What are we screening for in Cats?

Echocardiography (ie ultrasound scan of the heart echo/ colour Doppler) is used to screen cats for all forms of heart disease, although most importantly we are screening for hypertrophic cardiomyopathy (HCM).

Congenital heart disease

The cat is born with this type of heart disease and includes problems such as a hole in the heart and heart valve deformities.  These defects can be passed onto kittens and breeding from cats with congenital heart disease is not advised.

Hypertrophic Cardiomyopathy (HCM)

Cardiomyopathy is, broadly speaking, disease of the heart muscle cells which in turn causes them to function abnormally.

HCM is the most common form in cats in the UK and is thought to be present in some form in 15% of all UK cats. It is more prevalent in certain breeds of pedigree cat, including the Ragdoll, Maine Coon, Norwegian Forest, Sphynx, Bengal and Persian cats.

In this form of cardiomyopathy, the heart muscle becomes thick walled and stiff.

HCM is mostly caused by genetic abnormalities, often in more than 1 gene, and parents with the disease are likely to pass on genes causing HCM to their offspring.

Commonly there are no signs of the disease until the cat is a mature adult and there may not be any symptoms for years even though the disease is clearly present on echo.  However, some younger cats will unfortunately develop symptoms, such as: congestive heart failure and clots (thrombo-embolism). Sadly, sudden death can also result from this disease.

Other Heart Disease.

There are types of cardiomyopathies leading to a range of cardiac abnormalities, including a thin walled poorly contracting heart (dilated cardiomyopathy, DCM). There are a whole range of presentations that do not fit into either the DCM or HCM category, but where the heart muscle is clearly abnormal.

Rarely the heart muscle can become affected by inflammation which can cause temporary changes.

The heart valves can also become affected by inflammatory disease and aging.

How are cats screened?

Examination and echocardiography are used in the VCS breed screening for all cats.  DNA testing can also be useful in some breeds.

Examination.

There can be findings suggestive of heart disease when the cat is examined. There may be signs of poor circulation, abnormal breathing and a fast or irregular heart rate with a murmur or gallop sound.  However, in the early stages of the disease, none of these may be present or only present intermittently.

Echocardiography (ultrasound of the heart/echo Doppler).

When this is performed by a vet experienced in scanning cat hearts, abnormalities in the heart related to the presence of HCM can be detected & heart disease other than hypertrophic cardiomyopathy can be found.  This remains the most important and sensitive test that is available to check for HCM in cats, although in the early stages the findings can be subtle and hard to detect.

DNA testing.

Maine Coon LINK and Ragdoll cats LINK have a validated DNA test for hypertrophic cardiomyopathy, which also forms an important part of the screening for these breeds.  However not all cats who are positive for these tests go on to develop HCM, and not all cats with HCM give a positive test result– meaning that there is more than one gene responsible and there may be other unknown factors involved.  Therefore, screening by echocardiography is still recommended in breeding cats and other individuals.

When validated in the future, other breed DNA tests may also be useful.

How often should cats be screened?

Cardiomyopathies are not usually present at birth and develop when the cat is an adult.

Ideally each breeding cat should be screened annually so that we have the best chance of catching the early signs of the disease developing.

VCS members appreciate the demands on time and cost that this involves, but we also strongly wish to encourage breeders to screen older cats who may only develop HCM after they have finished breeding.

As part of modernising the scheme the following will be the NEW VCS advice.

  • BREEDING FEMALE : Screen every 2 years from 2 years old.
  • BREEDING MALE : Screen every year from 2 years old.
  • OLDER AND NON BREEDING MALES AND FEMALES : Continue to screen every 2 years.
  • Males and females can be screened before 2 years old, but negative HCM results will only be put onto the VCS list (being developed in the near future) for screens performed after 2 years of age.
  • It is not advised for the tom or queen to have more than 1 litter before first screening at 2 years. If the parents and grandparents are currently known to be HCM negative, breeding from cats less than 2 years old can be done with more confidence.

Who can screen cats and how to arrange to have a cat screened.

VCS holds a list of veterinary cardiologists specifically trained and accredited to heart screen cats, which can be found on this site. Only these cardiologists can provide an official heart screening certificate.

Please contact the individual cardiologists for details of their appointments & charges.

You will need to provide your registration details for pedigree cats and ask your usual veterinary surgeon to refer you to your chosen screener.

What happens with the results of a screen?

Currently, the VCS scheme uses paper and carbon copies.  One copy is kept by the owner and there is one for their vet.  Another copy is retained by the cardiologist, and one is sent to GCCF.  VCS are working on an online screen form and once this is set up, would like to provide a HCM negative register.

Currently there is a list of cats who have been screened negative for HCM held by GCCF.

https://www.gccfcats.org/wp-content/uploads/2024/05/Negative-HCM-register-05.29.2024.pdf