PROPER USE OF GENETIC TESTS IN MAKING BREEDING DECISIONS

[Elaine]

Here is an article by Jerold S. Bell, D.V.M. I thought is was well worth reading, it speaks to many of the concerns we have about the "proper" use of the data we have.

http://www.spanielsinthefield.com/spaniel-health-05.asp

[Elaine]

We are using the evaluation of a phenotype as though it was accurately predictive of genotype (what the dog will transmit). The "Holter Your Dog" approach to breeding decision is a great example of using data the wrong way.

Quoting from Dr. Bell:
Genetic defects are controlled by single, or a handful of genes, compared with the estimated 10,000 to 40,000 genes in the dog genome. Prudent breeding practices dictate that you do not throw the puppy out with the bath water in genetic disease control.

...

In polygenic disorders, the phenotype of the individual does not directly represent its genotype. As we have learned from farm animal breeding systems, the phenotype of the full and half brothers and sisters more directly represent the range of genes present in the breeding individual. In other words, the breadth of the pedigree is more important than the depth of the pedigree in polygenic disease control. Breeders should be monitoring all of the individuals in a litter as a measurement of the genes of the dog they are selecting.