If you ever lounged on the couch with your cat, you may have noticed that your cat's heartbeat probably didn't align with your own. Cats have a higher heart rate than humans, so what seems rapid to you may not be all that fast for her. If your cat's heart rate is a little too rapid, there are several potential causes, and fixes.
Your cat's heart rate has a large normal range, typically beating between 140 and 220 times per minute. If you want to confirm that your cat's heart rate really is rapid, find a watch with a second hand, or use the timer app on your phone to count the seconds. Place your hand behind your cat's front leg on his left side and feel to detect his heart beat. When you've located a steady heart beat, count 15 seconds on your watch, or set it on your timer and count. Multiply the result times four and you'll have your cat's beats per minute.
If your cat's heart rate is above normal, the first thing to do is consider the circumstances. Has she been racing about the house in one of her playful fits? Has something stressful or startling happened, such as loud, surprising noises? It's normal for a cat's heart rate to elevate if she's been engaging in strenuous exercise or if she's in a stressful situation. If that's the case, give her some time and soothe her with pets, checking her heart rate after she's had a few minutes to relax. However, if she's in her routine relaxation mode and her heart rate is rapid, you should look for other potential symptoms indicating a medical problem and contact your vet. An undiagnosed, untreated rapid heart rate can be dangerous, leading to heart failure.
Sinus tachycardia, a rapid heartbeat of more than 240 beats per minute for a cat, can be caused by stress or disease. Since this condition can be from a variety of causes, ranging from stress to primary heart disease and congestive heart failure, the symptoms will vary. Some of the symptoms the cat may present with include fever, cough, shortness of breath and pale mucus membranes, or she may show no symptoms at all. Since so many conditions can cause sinus tachycardia, the vet will need to perform a thorough exam to get to the root of the problem. Treatment to address the primary illness will reduce the rapid heart rate, and may include antibiotics for infections and fluid therapy for dehydration.
If your cat's heart rate is elevated despite being relaxed or at rest, she's experiencing supraventricular tachycardia. The slower version of supraventricular tachycardia often doesn't present other symptoms, however, when the heart rate speeds up to more than 300 beats per minute, it's considered fast supraventricular tachycardia, which may be accompanied by weakness or fainting. Supraventricular tachycardia can lead to heart muscle failure, also called myocardial failure, as well as congestive heart failure. Electrolyte imbalances, heart disease and systemic diseases are among the causes of supraventricular tachycardia. A cat in congestive heart failure should be hospitalized immediately to be stabilized. After the vet has determined the underlying cause, prescription medication and dietary changes may be part of her treatment protocol to lower her heart rate and treat the root cause.
When your cat's thyroid produces too much of the hormone thyroxine, or T-4, she has hyperthyroidism, a disease common among older cats. A racing heart rate is one of the classic signs of this disease, accompanied by weight loss despite an increase in appetite, increased thirst and urination, vomiting, diarrhea and restlessness and irritability. Blood tests will reveal the level of T-4 to confirm the disease and treatment ranges from radioiodine therapy, to surgery to medicine to manage the thyroid's output.