BY TRACEY DELIN
Often I read about tight breeding on message boards and it's always the same old thing; two sides arguing over its validation to a breeding program. Eventually the argument tires out with no real outcome while onlookers are left more confused than ever. This is my source motivation for addressing and writing this article, as an attempt to clarify some of the mysteries behind the logic. Let me begin by saying a tight breeding program is only as good as the decisions the person utilizing it makes. There are just too many variables at play all interdependent upon the person making the selection. The validity of a tight breeding program therefore depends upon the integrity, intelligence and the commitment to producing a better AB of the breeder. With that said, I will try and explain, as simply as possible, the rationale behind tight breeding.
Below are a few basic terms and definitions as generally defined by most scientific journals:
Inbreeding - The mating together of animals more closely related to one another than the average relationship within the breed.
Line breeding - The mating of a present generation back to some ancestor or descendent. Line breeding is essentially a form of inbreeding.
Phenotype - The outward, physical parts, anything that is part of the observable/visible structure, function or behavior of a living organism.
Genotype - The stored "blueprint" of internal inheritable information. Produces the phenotype of a living organism. Also referred to as the genetic make-up of an organism.
Type - Loosely refers to either genotype or phenotype or both, but generally phenotype.
Trait - A small part of the phenotype. Ex "blue eyes".
Homozygous - Having inherited the same "gene" for a particular trait from each parent (Meaning that all offspring of the homozygous individuals will inherit that gene.)
Heterozygous - Having inherited a different gene for a particular trait from each parent. (50% of offspring will inherit one form and 50% the other.)
COI aka Coefficient of inbreeding - A precise mathematical formula to determine the proportion of genes for which an individual, or the litter from a proposed mating, is likely to be homozygous.
Just so we are all together, for most, no further than a single generation (Ex. Father x Daughter) refers to inbreeding where as breeding with generations further removed (Ex. Aunt x Nephew) is considered line breeding. Additionally, others have been known to refer to inbreeding as a high COI regardless of how the dogs are placed in the pedigree.
Another thing that is often confused is that a one-time inbreeding does not equate to a tight breeding program. More often than not the offspring are not as tight as expected. For instance, someone who has a looser appearing program (linebred opposed to inbred) but has several generations behind it may actually be producing a higher COI. This is where COI becomes important, the higher the number the tighter the line on a particular dog or dogs. COI is a subject in and of itself and we will save that for a future article.
Now that a few terms and misconceptions have been defined, we can begin to explain why one would breed so tightly.
1: To find out what is in their lines.
2: To weed out the recessive, "bad genes" as best they can and focus on the strong.
3: To gain consistency in looks and temperament.
4: To perpetuate the genetics of peak dogs in the pedigree and to keep those genetics running strong throughout the program generations later (as opposed to being the great dogs of years ago you wish you kept sperm on).
I'm sure there are other reasons as well. Once a breeder has decided they would like to develop a tight breeding program, there are two ways to go, either for phenotype or away from phenotype. Some in/line breeders contend that breeding for phenotype will help "set" your lines, while others breed away from phenotype declaring it helps to maintain diversity of the genes while "fixing" the lines on a particular quality. The best option is probably to "set" your phenotype first and then "fix" the traits within your line for perfection.
Once type is established a dog can be outcrossed, introducing new genes into the program while still maintaining type. A great example of this is our dog, Sugar Daddy (SD). SD's dam, Osgood's Jezebel, is the product of a father x daughter breeding already set in type outcrossed to a dog known to be a producer of healthy offspring with great drive. This outcross, Mullen's Bubba, is completely opposite in type as Jezebel. One could take SD and place him next to ancestors on his dam's side and still see the set type even though his sire is the complete opposite. He looks like a littermate to many of his ancestors and acts that way too. This is a perfect example of a tight program (although probably not the best choice in outcrosses as explained below) going to an outcross and still maintaining type. A dog like this is a great candidate to maintain in the program as his phenotype has been maintained while adding (a healthy) genetic diversity.
So, is it true that tight breeding will create dogs with deficient immune systems or dogs that are plagued with health problems? Yes and no. No it will not "create" anything that isn't there. Yes, it can compromise a dog's immune system and produce unhealthy dogs. The reason this happens is that some of these "bad" genes are recessive and homozygous and therefore come to light in the offspring. That is also the point. As stated above, one of the reasons tight breeding is utilized is to bring to light some of these "bad" genes that can otherwise be masked by constant outcrossing. No one should ever consider inbreeding (or breeding for that matter) if they do not expect a few bad pups to be produced that need to be handled accordingly. Any breeding can produce recessives if the genes double up, this should always be remembered. By bringing the recessives forward through tight breeding you can begin to pinpoint them and therefore, weed them out of your program.
I know this sounds awful at first, breeding with the expectancy to find faults, but remember not only does a tight program double up on the "bad" but it also doubles up on the good in the lines. If a 'breeder' constantly outcross they will have no idea what is in their lines or when it will show up. They are just passing it along to the next dog with out knowing. If a program is tight, specific traits can be bred away from or bred for. The biggest and most important element to tight breeding is outcrossing, especially in ABs. This is why selection is vital to a tight breeding program. Eventually outcrossing will become necessary. If you never outcross then your program can be compromised by backing yourself into a hole. Outcrossing adds diversity back into a tight program. We have to remember that to run a tight line outcrossing must be incorporated at some point. To maintain consistency an outcross that balances the line should be used. It is important to practice all of the breeding methods aforementioned and outcross to gain genetic diversity, not to gain phenotypic diversity. In other words, outcross to a dog that represents what your line is lacking while maintaining the phenotype you have worked so hard to obtain. As previously mentioned this is the reason SD's sire was probably not the best choice. Although he added genetic diversity and a healthy one at that, his phenotype was completely opposite of the dam's tight lineage. A breeding such as this will tend to give an inconsistent litter, which is the opposite of what we are working so hard to obtain. However, it can also show a breeder how 'set in type' their program is running. This is why the breeder's ability to select dogs for their program and the dogs used are what will make or break the program. Tight breeding should never be done unless a true and thorough understanding is obtained. In contention with that, no breeding should take place without a thorough and complete understanding of genetics. So why not practice continuous outcrossing?
1: The breedings are less predictable.
2: Lack of consistency within the litter.
3: You never know how the recessives are lining up.
4. You may never know exactly where the problems lie within your lines.
If a breeder keeps covering up the faults are they really making progress or are they just continuing them in the line for future generations to deal with? It all comes back to research and knowing what is in your lines.
I was never a "ped head" before, recently some things have come to light that were previously unknown or inaccurate, either within our pedigrees or traits of our pedigrees, and science has shown itself to be accurate. Now I know pedigrees are just as important as the dogs behind it but more importantly pedigrees don't always tell the whole story. Pedigrees can tell you a great deal of information about the dog in front of it. In fact, because there has been so much paper hanging with the American bulldog as a breed, if you see a dog that does not match the characteristics of his known pedigree chances are the pedigree is not correct. For instance, a dog that reproduces himself on a consistent basis with different females and has a "loose" pedigree, probably has some paper hanging in his background. This is why it is always important to look at the dog in question before the pedigree. I am to the point now where I can know a line just by looking at certain dogs. That is the way it should be and is pretty cool, I think anyway.
With that said, never base a breeding on a pedigree alone. This is also referred to as "paper breeding". The dog itself should always come first. A pedigree is a map to a destination but not always the best way to go. If you don't know your lines no matter how tight (high) your COI is you will not be making progress. You cannot get what is not already there. In ABs we have to be super careful because of all the unknown pedigrees. If you go too tight on the wrong dogs you may just wind up with a St Bernard with a bulldog pedigree.
In short there are two types of breeding practices, educated and uneducated, aka smart and stupid breeding. As a bare minimum, research your lines and know their strengths and weaknesses. This is not always an easy task, as many "breeders" do not wish to acknowledge the weaknesses in the lines. Even worse is that because of this, MOST breeders don't have a clue what is in their lines. My suggestion is take every rumor you've heard with a grain of salt but never completely forget it.
In closing I would like to share a quote although the author is unknown, "research everything you can, use your pedigree intelligently, inbreed complementarily, outcross assortatively and select honestly. Use the COI as a commentary not as a commandment."