The Importance of Genetic Management
The goal of every breeder is to leave their breed healthier and stronger for future generations. However, without the right tools, achieving these goals can be like navigating without a map.
The biggest problem for purebred dog breeders is the high rate of inbreeding and its consequences for health. We know that inbreeding has a number of harmful effects in animals. It increases the risk of expression of recessive genetic disorders, causes inbreeding depression which also affects health, and leads to the loss of genetic diversity, which ultimately increases the rate of inbreeding.
Purebred dogs as a group show extremely high rates of inbreeding, which is a consequence of closed stud books that prevent the introduction of new genetic diversity to restore that which has been lost over generations. In addition, it is difficult for breeders to implement genetic management strategies that would control inbreeding and diversity loss because they simply lack the necessary information. Creating a genetic management plan requires information about the "genetic landscape" of the entire breed - not just individual dogs or average values of things like inbreeding and relatedness, but also data on the variability of these values in the population.
What's the problem?
Breeders realize that breeding for health requires them to know more about dogs and breeds than in the past. DNA tests and pedigree analysis can now provide data on the genetics of individual dogs that can be used to reduce the risk of genetic disorders in offspring. What breeders lack, however, is information about the genetic environment of their breed. When breeders identify a potential genetic problem, they try to "work around" it or eliminate its carriers from breeding. These strategies assume that the genetic solutions they need exist within the breed and they can solve the problem by moving the breed in that direction.
Imagine you are a tourist planning a trip to a place you've never been before. Without a map, you can only navigate by guesswork and you can easily end up in the wrong place or at least waste a lot of time and energy with wrong turns and hitting dead ends. Without the right information, breeding decisions work the same way. Without knowing the genetic landscape of your breed, you can't plan the path ahead or determine if it's even possible to get where you want to go.
The problem is the assumption that solutions exist within the breed. Remember that recessive mutations cause problems when a dog inherits two copies of the mutation. It's not about the presence of the mutation, but about the absence of the "wild type" (normal) version of the allele that is necessary for the gene to perform its function. However, breeders focus on mutations and diligently try to solve this problem through selective breeding. This constantly takes a toll on the gene pool and ultimately increases the risk that some other defective allele becomes the next problem in the breed. You can see how this becomes a cycle of genetic whack-a-mole that damages the gene pool with each successive cycle while making no progress in solving the real problem. This is the state most breeds are in after decades of selective breeding now guided by DNA tests. We have failed to improve the health of purebred dogs because we have not identified the right path to health. Without a map, we can't see the destination and we can't choose a path that will get us there. We invest time, energy and money, all with crossed fingers and hope that the situation will at least not get worse.
What's the solution?
The solution to this problem is obvious. Breeders need more information about the genetics of their breed. Not just about one or a few dogs, but about dogs characterizing the full breadth of the breed's genetic landscape. Breeders must be able to determine, before they set out on the journey, that the chosen breeding path will take them where they want to go. They must also adopt breeding strategies that will not work against them along the way. Simply culling every dog that has any problem from the gene pool, or restricting breeding to only a small portion of the dogs produced, will maintain the current situation and thwart attempts to improve it. We must be able to identify dogs with the greatest genetic value so they can be favored for breeding. We must identify sires before they have litter after litter of puppies that skew the entire gene pool in one direction and flood the breed with their unique assortment of genetic mutations.
Breeders - and breeds - need a map of the breed's genetics across its full range so they can design well-planned solutions to problems. We need genetic management plans that determine the path to solutions, rather than trying to solve problems by trying to run away from them in some random direction.
We have the information we need to create at least a basic plan. Pedigree and individual genotype data can be used to begin filling in the gaps in the genetic landscape with useful information - where to find dogs with useful genetic diversity, where to find outcross candidates for specific dogs, which sires are overbreeding at the expense of other genetically valuable dogs, and more. The information breeders need can be derived from pedigree and DNA data and used to address the questions breeders ask when making breeding decisions. With regular updates, this information resource can display the current genetic status of both the breed and individuals. It can also document progress resulting from breeding strategies designed to reduce inbreeding and protect and improve genetic diversity.