Symptoms of Hypertrophic Cardiomyopathy in Cats

Hypertrophic cardiomyopathy in cats is a condition in which the walls of the left ventricle of the heart thicken. Thickening of the muscles stiffens them and makes it harder for the heart to pump blood efficiently. Read on to learn more about this condition that can seriously affect your cat's health.

Causes and Risk Factors for Feline Hypertrophic Cardiomyopathy

In hypertrophic cardiomyopathy, the walls of your cat's left ventricle thicken, reducing the heart's efficiency. The left ventricle is the major blood-pumping chamber in your cat's heart, and when the muscle walls of the ventricle thicken, your cat's heart can't work as hard as it needs to. Thickening of the chamber walls makes the chamber smaller, so it holds less blood. Thickening and stiffening of the muscle means that it can't contract and relax properly to pump blood throughout your cat's body.

Vets don't fully understand what causes this feline heart disease. Heredity is thought to play a role. It strikes young adult and middle-aged cats most often. 

Symptoms of Hypertrophic Cardiomyopathy in Cats

In some cats, the symptoms of hypertrophic cardiomyopathy may be so mild as to be unnoticeable. In others, they may quickly become so severe they cause death. In many cats with milder forms of the condition, symptoms appear only when the cat is stressed or frightened, since stress and fright cause an increase in heart rate and a worsening of symptoms. Symptoms of hypertrophic cardiomyopathy in cats include:

  • Exercise intolerance
  • Gagging
  • Loss of appetite
  • Labored or rapid breathing
  • Weakness
  • Depression
  • Lethargy

Cats with hypertrophic cardiomyopathy are at increased risk for congestive heart failure, a condition that occurs when fluids build up in the pulmonary cavity and apply pressure to the heart. Thromboembolism can also occur in cats with hypertrophic cardiomyopathy. In this condition, a blood clot forms in or near the heart, then dislodges and blocks the flow of blood in another part of the body. Often, blood clots lodge in the artery that serves the hind legs, causing paralysis and discomfort in one or both hind legs.

Diagnosing and Treating Hypertrophic Cardiomyopathy in Cats

Your vet will need a complete medical history and a thorough physical exam in order to diagnose hypertrophic cardiomyopathy in your cat. X-rays, ultrasounds and EKGs may be used to make the diagnosis.

Once your cat has begun to show symptoms of hypertrophic cardiomyopathy, the illness may be far advanced. Treatment seeks mostly to improve the cat's quality of life, rather than extend his life.

Drugs such as atenolol and diltiazem can help improve your cat's heart function by relaxing the thickened muscle and reducing heart rate, to allow more time for blood to fill the ventricle between pumps. Drugs such as furosemide can help reduce fluid retention within the body to treat and prevent congestive heart failure. Blood thinners may be given to prevent blood clots. 

Most cats who receive treatment survive an average of two years after being diagnosed with hypertrophic cardiomyopathy.