The Schipperke breeding population is very small and the practice of line breeding to create beautiful and consistent ‘type’ has created high coefficients of inbreeding. When COI’s exceed 5%, there are scientifically confirmed, deleterious results. Genetic malfunctions that are obvious (like MPSIIIB) are easy to breed away from, especially when there are genetic tests for them.
If a breeder produces a puppy that has an obvious condition, they won’t breed that pair again.
It’s the deleterious genes we can’t easily see that are the challenge, because many effects of inbreeding are very subtle. Enter, genetic testing.
Embark offers a Matchmaker tool that allows breeders to screen the available males in a growing database of Schipperkes. My first step was to filter against males who might carry the same recessive genes that Ruby carries. She carries one copy of a dilute coat gene and one copy of a canine retinopathy gene. One copy, no harm. Two copies, potential problems.
Then I filtered for the lowest coefficient of inbreeding for her potential litter. That’s where it really got interesting. Of 149 potential males in the database, only 16 dogs were in Embark’s “Green”
( safer to breed) category, ranging from 0 to 20. The lowest COI available was 7 and the highest was 19. 6.25% is the equivalent of having children with your first cousin.
The vast majority of available dogs (126) were in the “Amber” (proceed with caution) category, and would give Ruby’s litter a coefficient of between 20 and 30. By far, the majority ranged from 26, 27, 28 and 29. A COI of 25 is the equivalent of a mating a brother and a sister. A COI of 25 means that the risk of having a puppy with some type of genetic disease, subtle or obvious, is also 25%.
Ruby and Rebus do not share many common ancestors. This is what breeders commonly refer to as an outcross. Responsible breeders make use of out crosses in their breeding programs, for exactly this purpose, to reduce COI’s. In the past, breeders have had to rely on pedigree analysis, which is subject to error. You can read more about that here.
The ability to test for genetic similarity (homogeneity) is a very recent advancement, and understandably some people are reluctant to trust it. Ruby was tested twice. The first time, she was part of the Schipperke Foundation of America’s program to test 100 Schipperkes for 162 genetic diseases, as their way of building a database for supporting breeders and research in the future. I chose to test her a second time. Both tests returned the same results.
Ruby and Rebus’ litter will have a COI of 10%. (Individual puppies’ numbers may vary slightly, because genes don’t distribute exactly the same, every time) A 10% COI, means that Ruby’s puppies have only a 10 % risk of genetic disease, compared to a 25% risk. Her Embark test revealed the recessives that she had, which I ensured that her mate did not share. However, genomes are big and complicated and there are many, many recessives that we do not yet have the ability the test for. That’s why reducing COI’s, reduces risk.
If I’m going to produce puppies, I’m darn sure I want to make use of the best tools available to give them the best chance I can, for a long, healthy life. Genetic testing doesn’t guarantee good health in the puppies, but it gives me the power to reduce the genetic risk.