Arrhythmia in dogs is common, and many of our canine companions can live long, healthy lives even with this heart condition, but sadly that is not always the case. Today's post explains the types of arrhythmia in dogs, signs to watch for, and treatment options.
What is a cardiac arrhythmia?
Arrhythmias are when your dog has an irregular heartbeat. Arrhythmia's irregularities can include the heart's speed, strength, or regularity of heartbeats. It is a condition generally caused by unusual electrical activity in your pup's heart muscle. Arrhythmia in dogs can be genetic and present from birth, or be the result of something that has occurred in your dog's life.
While any dog can suffer from arrhythmia, there are certain breeds that are predisposed to the condition, most notably brachycephalic breeds including bulldogs, Lhasa apsos, Pekingese, pugs, Shar-Peis, Shih Tzus, and boxers.
If your dog shows signs of having an unusual heartbeat, it is essential to contact your vet. Arrhythmia can be a sign of a serious underlying health condition that requires immediate treatment in order to avoid long-lasting side effects.
Here’s what you should know about the symptoms, causes, and treatments for dogs with heart arrhythmia.
What are the causes of heart arrhythmias in dogs?
Irregular heartbeat in dogs can be caused by a countless factors. Some of the most common causes of cardiac arrhythmias in dogs include:
- Genetics/hereditary
- Age
- Injuries
- Infections
- Stress
- Gastrointestinal disease
- Respiratory disease
- Exposure to toxins
- Electrolyte imbalance
- Congestive heart failure
- Congenital heart abnormalities (present from birth)
- Heart disease
- Trauma to the heart (ie, car accident)
- Age-related changes to the heart
- Diseases that affect the vagus nerves
- Cerebral disorders
- Conditions that cause pressure within the skull
- Fungal, bacterial and viral infections
- Heartworm disease
- Severe anemia
- Gastric dilation or bloat
What are the symptoms of cardiac arrhythmia in dogs?
Dogs with heart arrhythmia may show one or more of the following signs:
- Weakness
- Sudden collapse, or loss of consciousness
- Exercise intolerance
- Long pauses between heartbeats
- Abdominal swelling
- Labored breathing
- Sudden death
What are types of arrhythmias?
Heart arrhythmias in dogs fall into 5 main categories, they are:
Ventricular Arrhythmias
Ventricular premature contractions (VPCs) are premature heart beats that originate in the heart's lower chambers (called the ventricles) rather than in sinus node which is considered the normal pacemaker of the heart. Ventricular arrhythmias are typically due to underlying heart disease. This type of arrhythmia tends to appear in boxers, bulldogs, and German shepherds.
Bulldogs develop a variation of this disorder, and German shepherds have an inherited ventricular arrhythmia that affects young dogs between three and 24 months old. After 24 months of age, the arrhythmias tend to disappear in German shepherds and they will no longer be at risk. However, this condition can be passed on when these German shepherds are mated to a dog with a genetic background of risk for this condition.
Arrhythmogenic right ventricular cardiomyopathy or ARVC (also referred to as Boxer Cardiomyopathy), occurs in the right ventricle. Boxers can also have arrhythmias develop in other areas of the heart. Ventricular arrhythmias that occur in rapid succession are called ventricular tachycardia, which can lead to a decrease in blood flow to the body. Dogs may collapse if perfusion to the brain (the amount of blood delivered to a unit of tissue per unit of time) decreases to a certain level.
Atrial Fibrillation
Atrial fibrillation in dogs is a condition that occurs when the top chambers of the heart generate electrical signals too quickly to fully contract, leading to a very fast quivering known as fibrillating.
This form of arrhythmia is often seen in Great Danes, Doberman pinschers, Newfoundlands, Irish Wolfhounds, Boxers, and other large breeds, and can occur even when the heart is structurally and functionally normal.
Sick Sinus Syndrome
Sick sinus syndrome in dogs occurs when the heart's sinus node (which is responsible for initiating heart contractions) fails to discharge a signal. As a result, the heart stops beating. The sinus node typically starts up again, but the dog will have a heartbeat with frequent, long pauses.
Some dogs with sick sinus syndrome will have a more constant sinus bradycardia (too slow) because the sinus's firing rate is lower than normal. Other dogs with sick sinus syndrome will have periods of excessive tachycardia (rapid heart rate) in addition to pauses or bradycardia.
West Highland White Terriers, Dachshunds, Miniature Schnauzers, boxers, and cocker spaniels are more likely to be diagnosed with sick sinus syndrome.
Heart Block
Heart block in dogs occurs when the heart's upper chambers do not communicate properly. The electric signals that control your dog's heartbeat are delayed or blocked, causing the heart to beat very slowly or irregularly. This condition is diagnosed in degrees with complete heart block (the most serious) leading to fainting or sudden collapse.
Your dog may develop heart failure as a result of this abnormality, which can affect dogs of any breed.
Myocarditis (Heart inflammation)
Myocarditis is an inflammation that causes the heart to swell, typically leading to an irregular rhythm. This heart condition can occur due to a variety of underlying conditions including fungal, bacterial or viral infections; immune system disorders; mineral deficiency; exposure to toxins and more.
While myocarditis can be diagnosed in any breed, it is typically found in medium to larger-sized dogs. Some dogs with heart block or ventricular arrhythmias may have myocarditis or underlying inflammation of the heart.
How is cardiac arrhythmia in dogs diagnosed?
Your vet will begin by listening to your dog's heart with a stethoscope. If a problem is suspected, an EKG (electrocardiogram or ECG) may be recommended to help identify and diagnose the specific type of arrhythmia.
A Holter monitor is an EKG that your dog can wear at home to record their cardiac rhythm over the next 24-48 hours. Holter monitors are helpful for determining how often the arrhythmia occurs and its severity.
Other diagnostic tests that may be used include:
- Blood tests (CBC and blood chemistry panel)
- Urinalysis
- Electrolyte tests
- Chest X-rays
- Atropine response test
What are the treatment options for cardiac arrhythmia in dogs?
The best treatment for cardiac arrhythmia in dogs depends upon the type of arrhythmia, its severity and cause, as well as the breed, age and overall health of your dog.
Your dog's treatment may include:
- Medications to speed or slow heart rate
- Implantation of a pacemaker to regulate heart rate
- Anti-inflammatory drugs to reduce heart swelling
- Holter monitor to track heart rate
- Synchronized electrical cardioversion to help restore normal rhythm
Your dog's arrhythmia will need ongoing monitoring and treatment from your veterinarian to help ensure that your pup maintains a good quality of life.
Are there heart specialists for dogs?
Yes! At Carolina Veterinary Specialists in Matthews, our board certified veterinary cardiologist offers advanced diagnostics and treatment to dogs and cats suffering from a range of heart conditions. If your dog is diagnosed with a heart condition our experienced team can work with your primary care veterinarian to ensure that your precious pet receives the very best treatment for their condition.
Learn More About Veterinary Cardiology at Our Hospital
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. Please make an appointment with your vet for an accurate diagnosis of your pet's condition.