Mitral Valve Disease in Dogs: Symptoms, Breeds & Testing

Mitral valve disease, often called endocardiosis, is the most frequent heart condition in aging dogs, especially those of small to medium size. It typically progresses slowly over several years and might not cause any noticeable signs until dogs reach their senior stage, often after 10 years old. This disease gradually impairs heart function, which diminishes quality of life and frequently results in congestive heart failure.

What is Mitral Valve Disease in Dogs?

The mitral valve is essential for proper heart operation. It separates the left atrium from the left ventricle, opening to let blood flow into the ventricle and shutting to prevent it from flowing backward. In cases of mitral valve disease, the valve thickens and changes shape due to a plaque-like buildup, allowing blood to leak back into the atrium during the heart's pumping action. This backflow produces a heart murmur and forces the heart to work harder, which can hide early symptoms but eventually causes the heart to enlarge and fail.

Typical signs of advanced disease include a persistent dry cough that worsens at night or after exercise, difficulty breathing, and decreased stamina.

Which Dogs Are at Risk and Why?

Genetics can play a significant role in mitral valve disease, with certain breeds being more susceptible. Yet, aging alone is a major factor, meaning older dogs without a family history can also develop this disease. In the U.S., male dogs are about twice as likely to be diagnosed with mitral valve disease compared to females.

Breeds Susceptible to Mitral Valve Disease

Although any dog can get mitral valve disease, some breeds are much more prone to it. The Cavalier King Charles Spaniel stands out with a risk roughly twenty times greater than other breeds. Other vulnerable breeds commonly cited in American veterinary circles include the Chihuahua, Miniature Poodle, Norfolk Terrier, and the Miniature Schnauzer.

How Is Mitral Valve Disease Screened Before Breeding?

Given the hereditary patterns especially noticeable in the Cavalier King Charles Spaniel, American breed clubs and animal welfare groups advocate for vet-based screening to detect this disease early. However, developing genetic testing remains challenging due to the complex nature of the condition.

Veterinarians recommend annual heart evaluations, typically by a cardiologist or an experienced veterinary professional, using auscultation to listen for heart murmurs signaling early mitral valve involvement. Still, murmurs may not appear until later, so ongoing monitoring is crucial. Because early silent progression is common, no mandatory registries excluding affected dogs currently exist in the U.S.

Responsible breeders focus on routine cardiac exams and informed breeding choices to reduce inherited risk and promote the heart health of future litters.

Managing Life with Mitral Valve Disease

Mitral valve disease cannot be cured, but with proper veterinary medical management, many dogs live comfortably for years. Treatments aim to ease symptoms and slow progression, often using medications like pimobendan in early stages, alongside diuretics, ACE inhibitors, or spironolactone if congestive heart failure emerges. Frequent vet visits are needed to track the disease and adjust therapies to keep your dog comfortable and active.

Commonly Asked Questions

How early can mitral valve disease be detected?

Short answer: Detection usually happens when a vet hears a heart murmur during a routine exam before symptoms show up.

The disease develops gradually, and symptoms may be subtle or absent for a long time. That’s why regular veterinary check-ups are vital, especially for high-risk breeds. If a heart murmur is suspected, further testing like echocardiograms can confirm the diagnosis.

Can younger dogs get mitral valve disease?

Short answer: While mostly an issue in senior dogs, some breeds may show disease signs at a younger age due to genetics.

Cavalier King Charles Spaniels, for example, can develop early-onset disease with signs typically beginning in middle age. Being vigilant about heart health through all life stages is important for owners and breeders alike.

How can I lower my dog’s risk of developing mitral valve disease?

Short answer: You can’t entirely remove genetic risk, but breeding dogs with clear heart exams and keeping your dog healthy helps reduce chances.

A balanced diet, weight management, avoiding very strenuous activity once the disease is diagnosed, and regular veterinary heart monitoring can slow disease severity. Breeders must adhere to screening protocols and not breed dogs showing signs early in life to minimize hereditary disease in future generations.

Where can I find reputable Cavalier King Charles Spaniel puppies?

Trustworthy Cavalier King Charles Spaniel breeders can be contacted through U.S. breed clubs and the American Kennel Club (AKC) recommended breeder programs. These breeders undertake heart health testing and aim to reduce inherited conditions like mitral valve disease. Ethical breeders also provide ongoing support for puppy owners.

Always verify that your chosen breeder follows responsible breeding practices prioritizing canine health and welfare.