KC/VCS/CKCS Heart Scheme Breeding Guidelines

Mitral valve disease is a complex condition, affected by both genes and environmental factors. Thus it can be challenging to make breeding decisions with the aim of reducing the genetic risk over generations. However, multiple studies have estimated that there is a moderate to high heritability of mitral valve disease (MVD) in the Cavalier King Charles Spaniel, implying that selective breeding can enable breeders to greatly reduce the incidence and severity of the disorder. Carefully applied this can allow breeders to continue with their bloodlines while making balanced breeding decisions. 

The advice below provides guidelines which will help reduce the risk of producing affected puppies. However, following these guidelines cannot be used as a guarantee that an individual dog will not be affected by MVD to some degree (given the complex nature of the condition). The screening consists of auscultation (listening to the heart using a stethoscope), which gives a murmur grade, and an echocardiograph (cardiac ultrasound), which gives a Mitral valve prolapse (MVP) grade, and both of these results are used to determine the outcome of the test. Some dogs can have quiet murmurs which are NOT caused by mitral regurgitation or other heart disease, and these murmurs are termed ‘innocent’ or ‘flow’ murmurs. These can only definitively be determined using a heart scan, and dogs with innocent murmurs should not be excluded from breeding.


Mitral valve regurgitation murmur is graded 0-6 with 0 indicating no murmur and 6 indicating the most severe murmur (and hence the most severe mitral valve regurgitation).

MVP is graded 0-3 as follows:

  • 0 - none
  • 1 - mild
  • 2 - moderate
  • 3 - severe

Dogs with grade 0 or 1 murmur plus grade 0 or 1 MVP, or dogs considered to have an ‘innocent’ murmur, (both categorised as green under the traffic light system shown below) are considered to be at the lowest risk of developing clinical mitral valve disease and to represent the lowest breeding risk.  Dogs with a grade 2 murmur OR grade 2 MVP (but not both), denoted amber, have a greater risk of developing a passing on the condition to offspring.  The KC advises that, to reduce the genetic risk of MVD in offspring, that only amber dogs in excellent health, and with good results from other screening schemes, may be used cautiously for breeding with particular care to use mates which have been categorised as green under this traffic light scheme, preferably at 4 years of age or older.  Dogs categorised as amber at 4 or 6 years of age (or older) are considered to represent less of a risk than those categorised as amber at the first examination at 18months-2 years.  Dogs which are categorised as red, with a grade 3 murmur or higher, grade 3 prolapse or significant congenital heart disease represent the greatest breeding risk and it is advised that these dogs are not used for breeding.  This advice is summarised in the table below.  The advice may change, however, as further research is undertaken.

Heart Scheme information

Making balanced breeding decisions

Mitral valve disease is not a condition that is present at birth, therefore the older that a dog is at testing; the more confident we can be about the result of its test. We therefore recommend that dogs are as old as possible when breeding is undertaken and that where possible the results of older relatives is also taken in to account.

As well as considering the implications of the condition you are concerned about, there are other equally important factors to consider when deciding whether two dogs should be mated together, such as temperament, genetic diversity, conformation, other available health test results, the general health of the dogs etc. Your breeding decisions should always be well balanced and take into consideration the qualities and compatibility of both the sire and dam that you are considering.


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