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Cardiomyopathy means disease of the heart muscle; feline hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats. It can be primary or idiopathic i.e. with no known cause, and is typically seen in younger (usually male) cats.
Or it can be secondary meaning resulting from other disease conditions e.g. kidney problems, diabetes, hyperthyroidism, etc. This is typically seen in older cats, and in some ways is more challenging to treat.
Boo Boo my fluffy black boy, the love of my life developed HCM as a result of kidney insufficiency around age 10. Three and a half months after his passing, as karma would have it, Boo sent me Trikki, an even fluffier orange fella who as it turned out had primary HCM. With homeopathy, and all I learned from Boo Boo, Trikki's heart (as per ultrasound) and kidneys (as per blood work e.g. BUN, creat, etc) remained perfect until his last day; alas, we lost him to lymphosarcoma.
Cats with hypertrophic cardiomyopathy have excessive thickening (stiffening) of the left ventricular wall, the papillary or small muscles that anchor the heart valves, and the thin membranous structure between the two atria or the thick muscular structure between the two ventricles called the septum. In some cases, cats can have concentric/symmetric cardiomyopathy where there is thickening all around not just the left ventricle.
Symptoms of hypertrophic cardiomyopathy
Many cats with hypertrophic cardiomyopathy are asymptomatic. Sometimes there is no inkling of a problem until “sudden death”. Yet another reason to treasure each day with our little ones.
When cats do display symptoms, one sees inappetance, poor energy including not as much interest in playing. If the problem is more serious, there can be difficulty breathing. Sometimes there is a "cardiac cough" as well.
Your cat’s vet can tell a lot by listening to the heart with a stethoscope e.g. a heart murmur, a gallop rhythm/irregular heart rhythm, and/or a rapid heart rate. S/he may elect to do a chest x-ray to check for pulmonary edema and/or heart enlargement.
If some or all these signs are present, the vet may refer you to a cardiac specialist who in turn will perform an Electrocardiography (ECG) to check electric activity such as heart rhythm, and/or ultrasound scan to confirm if the heart walls are thickened. If at all possible, get Doppler imaging because it will provide information regarding blood flow direction and velocity.
It is important to get a copy of your cat’s ultrasound report so you can be proactive. Monitor your cat’s blood pressure regularly, and get an honest evaluation from the cardiologist as well as your regular veterinarian regarding risk of Congestive Heart Failure (CHF) and/or saddle thrombosis (left atrial enlargement is one clue).