Heart Murmurs & Heart Disease
General Information

Hopefully, every puppy that visits the vet for its first vaccination at 6 to 8 weeks of age, will have its heart listened to. The reason for this is to check that the heart sounds normal. If it doesn’t sound normal, the puppy is said to have a “heart murmur”. The murmur is caused by blood flowing faster or slower or more turbulently than usual. If a heart murmur is detected, usually the vet will request that the puppy is checked again in a few weeks (unless it is showing other signs of heart disease), because some heart murmurs do not signify heart abnormalities.

Symptoms of heart disease are generally the same in adults and in puppies; the main difference being that in puppies it is mostly congenital disease (inherited, or caused by some factor during pregnancy) while heart disease in older dogs is mostly acquired disease (infection or wear and tear). What you will see is panting, weakness, pale or bluish gums, coughing, enlarged abdomen, and reluctance to exercise. Puppies will be smaller than littermates.

All these symptoms are caused by a lack of blood flow to body organs, as the heart is unable to pump well enough to keep up with demand for oxygenated blood.

When a puppy is found to have a heart murmur on two or more occasions, further tests will be suggested to diagnose just what sort of problem the heart has. Some malformations are correctable by surgery (at a price!!), while others can only be managed with medications. Radiographs (X-rays) and ultrasound are the most commonly used diagnostic tests. Problems will involve the heart structure (valves, blood flow patterns) or the heart muscle itself being weak.

If your dog is diagnosed with heart disease, there are three main types of medication that may be prescribed. Usually the first drug used is what is called an “ACE inhibitor” (Fortekor) These work by lowering blood pressure. When the body does not receive enough oxygenated blood, it reacts by raising blood pressure. This works well if there has been haemorrhage, but poorly if the heart is faulty. The weak heart must now pump against increased blood pressure in the arteries. The ACE inhibitors improve blood flow to many organs especially the kidneys, and reduce coughing by reducing lung blood pressure.

The second drug group used is diuretics. These act on the kidneys to increase fluid excretion (as urine). This sucks fluid out of the body, especially the chest where it causes coughing, but of course our dog is thirsty and replaces the fluid by drinking. Any fluid distending the abdomen (ascites) will also be reduced.

Vetmedin is the third drug used in heart disease. Vetmedin improves the strength of the heart muscle contractions, and so is only used where the heart muscle is weak.

As heart transplants are not a reality for dogs, any medication will only be to improve the quality and length of your dog’s life, not to cure the condition. The exception to this is a congenital condition, which can be surgically corrected. Such surgeries are performed at specialist centres such as Massey University. These puppies can go on to lead a normal life, but should not be bred from.