Hypertrophic cardiomyopathy (HCM) causes the walls of a cat's heart to thicken, reducing the heart's ability to pump blood. It's the most common heart disease in cats, and it affects breeds across the spectrum — Ragdolls, Maine Coons, British Shorthairs, Sphynx, Persians, and Bengals all carry documented risk. The frightening part: affected cats often show no symptoms until the disease is advanced, and the first sign can be sudden death or a blood clot.
The gold standard for detection is an echocardiogram performed by a board-certified veterinary cardiologist — not a stethoscope check at a routine vet visit. Auscultation misses most early cases, and many HCM-positive cats have no heart murmur at all. An echo actually images the heart wall and measures it. Nothing else substitutes.
Responsible catteries scan breeding cats annually, because a clear result at age two says nothing about age four — HCM can develop at any point in a cat's life, and some lines develop it late. This is why a breeder showing you a single old scan has not screened their cats; they've screened them once. Ask for the dates and the cardiologist's name.
Some breeds also have DNA tests for specific HCM mutations: the MYBPC3 mutations in Ragdolls and Maine Coons are well documented. These tests are valuable — a cat with two copies of the mutation should not be bred. But a negative DNA test does not replace the echocardiogram, because other, undiscovered mutations exist in every breed. DNA testing and imaging are complementary, not interchangeable.
There's a hard decision every ethical cat breeder faces: what to do when a beloved, beautiful breeding cat scans positive. The answer is retirement from breeding, immediately, along with notification to the owners of that cat's previous offspring. Breeders who have made this painful call — and will tell you about it — are the ones you want to work with.
If you're looking for a feline breeding partner on PetsRulez.com, ask when the cat's last echocardiogram was and who performed it. Listings like Luna, our Ragdoll queen, include HCM screening dates right in the health records — that's the standard to expect, and anything less is a gamble with the kittens' lives.