While heart disease is considered more common in humans and pets like dogs, cats are still susceptible to developing these health concerns. In fact, feline heart disease is often a "silent" disease at first because cats are experts at hiding signs of illness. If left untreated, heart disease can cause other serious symptoms in the body and potentially be fatal. Different types of heart conditions can affect many breeds of cats, but some like Maine Coons, American and British Shorthairs, Persian cats, Ragdoll, Sphynx, Burmese, and Siamese cats are more susceptible to certain problems including cardiomyopathy. Heart disease can be present from birth due to heart defects, but it can also be acquired later in life from causes like other feline health problems. If you notice symptoms like lethargy, changes in appetite, breathing problems, pale gums, or even collapse, it's important to take your cat to the veterinarian right away.

What Is Heart Disease?

The term "heart disease" is a general way to describe a number of different disorders that cause abnormal cardiac function and affect the heart. Cats can experience one or more types of heart disease at the same time.

The heart is divided into four chambers: The left atrium and right atrium are the upper chambers; the right ventricle and left ventricle are the lower chambers. Oxygenated blood from the lungs enters the left side of the heart and is then pumped throughout the body, delivering oxygen to the tissues and cells.

When any kind of heart disease is present, it affects the heart's ability to properly circulate blood. Heart disease of the muscles can prevent the muscles of the heart from contracting as needed. Valvular heart diseases can make blood flow in the wrong direction.

Symptoms of Heart Disease in Cats

Heart disease can cause a large variety of symptoms. Your veterinarian might hear a murmur when listening to your cat's heart through a stethoscope, which can be further diagnosed after observing any of the following additional symptoms:

Heart Murmur

A heart murmur does not always indicate the presence of heart disease in cats (and not all cats with heart disease have murmurs). This occurs due to turbulence in the blood flowing through the heart. A murmur sounds like swishing or whooshing through a stethoscope. This may occur secondary to a heart condition, but it can also be caused by stress. If your vet detects a heart murmur, it's a good idea to do further testing to rule out heart disease.

Lethargy

If your cat is acting lethargic, it may also be accompanied by symptoms like weakness, exercise intolerance, or even collapse. Heart disease prevents the heart from functioning normally, so any type of physical activity may cause your cat's energy levels to significantly decrease.

Changes in Appetite or Weight

Your cat may lose its appetite or become anorexic (refusing to eat) when dealing with heart disease. This can also lead to weight loss, which can happen quickly depending on the severity of the condition.

Irregular Breathing

Labored or rapid breathing is common in cats with heart disease when the heart is unable to transport oxygen normally throughout the body. Shortness of breath, wheezing, and coughing may also occur, though coughing is a less common sign of heart disease in cats than in humans or dogs.

Pale or Blue Gums

Pale gums are a telltale sign of heart disease in cats and many other animals. This is because the heart cannot pump normal levels of blood throughout the body, leading to blood loss in tissues.

Arrhythmia

Arrhythmia means that your cat's heartbeat is irregular. This can be caused by heart disease, but doesn't necessarily mean that your cat has heart disease. An irregular heartbeat should always be further diagnosed by your veterinarian.

Acute Weakness or Paralysis

In its hind limbs, your cat may experience acute weakness or paralysis, which is caused by blood clots (thromboembolism). This is a serious sign that can lead to heart attacks.

Distended Abdomen

Heart disease commonly affects other organs like the liver. This can cause the liver to become enlarged, which in turn makes your cat's abdomen appear swelled (distended).

Stunted Growth in Kittens

If your kitten is not growing at a normal rate, heart disease may be the underlying reason. Always monitor the growth of kittens with supervision from your veterinarian.

Sudden Death

Because heart disease can lead to conditions like arrhythmia and blood clots, it's possible for cats with these diseases to experience heart attacks that may be fatal. These serious conditions should always warrant a prompt visit to the veterinarian to begin diagnosis and treatment as early as possible.

Causes of Heart Disease

Feline heart disease is either congenital (present at birth) or acquired in adulthood. There are many different types of heart disease that affect cats. Some types of heart disease develop secondary to another health condition, while others are hereditary and known to affect certain cat breeds.

Congenital Heart Disease

Congenital heart defects are uncommon in cats. These disorders may or may not be genetic, and many are discovered during a routine examination or cardiology exam. Congenital heart defects begin in the womb as the fetus is developing, and may include these conditions:

• Ventricular septal defect is the most common type of congenital heart defect in kittens. A kitten can be born with a hole in the ventricular septum, which separates the left and right ventricle and keeps blood from flowing into the wrong chamber. If the cat has a small hole in the ventricular septum, there may be no noticeable signs. These cats can often live normal lives. Signs are typically seen when a cat has a medium or large hole in the heart. Congestive heart failure can occur with very large holes.
• Patent ductus arteriosus is the second most common congenital heart defect in cats. A developing fetus has a blood vessel that connects the aorta and pulmonary artery (leading to the lungs). This vessel is supposed to close up soon after birth. When the vessel fails to close, the kitten will have too much blood flowing from the heart to the lungs. While PDA can cause heart failure, it may be surgically repaired by a veterinary surgeon when the kitten is a few months old.
• Mitral valve dysplasia (MVD) is another congenital heart defect in cats. The mitral valve regulates the blood flow from the left atrium to the left ventricle. When a cat has MVD, the blood cannot flow properly and builds up in the left atrium. Cats with MVD may be weak and tired. They may also develop blood clots.
• Pulmonary stenosis is rare in cats. This heart defect causes a narrowing of the pulmonic valve, which is responsible for pumping blood from the heart into the lungs via the pulmonary artery. This obstruction may cause the blood to back up. The cat may develop excess fluid around the lungs or in the abdomen.
• Aortic stenosis is another rare heart defect in cats that causes a narrowing of the aortic valve, which pumps blood from the heart to the rest of the body. Lack of adequate blood flow throughout the body can cause a variety of complications.

Acquired Heart Disease

Most forms of heart disease in cats are acquired in adulthood. Some develop due to genetic predisposition while others may be connected to other health issues like obesity, hypertension, kidney disease, and hyperthyroidism.

Most cardiac disorders diagnosed in cats are called cardiomyopathies. The term "cardiomyopathy" simply means a disease or disorder of the heart and is used to describe structural or anatomical abnormalities in the heart. Cardiomyopathy has several forms:

• Hypertrophic cardiomyopathy (HCM) is considered the most common form of heart disease in cats and is generally a common health issue in cats. HCM causes thickening of the heart walls. It especially affects the left ventricle, making it difficult to pump blood throughout the body. HCM may cause the heart to beat too fast, preventing oxygen from reaching the cells. HCM often leads to congestive heart failure. Predisposed cat breeds include the British Shorthair, Chartreux, Maine Coon, Persian, Ragdoll, and Sphynx.
• Restrictive cardiomyopathy occurs when there is excess scar tissue on the lining of the ventricle. This keeps the heart from effectively contracting and expanding to pump blood. Restrictive cardiomyopathy typically affects older cats. The Burmese breed may be predisposed.
• Dilated cardiomyopathy (DCM) is rare in cats, occurring when the left ventricle is enlarged and has difficulty contracting. DCM was once more common in cats as it was connected to an insufficient amount of taurine in the diet. Commercial diets that follow AAFCO guidelines have the appropriate amount of taurine for cats, therefore DCM is rarely seen in cats today.

Congestive Heart Failure 

The term "congestive heart failure" broadly refers to heart disease that is so severe that the heart is unable to pump blood forward through the body, causing fluid to back up and accumulate in the lungs or abdomen. CHF is a life-threatening condition. Any of the above conditions can lead to CHF in cats.

In general, the term heart disease is used in earlier stages, while heart failure is used in advanced stages. Cats with heart disease may simply be monitored or administered basic treatments, while cats with CHF need more aggressive treatment.

Cats of any age or breed can suffer from CHF, but it is most common in middle-aged and senior cats.

Diagnosing Heart Disease in Cats

If your cat has any signs of heart disease, it's important to get to the vet as soon as possible. Your veterinarian will gather information about your cat's history and current clinical signs, then perform a physical examination. If the vet hears a heart murmur or otherwise suspects a heart problem, further testing will be needed.

Most vets will first recommend thoracic radiographs (chest X-rays) and general lab work (blood chemistry, complete blood count, urinalysis). Your cat's blood pressure may also be checked. The definitive diagnosis will be obtained via an echocardiogram (heart ultrasound). Diagnosing heart disease may involve referral to a veterinary cardiologist.

Treatment

The appropriate treatment for your cat's heart disease depends on the type and severity of the heart disease. Unless there is a congenital defect that can be corrected with surgery, feline heart disease is typically treated with medication. Medication does not fix a diseased heart but tries to help support the heart and body.

Your vet may prescribe diuretics to reduce fluid buildup around the lungs or in the abdomen. ACE inhibitors can help relax the blood vessels, enabling the heart to pump blood with less effort and lowering blood pressure. Pimobendan can help improve the force of heart contractions, while blood pressure medications are used when a cat has high blood pressure as this can worsen heart disease. Your veterinarian may also recommend medications to prevent blood clots or supplements such as antioxidants to support cardiac function.

Prognosis for Cats With Heart Disease

Because there are so many types of heart disease, your cat's prognosis will depend upon the specific condition that is diagnosed. Some forms of heart disease are mild and require only lifestyle changes or medication for the cat to live a happy, healthy life. However, severe forms of heart disease can be life-threatening and require aggressive treatment, and fatalities are still possible.

How to Prevent Heart Disease

Heart disease in cats cannot always be prevented. Because some forms of heart disease are hereditary, a cat with heart disease should not be bred. These cats should be spayed or neutered to prevent passing on the disease to another generation.

The best way to prevent heart failure in your cat is to take your cat to the vet at least once a year for a routine wellness exam. Listening to your veterinarian's guidance on cat food is also important. Your vet may detect a heart murmur or other sign that indicated early disease. The sooner your cat's heart disease is detected, the better the chance of treating it before the signs become severe.