Why the Signs of Heart Disease Occur in Cats

Many cats with heart disease are asymptomatic, showing no sign of their disease until the abnormality within the heart causes the heart to fail and not function normally.
There are many types of heart disease that can affect cats. Any type of heart disease can cause heart failure.
Why the Signs of Heart Disease Occur in Cats
In a normal healthy cat, the heart functions as a pump, responsible for moving the blood to various parts of the body. Essentially, as the heart disease progresses, the pump begins to fail.
One of the most common complications of heart failure is fluid build-up within the lungs. This is known as congestive heart failure. It occurs because the heart is no longer able to function as an efficient pump. Occasionally, fluid may build up in the abdomen and in the legs also.

Signs of Congestive Heart Failure in Cats
The signs seen in cats suffering from congestive heart failure include:

• weakness
• lethargy
• decreased appetite
• difficulty breathing
• increased respiratory rate
• increased respiratory effort
• cyanosis (a purple coloration of the gums), if the heart failure is severe enough to cause inadequate levels of oxygen to reach the body
• bloated, fluid-filled abdomen
• swelling of the legs

Unlike in dogs, where coughing is frequently a symptom of heart disease, in feline heart disease coughing is rare. Vomiting or dry heaving is sometimes seen as a symptom of heart disease in cats though.
Feline Thromboembolisms (Blood Clots) and Heart Disease
Another potential sequelae (negative outcome) of heart disease in cats is a condition known as a thromboembolic event. A thromboembolism is a blood clot that forms within one of the chambers of the heart.
In some instances, these blood clots break free and pass out of the heart and into the blood vessels. Eventually, these blood clots become lodged in a blood vessel, causing an obstruction of blood flow in the vessel.
The most common symptom of a thromboembolic event is paralysis in the hind legs. This occurs when the blood clot lodges in the large blood vessel known as the aorta near its end. The aorta normally splits into two arteries that supply the blood flow to the hind legs. When it becomes occluded (plugged), the blood no longer reaches the hind legs. This condition is also sometimes referred to as a saddle thrombus.
The signs seen when a saddle thrombus forms as a result of heart disease in a cat include:

• suddenly beginning to drag the hind legs
• crying in pain
• difficulty breathing, panting, open mouth breathing

Other Signs of Feline Heart Failure
Some cats will develop an arrhythmia (abnormal heart rhythm) as a result of heart disease. This may result in fainting episodes, also known as syncope.
Unfortunately, sudden death is also sometimes seen with feline heart disease. (http://vetmedicine.about.com)