Heart problems in dogs

There are different cardiac diseases encountered in the dog, the pathological dominants vary according to the size of the dog. In small dogs, the main cardiac disease is the degenerative valvular disease, while in large dogs, dilated cardiomyopathy is the most common. There are also cardiac diseases specific to young animals due to congenital malformations. We will only discuss here the most frequent cardiac pathologies in the adult dog, namely degenerative valvular disease and dilated cardiomyopathy.

The heart is a muscle capable of contracting and sending blood to the various organs (large circulation), but also to the lungs for oxygenation of the blood (small circulation).

The heart can be "divided" into two parts: the right heart and the left heart. The blood is brought to the heart by veins, it arrives at the level of the auricles. The blood is then sent to the ventricles and then leaves the heart through arteries.

Between the atria and the ventricles, there are valves that allow or not the passage of blood like flaps. They prevent the backflow of blood into the atria when the ventricles contract and eject blood into the arteries. The valve between the left atrium and the left ventricle is called the mitral valve. There are two other valves between the ventricles and the arteries.


What is degenerative valve disease?

Degenerative valve disease is a condition that primarily affects the mitral valve between the left atrium and ventricle. It is the most common heart disease in dogs.

This disease preferentially affects small, middle-aged to older dogs. There are certain breeds of dogs that are predisposed to it, such as Dachshunds or Cavalier King Charles.

It is due to a degeneration of the mitral valve: it no longer plays its role as a valve between the atrium and the ventricle. When the ventricle contracts, there is a backflow of blood to the left atrium. A murmur can be heard by the veterinarian during cardiac auscultation.

It is a progressive disease in dogs. The blood reflux can lead to a dilatation of the atrium and then to a heart failure.


What is dilated cardiomyopathy?

The most common heart condition in large dogs is dilated cardiomyopathy. Some breeds are predisposed: Golden Retriever, Labrador, Irish Wolfhound, German Shepherd, etc...

This disease is due to a damage of the heart muscle. There is a dilation of the heart and a decrease in the thickness of the heart muscle, which affects the activity of the heart. The heart does not contract as well as before to send blood to the body, which leads to a decrease in cardiac output and ultimately to heart failure.


How to know if your dog has a heart disease?

Various symptoms should lead you to consult a veterinarian: dejection, intolerance to effort, malaise, coughing, weight loss, abdominal dilatation (ascites), tachycardia (accelerated heart rate), etc...

A thorough clinical examination and additional tests will be performed to establish a diagnosis.

The complementary examination of choice to evaluate the functioning of the heart is the echocardiography. Chest X-rays are also used to assess the size and shape of the heart and lungs.