Heart Attacks in Cats

What Are Heart Attacks in Cats?

Heart attacks, also referred to as myocardial infarctions, are very rare in cats.

As with humans, heart attacks occur in cats when a large blood clot blocks blood flow to the heart. This can lead to changes in breathing and heart rate, weakness, and collapse.

Heart attacks can cause discomfort and pain to cats and are generally caused by an underlying heart condition, such as hypertrophic cardiomyopathy, or other systemic illnesses, such as hyperthyroidism.

Heart attacks most commonly happen in cats with pre-existing heart disease. They have a higher risk for blood clots because of the changes in the shape and function of their hearts. Parts of the heart can become enlarged or thickened and less efficient at pumping blood, which means that more blood collects in the heart chambers, which can form clots.

Heart attacks are often fatal, and cats showing signs of this condition should be brought to a veterinarian immediately.

Because heart attacks in cats are rare, there’s not much research available about survival rates, but cats in serious condition when seen by the veterinarian may not survive.

Symptoms of Heart Attacks in Cats

Many symptoms of a heart attack in cats are nonspecific and can be caused by a variety of conditions.

Taking your cat to a veterinarian for the right diagnosis is important if you notice any abnormal behaviors or symptoms.

Symptoms of heart attacks in cats may include:

• Difficulty breathing

• Panting

• Changes in heart rate

• Lethargy

• Changes in behavior, such as hiding or vocalizing

• Collapse

Blood clots in the heart that cause a heart attack may also break off and travel down the aorta (main artery) to cause a blockage in a condition known as saddle thrombus. This can lead to back leg weakness, paralysis, or legs that feel cold to the touch, in addition to the symptoms listed above.

Causes of Heart Attacks in Cats

Heart attacks in cats are caused by underlying diseases. Possible causes include:

• Hypertrophic cardiomyopathy is the most common heart condition in cats. It causes major changes to the walls of the heart and can lead to blood clots, since blood is not pumped through the heart very well. Ragdolls and Maine Coon cats have a higher risk of this condition because of their genetics.

• Hyperthyroidism is common in senior cats; it causes hypertension (high blood pressure) and can lead to heart disease, both of which can increase the risk of a heart attack. 

• Endocarditis is inflammation (swelling) of a cat’s heart lining from infection, which can result in blood clots forming within the heart and other blood vessels.

• Heartworm disease causes major damage to the heart and lungs, increasing the risk for blood clots. Indoor cats are still at risk, since mosquitoes can easily enter homes and spread the disease if the cat is bitten.

• Disseminated intravascular coagulation is a rare condition in cats that results in abnormal blood clot formation. It’s usually caused by another underlying disease, such as lymphoma.

How Veterinarians Diagnose Heart Attacks in Cats

Since heart attacks are medical emergencies, veterinarians will at first work quickly to stabilize the patient and provide life-saving treatment. Pet parents should let their veterinarians know when symptoms started, if their cat is taking any medications, and if their cat has been previously diagnosed with a medical condition.

Once the cat is stabilized, the veterinarian will try to determine the underlying cause of the heart attack. A thorough physical exam is done to find abnormalities. Testing may include:

• Blood work—A small sample of blood is collected to check for signs of infection, inflammation, clotting abnormalities, or internal diseases.

• X-rays—Pictures of the chest and abdomen may be taken to check for heart enlargement, fluid in the abdomen or lungs, or changes to blood vessels. 

• Echocardiography—A heart echo is a specialized test that uses sound waves to make detailed pictures of the heart. It’s used to diagnose underlying heart disease.

For cats in very poor condition when arriving at the veterinary hospital or who die at home, a postmortem examination is needed to get the right diagnosis.

Treatment of Heart Attacks in Cats

Because a cat having a heart attack is an emergency, treatment is mostly supportive at first. Oxygen therapy, intravenous (IV) fluids, anti-clotting medications, antibiotics, and pain management may be started.

After stabilizing, the main treatment goal is to get rid of the blood clot, which can be done using medications or surgery depending on the location and severity of a cat’s condition. A cat’s chance of recovery is usually not good, even with treatment, because of the seriousness of a heart attack.

Cats who do recover will be sent home on medications specific to the underlying disease. For example, cats with hypertrophic cardiomyopathy may receive beta blockers and ACE inhibitors (medications that decrease blood pressure and treat arrythmias). A veterinarian will prescribe medications that are right for each cat.

Recovery and Management of Heart Attacks in Cats

Recovery from a heart attack depends on the underlying cause, how quickly treatment is started, and the cat’s overall condition. Supportive care may help a cat having a heart attack if it is diagnosed early. However, heart attacks in cats are often fatal.

Cats that do survive often will have lasting damage to their hearts. This may result in exercise intolerance, weakness, and a failure to thrive.

Cats who have recovered from a heart attack should be kept in low-stress situations to not make extra work for their hearts. Keeping them separated from other household cats, or dogs if they do not get along, and keeping a consistent routine at home is helpful.

Pet parents should bring their cats to all veterinary follow-ups during their recoveries.

Prevention of Heart Attacks in Cats

Keeping your cat healthy with regular preventative veterinary care is important to catch diseases that can cause heart attacks.

During routine wellness visits, veterinarians can run blood work to check for signs of inflammation, infection, and metabolic diseases, such as hyperthyroidism. They are also able to complete a physical exam and listen to your cat’s heart and lungs to find issues that call for more testing or treatment.

Cats should be kept current on heartworm preventatives, such as Bravecto® Plus, year-round to prevent heartworm disease that can damage the heart and lungs.