Understanding heart failure in your dog.

The heart is a pump that transports blood, which is rich in oxygen and nutrients, to the cells and organs of the body and provides them with the energy that they need to function properly.

The two main heart diseases encountered in the dog affect:

 ❤ the heart valves (valvular heart disease)

Heart valves open and close as the heart beats and ensure that blood moves in the right direction. A diseased valve does not close properly, causing blood to flow in the wrong direction. This produces a noise (murmur) which your veterinary surgeon can detect when he or she listens to your dog`s heart with a stethoscope.

 ❤ the heart muscle (dilated cardiomyopathy)

When the heart muscle itself is affected, it is unable to pump as effectively and therefore becomes less efficient.

Both of these conditions lead to poor blood circulation, meaning that the cells and organs of the body do not receive enough oxygen and nutrients.

Schematic of the heart, representing changes observed during valvular heart disease

and dilated cardiomyopathy.

Schematic of the heart - valvular heart disease - dilated cardiomyopathy

Signs of heart failure

If your dog has heart failure, it may display one or more of the following signs:

Signs of Heart Failure in dog

The treatment that your veterinary surgeon prescribes will vary depending on the cause and the severity of the symptoms.


The purpose of heart failure treatment is to make the heart work more efficiently.

Several medicines are now available to veterinary surgeons and these can produce dramatic  improvements in the length and quality of your dog’s life. They act on different levels and will:

❤ Improve blood circulation

❤ Limit the accumulation of water in the lungs and the body (oedema)

❤ Improve the contraction of the heart

❤ Protect the heart and blood vessels against damage

Heart failure therapy involves a combination of more than one medicine in order to act on the different components of heart disease. Lifelong therapy is needed in all cases.

Commonly used heart failure therapies


Spironolactone has revolutionised the treatment of heart failure in people and is now available for dogs.

During heart failure, lesions appear on the heart and blood vessels which make the heart pump less efficiently and the transport of blood to the organs more difficult.

Spironolactone acts directly on the heart and blood vessels, protecting them against the damaging lesions which occur during heart failure. In a recent study, the addition of spironolactone to standard therapy improved the quality of life and reduced the risk of mortality for dogs with heart failure1.

1 - EPAR. Prilactone® V-C-105. 2007. 18/23

Spironolactone is well tolerated in dogs and designed to complement other available treatments, which have different modes of action.


Heart failure is commonly associated with oedema (the build up of fluid) in the lungs and, in some cases, within the abdomen. Furosemide is a diuretic that reduces this congestion by increasing fluid loss from the kidneys. It will therefore cause your dog to urinate more than normal.


Pimobendan widens the blood vessels, making it easier for the heart to pump blood around the body, and makes the heart work more effectively by increasing the force of heart muscle contraction.

ACE Inhibitors

ACE Inhibitors have a number of beneficial effects on the heart and widen the blood vessels, making it easier for the heart to pump blood around the body.

Your veterinary surgeon will be able to discuss which medications are most suitable for your dog and may need to tailor the treatments as your dog`s condition progresses.


The following measures are also recommended to complement heart failure medications:

❤ Avoid intense physical effort

❤ Avoid excessively salty food Like humans, dogs with heart disease cannot eliminate salt and this contributes to the build up of fluid (oedema)

❤ Beware of excessive weight Obesity causes extra fatigue for the body and the heart itself

❤ Protect from heat and stress


It is important to monitor your dog’s clinical signs closely.  The following signs may indicate a worsening of the condition:

❤ Breathlessness

❤ Heavy breathing

❤ Persistent cough

❤ Tiring easily during exercise

❤ Fainting/collapsing episodes

❤ Weight loss

❤ An enlargement of the abdomen

If your dog’s symptoms persist or deteriorate, then consult your veterinary surgeon immediately.


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