Pairing Dogs

• Key to successful matches
• Line breeding
• Pairing dogs of different sizes

Key to successful matches

Q: What is your secret to a successful match?

A: This is the “art and the science” of breeding. After nearly 40 years I would tell you that the best thing you can start with is knowing your dog’s pedigree, as well as the pedigree of the dog that you want to breed to. Think of pedigrees as the architect’s drawings for your breeding. 

What does each dog in the first four to six generations of the pedigree bring to the table, good and bad? If this is a line breeding, how many times does that influential dog(s) appear? If it’s an outcross, how phenotypically similar are the two dogs you are combining? 

Line-breeding is the breeding of relatively distantly related dogs, typically no closer than grandfather to granddaughter or grandmother to grandson. It increases the genetic homogeneity in the pups and can be an effective strategy to strengthen specific traits in a line. However, it os also thought to increase the risk of certain weaknesses, like decreased fertility and lifespan, and genetic disease.

Out-crossing is the breeding of relatively unrelated individuals. It is usually thought to lower the risk of genetic diseases but is less effective at solidifying phenotypic traits because it often increases genetic heterogeneity in pups. However, if two unrelated dogs are quite similar phenotypically, breeders may get the benefits of both line-breeding and out-crossing. 

Once you know what the pedigree brings to the table then you can think about the possible genotypes and phenotypes you will see in the pups. As an example, if I know that many of the dogs in the pedigree carry a low tail set I can weigh that against what I see, which may not be a low tail set, but what if that genetic trait gets passed on, how important is that attribute to me? Phenotype, what you see, can be as simple as ear set and desired coat, or as complex as correct front structure. See why this is an “art” and a “science” when you breed!

The other part is knowing how dominant your bitch lines are, or how prepotent (which is the ability to be effective in transmitting hereditary characteristics to offspring) the stud dog is. So, a known stud who is an outcross and producing well with a variety of girls with different pedigrees is prepotent and can be used for what he does for the puppies. Conversely, if you have a very strong bitch line you may want to simply breed to a dog who will “do no harm” to what you have worked hard to create in your lines.

My secret to a successful match is to do my homework, as I outlined above, AND to talk to other breeders you respect. Getting their insights can be very productive and even shed light on aspects that you might not have been aware of. This may enable you to make an even better choice.

Line breeding

Q: Can you tell me about line breeding? How close is too close?

A: This is a very interesting and often difficult topic, but one that needs to be talked about so we all have a better understanding of how to keep our dogs healthy and set specific traits in our dogs. 

Let’s start with some fundamentals. It is fascinating to me to know that litter siblings from the same breeding do not have the all of same genetics. In fact, they share only about 50% of the same DNA. One brother may inherit a set of genes from the father that the brother did not, etc. This explains why littermates do not look the same, nor produce the same when bred. Starting out with this knowledge helps us understand more about the complexity of genetics. 

One of the earliest, and most quoted, regarding line breeding is Lloyd Brackett. The 1950s “Brackett Formula” relies on pedigree analysis, litter evaluation, the use of line- and inbreeding and a record system that was easy to use. Brackett is best known for his emphasis on the use of line breeding, but he was not afraid to inbreed if the situation dictated it.

Brackett believed that it made no sense to go forward with breeding before the needed information about the sire and dam had been collected. He placed great emphasis on health, temperament, and breed characteristics. His planned breedings were based on the results that he saw in his pups. In other words, he learned from his mistakes. This is one of the most important lessons for all of us.

Brackett’s formula concentrated genes in a pedigree. He did this by placing emphasis on the sire of the sire. Having the same dog appear on the sire and the dam's side of the pedigree. Brackett liked to use one important dog and have it appear twice in a three-generation pedigree. The basic formula he preferred can be stated as follows, "Let the sire of the sire become the grand sire on the dam's side". Said another way, choose breedings where the litter’s paternal grandfather is also the mother’s grandfather. 

We now have so much more information, and we can use the information on genetics and genomic analysis to help our breeding programs. Using this information can give us short-term gains in type and 2 year health and reduce long-term losses in fertility and shortened lifespan. This link to a video from the dairy industry will give you better insight into applying that https://www.youtube.com/watch?v=oQfbqKrKqjg

I believe that the key to success is a strong bitch line. So, I have line bred on a very strong bitch line that gives me what I want in my lines. However, when doing line breeding it is important to remember that not only are you embedding strong positive traits, but it will also embed bad traits that you might not realize are there. Things like cryptorchidism, etc. This is why line breeding may be a good tool for some but must be combined with pedigree knowledge, and genomic knowledge as well.

Pairing dogs of different sizes

Q: I will be breeding my small bitch, who is at the low end of the breed’s size standard. My vet is recommending that I select sires close to her size while an experienced breeder tells me size doesn’t matter when matching dogs of my breed.

A: Size does matter in breeding for several reasons, from the breed standard to the health of mom and pups. In addition, size is a complex genetic trait, the results of which are not always predictable. In fact, often pups show an array of sizes, including above and below parents.

Thus, breeding a small bitch to a large dog increases genetic variation in the combination and can result in pups of many sizes from smaller than the dam to larger than the male. Breeding small to small will typically move average size in the litter down and breeding large to large, usually moves average size up. This selection on size is how many of our mini-breeds were created. So if you want to increase size without wide variation, it's better to breed a small bitch to a mid-size dog, thus increasing size without going over. 

Breed Standard. Assuming there is a breed standard that you want to meet, I would look for the best male who suits your girl and is within your breed's size. Most breed standards have narrow enough size ranges that whelping ability is not affected. This is often NOT the case in cross-breeding, where size ranges and genetic variation can be significant and result in pups that are too large for the bitch to whelp.

Health of Moms and Pups. Although we often worry too much about pups with overly large birthweights, this issue can be a reality when we select much larger studs for our bitches. Breeding a male Great Dane to a female Corgi is likely to result in pups that are too big for her to whelp naturally and possibly to even carry through a pregnancy. 

I would encourage you to change the size of your dogs gradually over several generations by breeding dogs of similar if not identical sizes. However, if you are determined to change size rapidly, use the male to bring down size and the bitch to bring it up rather than the reverse. This method is less likely to result in too-large fetuses and birthweights.