Cardiac screening of breeding dogs: subaortic stenosis
A Newfoundland breeder wants to certify future breeding dogs as free of subaortic stenosis.
Which statement about screening is correct?
chevron_right Show answer and explanation
A. A puppy without a murmur at 8 weeks can be considered free of subaortic stenosis
The subaortic lesion is often absent or minimal at birth and progresses during the first months. Many affected dogs have no murmur at their first vaccination.
B. Definitive screening is done from 12 months of age, with auscultation by a cardiologist and Doppler echocardiography if there is a murmur or doubtful results
Correct. Subaortic obstruction can develop or worsen during growth, so an examination in a puppy is not definitive. A cardiologist detects soft murmurs that are easily missed, and Doppler measures aortic velocity and resolves equivocal cases.
C. A dog with mild, asymptomatic subaortic stenosis can be used for breeding without concern
Subaortic stenosis is inherited. Even if the dog has a good prognosis, it can pass it on, and its offspring may develop severe forms. Affected dogs should not be bred.
D. M-mode echocardiography is sufficient, without the need for Doppler
M-mode measures thicknesses and dimensions, but mild forms do not cause obvious hypertrophy. Diagnosis relies on aortic flow velocity measured with continuous-wave Doppler.
lightbulb Key takeaway
In predisposed breeds (Newfoundland, Golden Retriever, Rottweiler, Boxer), screening programmes combine auscultation by a cardiologist and Doppler echocardiography in the young adult. There is a grey zone of aortic velocity (around 2.0–2.4 m/s) where the diagnosis is equivocal: also look for a subvalvular ridge, turbulence and aortic regurgitation. Measure with the dog calm and unsedated.
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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.