HCM in Maine Coon Cats: Signs, Genes and Screening

If you share your home with a Maine Coon, HCM is the heart condition worth knowing about. It's the most common heart disease in cats, and the Maine Coon is one of the few breeds with a known gene change linked to it [1][2][4].

What is HCM in cats?

• HCM is a disease of the heart muscle [1][2].
• The heart walls, mainly on the left side, become too thick [1][2][3].
• A thick heart holds less blood and can't relax properly between beats, so it pumps less well [3].

It's common: it may affect as many as one in seven cats [2]. Many affected cats show no outward signs for a long time, sometimes for life [1][2][3].

Is HCM inherited?

In Maine Coons, yes. A change in a gene called MYBPC3 (known as A31P) has been linked to the disease in this breed [2][4]. It isn't an infection; it's a problem in the heart muscle itself [2].

• Cats with two copies of the gene change, one from each parent, are the ones that mainly develop serious HCM [2].
• A single copy can also be linked to the disease [4].
• A gene test can show higher risk, but it can't promise a cat will or won't get sick [1].

Males also tend to develop more severe disease earlier than females [2].

Which other cats get it?

Any cat can get HCM. It's seen more often in some breeds, including Ragdolls, British Shorthairs, American Shorthairs, Sphynx, Bengals, Norwegian Forest Cats and Persians [1][2]. Ragdolls have their own gene change in the same gene [2][4].

What are the signs of HCM?

Early signs are easy to miss, such as less energy or tiring more easily [1][3]. Book a vet visit if your cat has:

• Fast or laboured breathing [1][3].
• Breathing with an open mouth [1][3].
• Ongoing tiredness or lack of energy [1][3].

Emergency: If your cat has severe difficulty breathing, or sudden pain, weakness or paralysis in one or both back legs, go to a vet immediately [1][2][3].

Only a licensed vet can tell what's behind these signs.

Can HCM be prevented?

Not through diet or home care in a cat that already carries the gene [2][3][4]. Prevention happens mainly before a kitten is born: breeders can screen their cats with a gene test and a heart ultrasound, and avoid breeding from affected cats [3].

Did you know? Breeding cats are advised to have a heart ultrasound every year during their breeding years [3].

FAQ

What should I ask a Maine Coon breeder?

Ask whether both parents were gene-tested for MYBPC3 and had heart scans, and ask to see the results [2][3][4].

Can a cat have HCM without symptoms?

Yes. Many cats show no signs for a long time. Ask your vet about your cat's heart health [1][3].

Is there a cure for HCM?

No. A licensed vet can help look after your cat's heart health over time [1][2].