Breed Health Guide • Reviewed by Dr. Tiffany Delacruz, DVM
Myxomatous Mitral Valve Disease (MMVD) in Cavalier King Charles Spaniels
Also known as: MMVD
Mitral valve disease — degeneration of the heart's mitral valve causing blood to leak backward — is the single most common health issue in Cavalier King Charles Spaniels. The disease is nearly universal in the breed by age 10. Catching it early with screening, starting pimobendan at the right disease stage, and managing congestive heart failure when it develops are the pillars of care.
Why Cavalier King Charles Spaniels are predisposed to myxomatous mitral valve disease (mmvd)
Genetic. The breed has the highest documented prevalence of MMVD of any breed. Estimates suggest >50% of Cavaliers have a heart murmur by age 5, and >90% by age 10. Onset is typically earlier than other breeds with MMVD (smaller breeds like Chihuahuas develop it but later in life).
What you'll see at home
- Heart murmur on routine vet exam (often the first finding)
- Coughing — particularly at night or with excitement
- Increased respiratory rate at rest (count it; >35 is concerning)
- Reduced exercise tolerance
- Reluctance to play
- Restless sleep, frequent position changes
- Bluish gums during exertion (advanced)
- Fainting or collapse (advanced)
Red flags — go to an emergency vet
- ⚠ Severe respiratory distress with rapid breathing — congestive heart failure
- ⚠ Collapse
- ⚠ Blue or gray gums
- ⚠ Sudden onset coughing with respiratory effort
- ⚠ Sudden change in breathing pattern in a known MMVD Cavalier
How vets diagnose myxomatous mitral valve disease (mmvd)
Annual cardiac auscultation starting from puppyhood. Once a murmur is heard: echocardiogram to grade the disease (ACVIM stages B1, B2, C, D). NT-proBNP blood test is a useful adjunct. Chest radiographs and ECG add information as disease progresses.
Treatment options
Stage B1 (murmur but no enlargement): monitoring only. Stage B2 (significant enlargement, asymptomatic): pimobendan starts — the EPIC trial showed pimobendan delays onset of CHF by ~15 months in this stage. Stage C (clinical CHF): pimobendan + furosemide + ACE inhibitor + spironolactone. Stage D (advanced): more aggressive diuresis, sometimes hospitalization. Cardiology referral appropriate at stage B2 or earlier.
Living with a Cavalier King Charles Spaniel who has myxomatous mitral valve disease (mmvd)
- 1 Annual cardiac auscultation by your vet starting young
- 2 Echocardiogram when a murmur is detected to stage the disease
- 3 If pimobendan is started, do not stop without veterinary guidance
- 4 Count resting respiratory rate at home; track over time
- 5 Lean body weight
- 6 Low-sodium diet once symptomatic
- 7 Pet insurance for cardiac conditions — buy young, before any murmur
- 8 Discuss with breeders: MVD screening of breeding stock is critical for the breed
Can RexVet help with this online?
RexVet is well-suited for: explaining echo results and disease staging, refilling cardiac medications established with a cardiologist, coaching on home respiratory rate monitoring, weight management, low-sodium diet transitions, and quality-of-life conversations.
Start a $64.99 video visit →We cannot perform cardiac auscultation, echocardiograms, or chest radiographs by video. Cardiac diagnosis and ongoing cardiology care belong with a veterinary cardiologist for this breed specifically — the disease is too important to not work with a specialist.
Prognosis — what to expect
With pimobendan started at stage B2, median time to CHF is ~15 months longer than untreated. Once CHF develops, median survival is generally 9-15 months with treatment. Many Cavaliers live a relatively normal life into their senior years with proper management.
Frequently asked questions
Frequently asked questions
When should my Cavalier get a cardiac workup?
Annual cardiac auscultation from puppyhood is the standard for the breed. Once any murmur is heard, get an echocardiogram to stage the disease — this directly affects whether and when pimobendan should be started. Don't wait for symptoms; the breed-prevalence is too high.
Does my Cavalier need pimobendan if it's just a murmur?
Depends on disease stage. Pimobendan changes the natural history when started at stage B2 (significant cardiac enlargement, still asymptomatic). The EPIC trial established this. The decision requires an echocardiogram to stage the disease — auscultation alone isn't enough.
How long can a Cavalier live with mitral valve disease?
With early detection and proper staging-appropriate treatment, many Cavaliers live a relatively normal lifespan into their senior years. The disease is progressive but treatable; the medications work. Untreated, advanced MMVD significantly shortens life.
Other conditions common in Cavalier King Charles Spaniels
Further reading from the RexVet blog
Other helpful RexVet resources for Cavalier King Charles Spaniels parents
Sources
- ACVIM Consensus Statement on MMVD
- EPIC trial — pimobendan in pre-clinical MMVD
- AKC Cavalier King Charles Spaniel Breed Page
Last fact-checked: 2026-06-04. Reviewed by Dr. Tiffany Delacruz, DVM.
Worried about your Cavalier King Charles Spaniel?
Talk to a licensed RexVet veterinarian from home — Cavalier King Charles Spaniel parents nationwide get answers in under an hour.