Cat Hypertrophic Cardiomyopathy: Genetic Testing and Breeding

Hypertrophic cardiomyopathy is the most common inherited heart disease in cats; genetic testing can reduce prevalence in susceptible breeds.

Key Facts

HCM causes abnormal thickening of the heart muscle, reducing cardiac output and predisposing to thromboembolism.
Maine Coons carry a MYBPC3 A31P mutation; Ragdolls carry a distinct MYBPC3 R820W mutation.
Genetic testing for these mutations allows breeders to select against the variants systematically.
Mutation-positive cats may not develop clinical disease; penetrance is incomplete and variable.
Annual echocardiography screening is recommended for all breeding cats in susceptible breeds.
ATE (aortic thromboembolism) secondary to HCM causes sudden, severe hindlimb paralysis and is often fatal.

Welfare Considerations

HCM causes progressive cardiac compromise that culminates in congestive heart failure, sudden death, or catastrophic thromboembolism. The welfare cost is substantial: affected cats experience breathlessness, discomfort, and sudden death or paralysis. Responsible breeding using DNA testing and echocardiographic screening is the most effective available welfare intervention. Breed clubs should make screening a condition of registration.

What You Can Do

Ask breeders for HCM genetic test and echo screening results for both parents before buying a kitten.
Annual echo screening for Maine Coon and Ragdoll cats is recommended — discuss this with your vet.
Join breed club health committees supporting HCM screening as a registration requirement.
Donate to feline cardiology research working to identify further causative mutations.