Heart Disease


A healthy dog's heart works to pump blood around the body.   It provides oxygen and nutrient enriched blood to all the vital organs.   Your dog's heart is just like our human hearts and is made up of four chambers inside a 'bag' of muscle.   These chambers are separated by four valves, sometimes refered to as trap doors! They are one way only valves and when these valves shut we hear the lubb-dubb sound when listening to your dog's heart - we associate this sound with a normal heart beat.   Heart disease can be congential, (present from birth) or it can be acquired due to a number of different factors.   Heart failure can occur if there is damage to the heart muscle, heart valves and or the major blood vessels connecting to the heart.  The following information gives a brief overview of the more common heart conditions, general signs and advice.
Congenital Heart Disease

There are a number of recognised dog breeds that are pre-disposed to a specific heart defect/s.  It is important to do your research when looking for a specific breed, the Kennel Club website is excellent for inherited health disease advice. Heart defects may be detectable when your puppy has its first full health check with the vet, usually at the time of first vaccination.

It may be difficult to detect changes in your puppy if you have just brought them home from a breeder.   You may think that they are just a bit quiet, but have no gauge of what the puppy should be like.  This makes it difficult for you to spot and is why a full health check with your vet is so important.

Depending on the severity of the heart condition signs can include poor growth, unwilling to exercise; lethargic, difficulty in breathing and coughing.   Diagnosis is made using your puppy's history and clinical examination.  X-rays will be used and an ECG.

Patent ductus arteriosus (PDA) This is the most common congenital heart condition in dogs.  This PDA allows the blood to bypass the lungs and at birth it should close naturally.  If this doesn't happen it will cause left sided heart failure which can lead to death if not treated.  This involves surgery to close the vessel and with treatment the prognosis after surgery is excellent.

Heart valve or septal defects Aortic or pulmonic stenosis is a narrowing of the aortic or pulmonic valves. This leads to obstruction of the the blood flow leaving the ventricles.  The heart muscle has to work harder as a result and leads to a thickening of the heart muscle. The only treatment is surgery.
The septum is a normally intact band of tissue that permanently divides the left and right side of the heart.  Patients with septal defects otherwise known as holes in the heart, have a hole through their septum connecting heart chambers together which would not be present in the normal patient.   Blood flows through the heart abnormally and this leads to heart failure.

Persistent right aortic arch  This is a malformation of the major arteries of the heart present from birth.  The malformed position traps the dog's oesophagus which obstructs boluses of food from entering the stomach.  Signs include regurgitation, weight loss and poor development.  Aspiration pneumonia can also develop and coughing may be noticed, and not always at feeding times.  Treatment is surgery and management of any associated conditions, such as feeding considerations if their oesophagus is damaged.

Acquired Heart Disease

In dogs the most common condition of the heart muscle is Dilated Cardiomyopathy (DCM) and a common disease that effects the heart valves is known as Mitral Valve Disease.

Dilated Cardiomyopathy tends to effect larger breeds of dogs.  The muscle of the heart weakens over time and become floppy, as a result the chambers of the heart become enlarged.   The heart then has to work harder and harder to pump blood around the dog's body.  As the disease progresses the heart is unable to pump out enough blood and some blood backs up the wrong way.   

This results in pressure changes and the accumulation of fluid in the dog's abdomen or lungs.  As the disease progresses the heart tried to compensate until it can no longer cope.   We refer to the different stages to heart failure according to the degree of heart failure the dog is in.

Mitral Valve Disease occurs more frequently in small - medium size breeds.   Heart failure, occurs when one of the heart valves (the mitral valve) becomes thickened and an abnormal shape - the result, the valve does not close with a tight seal.   This allows blood to flow the wrong way and reduces the amount of blood flowing out of the heart the right way into the circulation.   

This change in blood flow leads to pressure changes and fluid accumulation in the dog's lungs.   We can hear the blood flowing the wrong way when we listen to their heart, as an abnormal heart sound. These changes can develop slowly and your dog's heart will try and compensate for these changes, but only up to a point after which it will no longer be able to cope.  As with DCM we also recognise different stages of the heart failure.

Treating Acquired Heart Disease  There are a number of veterinary medicines to treat heart failure in dogs, which are used to improve the efficiency of the heart and reduce the symptoms of heart failure.   Unfortunately treatment will not cure your dog's heart failure but it will improve their quality of life.   These drugs can be categorised into three groups: those that work to strengthen the dog's heart; vasodilate blood vessels making the vessels wider and therefore easier for the heart to pump blood around the body and diuretics to remove fluid.

Signs of Heart Disease
In heart failure cases your dog's heart isn't working efficiently enough to get valuable nutrients and oxygen to its vital organs.  This may result in some or all of the following signs:
  • Fatigue when exercising
  • Wanting to rest more at home and show reluctance to go on normal walks
  • Breathing may become quicker
  • Their abdomen may appear larger than normal 
  • A cough may develop especially in the morning and at night
  • Becoming less interested in food and loosing weight
  • They may collapse or faint

Looking after your dog at home
It is vital that your dog receives their heart medication at regular intervals as prescribed by your vet.   
  1. This should be at the same time every day, e.g. if the medication states twice daily this should be every 12 hours, e.g. 8 am then 8 pm
  2. Your dog will need their exercise regime reviewed.  Some dogs need to rest while other may benefit from gentle exercise, so we may recommend a change to their daily routine
  3. Weigh and record your dog's weight regularly, let us know if there are any changes
  4. Monitor what your dog eats and drinks - they may need to change diets as part of their treatment
  5. Watch your dog's breathing pattern and record your dog's breathing rate by watching their chest move up and down.  This should be done when they are resting, to be more accurate.

If you are concerned that your dog may have any of the signs noted above, please ring us Tel: 01376 3245511

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