Cat Breeds More Likely to Suffer from Hypertrophic Cardiomyopathy

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

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

Breeds Most Likely to Develop HCM: Maine Coon and Ragdoll

The Maine Coon and Ragdoll breeds are the most studied for HCM, as specific genetic mutations linked to this disease have been identified in both. Up to one-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 and face higher risks, including sudden death. Carriers with one copy (heterozygous) may have milder or no symptoms but still can pass the gene on.

Responsible Maine Coon breeders 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 with Possible HCM Risk

Beyond Maine Coons and Ragdolls, several other breeds are considered at higher risk, although conclusive genetic evidence is less established and ongoing research is investigating further:

• British Shorthair
• Persian
• Bengal (noted for genetic narrowness)
• Sphynx
• Norwegian Forest Cat
• Oriental breeds including Himalayan and Burmese
• Devon Rex
• American Shorthair
• Chartreux and Siberian cats

While some breeders and sources suggest a higher HCM prevalence in these breeds, owners should treat such claims cautiously and rely on veterinary advice and screening where recommended.

Recognising and Testing for HCM in Cats

HCM may be asymptomatic in early stages, making veterinary screening vital, especially for high-risk breeds. Common signs to watch for include weakness, lethargy, rapid breathing, coughing, or fainting, though symptoms often go unnoticed until the disease progresses.

Testing approaches include:

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

Responsible breeders screen all breeding cats to exclude affected or carrier individuals from breeding programmes. In the UK, the Veterinary Cardiovascular Society’s register, supported by International Cat Care, tracks breeding cats' HCM status, helping maintain healthy breeding standards and reduce HCM prevalence.

Promoting Responsible Ownership and Breeding

If you are considering getting a kitten from a breed predisposed to HCM, ensure your breeder takes health testing seriously and provides documentation on HCM screening. This reduces the risk of acquiring a cat affected by this serious condition and supports ethical breeding efforts.

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

Conclusion

Hypertrophic cardiomyopathy is a serious but manageable inherited heart condition predominantly affecting certain breeds, especially the Maine Coon and Ragdoll. Thanks to advances in genetic testing and veterinary screening, responsible breeders now actively combat this disease through selective breeding.

Potential cat owners should prioritise health screenings when selecting a breeder and stay informed about HCM symptoms and care. This knowledge helps ensure your feline companion enjoys a longer, healthier life.