Heart Disease in Cats

What types of heart disease do cats get?

Heart disease can be divided into two groups, congenital and adult onset forms. In congenital disease the defect is present at birth. Although signs of congenital disease are often seen at quite a young age, in some cases they can go undetected. 

Congenital disease can affect a single individual associated with malformation of the heart as the embryo develops or can be genetically controlled having an hereditary basis and affect more than one kitten in the litter. Adult onset disease can occur as the result of damage to the heart at some time during the cat's life preventing the heart from functioning normally or, in some cases, can be hereditary disease which has been silent until the cat is full grown. The cause of most types of adult onset heart disease is unknown.

The heart can be divided into 4 parts,

i)  the heart muscle which pumps the blood around the body

ii)  the heart valves which act to prevent the blood going in the wrong direction

iii)  the pericardium which is a tough membrane surrounding the heart

iv)  the electrical conducting system which acts to initiate and transfer electrical impulses around the heart allowing it to beat in a co-ordinated fashion

All of these parts can be affected by disease.

The most common type of adult onset disease is cardiomyopathy, a disease affecting the heart muscle.

How common is heart disease in cats?

Heart disease is relatively common in cats, the most common type of heart disease being adult onset cardiomyopathy (see information sheet on cardiomyopathy). Cats tend to be quite secretive when they are unwell making it difficult to spot the subtle signs present in early disease. Unlike dogs, coughing is an uncommon sign of heart disease. Exercise intolerance does occur but, as cats aren't often taken for walks, their lack of ability to exercise goes unnoticed! With advancing disease and declining exercise tolerance, cats tend not to wander from home as much and sleep more than usual.

What are the signs of heart disease in cats?

The most common signs of heart disease in cats are :

• lack of appetite
• weight loss
• lethargy
• increased respiratory rate & effort
• collapse
• pain and hindlimb dysfunction
• stunted growth (kittens)

Congenital heart disease

Congenital heart disease most commonly involves the heart valves (with one or more valve being incompetent) or a failure of the division between the left and right sides of the heart to form properly. In both circumstances, the defect results in an abnormal blood flow causing turbulence. Tubulence leads to a heart murmur that is often first heard when a kitten presents for their primary vaccination course. The loudness of the murmur reflects the amount of turbulence but is not indicative of the severity of the disease. Not all heart murmurs are associated with heart disease but may reflect another disease process, for example anaemia. We now recognize that many normal cats can have intermittent heart murmurs that are of no consequence to their health.

What can be done for my cat?

Depending on the murmur and the degree of signs (if any), further investigation may be advised. This generally involves radiographs,

electrical recording of the heart (ECG) and ultrasound examination (echocardiography). In some cases, where it is felt that the heart murmur is secondary to another disease, other tests such as blood and urine tests may be required. Particularly in cats over 6 years of age, their blood pressure should be checked to see if it is normal.

What treatments are available?

Available treatments will depend on the cause of the problem. At this time, few congenital abnormalities apart from patent ductus arteriosus (PDA) can be corrected surgically. This means that a decision has to be made as to whether medical management is appropriate or necessary. In many situations where a heart murmur has been detected on a routine examination but the cat is not showing signs of problems, monitoring alone is the best option. The presence of a heart murmur does not always mean that your cat's quality of life or life expectancy will be affected.

What inherited heart diseases do cats get?

Maine Coon - a severe form of heart muscle disease (hypertrophic cardiomyopathy) is seen in some Maine Coon cats. Cases can start showing signs by 3 months of age whilst less affected cats show signs of heart failure by 2-4 years of age.

American shorthair - a relatively non-serious form of heart muscle disease is seen in this breed with most cases showing few symptoms.

Persians - this group seems to be over-represented in studies looking at heart muscle disease.

Siamese cats are more commonly affected by patent ductus arteriosus, a communicating vessel which affects blood flow to the chest, abdomen and hind limbs.

What heart diseases do cats get in adulthood?

The most common heart disease presenting in adulthood is cardiomyopathy. A separate information sheet is available that deals specifically with this topic. Diseases affecting the heart valves and pericardium are rare in adult cats.

A number of conditions can affect the heart rhythm in cats, some need treating with drugs to try and return the rhythm and rate to a more normal state. Many cats with rhythm disturbances show relatively few signs of disease.

Diet and heart disease

Cats with heart disease have no specific dietary requirements but it imperative that they are fed on a diet containing sufficient taurine.  Low salt diets are unlikely to be helpful unless the heart disease is associated with high blood pressure (hypertension). Other than this, a diet that maintains a constant body weight is ideal. Supplementation with vitamin E may also be helpful.

Notes on medication

It is essential that the instructions for medication are followed closely. For drugs given more than once daily, doses should be spread out over the day as evenly as possible. Some medications can have serious adverse effects if stopped suddenly so it is important that fresh supplies are requested ahead of time.