A term used to describe the use of a popular stud dog and the effects on the genetic diversity within a breed.
I thought i would share with you a simplistic view of breeding and the effects Of one dog on a gene pool.
Many breeds go through stages of using popular sires, producing large numbers of puppies with many matching genetic markers. This is one of the biggest contributors to reduced genetic diversity, increased inbreeding and elevated levels of genetic diseases within a breed. This method when used carefully is well-known for producing ‘type’, and while breeding miniature horses we would use this system successfully for many years - until a condition affecting the red blood cell levels started to keep appearing in one of the lines. Before long we had a serious problem and had to breed very carefully, selecting which new lines to add. Unfortunately we did not have any of the tests and knowledge we have today, so it could only be an educated guess, but luckily in this case we soon managed to restore health to our stock.
Dogs are often chosen because they have the desirable characteristics listed in the breed standard and are both receiving numerous awards within the breed ring and producing prize-winning puppies. As a result, breeders are drawn to use that sire to improve and install more ‘type’ within their own lines. Unfortunately, this not only includes his qualities but also any detrimental recessive genes he carries.
The result of this is that one dog can have an effect on his entire breed through his genetic influence. The excessive use of a male by a single breeder or by the community as a whole can cause detrimental effects to the health and diversity of the breed, even with just a few litters.
CH. & IR. CH. Shargleam Blackcap
Best in show winner Crufts 1980
Unfortunately, many breeders fail to look further than the ring to pick the right sire for their bitch. Popularity means that a sire is more likely to become the subject of gossip around the rings, which can make or break a dog. A stud dog often rises in popularity after his own success within the breed ring, and his status is cemented by him successfully passing on his winning qualities to his offspring.
Ringside gossip can of course have the opposite effect on a successful show dog, if his progeny fail to reach the standards of their sire, although this way of thinking overlooks the other 50% of the genes acquired from the mother’s side. If he does not produce top quality offspring, or heaven forbid produces any puppies with health complaints, this will spread like wildfire, whether the impact on the breed as a whole is large or small.
Despite our tendency as human beings to over or underplay scenarios based on individual circumstances, it is true to say that in general, a popular sire has the potential to impact his breed much more than a less popular sire. Consider a case where a less popular sire produces puppies with a health issue; the fact that he has fewer offspring, who are in turn less likely to be bred from means that the impact is much smaller on the breed and the resulting problems can be bred away from more quickly. Conversely, if the less popular sire produces high-quality offspring, people may not see them, as they might be from a less well-known kennel, and/or homed in pet homes, so the stud’s virtues will be lost.
A picture of a simple DNA chain.
When a recessive trait or a genetic disease exists in a breed there will be three types of dogs in the gene pool: carriers, affected dogs and normal or clear dogs. The popular sires and founders of a breed have a high percentage chance of being mated with bitches who are carriers, and therefore if they are also a carrier, this gives them more opportunities to produce genetic problems and spread them quickly within the a breed. Lurking recessive genes may find a match in some of the pairings, and the observable characteristics or conditions they link to will then reappear.
The CoI tells us a lot about a dog. For example, a CoI of 12.5% shows that there is a ⅛ chance that a dog will inherit the same version of a gene from a dog that appears in both parents pedigrees. The puppies born to a mother/son, father/daughter or brother/sister mating would be at least 25%, while the CoI of puppies resulting from a grandfather/granddaughter mating would be at least 12.5%. Health wise you want the CoI to be as low as possible.
Unfortunately it can take some years before the effects of this matching up of genes starts to become clear. As an example of this the pedigrees of a high percentage of flatcoat retrievers is a dog named Shargleam Blackcap, who won at Crufts in 1980. He is the sired 252 puppies from 47 litters, and many believe his genes are behind the high rate of cancer in the breed today. Now without a time machine or a magic wand we can only speculate the notion.
Recessive genes are normal the culprits behind most health issues, so by pairing dogs with many of the same dogs in there pedigree raises the risk of the unknown condition that has been lurking and waiting to meet it match or of a known condition, thought to be irradiated springing back up. Now we still run the risk of striking unlucky using dogs with a low COI but the change is less and with less popular sirs the chances are slim with the overall effect on the breed as a whole if this does happen, being a lot less of an impact.
So to conclude all breeding runs risk, but we have lots of tools at our disposal to help make these more educated risks. Health screening the more the merrier, recording of data, collecting DNA for a condition found this may seem a pointless exercise but with the advancements in science growing daily who knows how helpful this information will be in the future? Spend time to follow lines back as far as you can then look sideways with dogs producing multiple offspring it's a good idea to follow what full and half brothers and sister have done and what there offspring is the more dogs you look at from all directions the better understanding you will have of the possible pros and cons of the desired dog.
Remember just because this dog has everything you want does not mean he is not also carrying something you don't want, ears is one of my things! my dogs have bigger ears then I would like but are set well. Now I could lose. My ear set in my quest for smaller ears, or I could use a dog with tiny ears but behind him is dumbo and his mum those genes would most likely match up and dominant my desired little ears. A simple check of close relatives would indicate this.
I believe it is the owners of stud dogs to assess if the bitch is of value to the Breed and the gene pool. A popular dog can soon flood a gene pool and leave very little choice and diversity with in a breed in a very short time. Bitch owners should not assume they can use a dog just because they want to, but also do not take offence if the stud dog owner says no. They might know something you don't, they might be wanting to use him in a breeding program they have for themselves and adding him in elsewhere will not be beneficial to the Breed but they may be happy for one of his offspring to be used at a later date?
We as humans the supposedly intelligent species have the control, we choose the fate of our dogs and in turn our breed. Only you can choose the outcome. I hope this has planted a seed of thought in the mind this topic is so vast I just wanted to give an outline of the effects 1 dog can have on an entire breed with in 1 or 2 generations.
Comments