What is it and why is it important?

Hypertrophic Cardiomyopathy (HCM) is the most common heart disease in cats, whether they are pedigreed (purebred) or of unknown lineage. HCM is a progressive muscular disease of the heart in which the papilary muscles in the left ventricle that anchor the mitral valve and the the walls of the left ventricle become abnormally thickened. When this thickening occurs, it happens inwardly, reducing the size of the chambers and, therefore, reducing the efficiency of the muscle and the amount of blood that can be diffused to the body. As the condition progresses, the cat's heart will eventually fail. HCM has also been known to cause blood clots that may be fatally passed to the brain or other organs, or cause paralysis.

HCM is thought to be a genetic disease. In Maine Coons and American Shorthairs, HCM has been confirmed as an autosomal dominant inherited trait with genetic mutations on specific genes, meaning it is passed from parents to offspring as a dominant trait. If one of the parents is positive for HCM, chances are at least some of the kittens will also be positive. HCM is also known to affect Bengals, Norwegian Forest Cats, Ragdolls, Savannahs and Sphynx breeds. The disease can strike a cat of any age, from very young kittens to older cats. HCM is a primary disease of the heart muscle, but can be exacerbated by high blood pressure or hyperthyroidism.

There is no cure for HCM at this time and prognosis for a cat diagnosed with HCM is generally not good. Most positive diagnoses happen after the cat has passed away. With early detection, however, medication can be given that may prolong the spread of the disease. Symptoms to watch for can include heart murmurs, lethargy, anorexia, labored breathing, or weakness.

There is a blood test available for Maine Coons that shows genetic mutation even when they are kittens. Unfortunately, a test like that does not exist for Bengals. The only way to diagnose a Bengal currently is by echocardiogram - an ultrasound done of the heart muscles. In time, if enough positive Bengals are identified, we may be able to have a blood test of our own. As breeders, it is our responsibility to ensure we are not breeding positive cats. The only way this tragic disease can be slowed is for all breeders to test and remove positive cats or cats with questionable findings from their breeding programs.

Here at Leopardfuzz, our cats are monitored closely by our veterinarians to ensure they do not have heart murmurs and have an echocardiogram each year to measure the heart walls. We will only breed cats that test within normal limits. We have also decided that all new cats entering our cattery must be from parents who were screened within the last year and the results of both parents were negative for HCM. 

If we are unable to help you in adding a new member to your family, we can give you a list of breeders who also test their cats. If you are searching on your own, ask to see the reports. Any breeder who is truly testing should be happy to share their results with you. Cats who go through rigorous testing may be a little more expensive, but you deserve the security of knowing everything was done to produce a healthy kitten!

If you have further questions on HCM, please contact me here.