Estimated Breeding Values (EBVs) for hip and elbow scores

 

Your help is needed

 

Groundbreaking research for dogs is taking place at various institutes worldwide, the Golden Retriever Club of WA under Dr Carla O’Donnell aims to provide Estimated Breeding Values (EBVs) for Golden Retrievers in Australia.

 

The aim of this project is to provide information to breeders that will aide in decisions to improve hip and elbow dysplasia while safeguarding the long term health of the breed by maintaining genetic diversity.

 

How is this done?

 

The greater the number of Golden Retrievers used to calculate the EBVs the more useful the EBV will be in determining the genetic risk for an individual. Therefore, to provide accurate EBVs for hip and elbow dysplasia, data from as many Golden Retrievers as possible with known pedigrees needs to be collected. This data is correctly termed ‘phenotypic measurements’ A dog’s phenotype is what we see in the dog. It includes its physical characteristics, clinical signs, and also hip and elbow score information.

 

Hip Dysplasia is a complex disease in that several genes are involved.  In addition whether a dog is severely, moderately or mildly affected by the condition in not only determined by how many of these genes are inherited but the clinical presentation of the disease is also influenced by environmental factors.

What are Estimated Breeding Values?

 

An Estimated Breeding Value reflects the genetic risk for an individual dog with regard to disease. It removes the effect of environmental factors and is the most accurate measure of breeding potential. An offspring’s score is the sum of its parents’ score divided by two. The EBV indicates where an individual Golden Retriever is in the breed’s scale of risk and enables more accurate and sensitive selection against the disease. As more Golden Retrievers are added to the database the more accurate the EBV.

 

In the current project, EBVs will be given for Hip and Elbow Dysplasia. Other diseases which are inherited in Golden Retrievers can also be added in at a later date.

Diagram showing EBV for a Golden Retriever from the UK EBV hip and elbow database.

 

 What does the EBV value mean?

  • The breed average is always set to 0. Higher risk EBVs are shown as a positive number (red area on the left of the centre bar) and lower risk EBVs as a negative number (green area on the right of the centre bar).
  • The further a dog’s EBV is from the average, the higher or lower its genetic risk. One standard deviation is represented by 20 units. So a dog with an EBV of +40 is two standard deviations worse than average, while a dog with an EBV of -20 is one standard deviation better than average.
  •  At birth a puppy’s EBV will be the average of its parents’ EBVs. A dog’s EBV can change during its lifetime, as more information becomes available, either about the dog itself or its relatives.
  • The accuracy (Confidence % in above diagram) is a measure of how much information has been used to calculate the EBV. If the dog has been hip or elbow scored itself and has several relatives with scores then the accuracy will be higher than if it has not been scored and has few relatives with scores. Individuals with several scored offspring tend to have high accuracies. Accuracy is the correlation between the estimate of the breeding value and the true value. The more information available the closer the estimate will be to the true value.

 

 

Can EBVs change?

 

<!– [if supportFields]>PRIVATE “TYPE=PICT;ALT=Breeding Value Diagram”<![endif]–><!– [if supportFields]><![endif]–>Most certainly, yes. As more information from the dog itself, or its relatives, becomes available, the EBV can change as the accuracy of the estimate improves. And since the EBV represents a dog’s genetic risk of disease relative to the rest of the breed, if selection away from a disease is successful then the EBV will fall slightly.

 

This will also affect the average breeding value for the breed as a whole. Puppies born to sires and dams with breeding values which are better than average will lead to a shift of breeding value distribution, with a new, better average – meaning the breed is getting healthier. For example, a dog previously in the best 20% is now only in the best 40%, since selection has improved breeding values throughout the population.

 

 

Improving the accuracy of EBVs

 

For EBVs to be accurate you need to have information on as many family members as possible and as many Golden Retrievers as possible throughout Australia. This will come in the main from breeders but the contributions from pet owners are also extremely valuable.

 

 

How can you Help?

 

The GRCWA currently has hip and elbow certificates dating back to the 1990’s for WA registered dogs. To provide EBV for Australian Golden Retrievers additional current hip and elbow certificates are needed. The GRCWA is collecting hip and elbow certificates and pedigree information to provide EBV for Golden Retrievers in Australia. If you like to be a part of this project could you please send a copy of your hip and elbow certificates to Carla O’Donnell either via:

 

email: carla@aneirabygoldens.com

 

Electronically input the data: Golden Retriever Database