Unlike humans, who most suffer from disease of the coronary arteries, and dogs, that most usually suffer from disease of the heart valves, cats usually suffer from disease of the heart muscle itself, a condition known as cardiomyopathy.

Signs Your Cat May Have Heart Disease

The main sign shown by a cat with a cardiomupathy is labored respiration caused by a build-up of fluids on the lungs, as well as lethargy and lack appetite. Some cats suddenly become paralyzed in their hind legs due to a blood clot forming in the main arteries, resulting from the poor circulation. A radiograph of the heart will often diagnose the heart problem, although fluid may have to be drawn of the lungs before a diagnostic X-ray can be taken. A referral center may use more specialized techniques such as an electrocardiograph to measure the electrical activities of the heart, an echocardiograph to record the heart sounds, and ultrasound, which can make visible the flow of blood through the heart.


The condition is caused by degeneration in the heart muscle itself (as opposed to disease of the heart valves, which is by far the commonest condition in the dog). It can take two firms – dilated cardiomyopathy, where the heart muscles become weak and dilated, and hypertrophic cardiomypathy, where the heart muscle becomes greatly thickened and loses its ability to expand and contract properly.

Dilated cardiomypathy used to be quite a common condition, until it was discovered that the major cause of the problem is deficiency of an amino acid called taurine in the diet. Although the vast majority of cats were able to manage perfectly well on the levels previously recommended in commercial cat foods, some cats seemed to have a higher requirement than others. Since this has discovered, the manufacturers of cat foods have boosted the levels of taurine in their diets. As a result, the incidence of the problem has been greatly reduced to the point where is it not only likely to be seen in cats eating very poor quality commercial or home make diets.

Hypertrophic cardiomyopathy can develop when a cat suffers from chronically high blood pressure, although this cannot easily be measured. An overactive thyroid is one of the major causes of the condition, although in many cases no underlying cause can be found.

About 2 per cent of cats born with congenital heart disorder, ranging in severity from those that show no clinical signs through their life, to those that die of the problem sooner after birth. Affected cats tent to grow less quickly than others in the litter, they tire quickly and may develop breathing difficulties.


If an underlying problem causing cardiomyopathy, such as an overactive thyroid or a dietary deficiency, can be corrected, then the long term outlook for the cat is quite good, but often the best that can be achieved is permanent drug treatment to try and control the problem, including the use of anticoagulants to try and prevent unwanted blood clots from forming. The life expectancy for a cat with severe congenital heart disease is poor, but surgical correction can sometimes be attempted.