HCM, or hypertrophic cardiomyopathy, is a hereditary disease. It is the most common heart disease in cats and the symptoms usually start at 2 to 4 years of age.
Symptoms can also be detected earlier, especially if both parents have had the disease. Male cats are affected more often than females, and the disease occurs in both purebred and domestic cats.
HCM is a disease that can be difficult for the owner to detect. Symptoms may include loss of appetite, fatigue and shortness of breath. The most common way to suspect the disease is in connection with the annual health check when the veterinarian listens to the cat’s heart. You can hear wheezing or irregular heartbeats, in which case the cat should undergo an ultrasound examination of the heart, at which the diagnosis can be made. The changes in the heart consist of the heart muscles becoming thickened. This means that the cavity in the heart becomes smaller and a smaller amount of blood is pumped out into the body at each heartbeat. Since the blood has to transport oxygen to the body, symptoms of poor oxygenation in the form of poor stamina and shortness of breath then arise.
The disease can also lead to small clots of clotted blood forming in the heart and being excreted into the body. When the blood clot gets stuck in a narrower blood vessel, often where the carotid artery divides into the hind legs, this causes paralysis and pain in one or both hind legs. This is called a blood clot or thrombus.
Thickening of the heart muscle can also be caused by high blood pressure and / or too high metabolism. When diagnosing HCM, it is important to examine the cat for these conditions as well.
Unfortunately, you can not cure or prevent the actual change in the heart, but you can prevent blood clots from developing by giving blood-thinning medication. If high blood pressure or high metabolism is the cause of the heart muscle thickening, the development can be slowed down when these disease states come under control. Once a cat has been diagnosed with HCM, it should be checked approximately every six months. Cats treated with blood-thinning medication should be screened once a year.
Fortunately, most cats that receive proper medication and regular checkups can live long with the disease without suffering from it.