I was talking with another breeder this week about the “state” of Gordon Setter litters, the quantity of litters being produced as well as size of the litters surviving. The conversation centered around the observation that overall, the Gordon Setter breed appears to be experiencing a decrease in fertility as well as in the viability of newborn offspring. Fewer breedings are taking, fewer puppies are surviving. As breeders I believe we all (yes, I include myself) need to hold ourselves responsible for understanding what may be causing the creation of fertility issues and for the creation of their solution. It’s been said many times by numerous authors before me, when choosing a breeding pair we must consider the fertility and nurturing qualities of the sire and dam in addition to every other trait we consider desirable. To do that, breeders need to understand pedigrees and how they speak to us about the inbreeding coefficient of the litter – as that coefficient my friends, can drive what is known as “inbreeding depression.” To eradicate inbreeding depression we first need to learn how to identify it and when it appears we need to acknowledge that this could be at play and then we need to plan our breeding accordingly.
I’m not a geneticist and I won’t ever pretend to be, luckily though I am a voracious reader, and with all of the information at our fingertips on the internet today I can find a wealth of expert information for my own, as well as your reading pleasure. I urge you to explore with me, if you’ve not already done so.
First let’s understand what’s meant by inbreeding. Inbreeding would be the breeding of related dogs who may be closely or distantly related to each other. Some, including me, designate inbreeding as close relationship breeding, like mother-son, father-daughter, sister-brother, and call “less close” breeding like a nephew-aunt breeding a line-breeding. But when reading articles written by the genetic expert you’ll find that it’s all packaged together under the name inbreeding. Don’t let that confuse you. With that said, if inbreeding is used carefully as part of a breeding plan that includes balancing the benefits with the dangers it can be a powerful tool. Using inbreeding without consideration of both positive and negative effects can be destructive.
Now let’s go back to inbreeding depression and talk about how that is related to the opening subject of decreased fertility in Gordon Setters and viability of newborn offspring. Inbreeding depression is not about an increase in the number of genetic disorders in the breed, like PRA for example. It refers to a loss of what a biologist would tell you is called fitness. Fitness in this context refers to the dog’s ability to pass on its genes to the next generation. So to a biologist, if a dog dies from disease before it can reproduce it has a fitness of zero. If a bitch successfully reproduces a litter but won’t properly care for her offspring (which will die without intervention) she has a fitness of zero. To breeders like us then, if our Gordon Setters have a high level of fitness they will produce offspring that can go on to reproduce themselves and perpetuate their genes in the population, where a Gordon Setter that cannot reproduce (without human intervention) or reproduces less effectively (below average litter size for example) have a low or zero fitness. In the Gordon Setter breed we could be experiencing evidence of inbreeding depression if we are in fact seeing an decrease in fertility and a decrease in litter viability. Evidence of inbreeding depression can be indicated by singleton litters, decline in conception rates, reduced sperm count, reduced litter size, lower pre and post-natal survival rates, shorter lifespans, higher cancer rates in young dogs, allergies, and many other issues that we might be taking for granted as normal in dog breeding these days. The “fitness” of the dog should be kept in mind as we make breeding choices.
My next step is to send you to some very informative articles I found at The Institute of Canine Biology (as I said earlier I am not a geneticist and won’t pretend that I can write in-depth articles about this topic). What a wonderful resource site!
- Start your understanding off by reading about the Co-efficient of Inbreeding (COI) by clicking this link to Wright’s Coeffcient of Inbreeding.
- A second article that is very informative is The Costs and Benefits of Inbreeding.
- And my final recommendation, for today at least, is The myth of hybrid vigor in dogs…is a myth.
(Quick note – the photos included in this article are simply for your viewing pleasure, they have nothing to do with the content of the article).
Now, “don’t go throwing the baby out with the bathwater” my friends – that’s not the message here. Oh,and don’t forget to pass it on! Your comments, questions and suggestions are always encouraged in our comment section.
Sally Gift, Mesa, AZ