Author: Kit Goodwin
HCM, or hypertrophic Cardiomyopathy, is an inheritable heart muscle disease that affects cats, usually between the ages of 1 year to 6 years. The heritability of HCM was demonstrated in a family of Maine Coon cats, by Dr. Kittleson, of Michigan University, but HCM can be found in other breeds, including domestics.
HCM cannot be detected accurately and consistantly by the use of an ECG. Only murmurs can be found by auscultation, when performed by a board certified cardiologist, and this does not give results for the cause of the murmurs found. At best, auscultation is only a screening for extremely advanced disease, and is not a recommended method of screening breeding animals.
HCM can only be identified via ultrasound. A website for MainE Coon breeders who are testing for HCM says, "HCM screening should be done by a Board Certified Veterinary Cardiologist or other equally qualified, trained, and experienced veterinary professional. Early stages of HCM are usually not detectable via ECG or auscultation. At minimum, HCM screening should include a thorough physical exam and a two-dimensional cardiac ultrasound (echocardiogram). Additional tests such as color flow Doppler ultrasonography may be done at the discretion of the breeder and/or veterinary professional. "
In the Turkish Angora, HCM has been found in a number of bloodlines, by those breeders who are doing regular testing for clinical signs of the disease. We have been reluctant to publicly identify those bloodlines in which this has occurred, due to the volatile nature of politics in breeding animals. However, suffice it to say that the author of this article once thought that massive out-crossing between different bloodlines would eliminate the problem, and in the course of that out-crossing, has found positive results for HCM in cats from six distinct US bloodlines and two from Europe. Clearly, out-crossing without testing is useless.
I usually advise breeders to be aware that testing is not the end-all, be-all of breeding. Many decisions go into the choice of male and female for the next litter. The HCM gene is dominant, and out-crossing will not bury it as if it were a recessive. Breeding a cat with the gene for HCM will ensure that 50% of the offspring are likely to have the gene. Geneticists advise that 25% of that litter, or 50% of the kittens who have the gene, may fail to express the disease, but may still pass the gene to their offspring. Thus far in my breeding program, however, I have not had this exact problem.
I have had two instances where a cat tested negative for HCM, but positive for other associated heart diseases. One such cat developed an aortic aneurism and died at age 3 1/2. This cat did not have classic signs of HCM, but later testing revealed HCM in his family.
Another cat that I tested was brought in as an out-cross to my bloodline, in hopes of "losing" the gene. This cat tested negative for heart problems, and had three litters of kittens, sired by three different males, all tested negative at the time of breeding. Her first litter exhibited no signs of problems. The second litter consisted of three males, two of which died early in life, of HCM. The third litter consisted of three females and two males. The entire third litter was lost during the first two weeks. Subsequently, the female and all involved sires were re-tested. The males were negative, and the female only tested positive for mitral valve regurgitation. She was spayed, her offspring removed from my breeding program, and the owners of all whole descendants were notified. Subsequently, a grandchild of this female tested positive, although this is inconclusive, due to the fact that not all of the cats in the pedigree were tested. This "out-cross" female is still living here, and still appears outwardly healthy, at age eight! It cannot be stressed enough, that the fact that your cats appear healthy and live to normal ages, does not mean they are HCM clear.
A third associated sign of HCM found in some tests is shortened papillary muscles inside the heart. Again, this sign can be found without classic signs of HCM. I feel it is the best policy not to breed any cat with abnormal findings, regardless of their nature. A reasonable second choice would be to keep all whole offspring from such a cat, internal in one's own breeding program only, with the testing of all whole descendants.
Clinical signs of HCM that breeders have reported can include: shortness of breath, labored breathing, fluid in the lungs and around the heart, coughing, sudden onset of timid behavior (particularly regarding climbing to high places), hiding or unusual spraying (usually in combination with other signs in this list), saddle thrombosis (sudden onset paralysis of hind limbs), coldness in a limb, or sudden un-explained death. Several people I have talked to, who have lost cats to HCM, have reported that the cat was fine until given a bath, and collapsed during or immediately after the bath. This is caused by the expanding and constricting of the vascular system in response to the warm water and the chill at the end of the bath, and is not a causitive factor, per se. These cats would have continued longer before exhibiting the disease, but would have eventually succumbed anyway.
Another difficulty in testing is the fact that the age of clinical onset of the disease can vary greatly. A cat may test negative at age two, and positive at age four or six. However, two vets have told me that tests on eight year old cats are very likely to be accurate. Of course, eight year old cats are not often still breeding.
Due to the great expense of the tests, and the fact that the probability of finding a positive result increases with age, it has been my personal policy to breed un-tested females at one year of age, and to sell the kittens with a five year health guarantee on hearts. It is hoped that pet owners who've purchased my cats, will test their cats should they develop signs of heart problems. Upon receipt of the test results, the pet owner receives a kitten (and keeps the former cat if desired), while I receive data on my breeding program. Subsequently, at two years of age, I test all of my breeding females. Any found positive are altered and placed as special needs cats. Any found negative, continue to breed for two more years, and are tested again at an age of four. I tend to retire my girls at age four or five, after one or two more litters.
Males are a different story. I tend to keep males for two years or less. I test at one year of age, breed them for six months to two years, alter them for retirement, and wait six months before offering them as adoptable. They are tested again just before being placed in a new home, and again, the five year guarantee is given.
Whatever policy for testing you decide to implement, the possible suffering of your cats, as well as your cattery reputation will be the better for it. Although testing can be highly expensive, the expendature is well worth it when you consider the cost of losing a wonderful breeding cat and having to search for a replacement. You should also weigh the costs of such a loss against possible vet bills and necropsy costs on an animal you have lost. If you are having a hard time with such expendature, consider charging an extra $50 for each kitten in a litter, or consider seeking a vet with cardiology training, who is not board certified. These measures will be much better than doing nothing.
If you are seeking a Turkish Angora kitten as a pet, there are no guarantees that a testing program will keep you from such losses, but at least you will have a better chance, and you will encourage breeders who test their cats, to continue to do so.
It is the hope of everyone that loves the Turkish Angora, that this problem can be greatly minimized, making the Turkish Angora a healthier and happier breed.