Enlarged Heart in Labradors

A Labrador with an enlarged heart struggles completing physical activities.
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The Labrador are known for their faithful heart full of love for and protecting their human companions. But sometimes their big hearts get stretched -- physically -- to the point of developing a life-threatening disease known as enlarged heart leaving the cardiac muscles unable to efficiently pump blood.

Exact Cause Unknown

It's a disheartening fact, but the truth regarding an enlarged heart in any breed of dog -- Labradors included -- is that the exact cause is largely unknown. Researchers at several leading U.S. veterinary colleges are closing in on a biological culprit. Current research indicates a nutritional deficiency in the amino acids taurine and carnitine as a contributing factor causing enlarged heart in canines. Taurine plays a role in regulating heartbeat and preventing calcium overload. Carnitine aids the muscle's ability to convert fatty acids into usable energy for muscle activity. Current theory supposes that malfunctioning of or an inadequate presence of these two acids leads to strain on the heart muscle.

Veterinary Definition of an Enlarged Heart

In diagnostic terms, veterinarians refer to an enlarged heart as dilated cardiomyopathy. This is one of the leading causes of congestive heart failure in dogs. The heart muscle that becomes stretched over time loses its elasticity. This leads to inefficient pumping of blood by the ventricles of the heart out to the lungs. When the rest of the body does not get an adequate amount of blood flow, the brain signals the heart to pump harder. This becomes a vicious and destructive circle as the challenged heart attempts to push more blood only to further damage itself.


Many of this disease's symptoms -- lethargy, rapid and excessive breathing, shortness of breath, coughing and abdominal distension -- are often also associated with other ailments that require time and testing to rule out. Unfortunately, once these symptoms become clearly recognizable as attributing to enlarged heart, the damage is already done. A dog displaying the abdominal distension symptom more commonly called an enlarged abdomen due to fluid build-up is quite possibly already experiencing the later stages of the disease. The condition mainly occurs in middle age dogs.

Early Detection Helps

The earlier you detect your Labrador's enlarged heart, the greater chance you have that supportive therapies will extend his life. A little dedication coupled with keen observation on your part could lead to an earlier diagnosis. Louisiana State University's School of Veterinary Medicine suggests taking your dog's resting respiration rate on a regular basis. It's easiest to do this when the dog is asleep. Simply count the number of times you see him breathe in and out as indicated by the heaving of his chest. Do this for 15 seconds and multiply by four. If the obtained result is more than 40 on a regular basis, a veterinary evaluation is recommended.

Getting A Diagnosis

A series of tests including an X-ray image showing the enlarged ventricles and presence of fluid in the lungs are required to obtain an accurate diagnosis from which a veterinarian can prescribe a supportive treatment plan. Most veterinarians will want further testing to confirm. An electrocardiogram documents any rapid beating of the heart. An ultrasound aided by echocardiograph imaging gives a veterinarian the exact size of the heart, its ability to contract and whether the left side of the heart where the bulk of the pumping motion originates is larger than the right side.


When a Labrador's heart has become enlarged, it will not shrink back to its original size. There is no "cure" for this disease. However, supportive therapy medications may control symptoms by reducing fluid build-up and assist the heart with muscle contraction.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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