Stage A MMVD: the Cavalier King Charles with no murmur
Healthy 2-year-old Cavalier King Charles presenting for vaccination. Normal auscultation, no murmur. The owner asks whether to start some 'heart' treatment now, knowing the breed has mitral valve problems.
Which statement is correct according to the 2019 ACVIM consensus?
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A. It is stage A: no treatment; auscultation at least yearly and, if used for breeding, screening programmes
Correct. Stage A includes high-risk dogs (Cavaliers, Chihuahuas, Miniature Poodles, Dachshunds…) with no identifiable structural lesion. No drug prevents the disease; yearly checks and selection of breeding animals are recommended.
B. It is stage B1 because it belongs to a predisposed breed
Stage B requires a structural lesion (mitral regurgitation murmur or echocardiographic changes). Breed predisposition alone defines stage A.
C. A low-dose ACE inhibitor should be started as prevention
There is no evidence that ACE inhibitors prevent or delay the onset of MMVD in dogs without lesions, and they add unnecessary cost and adverse effects.
D. Low-dose pimobendan should be started as prevention
Pimobendan has only shown benefit in the preclinical phase with cardiomegaly (stage B2). It is not indicated in a normal heart.
lightbulb Key takeaway
Stage A is a risk stage, not a disease stage: the intervention is periodic auscultation and responsible breeding (avoid breeding dogs with early-onset murmurs). In Cavaliers the murmur often appears before 5–6 years of age. Exercise and diet should be those of any healthy dog.
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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.