Pedigree Analysis

submitted with permission by Marj Brooks with thanks to Kevin & Donna Frizzell of DeSaix St. Bernards for generously allowing us to use many of their superb array of articles

While a pedigree analysis is fun , illuminating and of historical import …. it IN ITSELF should not be a primary factor in your breeding decision. A dog’s pedigree provides names and the percentage of CH’s. If this told the story … anyone who can count could breed a good Saint.

But, you say – I’m going to line breed so the pedigree is very important. Well sometimes line breeding is the answer and sometimes an outcross is the way to go.

Ultimately, whether line breeding or out crossing, the selection of that “perfect” mate should be based on phenotypic considerations taken in context of the genotype of the two dogs.

By phenotypic considerations, I mean what weaknesses of your dog to you want to improve and what strengths do you want to preserve. You often hear the statement, “never double-up on faults” – and this is sound advice. But it is not the whole story. The problem still remains to find that mate which will solve problems without detracting from your Saints strengths or introducing new faults. It doesn’t help to improve the head or “bone” and at the same time introduce weak fronts.

So if phenotype is so important, why not just find the stud dog or bitch that is the “complementary” physical match to your animal. I submit, that this approach has very little chance of success. Furthermore, even the “phenotype breeders” in actuality do not depend solely on physical appearance to select a mate. Every dog has buried within it’s DNA the potential for producing many different genetic combinations and thus many different phenotypes. The trick to breeding is to maximize the *probability* that the offspring will carry the genotypic combinations that lead to a desirable phenotypic expression.

By now, you are probably saying – “Lennard, get real!” There is no way of determining a Saints genotype. Well actually, this is where the pedigree becomes important. Not in terms of the number of Champions – or even in terms of how beautiful the ancestors looked (if you are lucky enough to have pictures). The pedigree is the jumping off point to learning about the HISTORY of each ancestor. Through this HISTORY we can gain insight into the likely genotype of the dogs involved!

What do I mean by HISTORY. Well, Hazel Gregory suggests that you take each dog in the pedigree and rank phenotypic attributes such as fronts, rear, topline, head, size etc. in terms of “Good”, “Average” or “Poor”. Her suggestion is that the probability of offspring with a “Good” (or “Poor”) phenotype will be directly related to the percentages of “Good” (or “Poor”) ratings found in the 5-gen pedigree. I personally find this a bit simplistic – but it *does* engage in the critical exercise of “inferring” genotype from the breeding HISTORY.

For me, the weakness of this strategy is that it doesn’t weight more strongly the contributions of closer ancestors and that it does NOT taken into account prepotent animals. What do I mean by this…. there are some animals that show an above average likelihood of passing along a trait – they are prepotent for that trait. I have an interesting question for you to ask some long-time breeders. Instead of asking them who was the best Saint they ever had, ask them who was the *most influential* Saint that was ever in their kennel. The answer will often be a dog or bitch who you never heard of and who did not have a “Ch” in front of their name. For instance, it might be a bitch that seemed to ‘never throw a bad front.’ – Ahh, now there was an animal that could be used to correct weak fronts in otherwise excellent Stud dogs.

For me, the HISTORY of a Saint means finding out not only the phenotype of each ancestor, but their genotypic strengths and weaknesses as reflected in the offspring they produced. This is a big job and must necessarily require the cooperation of the parties involved in breeding the ancestors.

I truly believe that sometimes the “good results” attributed to line breeding are not really so much related to the homozygosity of the breeding pair, but rather to the fact that the breeder intimately knew the dogs and their ancestors and thus, consciously or unconsciously, had a correct intuition of the HISTORY & genotype of the dogs to be mated.

I would be remiss if I didn’t urge you to follow the same thorough “Sherlockian” approach to uncovering the health/medical histories within the pedigree. Phenotype includes the expression of genetic wellness, predisposition to illness and out-and-out genetic disease.

Finally … a caution about breeding for size. Size, as we think of it, is a quantitative polygenic trait. In any litter, you should see a range of sizes varying around a mean. The atypically large dog in a litter will not necessarily have offspring that are large. So when selecting a mate, don’t be overly swayed by size (especially without knowing the size of the littermates). Furthermore, when deciding on “keepers” from the litter, be careful about letting size be too large a determinant. Look for well-balanced puppies. If all else is equal, of course go for the larger of the too. In any event, be cautious about that “one humungously large puppy in the litter” – it may have some unpleasant surprises for you down the road.

Do NOT follow this link or you will be banned from the site!