A diseased heart 'compensates' for months or years. It usually does so by increasing in size. Eventually however, valvular heart disease may lead to congestive heart failure. This may occur gradually or suddenly.
The signs of early heart failure include reduced exercise tolerance and activity. Because congestive heart failure occurs in older pets, these early signs are often mistaken as natural age-related changes. In dogs, a dry, nonproductive cough develops, initially after exercise and at night. This noticeable sign does not usually occur in cats, one reason why it is more difficult to make as early a diagnosis in cats.
As heart failure continues, more changes are noticed. Some pets lose their appetite. Others lose weight, breath more rapidly or develop swollen abdomens, even swollen limbs, the result of congestion and high venous pressure with fluid seeping from heart-failure-induced swollen liver and veins. Eventually fluid back-up in the lungs may cause a more breathing difficulties. Bubbly pink fluid may be produced by dogs, a worrying sign of pulmonary edema.
In late stages of heart failure, a pet braces itself on its elbows and extends its head to breath. The gums and tongue become blue. The pulse becomes rapid and may become irregular. Fainting easily occurs with the slightest exertion.
Pets with heart disease but no clinical signs of heart failure are treated normally, having full routine exercise. When the first signs of heart failure develop a pet may benefit from treatment with a combination of ACE (angiotensin-converting enzyme) inhibitors such as enalapril and diuretics such as frusemide. The ACE inhibitor blocks some of the harmful hormones produced by heart failure, reduces high blood pressure in cats and prevents dangerous salt retention. The diuretic is a "water pill". It makes your pet urinate more, clearing congestion from the lungs and veins. Statistical evidence confirms that this form of treatment prolongs the quality life for a pet. Other medications are also commonly used.
Dietary treatment remains controversial. Certainly, excess salt should be avoided although low-salt diets have never been evaluated in controlled trials.
Routine, daily light exercise is beneficial but not to the extent that it causes a pet to cough, tire easily or breath rapidly.
Essential fatty acid (EFA) supplements may be of value for some pets with congestive heart failure. So too may be the antioxidants selenium and vitamin E.