Genetic analysis with regards to dog breeding is not 100 % accurate. It is an indicator of the chance and probability that a certain gene/inherited trait will be passed on to the next generation. Traits influenced by only one gene such as coat colour gives us a 100 % probability with regards to the coat colour in the next generation. This is far more complex with regards to traits consisting of multiple genes (example tail set and head type).
Each sperm cell has a different genetic composition as does every female egg cell (oocyte ) in the bitch. There are no two sperm cells or egg cells that are 100 % identical. Therefore it is a matter of probability that the correct sperm cell (DNA composition) combines with the correct egg cell so that fertilization can take place resulting in the desired genes combining with each other.
Take into consideration that the next time when your bitch is bred to remember all of the millions of sperm cells that are deposited by the male in the reproductive tract of the bitch. Of these millions of sperm cells only a few are able to fertilize the egg cells that are ripe at that time. Then take into consideration that the genes in the sperm cell have to complement the genes of the egg cell. That is why breeders prefer to breed dogs that are similar in type to one another in the hope that the same type is present in the litter and that both parents can complement each other with regards to the faults needed to be improved.
Uniform litters otherwise referred to as “peas in a pod” occur when all of the puppies in the litter exhibit the same physical features. Such features may include bone, coat texture, angulation or head shape. When this occurs it can be said that one or both of the parents carried a lot of the genes for the desirable trait in a dominant form in its DNA. Should the puppies in the litter strongly resemble each other, then this is a positive attribute with regards to future breeding. This gives the breeder an indication that all of the puppies possessed the desirable traits in their DNA is most likely in a homozygote or heterozygote form. Should one of these puppies be bred from in the future we have a strong indication to predict that such desired traits will also be passed on to their offspring.
Examining a dog only based on it’s outward appearance is not an indication that “what you see is what you get” in the next generation. It is only a possible indication! That is why I place such a strong emphasis on the family of the dog and to a lesser extent the dog itself when selecting breeding stock. Knowing who the littermates, cousins, aunts and uncles are gives me a good indication as to whether the desired characteristics of the dog in question are “accidental” or actually “fixed” in it’s DNA. This is known as predicting and evaluating the breeding potential of an animal. Is the dog in question from a strong family or a “flash in the pan” with no pedigree to support itself?
Even though a puppy has the correct genotype does not necessarily imply that the puppy will mature as indicated by his genetic makeup. Other factors include nutrition, exercise, upbringing and socialization. These factors combined are referred to as environmental factors. You cannot win a car race with a FIAT car (used for travelling in the city), but you can also not expect to win a car race with a Porsche that has not had it’s oil changed or the tires examined on a regular basis. The point made is that you cannot expect to win with a dog of inferior conformation but also do not expect to win and succeed with a dog that has not been raised properly.
An example is of a dog from a family of dogs known for their bone and substance as well as having an outgoing temperament. When the litter is evaluated and the pick of the litter displays these characteristics then this is an indication but not a guarantee that the puppy in question will continue to develop these traits as an adult and live up to its “predicted” potential.
If such a puppy be placed in an environment where the nutrition is not optimal (causing the puppy to lose its bone and substance), raised on a slipper floor and allowed to play with a frisbee and not given a correct upbringing we get an animal who has not lived up to its genetic potential. Instead of the confident healthy adult with plenty of bone and substance we end up with a skinny insecure animal lacking the desired temperament.
The question arises as to whether this animal should be bred from. Always take into consideration that the environment plays a large role in this situation causing the genes to be suppressed in preventing them from revealing their true potential. In this case the genes are present but hidden due to the environment. Should such an animal be placed in an environment where it does get the correct upbringing should help in regaining its confidence and true temperament. In such a case if this animal were to be bred form to a suitable breeding partner, the puppies born should express the phenotype as indicated in their genetic package (provided that they are now raised properly in the proper environment).
1. Beauchamp, R. Solving the Mysteries of Breed Type. Doral Publishing, United States Of America, 2002. P.67 -68, 201- 208.
2. Craig, P. Born to Win Breed to Succeed. Doral Publishing. United States of America, 1997. P.70 – 147, 170 – 173.
3. Hendrik, P. Genetics of Populations. Jones & Bartlett Publishing inc., Boston. 1983. p. 523-537.
4. Glengarry, J. Let’s Breed A Champion Racehorse. 2000, New Zealand. Jack Glengarry Racing Services. P. 6 – 50.
5. Glengarry, J. Upgrading Thoroughbred Families (Using The Guidelines Laid Down By Federico Tesio). New Zealand, 1995, D. Bateman Ltd. P. 4 – 35, 60 – 70.
6. Grossman, A.. The Standard Book of Dog Breeding. 1992. Doral Publishing, U.S.A. p. 31 – 34, 43 – 45, 105 – 110.
7. Hampton, H. The First Scientific Principles of Thoroughbred Breeding. Part 1 and 2. Scientific Breeding And Racing Publications LTD. 1954. New Zealand. Part One p. 2 – 18. Part Two p. 42 – 70.
8. Labradorikirja 2000 (Labrador Pedigree Boog Finland 2000). Painotalo Alprint Kajaani 2000. P. 1 – 323.
9. Lewin, B. Genes. Oxford University Press. Oxford. 1990. p. 466-477.
10. Pedigree dynamics & Jane Henning Bloodstock. Cheating at Genetic Loto.
11. Robinson, R. Genetics For Dog Breeders. Pergamino Press. Oxford. 1990. p. 187-210.
12. Roslin Williams, M. Reaching For The Stars.Doral Publishing, United Kingdom 2000. P. 61 – 72, 87 – 95.
13. Russell, P. Genetics (4th Edition). Harper Collins College Publishers 1996.
p. 9 – 12, 18 – 39, 66 – 87, 100 – 102, 134 – 140 695 – 707
14 Spryer, L. Biochemistry 4th edition. W.H. Freeman & Company. New York. 1995. p. 975-994.
15.Ting, B & G. Labrador Stammbaumbuch 1997. Digital Print, Germany p. 1 -121.
16. Wikipedia encyclopedis http://en.wikipedia.org/wiki/X_chromosome