Mitral Valve Disease in Dogs: The Most Common Canine Heart Condition
Mitral valve disease affects the majority of small-breed dogs as they age. Learn about signs, progression, and management.
Myxomatous mitral valve disease (MMVD) is the most common heart condition in dogs, affecting up to 85% of small-breed dogs over 10 years old. The mitral valve degenerates over time, allowing blood to leak backward, which eventually leads to heart failure. Early detection and proper management can significantly extend your dog's life.
- Affects up to 85% of small-breed dogs over 10 years old
- Cavalier King Charles Spaniels are genetically predisposed
- A heart murmur is the first sign — often detected years before symptoms
- The disease progresses through 4 stages (A through D)
- Medication can significantly slow progression
- Regular monitoring is essential for optimal management
What Happens in MVD
The mitral valve separates the left atrium from the left ventricle. In MVD, the valve leaflets thicken and become deformed, so they can't close properly. Blood leaks backward (mitral regurgitation) with each heartbeat. Over time, this increases pressure in the left atrium and lungs, leading to fluid accumulation (congestive heart failure).
The 4 Stages
Stage A: At risk but no disease yet (breeds prone to MVD). Stage B: Has a heart murmur but no symptoms. B1: Mild — no heart enlargement. B2: Moderate — heart is enlarged but no symptoms. Stage C: Current or past heart failure symptoms. Stage D: Heart failure that no longer responds to standard treatment. Most dogs are diagnosed in Stage B during a routine checkup.
Signs and Monitoring
Early stages: a heart murmur detected by your vet (grade 1-6). As it progresses: coughing (especially at night or after exercise), exercise intolerance, faster breathing rate, restlessness, and fainting. Counting your dog's resting respiratory rate (should be under 30 breaths per minute) is an excellent way to monitor at home.
Treatment
Stage B1: Monitoring only. Stage B2: Starting pimobendan (Vetmedin) has been shown to delay the onset of heart failure by an average of 15 months. Stage C: Pimobendan + diuretics (furosemide) + ACE inhibitors. Stage D: Additional medications and specialist care. Regular vet checkups (every 6-12 months) with chest X-rays and echocardiography guide treatment decisions.
- Coughing, especially at night
- Exercise intolerance or tiring easily
- Faster breathing rate at rest
- Fainting or collapse
- Restlessness at night
- Your vet detected a heart murmur
RVC
RVC provides comprehensive cardiac care including echocardiography, chest X-rays, and all stages of MVD treatment. We follow the latest ACVIM guidelines for optimal management. Call +853 6677 6611.
+853 6677 6611