Heart Failure

This is for background information only, if you are concerned your animal is in any distress please call the practice immediately.


Heart failure is a relatively common condition in terrier or spaniel breeds as well as large breed dog.

Smaller breed dogs with heart problems most common develop mitral valve insufficiency. This is where the valve between two of the chambers becomes thickened and so cannot close properly to form a seal when the heart contracts. A a result, blood that should be flowing in a forward direction through the heart, is able to flow back on itself, making the heart inefficient at pushing blood around the body. As the heart continues to have to work harder to try and keep up with the body demands, it will often become enlarged and a “big heart” can be seen on an xray.

The picture on the right shows an xray taken of a dog in heart failure due to mitral valve insufficiency. The heart is very enlarged and pushes the trachea (windpipe) up towards the spine. This can cause the dog to cough.

Larger breed dogs tend to suffer from a group of conditions generally referred to as “dilated cardiomyopathy” or DCM; this is where the heart enlarges and the muscle becomes stretched and cannot pump as strongly and efficiently. The amount of blood moved by each push of the heart muscle becomes less. The stretching can also result in valves being pulled apart and so that they are unable to seal properly and blood can flow backwards in what should be a one way system.

In large and small dogs the changes in the heart muscle or valves results in insufficient oxygenated blood being provided to the body. Changes of pressure can also affect result in fluid accumulation with the lungs or sometimes within the abdomen.

Symptoms you may notice include:

  • Reluctance to exercise or slower on walks
  • Short of breath
  • Coughing
  • Reduced appetite
  • Swollen abdomen (pot-bellied appearance)

As heart disease advances the symptoms become more pronounced and can require emergency treatment.

If your dog is:

  • Collapsed
  • Struggling to breathe
  • Has a purple/blue coloured tongue (unless Chow Chow breed – this is normal in the breed)


Your dog may have had a heart murmur picked up previously on a routine examination and we may have discussed signs to watch out for. The first symptom may just be your dog slowing down on walks. Some owners notice a cough early on in the disease process while others may not see a difference until your dog is struggling more.  Recent studies have now shown that in some cases, treatment initiated whilst in the early phases of heart disease can be beneficial and improve life expectancy. To learn more about our DCM screening programme for large breed dogs click here:

DCM Screening Programme

We hope to be introducing other screening programmes later in the year but if you have a concern about your dog and risks of a heart condition then please speak to your vet.


Cats can also suffer from heart disease and failure. The most common is a condition called “hypertrophic cardiomyopathy” or HCM. This is where the heart muscles become thickened and therefore decrease the amount of space left for blood within the heart. This makes it harder for the heart to pump blood around the body and in cats this most commonly results in fluid collecting outside the lungs but within the chest wall- we refer to this as the pleural space. The lungs become squashed and unable to inflate properly and the breathing effort has to be increased to compensate. Often an increase of breathing effort is the first indication that a cat is suffering from heart disease although there can sometimes be a early indicator such as a heart murmur or abnormal heart rhythm called a “Gallop rhythm”, which can be detected by listening to the chest. We listen to your cats heart every year if they are brought for vaccination or routine health checks.

Younger animals can suffer from heart conditions too, most commonly when this occurs a murmur is picked up at first vaccination and may be followed up immediately or at a later date depending on what your vet feels is most appropriate. The conditions affecting younger animals are different to those seen in later life, each case has to be taken individually and discussed on a case by case basis with your vet.

Please do book an appointment to see a vet if you think your dog or cat is slowing down or your dog has started coughing. If you think your dog or cat is breathing more rapidly at rest or there is more effort involved in their breathing then please call immediately on 01543 262464, regardless of time of day or night.

An animal having any difficulty breathing may require emergency treatment!

Pool House Vets