How to treat an irregular heartbeat in cats

Disclaimer: This article, its content, and its related references do not constitute veterinary advice and should not be considered a substitute for veterinary care. If your pet is showing any symptoms that could indicate a medical emergency, please seek immediate emergency care.

An irregular heartbeat (cardiac arrhythmia) is the result of a disturbance to the electrical system that regulates heart muscle activity. There are many different types of arrhythmias in cats that affect their heart rate and rhythm in different ways. If your cat has been diagnosed with a heart arrhythmia, read on to learn:

• Symptoms of heart arrhythmias in cats
• Why cats develop irregular heartbeats
• How abnormal heart rhythms are diagnosed and treated

Cats with an abnormal heart rate often don’t have noticeable clinical signs unless the arrhythmia is severe or happens frequently. Sometimes, arrhythmias are caused by an underlying health issue, such as cardiac disease, high blood pressure, hyperthyroidism, or an electrolyte imbalance, and in these cases there may be more obvious clinical signs. Treatment options vary depending on the arrhythmia type, severity, and whether an underlying medical problem is contributing to the abnormal heartbeat.

Cardiac arrhythmias, sometimes referred to as dysrhythmias in human medicine, are irregular heartbeats. “An arrhythmia is the result of a disturbance in the electrical system that regulates the rate and rhythm of the heart, including the coordination of individual heart muscle cells,” explains Dr. Jo Myers, a veterinarian on the Vetster platform. “This coordination allows the heart to beat as a unit to pump blood efficiently.” There are different types of arrhythmias, depending on which part of the heart is affected and what is causing the irregular heart rhythm. Examples include:

• Abnormally slow rate (bradycardia)
• Rate that is too fast (tachycardia)
• Premature contractions of certain parts of the heart (e.g., premature ventricular contractions)
• Unsteady or irregular rhythm
• Abnormally long pauses between heartbeats

Clinical signs of an abnormal heartbeat in cats

Not all arrhythmias cause symptoms, and arrhythmias do not always affect every heartbeat. The frequency and severity of the arrhythmia determine whether or not it produces clinical signs. Symptoms may include:

• Weakness
• Lethargy
• Loss of consciousness
• Difficulty breathing or increased respiratory rate
• Pale gums
• Loss of appetite

If the arrhythmia is being caused by another health issue, cats may have additional signs of illness, such as weight loss, excessive thirst and urination, or vomiting. In rare cases, a severe arrhythmia can cause sudden death. In these cases, the affected cat often has severe heart disease or heart failure.

The electrical system that controls the beating of the heart can be affected by several other abnormalities in the body, such as:

• Hypertrophic cardiomyopathy
• Dilated cardiomyopathy
• Disorders of the heart valves
• Congestive heart failure
• Kidney failure
• Hyperthyroidism
• High blood pressure (hypertension)
• Electrolyte imbalance
• Anemia
• Congenital heart defects
• Cancer
• Pancreatitis
• Toxicosis (from toxin ingestion)

An irregular heart rhythm in cats does not necessarily mean they have another health issue, but diagnostic testing with a veterinarian is warranted to rule out other conditions, such as hypertrophic cardiomyopathy (a common heart disease in cats).

Occasionally, a cat may have a temporary irregular heartbeat due to stress, anxiety, or fear. This is why diagnostic testing with a vet is important to determine if the arrhythmia is clinically significant or being caused by another underlying health issue.

Many cats with abnormal heart rhythms won’t have obvious symptoms unless:

• The arrhythmia is severe or happens often
• They have another condition that’s contributing to the arrhythmia

Abnormal heart rhythms may be heard by veterinarians during a routine physical exam when they listen to the heart with a stethoscope and compare it to the pulse felt in the cat’s rear leg. If this occurs, they may recommend diagnostic tests to fully evaluate and characterize the arrhythmia and to check for other underlying medical issues.

The coordinated, rhythmic contractions of the heart chambers are controlled by electrical impulses from a network of specialized cells in the heart called the cardiac conduction system. An electrocardiogram (ECG) shows the electrical activity within the cardiac conduction system, so it’s used to diagnose heart arrhythmias. This allows the vet to see what type of arrhythmia is occurring and how often it occurs.

Sometimes, a Holter heart monitor may be recommended to measure the electrical activity within the heart for about 24 hours. In addition, a vet may recommend keeping a diary of your cat’s activities, such as sleep and exercise, while they’re wearing the monitor so the effect of activity on heart rate and rhythm can be seen.

Additional diagnostic tests may be recommended to look for abnormalities and illnesses that can contribute to the development of an arrhythmia. These may include:

• Chest X-ray
• Blood tests
• Measuring blood pressure
• Heart ultrasound (echocardiogram)
• Testing for infectious diseases

Treatment options depend on the type and severity of the arrhythmia, as well as whether there are other contributing issues. A treatment plan may include:

• Heart medications, such as antiarrhythmic drugs
• IV fluid therapy for hydration and to replenish electrolytes
• Pacemaker implantation

Pacemakers are more often used in dogs and humans to control arrhythmias, but they can sometimes be used in cats. If there’s another health condition contributing to the arrhythmia, such as another heart condition or hyperthyroidism, the irregular rhythm may go away on its own once the other condition is treated.

If your cat’s been diagnosed with a heart arrhythmia, online vets are available on the Vetster platform to aid in long-term observation and management.

How do you treat arrhythmias in cats?

There are different treatment options for heart arrhythmias in cats, depending on the type and severity of the arrhythmia and whether there’s another contributing health concern. Not all arrhythmias in cats require medical treatment. If they do, affected cats may receive heart medications, IV fluids, a pacemaker placement, or other treatments for other underlying health issues.

How serious is an irregular heartbeat in cats?

Cardiac arrhythmias in cats can vary in severity from benign to potentially life-threatening. It’s important to follow a veterinarian’s treatment instructions if your cat has been diagnosed with a heart arrhythmia.

What causes heart arrhythmias in cats?

The regular, coordinated contraction of the chambers of the heart is controlled by the cardiac conduction system, a highly specialized network of cells that generate electrical impulses to trigger the contraction of a heart chamber. Heart arrhythmias can occur as a result of any disturbance to this system. The abnormality may be limited to the conduction system, or it may be due to another underlying health issue. Cardiac diseases, hyperthyroidism, an imbalance of electrolytes, and kidney disease are common reasons why a cat may develop an arrhythmia.