Mitral Valve Disease in Dogs (MMVD)
This article is for educational purposes only and does not promote or advertise prescription-only veterinary medicines. Any treatment or medication discussed should only be used under veterinary direction and supplied against a valid veterinary prescription where required.
Which Dogs Are Most Affected?
Mitral valve disease is especially common in small breed dogs. Some breeds have a strong genetic predisposition.
- Cavalier King Charles Spaniels
- Dachshunds
- Miniature Poodles
- Chihuahuas
- Shih Tzus
- Yorkshire Terriers
The earliest sign of the disease is usually a heart murmur detected during a routine veterinary examination.
What Happens in Mitral Valve Disease?
The mitral valve normally ensures blood flows in one direction through the heart.
In dogs with MMVD, the valve becomes thickened and misshapen. When the heart contracts, some blood leaks backwards into the left atrium instead of moving forward through the body.
This backward flow is called mitral regurgitation. Over time the heart enlarges and works harder to compensate for this inefficiency.
Common Symptoms
Dogs with early mitral valve disease often show no obvious symptoms. As the disease progresses, owners may notice:
- Persistent coughing
- Exercise intolerance
- Faster breathing rate
- Lethargy
- Reduced appetite
- Collapse in severe cases
If a dog develops breathing difficulty, collapse, or marked lethargy, urgent veterinary assessment is recommended.
How Mitral Valve Disease Is Diagnosed
Veterinary diagnosis is based on clinical examination and further investigations to assess heart structure and function.
- Heart murmur detection during examination
- Chest X-rays to assess heart size and lungs
- Heart ultrasound (echocardiography)
- Blood pressure monitoring
- Blood tests such as NT-proBNP
How Mitral Valve Disease Is Managed
Although MMVD cannot be cured, treatment aims to support heart function, reduce clinical signs, and slow progression where possible.
Management is typically guided by disease stage. Some dogs require monitoring alone initially, while others benefit from medication as structural changes or clinical signs develop.
Medications Used in Mitral Valve Disease
Dogs with MMVD may be prescribed a combination of medications depending on disease severity and clinical signs. These medicines are selected and adjusted by a veterinary surgeon.
Pimobendan
Pimobendan supports heart function by improving contractility and reducing vascular resistance.
It is commonly introduced in dogs with evidence of cardiac enlargement, even before clinical signs develop, and remains a key component of treatment once heart failure is present.
ACE Inhibitors
ACE inhibitors such as benazepril or enalapril reduce activation of the renin-angiotensin-aldosterone system.
They may be used to reduce cardiac workload and support circulatory stability in selected cases.
Diuretics
Diuretics are used when fluid accumulation develops, particularly in congestive heart failure.
They help remove excess fluid from the body, improving breathing comfort and reducing pulmonary congestion.
Use and dosing are determined by the veterinary surgeon based on clinical status.
Monitoring and Follow-Up
Regular monitoring is essential in dogs with MMVD to assess progression and adjust treatment appropriately.
- Routine clinical examinations
- Monitoring resting respiratory rate at home
- Repeat imaging when indicated
- Blood pressure checks
Early detection of changes allows timely adjustment of management.