The term bradycardia describes a heart beat which is either normally slow, or is lower than its usual rate. It is diagnosed if a small dog’s heartbeat at rest is less than 80 beats per minute or a large dog’s heartbeat at rest is below 60 beats per minute.

Many things may cause your dog’s heart rate to be slower than normal.

・ Heart disease such as problems with how electrical signals are conducted through the heart can cause a slow heart rate and even missed beats.

・ Hypothyroidism or low thyroid hormone levels, will cause an abnormal heart rhythm or slow heart rate in dogs. It’s not difficult to test for this condition, and it is easy to manage by giving your dog thyroid hormone supplements.

・ Addison’s Disease (deficiency of adrenal gland hormones) causes a slow heart rate in affected dogs; in fact in many cases it is the first indication that a dog has this medical problem.

・ Drugs and toxins, such as sedatives, can cause bradycardia while a dog is under their influence.

・ Bradycardia may not always mean a dog is unwell. Low heart rates of 50 beats per minute or below can sometimes be a normal finding in very fit dogs, and need not be associated with disease.

If your dog is found to have a low heart rate, it’s important to make sure there is nothing medically wrong. Your dog will have an electrocardiogram to assess his heart’s rhythm and make sure there are no skipped beats. Your veterinarian will also recommend blood tests and perhaps an ultrasound of his heart to further get to the bottom of the problem.

In Summary – It may well be that after testing, your dog is found to be perfectly healthy and his low heart rate is just an incidental finding. That’s good news, and the test results will give you peace of mind.