Congestive heart failure (CHF) in pets is a serious, life-threatening condition that occurs when the heart is unable to pump blood to the body. This results in retention of fluid in the lungs or other parts of the body. Heart failure in dogs and cats may occur because of a defect in heart contractility due to a weakness in the heart muscle, or in other cases, because of the inability of the heart to fill adequately. Because of reduced blood flow to vital organs, congestive heart failure may result in abnormalities in your pet's organ function, including renal failure, hepatitis/liver congestion, or pancreatitis. A subnormal body temperature may be seen because of lowered blood flow to the brain and vital organs. Pets with congestive heart failure may also experience weight loss because of changes in appetite and nutrient utilization by the tissues of the body.
Congestive heart failure in pets may occur when diseases of the heart muscle (known as cardiomyopathy), narrowing of major blood vessels (seen with many congenital heart defects and heart valve issues), and heart rhythm irregularities are present. The two most common causes of congestive heart failure in dogs are mitral valve insufficiency and dilated cardiomyopathy. In cats, hypertrophic cardiomyopathy is the most common heart disease. Genetic predisposition is clearly the most common underlying reason for the development of congestive heart failure. Other factors include certain viral infections and deficiencies of certain amino acids. Primary high blood pressure and thyroid disease may also cause congestive heart failure in some pets. Drugs that cause retention of salt and water such as prolonged use of cortisone type drugs can also trigger congestive heart failure in susceptible pets.
Although congestive heart failure may develop in any age or breed of dog or cat, most cases typically occur in middle-aged to older pets. Pets less than a year old that develop congestive heart failure often have genetic heart defects. Congestive heart failure may occur more commonly in certain dog breeds, including King Charles Cavalier Spaniels, Doberman Pinschers, Schnauzers, and Boxers.