Heart Arrhythmia in Dogs: A Must Read Guide

By Chelsea Hunt-Rivera / April 30, 2018
heart arrhythmia in dogs

Hearing about heart arrhythmia in dogs for the first time can terrify just about any pet parent. Who wouldn’t be extremely worried when they learn that there is something wrong with their fur baby’s heart? With that said, things usually tend to become a whole lot less scary when we understand them. The same goes for heart arrhythmia in dogs.

Heart arrhythmias are not always dangerous or serious. But they sure can be. For this reason, it is worth doing your homework and learning about them. Many a doggo’s life has been saved by pet parents who saw and identified the clinical signs of heart arrhythmias in their fur kids and got them the help they needed.

What is Cardiac Arrhythmia or Heart Arrhythmia in Dogs?

Heart Arrhythmia in Dogs

Arrhythmia Definition

The word “Arrhythmia” is the medical term for an abnormal or irregular heartbeat. If you consider the heart’s make-up, it’s not just an organ. It is an organ with many parts that each need to function properly in order to do its job. An arrhythmia is an indication that something, somewhere is causing the heart to not beat as it should.

The heart is a pump. It’s job is to pump oxygenated blood throughout the body. There are electrical impulses sent to the heart by the nervous system that stimulate the heart’s muscles to contract and relax repeatedly. Blood flows into and out of the chambers of the heart as the heart contracts and relaxes, and this results in a rhythm of heartbeats. A healthy dog will have a consistent number of heartbeats per minute. Arrhythmias can cause the “beats per minute” to go below or above what is considered healthy. Not good.

Arrhythmias are as common in young puppies as they are in older dogs. There are certain types of arrhythmias that are more common in specific breeds, but in general any dog of any breed can have them.

Regular Heart Rate in Dogs

The regular heart rate is also called a resting heart rate. This is the rate at which a normal, healthy heart will beat in a dog who is in a restive state. An incredibly excited Jack Russell Terrier who has been sprinting after a squirrel in the park will have a higher heart rate, but it will slow down again once they relax. That is perfectly normal. When the dog’s heart rate falls outside the limits without any obvious reason, that’s when things may become problematic.

  • The Regular Heart Rate of Adult Dogs: 70 – 160 beats per minute
  • The Regular Heart Rate of Giant Breeds: 60 – 140 beats per minute
  • The Regular Heart Rate of Toy Breeds: Up to 180 beats per minute
  • The Regular Heart Rate of Puppies: Up to 220 beats per minute

The term for a dog’s heart beating too slow is “bradycardia”. When a dog’s heart is beating too fast it’s “tachycardia”. Longer periods of either of these conditions are never a good sign.

Heart Arrhythmia in Dogs

Irregular Heart Beat Causes 

The heart is just a pump made of muscle. It beats when it receives electrical impulses causing it to contract or relax. There are a couple of things which may affect these impulses. Cardiac arrhythmias occur either because the heart itself is faulty, or because of a non-cardiac related factor.

Arrhythmias That Are Not Cardiac Related

Here are a few factors which are caused by factors outside of the heart:

  • Electrolytes: Electrolytes in the blood help to regulate the functioning of nerves and muscles. When there is an imbalance of electrolytes in a dog’s blood, it can cause the heart to beat abnormally. An imbalance of electrolytes is common in dogs suffering from illnesses such as kidney disease, Addison’s disease, or hypothyroidism.
  • Medications: Think of how taking a Xanax, or drinking 4 shots of espresso would affect you and your heart rate. It’s the same with dogs. Certain drugs and medications can slow down or speed up a dog’s heart rate.
  • Nervous System: Problems with the nervous system are often a cause of arrhythmias in dogs. Hardly surprising considering that the heart contracts or relaxes according to the electrical impulses it receives from the nervous system.
  • Tumor: It can happen that an arrhythmia in a dog is caused by a tumor that affects the heart’s ability to receive the impulses telling it to contract or relax.

Arrhythmias Related to the Heart

  • Heart Disease: Heart diseases such as Cardiomyopathy can cause the muscles of the heart to enlarge or become thicker. The added tissue makes it take longer for the electrical impulses to reach their target. This tiny little delay causes arrhythmia because the heart starts beating out of sync. Remember, the heart is continuously receiving and pumping out blood. So, when all parts of the heart aren’t in sync, it eventually leads to skipped heartbeats. A cardiac disease that if left to its own devices can lead to congestive heart failure, so arrhythmias are not to be taken lightly!
  • Congenital Heart Disease: Sadly, a lot of dogs are born with heart defects such as Sobaortic Stenosis (SA) or Pulmonic Stenosis (PS). Any defective part of the heart, whether it’s a chamber or a valve, is bound to cause cardiac arrhythmia.

Types of Heart Conditions and Arrhythmias Common in Dogs

  • Arrhythmogenic Right Ventricular Cardiomyopathy
  • Right-sided Heart Failure
  • Dilated Cardiomyopathy
  • Hypertrophic Cardiomyopathy
  • Respiratory Sinus Arrhythmia
  • Ventricular Arrhythmias
  • Heart Block
  • Supraventricular Tachycardia
  • Ventricular Tachycardia
  • Atrial Fibrillation: This condition is quite common in Doberman Pinschers, and causes their hearts to beat very fast.

Arrhythmia Symptoms in Dogs 

If you see any of the clinical signs or symptoms of arrhythmia in your dog, you need to get them to a vet immediately. Sure, not all arrhythmias are dangerous, but many of them are.

Here are the most common symptoms of dogs experiencing arrhythmias:

  • Fast or shallow breathing
  • Lethargy: a general weakness and lack of energy
  • Fainting

Heart Arrhythmia in Dogs symptoms

The Worst Case Scenario: No Symptoms

Sometimes there are no warning signs. It happens to even the most vigilant and dedicated pet parents that their dog’s heart simply stops. It’s so, so sad, but it’s simply one of those terrible things that we have absolutely no control over.

Diagnosing Cardiac Arrhythmia in Dogs

Vets and Veterinary cardiologists have a number of tricks up their sleeve to identify an arrhythmia and to diagnose its cause.

  • Stethoscope It seems like such a basic piece of equipment, but it tells vets so much. They can listen to a dog’s heart rate, diagnosing Heart Arrhythmia in Dogshear whether there are any murmurs, and listen to whether the dog’s lungs are doing their job.
  • Blood Tests – Heart arrhythmias can be a sign that a dog is suffering from a related illness such as Addison’s disease or hypothyroidism. The blood tests will show whether the problem lies with your dog’s heart itself, or whether the problem lies with an unrelated illness.
  • Chest x-rays  A vet can learn a lot from an x-ray of a dog’s chest. They can often see whether the heart is enlarged, or which part of the heart is causing problems.
  • EKG  An electrocardiogram (EKG) is the most reliable method of assessing an arrhythmia. A veterinary cardiologist will monitor a dog’s heart rate for 24 hrs – 48 hrs. This is called “Holter Monitoring”. Mere mortals won’t learn anything from looking at the EKG, but it can tell a vet specifics about the arrhythmia and what is causing it.

Arrhythmia Treatment in Dogs 

The prognosis and treatment plan for a dog with arrhythmia depends entirely on the diagnosis. Luckily, there are many ways of treating and managing heart arrhythmia and its causes!

  • Treating the underlying illness – Let’s say a dog is having arrhythmia because they have Addison’s disease. The vet will treat the illness, usually with medication, and as the illness is cured, the arrhythmia will go away.
  • Medication – There is a range of medications, such as beta-blockers, which can help to regulate a dog’s heartbeat. Heart Arrhythmia in Dogs medicationMedications can also be used to treat heart diseases which are causing the arrhythmia. If, for example, a dog has Myocarditis (an inflammation of the heart muscle), a vet can treat the condition with anti-inflammatory drugs.
  • Pacemaker: Oh yes, dogs can get pacemakers! They can even get secondary pace-makers. It’s a surprisingly common procedure that has successfully saved the lives of many dogs. When the dog’s heart beats too slowly, the pacemaker will stimulate the heart to reach a healthy, steady rhythm. Pacemaker’s for dogs, who would have thought?

As bleak as the world seems sometimes, let’s not forget the beauty of modern medicine! There are so many ways to help doggos that have heart problems.


What is an arrhythmia?

Are there different types of arrhythmias in dogs?

What are the symptoms of a heart arrhythmia in dogs?










About the author

Chelsea Hunt-Rivera

Chelsea Rivera is a Dedicated Pet Parent who loves to create amazing content for pet owners and is helping change pet wellness as the Head of Content for Honestpaws.com.