A low heart rate in cats, medically termed bradycardia, is a condition where the feline heart beats slower than its typical resting rhythm. This can signal underlying health concerns that require immediate veterinary attention. Understanding this condition is important for cat owners, as early recognition of symptoms can significantly impact a cat’s prognosis and overall well-being.
Understanding a Cat’s Heart Rate
A healthy adult cat’s resting heart rate is 140 to 220 beats per minute (bpm). Kittens typically have a higher resting heart rate, sometimes approaching 300 bpm. Bradycardia is diagnosed when a cat’s heart rate drops below this normal range, often considered below 140 bpm.
Cat owners can check their cat’s pulse at home by gently placing fingers on the inner thigh, near the groin area, to feel the femoral artery. Another method is placing a hand on the left side of the cat’s chest, just behind the elbow, to feel the heartbeat. Count the beats for 15 seconds and multiply by four to get the beats per minute.
What Causes a Low Heart Rate
Various factors can contribute to bradycardia, ranging from physiological responses to serious medical conditions. One common cause is increased vagal tone, where the vagus nerve, which influences heart rate, becomes overstimulated due to conditions affecting the gastrointestinal, urinary, or respiratory tracts, or neurological diseases. This overstimulation can lead to a slower heart rhythm.
Certain underlying heart conditions, such as sick sinus syndrome (SSS) or specific cardiomyopathies, can also lead to bradycardia by affecting the heart’s electrical conduction system. While low heart rates are uncommon in the initial stages of most feline heart diseases, they can become more prevalent as heart failure progresses. Electrolyte imbalances, such as those involving potassium, calcium, or magnesium, can disrupt normal heart function and cause a slow heart rate.
External factors and systemic illnesses also play a role. Hypothermia, a low body temperature, can significantly slow a cat’s heart rate. Certain medications, including anesthetics, beta-blockers, and calcium channel blockers, can have bradycardia as a side effect. Exposure to toxins can also depress heart function.
Recognizing the Signs
A cat with a low heart rate may display several observable signs and behavioral changes. Lethargy and generalized weakness are common indicators, as the reduced blood flow affects overall energy levels. In more severe cases, a cat might collapse or experience fainting episodes due to insufficient oxygen reaching the brain.
Changes in appetite, such as a reduced interest in food, and exercise intolerance are also frequently observed as the body conserves energy. Difficulty breathing or rapid breathing can occur as the cat’s body attempts to compensate for decreased oxygen delivery caused by the slow heart rate. Pale or bluish gums may also be present, indicating poor circulation and reduced blood oxygen.
Veterinary Care for Low Heart Rate
When a cat presents with a low heart rate, a veterinarian will typically begin with a thorough physical examination and heart rate monitoring. To determine the underlying cause, several diagnostic tests may be performed. An electrocardiogram (ECG or EKG) is often used to record the heart’s electrical activity, which helps confirm bradycardia and identify any specific conduction abnormalities or arrhythmias.
Blood tests, including a complete blood count and biochemistry panel, are often conducted to identify systemic issues such as electrolyte imbalances, kidney disease, or thyroid problems that might be contributing to the slow heart rate. Chest X-rays and an echocardiogram (an ultrasound of the heart) may also be performed to assess heart size, structure, and function. In some cases, a Holter monitor may be used for 24-hour heart rate assessment to capture intermittent abnormalities.
Treatment for bradycardia is highly individualized and depends directly on the identified underlying cause. For instance, if medication is the culprit, adjustments to the dosage or type of drug may be made. If hypothermia is the cause, warming the cat’s body temperature back to normal should resolve the bradycardia. Addressing underlying conditions like gastrointestinal, urinary, or respiratory diseases, or electrolyte imbalances, will often lead to the heart rate returning to a normal range. In emergency situations, veterinarians might administer medications like atropine or isoproterenol to acutely increase the heart rate. In rare, severe cases of persistent bradycardia, a pacemaker implantation might be considered to regulate the heart’s rhythm.