Cat Breeds More Likely to Suffer from Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common hereditary heart disease in cats, characterised by an abnormal thickening of the heart muscle walls, particularly the ventricles. This thickening reduces the size of the heart chambers, affecting the volume of blood pumped with each beat. It can lead to heart failure, thromboembolism (blood clots blocking blood vessels), and occasionally sudden death.

HCM can affect cats of any breed, including non-pedigree cats. However, research shows that genetic factors are significant, with certain breeds more predisposed due to heritable mutations. Understanding these risks helps cat owners and prospective buyers make informed decisions and supports responsible breeding practices to reduce the prevalence of the disease.

Breeds Most Prone to HCM: Maine Coon and Ragdoll

The Maine Coon and Ragdoll are the most studied breeds for HCM, as specific genetic mutations linked to the disease have been identified in both. Up to a third of these cats may carry the mutated gene, potentially passing it to their offspring without always being affected themselves.

Each breed has a unique mutation associated with HCM, inherited in an autosomal dominant pattern with incomplete penetrance. Cats with two copies of the mutation (homozygous) tend to develop severe disease early in life and face greater risks, including sudden death. Carriers with one copy (heterozygous) may have mild or no symptoms but can still pass on the gene.

Responsible Maine Coon and Ragdoll breeders now implement genetic testing to identify carriers and avoid breeding affected cats. This helps reduce the disease's impact and promotes healthier generations.

Other Breeds at Potential Risk of HCM

Beyond the Maine Coon and Ragdoll, several other breeds are considered at higher risk, although conclusive genetic evidence is less established and ongoing research continues to investigate:

• British Shorthair
• Persian
• Bengal
• Sphynx
• Norwegian Forest Cat
• Oriental breeds including the Himalayan and Burmese
• Devon Rex
• American Shorthair
• Chartreux and Siberian cats

Whilst some breeders and sources suggest a higher prevalence of HCM in these breeds, owners should treat such claims with caution and rely on veterinary advice and screening when recommended.

Recognising and Screening for HCM in Cats

HCM can be asymptomatic in its early stages, making veterinary screening essential — particularly in higher-risk breeds. Common signs to watch for include weakness, lethargy, rapid breathing, coughing, or fainting, though symptoms often go unnoticed until the disease is advanced.

Screening approaches include:

• Cardiac ultrasound (echocardiography): performed by veterinary cardiologists to detect thickening of the heart muscle and assess cardiac function.
• Genetic testing: blood samples or cheek swabs can detect known mutations in breeds such as the Maine Coon and Ragdoll, identifying carriers and affected cats.

Responsible breeders test all breeding cats to exclude affected or carrier individuals from their programmes. When considering a kitten from a predisposed breed, ensure your breeder takes health testing seriously and provides documentation of HCM screening. This reduces the risk of acquiring a cat affected by this serious condition and supports ethical breeding efforts.

For current cat owners, particularly of predisposed breeds, regular veterinary check-ups and awareness of the signs of HCM can lead to earlier diagnosis and treatment, improving quality of life.