Feline Hypertrophic Cardiomyopathy

Hypertrophic Cardiomyopathy (HCM) is a heart-related disease that affects 10% to 15% of cat breeds like the Maine Coon, Persian, Ragdoll, and Sphynx. HCM causes the wall in a cat’s heart to thicken. The thicker heart wall causes a decrease in the heart’s efficiency which can cause problems in other parts of the body. 

As the left ventricle thickens, the volume of blood that can be in the heart chamber decreases. The heart’s thickening can cause the heart to beat rapidly, using more oxygen in the process. If the heart can’t efficiently pump blood, it can starve the heart of oxygen. Oxygen starvation of the heart can cause cells in the heart to die which can make the heart even less efficient. A less efficient heart can lead to arrhythmias (a condition where the heart beats too rapidly). The less efficient pumping can cause blood to backup in the other heart chamber and lungs. The blood backing up can lead to congestive heart failure as well as causing blood clots to form in the heart.

The exact cause of HCM is not known. Doctors believe that genes play a role because only certain cat breeds are diagnosed with HCM.

Symptoms of Feline Hypertrophic Cardiomyopathy

Many cats that have Hypertrophic Cardiomyopathy don’t show any symptoms of being ill and live normal lives. These symptoms that they can have include:

  • Labored and fast breathing
  • Lethargy
  • Open-mouthed breathing
  • Congestive heart failure

These symptoms often occur as a result of fluids collecting in or around the lungs.

The formation of blood clots in the heart is potentially the most life-threatening condition. As the blood clot flows through blood vessels, they can cause blockages in the vessels preventing proper blood flow to other body parts. This condition is known as thromboembolism. Cats with HCM often get blockages in their hind limbs, causing acute hind limb pain. In extreme cases, the blockages can lead to hind limb paralysis.

Proper treatments and early diagnosis can decrease the symptoms and probably prevent thromboembolism from occurring. While rare, pets with HCM have an increased risk of sudden death.

Diagnosis of Feline Hypertrophic Cardiomyopathy

An Echocardiography can be done on an animal to check if they have HCM. Echocardiography is a test that uses sound waves to create a detailed image of the heart. The veterinarian will observe the image for thickened heart muscles and compressed left ventricles in the heart. 

The veterinarian will sometimes request a radiography or electrocardiography test to attempt to diagnose HCM. Thick heart muscles and compressed ventricles in the heart are also seen in patients with high blood pressure and hyperthyroidism. Make sure to point out if your pet also suffers from these conditions.

There are some new genetic tests that can identify HCM, but these should be done by a veterinary professional. Because not all cats with these specific genes will inherit HCM.

How HCM Hides

Most HCM patients can easily be overlooked because their early-stage symptoms can be hard to detect. If a heart murmur or arrhythmia is heard during the animal’s annual health check-up, get a detailed check-up of their heart.

Treatment for FelineHypertrophic Cardiomyopathy

There is no cure for Hypertrophic Cardiomyopathy, specialized care plans only suppress the symptoms. 

The only treatment currently available is medication. While cats with a mild case can be treated orally, more advanced cases may need to be given a shot and medicine like nitroglycerine that can be applied to their skin.

These medications are given to control the heart rate, reduce pulmonary congestion, remove pleural fluid if present, and reduce the chance of thromboembolism.

There are no vaccines to prevent your cat from getting HCM, and nothing can be done for your cats’ health until symptoms appear.

Prognosis of Feline Hypertrophic Cardiomyopathy

The eventual progression for Hypertrophic Cardiomyopathy is unpredictable because it differs based on the first symptom a cat has. Cats that have no symptoms can live many years with only slight breathing difficulties, while cats with different first symptoms will have a different progression of the disease.

Because HCM is a progressive disease, the worst cases include congestive heart failure, thromboembolism, and hypothermia (low body temperature). In many cases, medical therapy can significantly improve your cat’s quality of life

Related Questions

How Long can Cats with Feline Hypertrophic Cardiomyopathy Live?

Because the course of the disease is unpredictable, the lifespan of a cat with HCM varies with their symptoms. While an animal who has no symptoms can live a normal life, once symptoms appear, they will likely die within two years of the first symptoms appearing. If the first symptom is blood clots, the cat will likely only live for about six months.

Is Feline Hypertrophic Cardiomyopathy Painful?

Blood clotting is a symptom of this disease, and blood clots prevent blood from reaching some muscles. Blood clots can cause extreme pain and paralysis and are often fatal. Difficulty breathing also comes with the disease which can add to the pain.