What is canine pneumonia?
Pneumonia is inflammation of the lung parenchyma (alveoli and interstitial tissue), usually caused by infection. Unlike bronchitis or a cold, pneumonia compromises gas exchange, which can lead to hypoxaemia (low blood oxygen) and rapid deterioration.
In dogs, pneumonia can be bacterial, viral, fungal, parasitic or caused by aspiration. Bacterial pneumonia is the most common form.
Most common causes
Bacterial pneumonia
The most frequent pathogens are Bordetella bronchiseptica, Streptococcus, Pasteurella, Escherichia coli and Klebsiella. Often the bacterial infection develops as a complication of a prior viral infection (distemper, parainfluenza) that weakened the respiratory tract's defences.
Aspiration pneumonia
Occurs when a dog inhales gastric contents (vomit or regurgitation), food or liquid into the lungs. Common in dogs with megaoesophagus, dysphagia or those given oral medication while poorly positioned. The acidic content directly damages lung tissue and promotes secondary bacterial infection.
Viral pneumonia
Canine distemper virus and adenovirus can directly cause pneumonia, usually complicated by secondary bacterial infection.
Fungal pneumonia
Aspergillus, Cryptococcus, Coccidioides or Blastomyces can infect the lungs in immunosuppressed dogs or in specific geographic areas. Less common than bacterial pneumonia but more complex to treat.
Symptoms: red flags
- Wet, productive or persistent cough (different from the dry cough of tracheobronchitis).
- Rapid breathing (tachypnoea) or visibly laboured breathing — exaggerated chest and abdominal movement.
- Orthopnoeic posture: dog stretches neck forward to ease breathing.
- Blue or greyish gums: sign of severe hypoxaemia. Immediate emergency.
- Fever (rectal temperature above 39.5 °C / 103.1 °F).
- Severe lethargy, weakness.
- Loss of appetite.
- Purulent or blood-tinged nasal discharge.
If your dog shows visible breathing difficulty at rest, take them to an emergency vet immediately.
Diagnosis
Chest X-ray: the key investigation. Pneumonia produces infiltrates or consolidations in the lung visible on imaging. Indicates extent and location.
Blood tests: complete blood count for leucocytosis (bacterial) or leucopaenia (viral/fungal). Blood chemistry to assess overall status.
Bronchoalveolar lavage (BAL): lung fluid sample for culture and cytology. Identifies the causative agent and antibiotic sensitivity.
Pulse oximetry: measures blood oxygen saturation. Values below 95% indicate hypoxaemia and the need for supplemental oxygen.
Treatment
Antibiotic therapy
The cornerstone of bacterial pneumonia treatment. Usually started with broad-spectrum antibiotics (amoxicillin-clavulanate, doxycycline or fluoroquinolones) while awaiting culture results — then adjusted by sensitivity. The full course must be completed (minimum 3–4 weeks) even if the dog appears to have recovered.
Oxygen therapy
In hypoxaemic cases, supplemental oxygen is needed (oxygen cage, mask or nasal catheter). Severe cases may require mechanical ventilation.
Fluid therapy and supportive care
To maintain hydration, support the respiratory mucosa and reduce fever. Nebulisation with saline can help liquefy secretions.
Respiratory physiotherapy (coupage)
Gentle percussion on the chest wall 3–4 times daily to mobilise secretions and help expel them. Can be taught to owners for home care.
Home care during recovery
- Warm environment, free from draughts, with adequate humidity.
- Complete rest for the first weeks — no exercise until the vet clears it.
- Palatable, soft food if appetite is low.
- Always complete the full antibiotic course.
- Follow-up chest X-ray at 2–4 weeks to confirm resolution.
Prevention
- Keep Bordetella (kennel cough) and distemper vaccinations up to date.
- Avoid contact with sick dogs in parks and kennels.
- For dogs with megaoesophagus: always raise the food bowl and keep the dog upright for 10–15 minutes after eating.
- Never give oral medication to a heavily sedated or unconscious dog.