Introduction
A cardiac arrhythmia is a disturbance in the normal rhythm of the heart, either in frequency (beating too fast or too slow), in amplitude (beating too strongly or not strongly enough), in regularity, or most commonly in all of these areas. Cardiac arrhythmias can occur for many reasons, but fundamentally they involve abnormal electrical activity in heart muscle. Some cardiac rhythm disturbances are of no clinical significance, but others can be extremely serious and even fatal.
Causes of Cardiac Arrhythmia in Dogs
The causes of heartbeat arrhythmia in dogs (and cats) are many and varied. These can include abnormal heart structure, genetic factors, environmental stresses, infections, injuries, ingestion of poisons/toxins, underlying heart disease, breed predisposition and many other factors. Some animals live a normal life with mild heartbeat disturbances, while others are affected much more severely.
Which Dogs are at Risk?
Cardiac arrhythmias can occur in dogs of all ages and all breeds. Some breeds, including Boxers and Doberman Pinschers, are predisposed to a heart condition called cardiomyopathy and have an increased risk of suffering sudden death from heartbeat irregularities. French Bulldogs and young German Shepherds have also been identified as being more susceptible to severe consequences from arrhythmias due to inherited disorders. But again, all breeds (including mixed breeds) may be affected, and members of predisposed breeds certainly may never have any heart problems at all. Often, pet owners do not even know that their dog has a heartbeat irregularity until it is detected during routine physical examination by a veterinarian.
Symptoms of Heartbeat Arrhythmia
Dogs with mild to moderate cardiac arrhythmias often show no clinical signs. When signs do appear, they can be very nonspecific. For example, the owner may notice that the dog is not as active as usual, pants more when exercising or simply “poops out” with normal exertion. Severe arrhythmias can present with coughing, fainting spells, abdominal discomfort (belly ache), difficulty breathing, rapid and/or shallow breathing, fatigue, unwillingness or inability to be active, and even sudden death. It is not unusual for these signs to wax and wane. Sometimes, the signs appear and then disappear for months.
If you notice any of these signs in your dog, take him or her to a veterinarian as soon as you can. Be thorough in describing what you observed, when you observed it and why you are concerned. Cardiac arrhythmias often can be managed with medication and lifestyle changes.