Heart Disease

The heart acts as a double-sided pump sending blood around the body to provide all the organs and tissues with oxygen and nutrients.

The LEFT side of the heart pumps blood full of oxygen from the lungs to supply the body. Once the oxygen has been used up, the RIGHT side of the heart pumps the blood back to lungs to collect more. Needless to say the heart is a vital organ and if it starts to go wrong, action must be taken quickly.

Heart Disease and Heart Failure

Heart disease can be something that an animal is born with (a congenital disease) or something that develops as the animal grows older (an acquired disease).  In the early stages there may be no symptoms, but on examination with a stethoscope the vet may hear a heart murmur.  This is an abnormal ‘whoosh’ sound heard alongside the normal ‘lub-dub’ of the heart beats.  Murmurs are caused by turbulence as blood flows through the heart in an abnormal way; they are graded 1-6 depending on how loud they are.  In general, the louder the murmur, the more serious the problem but this is not true in every case.

As heart disease progresses and the heart begins to change shape as a result, it can lose the ability to cope with the demands of the body.  This is when symptoms start to show and the patient is said to be in ‘heart failure’; i.e. the pump is not longer doing its job properly.

Symptoms of heart failure can include:

Dogs:

Coughing, especially during/after exercise.
Reduced tolerance of/enthusiasm for exercise.
Lethargy.
Breathlessness.
Episodes of passing out/collapsing/fainting.
Fluid in the abdomen.
Weight loss

Cats:

Breathlessness
Lethargy
Open-mouthed breathing/panting
Weight loss
Fluid in the belly

If you notice any of these signs - on their own on in combination – then make an appointment to see your vet as soon as possible for a full check up.  Once an animal is in heart failure it is important that we act quickly and start treatment as soon as possible.  Try not to panic and fear the worst though; all of the above symptoms can be caused by a variety of other conditions other than heart failure!

Diagnosis

If heart disease is suspected in your pet, a variety of diagnostic tests may be performed:

Listening to the chest (thoracic auscultation).

To listen for heart murmurs.
To check for build up of fluid on the lungs.
To make sure the rhythm of the heart is regular.

Checking pulses and gum colour.

To make sure that the blood is being effectively pumped to all parts of the body.

ECG (electrocardiography, ‘heart trace’)

Wires are clipped to the pet’s legs to measure the electrical signals that are sent through the heart to make it beat.
This gives information about the rhythm of the heart as well as some clues about the size and shape of its chambers.
This is a painless procedure, usually done with the pet fully conscious.

X-rays (thoracic radiography)

To look for fluid on the chest.
To give an idea of the overall size and shape of the heart.
To rule out other lung/airway problems.
This is ideally performed under anaesthetic or sedation – the patient must be extremely still when the pictures are taken or blurring occurs which obscures the delicate lung patterns.

Echo (echocardiography, ‘heart scan’)

An ultrasound scanner is used to observe the heart beating.
Accurate and useful measurements can be taken and the internal structure of the heart can be checked.
This can usually be performed with the patient fully awake.  A small patch of hair will need to be clipped away over the chest so that the scanner can get good contact with the skin.

Blood Pressure

Measuring the blood pressure can give important clues as to the extent of heart disease and help us decide on the best course of treatment.

Blood Tests

Useful to rule out other problems which may confuse diagnosis.
To check for other problems causing or results from the heart condition.
Some special tests can pick up the early signs of heart disease.

Fluid Samples (thoracocentesis or abdominocentesis)

If there is fluid on the chest or the belly, a sample can quickly be taken to analyse and aid diagnosis.
If there is a large volume of fluid on the chest compressing the lungs, this can be drained off to make breathing more easy and comfortable.

Treatment

Fortunately, most forms of heart disease can be managed well – providing it is diagnosed early enough and treatment is started promptly.  We have a whole host of medication that can be used to support the heart, help it beat more effectively or more regularly, decrease blood pressure and workload on the heart, remove excess fluid  and to slow down the deterioration and changing of shape of the heart muscle.  Most cases will require a combination of different medication.

Draining of the chest fluid from time to time is required in some cases.

The need for surgery in our patients is very rare and is restricted to a handful of serious cases where the animal has been born with a heart defect that must be repaired.  In these cases, the patient is referred to specialist cardiologists.

Outlook

Realistically, heart disease will have an impact on a pet’s life span.  However, providing diagnosis is made early and a good treatment protocol is started and maintained, most heart disease patients recover very well and go on to lead happy, comfortable lives.

Regular check-ups will be needed and occasional tweaking of the prescribed drugs is normal.

If you are concerned that your pet is showing any of the symptoms outlines above, please call us straight away.  The quicker we see the pet, the quicker we can either put your mind at rest, or start treating a problem.

On the next page is some more detailed information about some of the specific heart diseases that we see.

Specific Diseases

Mitral Valve Disease (MVD/Mitral Insufficiency/MI)

The one-way valve between the chambers in the left side of the heart starts leaking.
This can be due to thickening of the valve, enlargement of the heart, or infection.
Blood is allowed to flow in the wrong direction making the heart work harder.
As the heart works harder, it grows – just like any muscle.  The larger it gets, the worse the problem.
Medication can be used to decrease the workload of the heart and the response is usually very good.
Most common in small breed dogs over 7 years old, especially Cavalier King Charles Spaniels.

DCM (Dilated Cardiomyopathy)

The heart grows very large.
The muscle of the heart wall becomes thin, floppy and weak.
The heart is unable to contract effectively so output is decreased.
Congestive heart failure develops as the circulation ‘backs-up’ – fluid builds up on the chest and sometimes the belly.  This compresses the lungs making breathing difficult.
Most common in large breed dogs over 5 or 6 years old, especially Dobermans.
Can be treated effectively with medication to begin with, but long-term outlook is not good.

HCM (Hypertrophic Cardiomyopathy)

The muscle of the heart wall thickens greatly, taking up space within the pumping chambers and the output of the pump is therefore decreased.
Congestive heart failure develops as the circulation ‘backs up’ – fluid builds up on the chest.  This compresses the lungs making breathing difficult.
Most common in cats as they get older.
Can be treated with medication if caught early enough.
Similar heart disease is often caused by an overactive thyroid gland in cats.

Rhythm Problems (arrhythmias, dysrhythmias)

Sometimes the heart is unable to co-ordinate a regular heart beat – this means that is does not pump efficiently and heart failure can develop.
This can be due to structural problems, or problems with the heart’s natural pacemaker, certain drugs and poisons can also cause these problems.
Some examples you may hear are: atrial fibrillation (AF), ventricular tachycardia (VT) and heart block, amongst others.
These conditions can often be managed with medication.

Aortic Stenosis

This is normally congenital, which means it is already present at birth
The valve allowing blood out of the heart to supply the body is narrowed.
The left side of the heart is made to work harder against this narrowing and can grow very large.
The circulation is compromised and fainting can occur.
As the circulation ‘backs up’ fluid can build up on the lungs.

This disease is less common and can require specialist treatment.

The breed most often affected is Boxers

Pulmonic Stenosis

The valve allowing blood out of the heart towards the lungs to collect oxygen is narrowed.
This means the right side of the heart must work harder to push blood out and will grow larger as a result.
This disease causes problems with providing oxygen to the body and can also lead to fluid on the abdomen as the circulation ‘backs up’.
This is less common disease and can require more specialist treatment.