Heart disease doesn't only occur in humans. Though considered less common in cats than in dogs or humans, heart disease can definitely affect cats. In fact, feline heart disease is often a "silent" disease at first because cats are experts at hiding signs of illness.
What is Heart Disease in Cats?
The term "heart disease" is a general way to describe a number of different disorders that cause abnormal cardiac function. Cats can be affected by one or more types of heart disease.
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 some kind of heart disease is present, it affects the heart's ability to properly circulate blood. Heart disease can prevent the muscles from contracting as needed. Valve diseases can make blood flow in the wrong direction.
Signs of Heart Disease in Cats
- Poor appetite
- Weight loss
- Exercise intolerance
- Shortness of breath
- Labored and/or rapid breathing
- Wheezing and/or coughing
- Pale or blue gums
- Heart murmur (abnormal heartbeat heard by the vet using a stethoscope)
- Arrhythmia (irregular heart rate)
- Acute weakness or paralysis in rear limbs (blockage due to blood clot, called saddle thrombus or thromboembolism)
- Distended abdomen (due to fluid buildup)
- Slow growth in kittens (congenital diseases)
- Sudden death
Note that a heart murmur does not always indicate the presence of heart disease. A heart murmur occurs due to turbulence in the blood flowing through the heart. This can be heard when listening to the heart with a stethoscope and sounds like swishing or whooshing. A heart murmur may occur secondary to a heart condition but can also be caused by something as simple as stress. If your vet detects a heart murmur, it's a good idea to do further testing to rule out heart disease.
Types and Causes of Heart Disease in Cats
Feline heart disease is either congenital (present at birth) or acquired in adulthood. There are many different types of heart disease that can affect cats. Some types of heart disease develop secondary to another disease. Many 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. Congenital heart defects begin in the womb as the fetus is developing.
Ventricular septal defect is the most common type of congenital heart defect seen in kittens. A kitten can be born with a hole in the ventricular septum, a part of the heart that 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 another 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 is somewhat common among congenital heart defects 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 are often weak and tired. They may also develop blood clots.
Pulmonary Stenosis is rare in cats. This heart defect causes blockage 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 backs up. The cat may develop excess fluid around the lungs or in the abdomen.
Aortic Stenosis is another rare rare heart defect in cats that causes 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.
Most congenital heart defects are discovered during a routine examination.
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 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 is rare in cats and occurs 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 severe enough to restrict proper blood flow throughout the body. 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. The 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. Based on the outcome of the testing, your vet may recommend an echocardiogram (heart ultrasound) and electrocardiogram (EKG). Diagnosing heart disease may involve referral to a veterinary cardiologist.
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.
- Diuretics may be used 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 dilate the blood vessels and improve the force of heart contractions.
- Blood pressure medications are used when a cat has high blood pressure as this can worsen heart disease.
- Medications to prevent blood clots may be used when the vet feels the cat is at risk of a blood clot, or thromboembolism.
- Supplements such as antioxidants may be helpful in supporting cardiac function in cats.
How to Prevent Heart Disease in Cats
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. 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.