Recent research has concluded that high inbreeding coefficients may lead to an increased risk of Vizsla Inflammatory Polymyopathy (VIP) (formerly Vizsla Polymyositis), therefore it would be wise to check that any proposed mating would result in a low inbreeding coefficient, while taking into account all the other factors – temperament, hip-scores etc.

The average inbreeding coefficient for the Hungarian Vizsla is 5.3% (May 2015).

The following explanation is taken from the Kennel Club “Breeding for Health” Leaflet – February 2015.

What are the effects of inbreeding? 
Inbreeding is the mating of related individuals, either close or distant. The more inbred a dog is, the higher the chance that the same version of a gene has been inherited from both dam and sire – both for desirable and undesirable traits. This could increase the chances of a dog being at risk for both known and unknown inherited disorders and can lead to inbreeding depression.  

Inbreeding depression is an overall decrease in general fitness, or general health, and may reduce, across the breed, things like litter sizes and fertility. It is impossible to make precise predictions about the exact impact that inbreeding has on an individual breed or dog, but we do know that, as the degree of inbreeding increases, the risk of having a serious and harmful impact on the breed as a whole will also increase.  

How can you measure the degree of inbreeding?
The degree of inbreeding can be measured by using an inbreeding coefficient. This is the probability that two copies of the same gene have been inherited from an ancestor common to both the sire and dam. The lower the degree of inbreeding, the lower the inbreeding coefficient. Breeders should be aware that the inbreeding coefficient is a measurement of risk and does not guarantee that puppies produced will or will not have any inherited health conditions.  

View your dog’s inbreeding coefficients on Mate Select The Kennel Club’s online health resource, Mate Select, provides breeders with inbreeding coefficient calculators. These calculators use pedigree records stored on The Kennel Club’s database to calculate the degree of inbreeding, or coefficient of Inbreeding (COI), for:

• potential puppies that could be produced from hypothetical matings  

• each individual Kennel Club registered dog  

• each breed as a whole 

These resources provide information about how a specific inbreeding coefficient for a mating is calculated, which includes how many generations the pedigree data extends back to in order to calculate a particular result.  

Putting your dog’s inbreeding coefficient in perspective

The lower the degree of inbreeding, the lower the inbreeding coefficient.  
An inbreeding coefficient of 0% indicates a dog that comes from two unrelated parents.  
An inbreeding coefficient of 12.5% would equate to the genetic equivalent of a dog produced from a grandfather to granddaughter mating.  
An inbreeding coefficient of 25% would equate to the genetic equivalent of a dog produced from a father to daughter mating.  
Inbreeding can be accumulative and so if it has occurred to a significant degree over several generations, the inbreeding coefficient may exceed 25%.  

Breeding advice 
When choosing a potential mate for your dog, the Kennel Club recommend that breeders use Mate Select to calculate the inbreeding coefficient of the puppies that could be produced from a hypothetical mating. By using this resource it helps breeders decide whether to mate a particular pair of dogs together. The current Kennel Club breeding guidelines are that, where possible, breeders should produce puppies with an inbreeding coefficient which is at, or below, the breed average. The breed average is recalculated annually and is presented each time you use the Kennel Club’s inbreeding coefficient calculators. Although the Kennel Club recommends breeding at lower inbreeding coefficients, there are similarly other important factors to also consider when deciding whether two dogs should be mated together, such as temperament, available health test results etc. Your decision should be well balanced between the inbreeding coefficient and the good qualities of the sire/dam that you are considering.