Heart Disease and Your Cat

We want to pump you up!

The heart is pretty much a never-resting, pumping muscle. Blood flows from the body into the heart and once inside, the blood travels through four chambers. The top chambers are called the atria and the bottom chambers are called ventricles. The chambers are named after which side of the heart on which they are located. The atria and the ventricles are separated by valves. These valves open and close with each heartbeat (a heartbeat is a cycle of muscle contraction and relaxation that pushes the blood through). These valves are very important in preventing the blood from flowing in the wrong direction during a heartbeat. Below is the flow of blood:

From organs through veins →
Vena cava →
Right Atrium →
Tricuspid valve →
Right ventricle →
Pulmonary valve →
Pulmonary artery →
Lungs →
Pulmonary veins →
Left atrium →
Mitral valve →
Left ventricle →
Aortic valve →
Aorta →
Back out to organs through arteries

This flow of blood from organs, to and though the heart, through the lungs and back out to organs is a very important function in sustaining a healthy life. It allows for deoxygenated blood to pass through the lungs and become oxygenated and then carry the oxygen to the organs. Without oxygen, organs would not be able to function and would eventually shut down. Being able to catch anything that could hinder this flow is extremely beneficial to your pet living a long healthy life.

We Cats

For our feline family members, the most common acquired heart disease is cardiomyopathy (structural changes in the heart muscles causing them to become thickened).

  • 75% of all diagnosed feline heart disease is a form of cardiomyopathy.
  • There are three forms of cardiomyopathy: Hypertrophic, Restrictive and Dilated.
  • Some studies show that there is an inherited cause.
  • The largest percent of cases are considered primary which means the cause is unknown.
  • Some cases can be secondary due to anemia, hyperthyroidism and/or elevated blood pressure.
  • Cardiomyopathy commonly affects the left ventricle.
  • Most commonly seen in middle to older age but can occur in young cats.
  • Males are at a greater risk than females.

Breeds most commonly affected by cardiomyopathy

Main Coon
Common Short-hair cats
Dilated Cardiomyopathy (DCM)
Dilated cardiomyopathy is very rare to see in cats, only in 1-2% of cases. DCM causes dilation of the left ventricle which decreases the ability of the heart to contract. The decrease in contractions causes the heart to act as a weak pump.
Restrictive or Unclassified Cardiomyopathy (RCM/UCM)
RCM/UCM is uncommon to see in cats, only in 10% of cases. RCM/UCM is caused by a buildup of scar tissue inside the ventricle along the inner lining of the muscle. This scar tissue prevents the complete relaxation or filling phase and the contraction or emptying phase of each heartbeat.
Hypertrophic Cardiomyopathy (HCM)
Most common cardiomyopathy, diagnosed in 85-90% of cases.
Means “thick heart muscle disease.”
Left ventricle is most commonly affected by the thickening of muscle tissue. This results in poor relaxation and contraction phases. This in turn results in a decrease of blood pumped out into the body, causing a backup of blood into the left atrium and into the lungs. Blood backing up into the lungs is the start of congestive heart failure.
Because the blood cannot flow correctly into the left ventricle it pools inside the left atrium. This pooling is what causes the formation of a blood clot. Once dislodged, this clot travels through the left ventricle to the aorta and then down to the rear limbs where the arteries become smaller to pass the clot. This results in the cat becoming paralyzed. It is extremely painful.
Most cats are asymptomatic or show no signs of there being any heart issues.
Sometimes there can be changes in heart rate, heart sounds, and/or heart rhythms.
Changes to the heart and its structure are irreversible.

A Weakened Heart Can Still Love Strongly!

The most important thing you, as an owner, can do for your cat is to make sure they are getting routine examinations by a veterinarian. Early detection and treatment are two ways to make sure your cat can live a long healthy life.

Examination – This is key to early detection. This time allows you to talk to the doctor about any changes you have noticed in your cat. This also allows the doctor to listen to your cat’s heart. They can hear the heart’s rate, rhythm, and if any heart murmurs are present. If there is a heart murmur, the doctor will be able to tell where it is located and the severity. At this time the doctor may suggest more diagnostic testing.
  • Bloodwork: To check for any changes in organ functions, white blood cell counts, red blood cell counts, platelet count, and heartworm disease.
  • Radiographs: This allows the doctor to evaluate the size of the heart, to check for any tumors/masses, as well as looking at the lungs.
  • Electrocardiogram (ECG/EKG): This is a test that records the electrical and muscular function of the heart.
  • Echocardiogram: Ultrasound of the heart tells the size of chambers, the thickness of the muscles, the function of the valves, and the ability of the heart to contract. These are also used to check for leaks by following blood flow through the heart. Since cat heart diseases usually change the heart muscle an echocardiogram is usually the best way to detect these changes early.
Treatments – Once a problem has been diagnosed, the veterinarian will start a treatment plan. These plans can vary based on the cat and the needs of that cat as well as the severity of the disease. Below are common drugs that are used either separately or in combination as part of the treatment.
  • ACE Inhibitors (angiotensin-converting enzyme): Used to open constricted blood vessels, reduce high blood pressure and reduce the onset of congested heart failure. It also helps block the activation of hormone (renin-angiotensin-aldosterone) stimulation. In healthy cats this hormone has a positive effect on the kidneys, but in cats with heart disease it can produce a negative effect on the kidneys. Commonly called: Enalapril, Benazepril, and Ramipril.
  • Beta-Blocker: Helps slow down the heart rate and also reduces the oxygen demand on the heart. Commonly called: Atenolol, Propranolol.
  • Calcium-Channel Blocker: Decreases the heart rate and the strength of the heart contractions. Helps the heart muscle relax and decreases the oxygen demand on the heart.
  • Diuretics: Helps remove excessive fluid that tends to build up within the lungs and body. Commonly called: Lasix or Furosemide.

Other things to consider are diet and exercise. A diet that is sodium (salt) restricted as well as eliminating “people food” may be helpful in some cases. Exercise is very important for all cats, but, cats with heart disease may need to be limited. The best plan is to ask your veterinarian for a recommendation.

At-Home – There are things that you can monitor/watch for at home.
  • Decreased eating
  • Depressed acting/withdrawn
  • Weight loss
  • Less playful
  • Sleeping/resting more than usual
  • Weakness
  • Changes in breathing: difficulty, shortness, labored, rapid
  • Fainting spells – Usually related to irregular heart beat (very uncommon)
  • Restlessness especially at night
  • Changes in gum color: Deep pink-normal healthy gums, Pale pink to white-Anemia, Gray/blue-decrease in oxygen level (Some cats have a dark pigmentation of gums, lips and/or tongue. Usually black to purple in color.)

Early detection, starting the appropriate treatment, and close monitoring by you will help your cat live a long and healthy life. Your cat has a special place in our hearts so we want to make sure we do all we can to take care of theirs.