Cough in dogs with MMVD: oedema or bronchial compression?
12-year-old Chihuahua with stage B2 MMVD on pimobendan. For two months it has had a dry 'honking' cough, especially when excited or pulling on the lead. Resting respiratory rate at home: 20–24 breaths/min. Radiographs: large left atrium elevating and compressing the left main bronchus; lung parenchyma without infiltrates and normal pulmonary veins.
What is the most appropriate management?
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A. Start furosemide because the cough indicates congestive heart failure
Without radiographic oedema and with a normal resting respiratory rate there is no congestion: the dog is still stage B2. Giving diuretics without congestion only adds adverse effects.
B. Double the pimobendan dose to reduce atrial size
Increasing pimobendan is not indicated in stage B2 and does not predictably resolve bronchial compression. The standard dose is already the recommended one.
C. Start an ACE inhibitor, which improves the cough by reducing congestion
There is no congestion to reduce. Moreover, this dog's cough is mechanical and airway-related, not something the ACE inhibitor will resolve.
D. Treat it as an airway cough (bronchial compression ± bronchomalacia): an antitussive such as butorphanol, weight control and a harness instead of a collar
Correct. A cough with a normal respiratory rate and clear lungs is due to compression of the left main bronchus by the dilated atrium, often with bronchomalacia or tracheal collapse. It is managed with antitussives and airway measures, considering bronchoscopy or anti-inflammatory treatment if it does not improve.
lightbulb Key takeaway
Resting respiratory rate is the best tool to distinguish airway cough from oedema: with oedema it usually exceeds 30–40 breaths/min, and the cough comes with tachypnoea and rapid deterioration. If in doubt, radiographs or NT-proBNP help. Remember that cats with heart failure almost never cough.
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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.