Difficulty breathing, open-mouth breathing, collapse or sudden painful limb weakness needs emergency veterinary attention. Do not wait for a screening appointment.
Hypertrophic cardiomyopathy (HCM) involves abnormal thickening of heart muscle. It is a common feline heart condition, and Maine Coons have a recognised inherited risk. Some affected cats show no outward signs; the course of disease varies.
What HCM can do
Thickening can interfere with the heart’s ability to fill. Complications may include congestive heart failure and blood clots. A diagnosis does not mean every cat will develop these complications. Cornell’s HCM guide explains the condition and veterinary treatment goals.
Genetic risk is only part of the picture
The MYBPC3 A31P variant is associated with HCM risk in Maine Coons. Testing for it does not establish whether a cat currently has heart disease, and a negative result cannot exclude HCM. Read our guide to interpreting an A31P result.
How vets investigate
Echocardiography, an ultrasound of the heart, is the principal diagnostic test. Your vet interprets findings alongside examination and may investigate other causes of heart-wall thickening, including high blood pressure or thyroid disease. A normal appearance at home or absence of a murmur does not rule out disease. The ACVIM feline cardiomyopathy guidelines describe this assessment.
A practical plan for owners
Discuss screening with your vet using your cat’s age, examination findings, family history and any genetic results. Keep copies of reports and ask when reassessment is appropriate. If buying a kitten, request the parents’ actual screening records; results cannot guarantee a kitten’s future health.
If your vet recommends home breathing counts, use an agreed schedule and contact threshold. Our sleeping respiratory rate guide explains counting. Neither home observations nor consumer monitors replace veterinary assessment.
General owner information. Treatment and follow-up depend on the individual cat’s findings.
