Heart failure in dogs occur when any kind of heart disease becomes so severe that a dog's heart is unable to circulate enough blood to meet all the needs of his body tissues. As a result of associated blood-pressure abnormalities, fluid may begin to pool in some of his tissues, and the blood supply decreases to those body tissues that are furthest away from the heart.

What can cause heart failure?

Any form of heart disease can cause this condition. A dog may be born with a defect that leads on to heart failure - such as a hole in the heart or a major blood vessel positioned wrongly - but in most cases heart failure is associated with an underlying heart disease that is not present at birth. These diseases include the following:

* Long-term disease of the major internal heart valves, making the valves ineffective as seals.
* Diseases of the heart muscle.
* An infestation of heartworms.
* Diseases of the tissues that surround the heart, leading to a build-up of fluid.
* Electrical disorders of the heart, affecting its beat rhythm and rate.
* Bacterial infections of the interior lining of the heart.
* Tumors of the heart.

Heart failure is obviously a very serious; life-threatening condition. For instance, heart-valve disorders are most common in middle-aged and older dogs, and in toy, miniature arid small breeds, especially the Cavalier King Charles spaniel, chihuahua, cocker spaniel, poodle and Yorkshire terrier. Heart-muscle disorders most commonly affect the boxer, cocker spaniel and doberman pinscher, as well as giant breeds, especially the Great Dane, Irish wolfhound, St Bernard and Newfoundland.

Early stages of heart failure: In the earliest stages of heart failure a dog may not show any symptoms, because changes that occur in his body will help to compensate for his failing heart. However, heart disease may still be detectable by a vet at an early stage. As the condition progresses, the dog will begin to exhibit symptoms. At first, this may only happen when his heart is under stress, such as on exercise, but later on his quality of life will deteriorate as he develops symptoms that are obvious on mild exercise or even at rest. Typical symptoms are mainly due to the build-up of fluid in the lungs and/or abdomen, to an increase in the size of the heart as it tries to compensate for its own failure, and to the inefficient pumping of blood around the body.

They may include the following: Exhaustion on exercise, Coughing, An increased breathing rate, Abdominal swelling, Weakness and lethargy, Cold extremities, Pale gums, Fainting, Weightloss, Reluctance to eat, and last but not least, Depression.