on the tumour's location, growth rate, and any existing lung disease. The most common are coughing, weight loss, lethargy, and laboured breathing. Other possible signs include poor appetite, reduced exercise tolerance, rapid breathing, wheezing, vomiting or regurgitation, fever, and lameness. Notably, about 25% of dogs show no signs related to the tumour at all it's sometimes found incidentally on X-rays taken for an unrelated reason.

Chest X-rays are the usual first step, but a definitive diagnosis needs a tissue biopsy. Surgery to remove the affected portion of lung is the recommended treatment in most cases; tumours that can't be operated on, or that have already spread, may be treated with chemotherapy. Outlook varies sharply by stage: a dog with a single tumour that hasn't spread to the lymph nodes has an average survival of about 12 months, while lymph node involvement or multiple tumours at diagnosis shortens that to around 2 months. Recurrence or spread remains the most common cause of death.

Metastatic Lung Tumours

A metastatic lung tumour originates somewhere else in the body and spreads to the lungs through the bloodstream, the lymph system, or direct extension from a nearby site. This is much more common than primary lung cancer in dogs. Signs mirror those of primary lung tumours, except coughing is less frequent. Severity depends on whether the spread is a single lesion or multiple, and on location.

Dogs with cancers known to commonly spread to the lungs should have chest X-rays done before surgery to check for metastasis though more than 40% of dogs with metastatic lung tumours have deposits too small to see on X-ray, which is where a CT scan can help. Because lung spread typically happens late in a malignant tumour's course, the outlook at this stage is generally poor. Chemotherapy or radiation may help for tumour types not well suited to surgery.

Recognising the Warning Signs Early

• A cough that persists for weeks without a clear cause
• Unexplained weight loss
• Lethargy or reduced interest in activity
• Laboured or rapid breathing, especially with mild exertion
• Reduced exercise tolerance
• Nosebleeds, chronic nasal discharge, or facial swelling
• A change in bark, voice, or noisy breathing

Because some of these signs coughing, lethargy, reduced energy overlap heavily with more common and less serious conditions, our guides on preventing and recognising coughing in dogs and preventing lethargy in dogs can help you decide what's routine and what warrants a closer look. If your senior dog's cough or energy level has changed and stayed changed for more than a week or two, that's the pattern worth a vet visit for, not just a single off day.

How Is a Lung or Airway Tumour Diagnosed?

• Chest X-rays — usually the first diagnostic step
• CT scan — better detail than X-rays, and can catch small tumours X-rays miss
• Endoscopy (laryngoscopy or tracheoscopy) — direct visualisation of the airway
• Biopsy — needed for a definitive diagnosis in almost every case

Diagnosis is often a staged process: your vet rules out infections, foreign bodies, and other causes of chronic cough or nasal discharge before confirming a tumour with tissue sampling.

What Does Treatment Involve?

Treatment is matched to the tumour's location, type, and how far it has spread. Surgery is the primary treatment for operable tumours, whether in the nose, larynx, trachea, or lung. Radiation therapy can help for certain tumour types, and chemotherapy is used when surgery isn't an option or the disease has already spread. Alongside definitive treatment, supportive care matters dogs losing weight or appetite may benefit from an easy-to-digest, calorie-dense recovery food such as Royal Canin Recovery Liquid, or an appetite and energy-support supplement like Polybion LC Syrup under your vet's direction. For dogs managing discomfort, a vet-prescribed NSAID such as Melonex may be part of a comfort-focused plan always dosed and monitored by your vet, since NSAID use requires careful case-by-case judgement.

Frequently Asked Questions

Are lung tumours in dogs always cancer?
Most are. In dogs, over 80% of primary lung tumours turn out to be malignant, and nose and sinus tumours are almost always malignant too. Benign tumours in these locations are the exception rather than the rule.

Can a dog have a lung tumour with no symptoms?
Yes about 25% of dogs with a primary lung tumour show no related signs at all, and the tumour is sometimes found incidentally when X-rays are taken for another reason. This is one reason routine senior wellness screening matters.

What's the difference between a primary and a metastatic lung tumour?
A primary lung tumour starts in the lung itself and is relatively rare in dogs. A metastatic lung tumour has spread to the lungs from cancer somewhere else in the body, and this is much more common than primary lung cancer overall.

How long can a dog live with a lung tumour?
It varies enormously by type and stage. A dog with a single primary lung tumour that hasn't reached the lymph nodes has an average survival of around 12 months after treatment; involvement of lymph nodes or multiple tumours shortens that considerably. Metastatic lung disease generally carries a more guarded outlook since it reflects cancer that has already spread.

Which dog breeds are most at risk of nasal tumours?
Long-nosed and medium-nosed breeds appear to be at higher risk than short-nosed (brachycephalic) breeds for tumours of the nose and sinuses.

References

1. Merck Veterinary Manual — Cancers and Tumors of the Lung and Airway in Dogs. https://www.merckvetmanual.com/dog-owners/lung-and-airway-disorders-of-dogs/cancers-and-tumors-of-the-lung-and-airway-in-dogs
2. Merck Veterinary Manual — Neoplasia of the Respiratory System in Dogs and Cats. https://www.merckvetmanual.com/respiratory-system/respiratory-diseases-of-small-animals/neoplasia-of-the-respiratory-system-in-dogs-and-cats
3. Merck Veterinary Manual — Introduction to Lung and Airway Disorders of Dogs. https://www.merckvetmanual.com/dog-owners/lung-and-airway-disorders-of-dogs/introduction-to-lung-and-airway-disorders-of-dogs