AKC Breeder Newsletter
AKC Breeder Newsletter is a quarterly newsletter covering a wide range of topics of interest (nutrition, breeding techniques, health concerns, etc.) to the purebred dog breeder. You can sign up for AKC Breeder here.
The following article appeared in the Winter 2015 issue.
The Art and Science of Breeding Better Dogs
Gail Knapp, Ph.D., J.D., Great Pyrenees Club of America
How does the experienced breeder choose which dogs to consider including in her own breeding program? Well, the really skilled breeders do not look at a win record as the major deciding factor. It is the pedigree and how the individual dog “fits” with her breeding program that really counts.
First, the breeder evaluates her own dogs as objectively as possible, asking questions such as “What are the outstanding characteristics that I really want to keep in the next generation?” and “Where are areas that are less desirable and need improving?”
Then the breeder looks at the pedigrees of the dogs she plans to breed in the future. (And not just the immediate litter; this is long-term planning.) Have these dogs been line-bred? Inbred? Out-crossed? Any book about breeding will give careful definitions for each of these terms; that isn’t what is important here. The issue is really about how often the same ancestors appear in those pedigrees, both within them and across them.
The advantage to breeding closely related dogs is that by doing so you get a lot of homozygous gene-pairs. What does that mean?
OK, here is a quick, very basic genetics lesson: Characteristics that you see when you look at the dog all come from a complex of interactions of gene pairs, where one half of each pair is from the dam and the other is from the sire. Some of these genes are recessive, and “hide,” while others are dominant, and don’t hide. There may be more than two possibilities at any spot on the chromosomes, but each individual only gets two of them. Most of the time, these pairs interact with other genes to create the final dog we see.
When you do a lot of close breeding, the gene pool is limited. This means that with repetition, you get pairs consisting of two identical genes—what geneticists call homozygous pairs. Sometimes this is a very good thing, and sometimes it is not. It depends on what the genes are controlling. When you do this kind of breeding, however, you will get great consistency. Since there are limited genes to pick from, the result will be the same over and over again.
At the opposite extreme is a pedigree where very few or no ancestors are repeated. This results in a more diverse gene pool and many heterozygous gene-pairs. These are pairs where the two genes are different. That will result in a wider variety of combinations and much less consistency. It will also allow the production of litters with new combinations, and thus new characteristics.
So what is the breeder to do? He decides what he wants to accomplish. Want to add new things to improve the quality of your line? Outcross with a line that has those characteristics you want. Want to be sure to keep the great things you have? Breed closely to get a very consistent litter. When you know what you want, then you can plan to attempt to create the result you desire.