Dog Mitral Valve Disease in Cavalier King Charles Spaniels

Cavalier King Charles Spaniels have an extremely high prevalence of inherited mitral valve disease. Breed health reform and proactive management are the most important welfare interventions for this breed.

Key Facts

Myxomatous mitral valve disease (MMVD) affects virtually all Cavalier King Charles Spaniels (CKCS) — by age 10, nearly 100% have a heart murmur from mitral valve degeneration
The condition is earlier-onset and faster-progressing in CKCS than in other breeds, reflecting a strong genetic basis for accelerated disease
The MVD Breeding Protocol, developed in the 1990s and refined since, recommends that breeding dogs be at least 2.5 years old with a clear cardiac auscultation at that age, and that both parents be clear at 2.5 years before being bred — this has been shown to reduce early-onset disease frequency when widely implemented
Compliance with the MVD Breeding Protocol varies significantly between breeders and countries — in some populations compliance remains low despite evidence of benefit
The EPIC trial demonstrated that pimobendan started at Stage B2 (cardiac enlargement, no clinical signs) delays time to heart failure by approximately 15 months
Annual echocardiography is recommended from middle age (4–5 years) to stage disease and guide treatment timing
CKCS also have elevated prevalence of syringomyelia/Chiari-like malformation syndrome — a separate neurological condition causing chronic pain from cerebrospinal fluid flow obstruction
A truly welfare-positive approach to CKCS ownership requires engagement with both the cardiac and neurological health issues simultaneously

Welfare Considerations

The hereditary cardiac disease burden in CKCS is one of the most significant welfare issues in companion animal breeding. Most CKCS will develop heart disease in their lifetime, many will progress to heart failure, and the genetic basis means this is not unavoidable — it is a consequence of breeding decisions. The breed health community has the tools (breeding protocol, early monitoring, effective treatment) to significantly improve welfare outcomes at the individual and population level. The welfare of individual CKCS requires owners to engage with proactive cardiac monitoring and treatment, while the population-level welfare requires breeders to implement health testing rigorously. Syringomyelia screening is an additional responsibility — MRI screening of breeding dogs for CM/SM reduces the propagation of a painful neurological condition.

What You Can Do

Only purchase CKCS from breeders who participate in the MVD Breeding Protocol and CM/SM MRI screening programme
Start annual cardiac auscultation from age 1 and echocardiography from age 4–5 for CKCS
If a murmur is detected, pursue echocardiography to stage disease and discuss the EPIC trial findings with your vet
Learn the signs of heart failure: increased resting respiratory rate, exercise intolerance, and nocturnal cough
Support the Cavalier Health Foundation and breed health committees working to improve MVD and SM screening compliance