HCM- Hypertrophic Cardiomyopathy
Disclaimer: Hello from Johnny Gobble, DVM. I would like to start by saying that this page is written by me. This page is to help guide people with the wonderful Sphynx pets and their health. I will continue to add to it as I can. This page is simply MY opinion and this is the stand that we take for our cats in our cattery. You can find other people that agree or disagree with everything I say. Again, this is my opinion as a pet owner, breeder, and veterinarian. If you have any other questions, please contact us for more information.
Hypertrophic cardiomyopathy is a disease that results in the increased wall thickness of the heart. More specifically in the left ventricle of the heart. The disease is defined as an enlargement in the absence of secondary causes. Other causes can include hyperthyroidism, nutritional, hypertension(high blood pressure), or aortic stenosis(a constriction in the main artery leaving the heart). In Sphynx cats, genetic HCM is the concern we have.
HCM is common in many other breeds and is diagnosed most commonly in domestic shorthairs(the common cat). There is some testing available to help locate the gene responsible for HCM in certain breeds of cats. There is research at this time to help isolate the gene in Sphynx. There is some evidence that there may be more than one gene responsible for the disease. Since there may be more than one gene at fault, a negative test for HCM will not remove the possiblities that a cat will develop HCM. It will, however, help greatly in determing which cats should continue to breed. Any genetic positive cats or carriers would ideally be removed from breeding programs.
At this time, there are a few items breeders can do to help remove HCM from our breed. First, pedigrees need to be examined to rule out any suspect geneologies that have reoccurring HCM. Any pattern that would indicate a genetic predisposition to the disease would indicate that the cats lineage is not ideal for breeding. Second, breeding animals should be removed from the program is there are suspiscions that HCM could be occuring their offspring. Finally, the use of cardiac ultrasound should be incorporated in a breeding program. The ultrasound should be performed by a board certified cardiologist to ensure that the measurements are accurate. Also, a cardiologist can help with determining any other heart conditions that might be present. If there is a diagnosis of HCM, the breeding animal should be removed from the program. Most breeding animals are scanned with an ultrasound every year. Any potential breeding animal should have an ultrasound at a year old and every year while breeding. Also, after retirment, at least two other scans should be performed if any offspring is to be used in a breeding program. Our cardiologist will state that a negative pet on a test can easily become positive. So routine checks are necessary. Also, a general practitioner veterinarian can listen for murmurs in the heart in between scans to determine if any changes have occurred. These items can help reduce the occurance of HCM, but there is still no way to guarantee that a pet cat will never get HCM.
Most cats do not show external signs of HCM. Many are diagnosed on a physical exam when a murmur is heard. These cats will have an ultrasound performed to determine the cause of the murmur (since many diseases can cause murmurs in the heart). Other signs can be weakness, open mouth breathing, hindlimb paralysis, coughing, anorexia, and vomitting. Many times, none of the signs occur, and the pet is found dead with no obvious causes. When sudden death occurs, a necropsy should be performed by an experienced veterinarian (preferably a veterinarinan pathologist) to determine if HCM is the cause of death. If signs occur, many purebred cats will show signs early. Juvenile ages to older cats have been reported. If HCM present in an older animal (over eight years old) it is less likely to be genetic. In the Spynx, HCM will in most cases show up earlier in males than females. We have great concern with any pet cats that are diagnosed as positive at less than five years old.
Once diagnosed, there are treatments that can be done to help pet cats. A favorite of our cardiologist is to use atenolol in the beginning, but other drugs can be used. If the HCM progresses, more drugs may be added to the treatment. HCM can become severe congestive heart failure, so pet cats will have to be treated based on the condition of their heart.
I hope this gives you some background on HCM. HCM is a disease that breeders and pet owners both should have concern about. We are doing our best to stop the breeding of this disease in the wonderful Sphynx breed.
**Dr. Kate Meurs did a wonderful webinar about HCM in Sphynx Cats. You can watch it by going to the WSU College of Veterinary Medicine or Click Here. There are many wonderful health articles on their website if you wish to do further reading.
**You can locate a Board Certified Cardiologist in your area by looking under "Links" on our Helpful Info page.
**The above page is copyrighted. No portion of the above may be used without written permission of Johnny Gobble!**