HYPERTROPHIC CARDIOMYOPATHY – HCM FOR SHORT – IS THE MOST COMMON HEART DISEASE IN CATS. THE DISEASE, THAT ALSO IS FOUND IN HUMANS, CAUSES THE HEART WALLS OF THE AFFECTED ANIMAL TO THICKEN. THE DISEASE CAN NOT BE SEEN FROM BIRTH AS IT DEVELOPS PROGRESSIVELY. SOME CATS WILL SUCCUMB TO THE DISEASE ALREADY WHEN THEY ARE YOUNG, BUT USUALLY THE CAT WILL BE WITHOUT SYMPTOMS FOR A NUMBER OF YEARS. MOST CASES, BUT NOT ALL, CAN BE FOUND BY ULTRASOUND BEFORE THE CAT IS ABOUT FIVE YEARS OLD. THAT IS IF THE EXAMINING VETERINARIAN HAS GOOD EQUIPMENT AND IS EXPERIENCED IN DOING SUCH EXAMINATIONS. HOWEVER, AN AFFECTED CAT HAS A NORMAL LIFESPAN DESPITE BEING AFFECTED. OFTEN THE CAT HAS NO SYMPTOMS UNTIL IT DIES SUDDENLY BECAUSE OF A SEVERE DISTURBANCE OF THE HEART RHYTHM, BY A BLOOD CLOT MOST COMMONLY LODGED NEAR TO OR IN THE HIND LEGS OR BY HEART FAILURE. A POSSIBLE MEDICAL TREATMENT CAN ONLY SERVE TO EASE THE SYMPTOMS OF THE DISEASE, THERE IS NO CURE.

IN THE MAINE COON, RAGDOLL, AMERICAN SHORTHAIR, AND THE BRITISH SHORTHAIR, THE DISEASE SEEMS TO BE INHERITED MAINLY AS A SINGLE AUTOSOMAL DOMINANT GENE. OTHER BREEDS HAVE NOT BEEN STUDIED IN THIS ASPECT, BUT THERE ARE REASONS TO BELIEVE THAT THE INHERITANCE IS SIMILAR. HOW THE DISEASE DOES DEVELOP VARIES THOUGH WITHIN DIFFERENT BREEDS. THERE SEEM TO BE SEVERAL DIFFERENT MUTATIONS THAT CAUSE THE DISEASE, ALSO IN DIFFERENT FAMILIES. THIS IS THE CASE IN HUMANS.