Dilated cardiomyopathy essentially means that the muscle of the heart is diseased. In dogs with dilated cardiomyopathy, the heart is unable to contract effectively, which results in the heart being unable to pump the blood normally through the body.
Signs of Dilated Cardiomyopathy in Dogs Are the Result of Heart Failure
In dogs, dilated cardiomyopathy normally affects the ventricle of the heart. Most often, the left ventricle of the heart is involved.
Because the left ventricle is the chamber of the heart that pumps blood out of the lungs and then through the rest of the body, when the left ventricle is unable to pump blood efficiently, fluid starts to build up in the lungs. This is known as congestive heart failure.
Less often, rather than the left ventricle, the right ventricle will be diseased. When this happens, instead of fluid building up in the lungs, the fluid builds up in the other body cavities, specifically the abdominal cavity and pleural cavity (the chest cavity outside of the lungs.) In this situation, fluid can also build up within the body tissues causing swelling (known as edema) of the legs. This is also a form of congestive heart failure and is termed right-sided heart failure, as opposed to left-sided heart failure when the left side of the heart is involved.
In still other cases of dilated cardiomyopathy, both ventricles of the heart will be diseased and the signs seen will be those of both left- and right-sided heart failure.
Signs of Heart Failure in Dogs with Dilated Cardiomyopathy
The specific signs that a dog experiences with dilated cardiomyopathy depend on the type of cardiomyopathy, the severity of the disease and which side of the heart is diseased.
In left-sided heart failure, the most common signs are:
- coughing
- difficulty breathing (increased respiratory rate and increased respiratory effort)
- cyanosis (purple coloration of the gums due to lack of proper oxygenation)
- pale gums
- fainting episodes (known as syncope)
- weakness
- lethargy
- lack of appetite
- weight loss
When the right side of the heart is involved instead of the left, the most common signs are:
- a swollen fluid-filled abdomen
- pleural effusion (fluid build-up in the chest cavity outside of the lungs)
- swelling of the legs
- discomfort (your dog may have a difficult time finding a comfortable position to sit or sleep)
Cardiac Arrhythmias (Abnormal Heart Beats) Can Also Occur in Canine Dilated Cariomyopathy
Disease within the heart muscle also sometimes causes disruption in the electrical impulses that travel through the heart muscle. These electrical impulses signal the heart muscle when to contract and keep the heart functioning as a whole. When they are disrupted, arrhythmias can occur. A cardiac arrhythmia is an abnormal heart rate or rhythm.
Depending on where the electrical impulse is disturbed and what type of arrhythmia occurs, the signs of cardiac arrhythmia can range from mild to severe and life-threatening.
Some of the signs expected in dogs with cardiac arrhthmias include fainting, weakness, cyanosis and sudden death.