Heart disease is defined as any abnormality of the heart. They may or may not lead to heart failure, which is where the heart can no longer pump blood around the body effectively.



  • Reduced ability to exercise
  • Coughing, increased breathing rate or difficulty breathing
  • Restlessness
  • Tiredness/Lethargy
  • Off food
  • Fainting
  • Fluid build up
  • Sudden death


Heart disease can be either congenital (the defect was present at birth), or acquired as the animal ages. Acquired diseases are common in older dogs and make up about 10% of all cases seen in first opinion practice. Acquired diseases can affect either the heart muscles or valves.

Congestive heart failure occurs when the heart can not keep up with the normal demand to pump blood and fluid builds up in the lungs (pulmonary oedema) and abdomen (ascites).

Heart valves are present within the heart, separating the four chambers and preventing blood flowing backwards when the heart pumps. Degenerative valvular disease occurs when the heart valves become weak and distorted. This can cause the chambers to enlarge and the heart has to work harder and harder to push blood forward in the circulation.

Heart muscle disease contributes to 20% of all cases of heart disease and dilated cardiomyopathy (DCM) is the most common cause in dogs. The cause of DCM in dogs is unknown but is more common in larger breed dogs.

The diagnosis of heart disease can involve

  • Clinical symptoms
  • Listening to the heart with a stethoscope
  • Ultrasound
  • ECG
  • X-Rays
  • Blood testing
There are numerous treatments available for heart disease which focus on trying to improve the ability of the heart to pump, to remove the extra fluid and to relax the blood vessels to reduce blood pressure.