A comprehensive welfare guide to degenerative mitral valve disease (DMVD), the most common heart disease in dogs, with focus on monitoring, treatment, and quality of life.
Key Facts
Degenerative mitral valve disease (DMVD) is the most common cardiac disease in dogs, affecting over 10% of all dogs and up to 90% of Cavalier King Charles Spaniels over 10 years old.
DMVD causes progressive thickening and incompetence of the mitral valve, leading to volume overload, cardiac remodeling, and eventually congestive heart failure (CHF).
The ACVIM (American College of Veterinary Internal Medicine) staging system classifies DMVD as Stage A (at risk), B1 (asymptomatic, no remodeling), B2 (remodeling), or C/D (heart failure).
The EPIC Trial (2019) demonstrated that pimobendan started at Stage B2 delays onset of CHF by an average of 15 months — this is a major welfare advance.
Dogs in CHF (Stage C) experience respiratory distress, exercise intolerance, and reduced quality of life — furosemide, pimobendan, and ACE inhibitors form the standard treatment triad.
Quality of life assessment in DMVD dogs includes: breathing rate at rest (<30 breaths per minute is target), exercise tolerance, appetite, and happiness scores.
The Cavalier Health Foundation funds DMVD research and advocates for mandatory cardiac health screening in breeding Cavaliers — selecting against early-onset DMVD is achievable.
Welfare Considerations
DMVD causes progressive cardiac suffering in millions of dogs. Early diagnosis and timely initiation of pimobendan at Stage B2 meaningfully extends life without heart failure. Any dog with a heart murmur should have echocardiographic staging. Breed health improvement through mandatory cardiac screening before breeding is the long-term solution for high-prevalence breeds like Cavaliers.
What You Can Do
Have any dog with a detected heart murmur echocardiographically staged by a cardiologist
Begin pimobendan at Stage B2 as per ACVIM guidelines — this delays heart failure by over a year
Monitor resting respiratory rate at home daily for dogs in Stage C to detect decompensation early
Only breed Cavaliers and other high-risk breeds from cardiac-screened, late-onset DMVD parents