Irregular Heart Rhythms in Dogs

Similar to irregular heartbeat, it can be mistakenly diagnosed as such, but the irregular heart rhythm will usually be consistent and continue for a longer period. Your veterinarian may notice your dog has a heart rate between 40 and 100 beats per minute during examination for other reasons. He may decide to watch this anomaly, but since it does not usually cause any danger to your dog’s health, it may be overlooked. If you suspect your dog has an irregular heart rhythm problem, speak to your veterinarian about it and he will do an ECG.

When the ventricle rhythm is faster than the sinus rhythm, but slower than tachycardia for more than three beats, this is considered an irregular heart rhythm. Sometimes called accelerated idiojunctional rate or accelerated idioventricular rate (AIVR). It is similar to arrhythmia, although it comes on slowly and the beats are not as fast. Irregular heart rhythm usually starts as a late premature heartbeat rather than suddenly, as with ventricular tachycardia (VT).

Irregular heart rhythm is often discovered by a routine veterinarian visit because there are rarely any noticeable symptoms. You may notice:

• Breathing trouble
• Lethargy
• Unsteadiness
• Losing consciousness
• Weight loss
• Seizures
• Confusion

 Types

• Accelerated idiojunctional rhythm is an abnormal heart rhythm caused by a faulty impulse from the junction between the ventricles and the atria. It is recognized by a heart rate of 60 to 100 beats per minute.
• Accelerated idioventricular rhythm is an increased heart rate from the ectopic ventricle. It is faster than the normal beat, but less than 100 beats per minute.

• Pancreatitis
• Imbalance of the electrolytes
• Hypoxia
• Heart disease
• Unknown

A thorough examination or your dog will be done with special care taken to get his heart rate and blood pressure. Let your veterinarian know everything you have noticed about your dog’s symptoms, diet, exercise routine, and anything else you think is important. If you feel that your dog has been acting different, you are the only one who can describe it for him.  

The veterinary technician will take blood and urine to get a CBC, blood chemistry panel, electrolytes, thyroid test, and blood glucose level.

 An electrocardiography (ECG) is the most important test that must be done to find the problem, if there is one. This will show fusion beats, missing P-wave, ventricular complexes, and QRS complexes more than 120ms. He will also need radiographs (x-rays) and an ultrasound to rule out physical cardiac abnormalities, tumors, or other anomalies. If the abnormality cannot be detected, the veterinarian may have you use a Holter monitor to get readings of your dog’s heart rhythm over a 24-hour period from home.

The treatment your veterinarian chooses depends on the underlying disorder, such as: 

Pancreatitis

• This is usually a cause for hospitalization depending on the severity of the attack. The veterinarian  will provide anti-nausea medicine, IV fluids, and rest for one to two days. If the attack is mild, the veterinarian will prescribe a diet that is low in fat and an enzyme supplement.

Insufficient Oxygen in the Blood (Hypoxemia)

• Hypoxemia is treated with oxygen and more tests to determine the cause of the condition. The veterinary caregiver may decide to hospitalize your dog until he is stable. Once he finds the cause of the hypoxemia, he will discuss treatment with you.

Heart Disease

• There are many types of heart disease caused by anything from diet to congenital defects. Because of this, the treatment for heart disease can be one of many, from a new food plan to surgery. The veterinarian will have to perform more tests to find the type and cause of the heart disease before it can be treated.

Electrolyte Imbalance

• The initial treatment for an imbalance of your dog’s electrolytes that is enough to trigger an irregular heart rhythm is IV fluids to restore his electrolyte levels. The veterinary team will also need to do some more tests to determine the reason for the imbalance. This disorder can be caused by many illnesses, from dehydration to diabetes.

Unknown Origin

• Irregular heart rhythm of unknown origin rarely warrants any medication or treatment unless it causes symptoms. The veterinarian will want to continue to monitor your dog’s blood pressure and get regular ECG recordings.

The most important part of recovery from irregular heart rhythm is regular visits to your veterinarian to get your dog examined and ECG recorded. If the veterinarian decides your dog needs any other treatment, such as medication, it is essential that you give these exactly as prescribed for as long as necessary. With continued ECGs and veterinarian visits, your dog should be able to live a full and happy life.