Irregular Heartbeat (Cardiac Arrhythmia) in Cats

What Is a Cardiac Arrhythmia in Cats?

An irregular heartbeat, or cardiac arrhythmia, happens when the heart beats at an abnormal rate or follows an abnormal pattern.

The heartbeat, along with the heart function, is controlled by a series of electrical impulses originating from various regions within the heart muscle. The sinoatrial node (SA node), a group of muscle fibers in the upper right atrium of the heart, is where the signal is generated, instructing the heart to beat. This signal travels through the upper heart chambers (atria), passes to the atrioventricular (AV) node, and finally reaches the lower heart chambers (ventricles), prompting the heart’s contraction. When the heart beats, it pumps oxygen-rich blood throughout the body, sustaining life. Any disruption of electrical impulses leads to an irregular heartbeat.

Underlying causes that can trigger a heart arrhythmia, which can be temporary or permanent. Some of these conditions may result in illness, while others may not. Although relatively uncommon, cardiac arrhythmias can occur in cats of any age, breed, or sex.

Symptoms of Cardiac Arrhythmia in Cats

Symptoms of an arrhythmia are uncommon unless they indicate an underlying disease or the arrhythmia has been present for a long time.

A veterinarian can hear an irregular heartbeat using a stethoscope. These irregularities can include the heart beating too fast, too slow, or skipping beats. Additionally, your vet might hear a heart murmur caused by an abnormal blood flow between heartbeats.

Symptoms of heart disease that might be noticeable in cats include:

• Lethargy and depression

• Weakness

• Sleeping more

• Vomiting

• Reduced appetite

• Coughing

• Rapid breathing

• Open-mouth breathing, difficulty breathing

• Exercise intolerance

• Fainting

• Unsteady gait while walking

• Pale or bluish mucus membranes or skin

If you notice any of these symptoms in your cat, take them to their veterinarian for an examination immediately.

Causes of Irregular Heartbeat in Cats

Certain breeds, particularly brachycephalic (smooshed-face) cats like Persians and Himalayans, as well as Maine Coon cats, are more prone to cardiac arrhythmias than others.

A variety of causes can lead to cardiac arrhythmias in cats including:

• Sinus arrhythmia (normal in dogs, but abnormal in cats): increased heart rate when breathing in and decreased heart rate when breathing out

• Heart disease

• Taurine (amino acid) deficiency

• High blood pressure

• Hypoxemia (low oxygen concentrations in the blood)

• Hyperthyroidism

• Electrolyte imbalances

• Medication reactions

• A birth defect

• Anemia

• Tumors

• Trauma

• Toxin ingestion

• Heartworm disease

• Disease of the spleen, kidney, liver, gastrointestinal tract, or brain

How Veterinarians Diagnose Cardiac Arrhythmia in Cats

An abnormal heartbeat can typically be heard using a stethoscope. Not all arrhythmias indicate underlying heart disease, but investigating them is important to ensure your cat remains as healthy as possible.

To determine the presence, type, and severity of an arrhythmia, your vet will do an electrocardiogram (ECG or EKG) of your cat’s heart. Once an arrhythmia has been diagnosed, your vet will likely recommend further testing to help pinpoint any underlying medical conditions causing the irregular heartbeat.

Depending on your cat’s condition and the available equipment at your vet’s clinic, you might be referred to a veterinary cardiologist for additional diagnostics. These tests may include:

• X-rays of the chest (examining the heart and lungs)

• Echocardiogram (a heart ultrasound)

• Bloodwork, including a complete blood count, biochemistry profile, and heartworm testing

• Urinalysis

• Abdominal ultrasound

Treatment of Cardiac Arrhythmia in Cats

Initial treatment for a cat with a cardiac arrhythmia aims at stabilization and treating the symptoms present. Treatment will be based on addressing the underlying condition causing the irregular heartbeat and will vary depending on your cat’s diagnosis.

In most cases, cats can be treated on an outpatient basis. However, for severe cases and cats experiencing breathing difficulties, hospitalization involving oxygen therapy becomes necessary. If your cat has an electrolyte imbalance or anemia, IV fluid therapy as well as a blood transfusion will likely be necessary. Any abnormalities detected through blood and urine testing will also be addressed and treated by your vet.

Many medications can be used to help regulate irregular heartbeats in cats with heart disease. If your cat has an underlying medical condition such as hyperthyroidism, medical treatment may help resolve the arrhythmia. If your cat is diagnosed with heart disease, they will likely be prescribed a special diet and lifelong medication regimen to manage the condition.

In severe cases of arrhythmias in cats that can’t be effectively managed with medication, surgery to implant a pacemaker may be required. This electronic device is designed to regulate the heart’s rate and rhythm.

Recovery and Management of Irregular Heartbeat in Cats

Once a cat is diagnosed with an irregular heartbeat, they should be monitored closely. The prognosis for a cat with an irregular heartbeat largely depends on the underlying cause. Your vet will have you return for frequent recheck exams to assess your cat’s heart rate and rhythm, ensuring their continued well-being and their therapy plan is working.

It’s important to monitor your cat closely at home following an irregular heartbeat diagnosis, especially if they have started any new medications. Medications for heart conditions in cats can have significant side effects. If you notice any adverse effects or abnormal behaviors in your cat, get them examined by their veterinarian right away. An alternative medication may be available that would work better.

If your cat has just an intermittent irregular heartbeat or one without an underlying disease-related cause and is otherwise healthy, no treatment—other than annual exam checkups by their veterinarian—will likely be necessary. 

Irregular Heartbeat (Cardiac Arrhythmia) in Cats FAQs

WRITTEN BY

Barri J. Morrison, DVM

Veterinarian

Barri Morrison was born and raised and currently resides in Ft. Lauderdale, Florida. She went to University of Florida for her...