Causes of Heart Disease in Cats

A summary of diseases that cause feline heart disease

Close-Up Of Cat
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Heart disease in cats is frequently diagnosed and it can be a frightening situation for a cat owner. There are many different diseases that can affect the heart of the cat.

Cardiomyopathies - the Most Commonly Diagnosed Feline Heart Disease

Cardiomyopathies affect the muscle of the heart and cause weakness of the heart itself. There are four forms of cardiomyopathy that are seen in cats.

  • Hypertrophic cardiomyopathy is the most commonly diagnosed heart disease in cats. In hypertrophic cardiomyopathy, the heart muscle is thickened and cannot perform properly, which causes abnormal heart function.
  • Dilated cardiomyopathy was previously diagnosed frequently as a result of a taurine deficiency in the diet. Most feline diets now contain adequate amounts of taurine and dilated cardiomyopathy is less frequently diagnosed than in the past.
  • Restrictive cardiomyopathy is a poorly understood form of cardiomyopathy that results in excessive stiffness in the ventricles of the heart.
  • Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a form of cardiomyopathy that affects the right side of the heart.

Feline Heart Disease and Hyperthyroidism

Feline hyperthyroidism results in elevated thyroid hormone levels in the bloodstream. These elevated blood hormone levels can have a toxic effect on the heart causing heart disease.

Thromboembolism (Blood Clots) and Heart Disease in Cats

Thromboembolism occurs when blood clots form in one of the chambers of the heart and then break off and pass through the bloodstream. Eventually, these blood clots become lodged within a blood vessel.

Although a blood clot may lodge in other areas, the most common location for a blood clot to lodge is at the end of the aorta which is in the area between the hind legs. This is known as an aortic thromboembolism. A blood clot in this area cuts off the blood supply to the hind legs. When this happens, the cat is no longer able to use the hind legs properly and will drag the legs.

Congenital Heart Defects in the Cat

Congenital heart disease can occur also in the cat. There are several types of congenital defects that can be seen in the feline heart.

  • Malformation (also known as dysplasia) of the valves of the heart is sometimes seen.
  • Ventricular septal defects are essentially "holes" which occur between the two ventricles of the heart. These defects are sometimes diagnosed in the cat also.
  • Atrial septal defects can also occur and are "holes" which occur between the two atria of the feline heart, rather than the ventricles.
  • Other rarely seen defects are patent ductus arteriosus (PDA), aortic stenosis and tetralogy of Fallot. PDA occurs when there is an abnormal vessel connecting the aorta and the pulmonary artery that causes the blood to bypass part of the heart. An aortic stenosis is a narrowing of the large vessel known as the aorta that exits the left ventricle of the heart and carries the blood to the rest of the body. Tetralogy of Fallot is a combination of four separate developmental defects within the heart.

Other Causes of Heart Disease in Cats

Other potential causes of heart disease in cats include injuries and infections with parasites such as feline heartworms.

Recognizing the signs of heart disease in cats can be challenging. Proper diagnosis of the cause of heart disease is essential to determine the proper course of treatment as well as the prognosis and home care for the cat.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.