ARDS in the dog: diagnostic criteria and causes
8-year-old Miniature Schnauzer hospitalised with severe necrotising pancreatitis. At 48 hours it develops marked tachypnoea and hypoxaemia with a PaO2/FiO2 ratio of 150. Radiographs show diffuse bilateral alveolar infiltrates; the left atrium is normal on echocardiography.
What is the most likely diagnosis?
chevron_right Show answer and explanation
A. Acute respiratory distress syndrome (ARDS)
Correct. It meets the criteria: acute onset (< 72 h), a systemic inflammatory risk factor, bilateral infiltrates, no evidence of raised hydrostatic pressure (normal left atrium) and hypoxaemia with P/F ≤ 200.
B. Cardiogenic pulmonary oedema
Cardiogenic oedema in the dog requires raised left atrial pressure, and the atrium is usually dilated; here it is normal.
C. Aspiration pneumonia
It usually causes an alveolar pattern in dependent lobes (cranioventral or right middle lobe), not diffuse bilateral infiltrates; aspiration is also a cause of ARDS and may coexist.
D. Pulmonary thromboembolism
It is a differential in patients with systemic inflammation, but typically causes hypoxaemia with normal or unremarkable radiographs, not diffuse bilateral alveolar infiltrates.
lightbulb Key takeaway
Causes of ARDS: sepsis, pancreatitis, severe trauma, aspiration, massive transfusion, smoke inhalation and near-drowning. Treatment is supportive (oxygen, protective ventilation with low volumes and PEEP) plus treating the cause; the prognosis is guarded.
References: Dorothy Russell Havemeyer Working Group: VetALI/VetARDS veterinary definitions (2007)
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.