Hypertrophic cardiomyopathy is the most common form of heart disease in the cat. We have received the following information from The Veterinary Cardiac Genetics Laboratory at North Carolina State University, which will be of interest to all cat owners, especially Maine Coon cat owners. More information is available at ncsu.edu at the vgcl info site.
In many breeds, hypertrophic cardiomyopathy is an inherited disease. A genetic mutation responsible for this disease has been identified in the Maine Coon cat breed. It is important to note that humans also get hypertrophic cardiomyopathy and there are many genetic mutations that have been identified in people. This is likely true for cats as well, but to-date there have been only 2 genetic mutations found that cause hypertrophic cardiomyopathy in cats, one found predominately in the Maine Coon cat, and one found predominately in the Ragdoll cat.
It is important to understand that the absence of the mutation (a negative test result) in a cat does not mean that it will never get the disease. A negative result is only saying that the cat does not have the only known mutation that can cause hypertrophic cardiomyopathy at this time. In the future, additional mutations may be identified for which we may be able to test as well.
Likewise, it is important to understand that a positive test result does not mean that the cat will necessarily develop life threatening heart disease. In fact, some cats that test positive will develop only a very mild form of heart disease and will live quite comfortably. Other positive cats, though they carry the genetic mutation, never develop disease at all. If your cat tests positive, we recommend an annual examination with an echocardiogram and discussion with your veterinarian, as there are treatment options if hypertrophy of the heart develops. The test is important to help us screen, looking for the cats more likely to develop this disease, so we can identify and treat the disease in earlier stages.
This test is also very important if you have a breeding cat. At this time, about 33% of Maine Coon cats test positive for at least one copy of the gene. If we removed all of these cats from the breeding population, we would dangerously dilute the gene pool. (Remember that Maine Coon cats who carry this genetic mutation also carry other important genes that we do not want to lose from the Maine Coon breed.) A positive test is reported as either heterozygous (the cat carries 1 copy of the genetic mutation) or homozygous (carries 2 copies of the genetic mutation). We do not recommend breeding the homozygous cats. If necessary, recommendations now are that a heterozygous positive cat can still be bred, but bred only to a negative cat so that we decrease the risk of producing more homozygous cats in the population. As we move forward, we want to select more and more negative kittens from these lines to be used for breeding.
Keep in mind that we are continually learning about this disease and recommendations will be altered as we obtain more information. Since September 2006, only Maine Coon cats have tested positive for this mutation, but remember that the search is on-going, looking for other genes that have mutations causing hypertrophic cardiomyopathy in other cat breeds. The test is run on either a blood sample or a cheek swab sample and is very easily obtained. Please talk to your veterinarian about having your Maine Coon cat screened.