MMVD (Myxomatous Mitral Valve Disease)

Myxomatous mitral valve disease (MMVD) is the most common cardiac condition in dogs, affecting the valve between the left atrium and ventricle. The valve degenerates over time, allowing blood to leak backwards with each heartbeat. Specialist cardiology is essential for accurate staging, optimising treatment timing, and — in selected cases — referring for valve repair surgery.

What it is

MMVD causes progressive thickening and distortion of the mitral valve leaflets. This produces a characteristic heart murmur and, as the disease advances, heart enlargement and eventually congestive heart failure (CHF). Management is primarily medical — ACE inhibitors, diuretics, pimobendan — but surgical mitral valve repair is increasingly available at specialist centres and can significantly extend life in appropriate candidates.

When it's needed

• Heart murmur detected requiring staging echocardiogram
• ACVIM Stage B2: heart enlargement detected — pimobendan now indicated
• ACVIM Stage C: congestive heart failure — hospitalisation, IV diuresis, medication optimisation
• Referral for surgical mitral valve repair (selected centres in Japan, UK, US, Europe)
• Monitoring of response to medication and progression every 6–12 months

The procedure

Most management is non-surgical — regular echocardiograms, chest X-rays, and blood pressure monitoring guide medication adjustments. Surgical mitral valve repair (requiring cardiopulmonary bypass) is available at a small number of specialist centres worldwide and offers a potential cure in suitable candidates, typically dogs in Stage B2–C with adequate cardiac function.

Recovery

Dogs in Stage B2 on appropriate medication have a median survival of 2–3+ years. Dogs entering CHF (Stage C) have a median survival of 12–18 months with modern treatment. Valve repair surgery outcomes are evolving — early data from specialist centres report good outcomes in appropriately selected cases.

Frequently asked questions