If you want to be an ethical breeder you must have a working understanding of the underlying principles of genetics. It is a complex science but of extreme importance when making selections for breeding pairs and foundation stock. You must have correct and complete understanding of ideas and concepts involved in inheritance. So far we have touched on only the basics of genetics from a mendelian perspective, seen what a complicated mess breeding really is, and hopefully realized that without considerable and logical knowledge of genetic theory our only hopes for producing good dogs lie in one thing = luck = . If I were a puppy buyer I would not want to rely on breeders luck without a lot of knowledge there to improve my chances!
Regarding breeder defined type: There is within our breed a devastating occurrence that is ultimately creating a sham, distorted view of what an APBT looks like. The UKC started as a show venue about 30 some odd yrs ago when dogs were still chosen for working type. Relatively recent we started with a standard and a vision that would preserve working type. Now based upon vision of a few breeders the working and functional aspects of the breed are being replaced by exaggeration and preference for a particular look and not a functional type. The same thing that took the working type out of so many other AKC breeds is now doing the same for the UKC APBT.
My own opinion is that within a set boundary defined by a set standard each breeder should strive for that which is ascetically pleasing to them. This asceticism should however start with maintaining working ability, temperament, increasingly stringent health criteria, intelligence, and working drive combined with and equal to the outward “type”. Hopefully there is an equal consideration for all of these aspects. If a breeder is breeding a specific line of dogs that are pleasing to their eye, have working ability and drive, fit within the standard but most of the puppies have serious faults or health problems then there is a definite problem. On the other side of the coin, if a breeder is breeding massively overdone dogs that win in the show ring but are unable to jump an obedience regulation height because they are too “big boned” then there is another serious problem.
We as breeders have taken on the responsibility of preserving not redefining the breed of dog we have chosen. The American Pit Bull Terrier was above all a working breed and as stated in the first line of the standard. They are capable of performing and excelling at a wide variety of tasks. Today we are moving toward defining a new type that is verging on substance and head type of American Bulldogs. I am now seeing GR CH APBT show dogs that could compete in the AB conformation ring. This is the fault of the judges and the APBT community for not providing a reference and visual tools to utilize.
The following are descriptions of methods utilized in breeding programs to improve our breed. My hope is that this honest essay will help breeders honestly look at their breeding programs. All similarity to actual events and people are merely coincident and not directed at anyone who might actually read this.
The following has not yet been thoroughly proofed. If you see spelling or gramatical errors pardon them or take time to let me know. I spend a lot of time producing these articles from a knowledge standpoint but in my profession I typically rely on technicians and editors to help proof things. -not enough time in my days ;-) Honestly I do hope you enjoy reading this!
INBREEDING
Matings involving parents and siblings.
E.g. of inbreeding
Brother/Sister (closest most dangerous)
Father/Daughter (useful for testing foundation and F1 genetic soundness or setting specific traits)
Mother/Son (useful for testing foundation and F1 genetic soundness or setting specific traits)
Half-Brother/Half-Sister (most useful and considered line-breeding depending on the non-shared parents)
LINEBREEDING
Matings involving relatives other than parents and siblings.
Cousins (have one or two Grandparents in common)
Nephew/Aunt (most rationale line breeding)
Niece/Uncle (most rationale line breeding)
G. Granddaughter/G. Grandson
Grandchild/Grandparent
NOTE: shared relatives past the 4th generation has little effect except in rare instances
BACKCROSSING
Breeding an outcrossed animal back into one of its original lines.
This assumes the outcrossed animal was derived from two specific germ-lines
OUTCROSSING
The breeding of unrelated animals. Only considered outcrossing if both are inbred or linebred and from separate lines.
SCATTERBREEDING
Do not share any common ancestors in the first 4 generations.
(Matings involve unrelated animals.)
There is often confusion and questions regarding the definition of these terms. To a geneticist there is less of a distinction but to most animal breeders, particularly dog breeders, there is a defined distinction between inbreeding (mating mother/son, father/daughter, brother/sister) and linebreeding (mating say grandparent/grandchild, aunt/nephew).
Line breeding
First lets define what line breeding is NOT:
Line breeding has nothing to do with a kennel name
I have seen dogs that were said to be line-bred that had no shared ancestors in a 5 generation pedigree. But many of the dogs had the same Kennel Name affixed to their registration. This is not line breeding this is scatterbreeding.
Line breeding is: A breeders tool used to develop, isolate and set specific desirable traits into succeeding generations. Line breeding can be seen in registered dogs by having specific high caliber or quality ancestors two or more times in the recent pedigree as noted in the table above. Line breeding often has more than one high quality ancestor multiple times in the same pedigree. However, from a purely scientific point of view, linebreeding can also be defined as breeding two individuals containing at least one common ancestor. This common ancestor may contribute a negligible amount to the descendants, or a great amount. This makes the scientific meaning lacking in true art and practice. You can do a line-breeding that has absolutely nothing to do with refining or setting specific traits or you can practice the art and craft of breeding better animals and make rational choices in your program.
Ultimately, linebreeding is simple concept that is extremely complicated as a breeding tool. One must remember that linebreeding is a program that produces animals from a single line of descent from a common or a few common and outstanding ancestors. The goal is not to reproduce the quality of the ancestors but to try maintain as many of their good qualities as possible while improving their deficiencies by refining the genetics of the line. If you know a breeder that is producing the perfect animals then why the hell do you need to breed? Just buy all your dogs from this breeder. If a breeder is producing superior dogs and you breed off their lines will you produce better dogs than that breeder? If not then do the breed a favor and do not breed.
OK so to repeated using different words line breeding is a popular but often abused or misused tool for maintaining “type” but should only be used when attempting to refine phenotypic characteristics in the APBT. The hobby breeders make use of this tool often without knowing what they are doing, maybe because they prefer a certain look and will select foundation dogs from breeders whose lines have this specific look or color. Unknowingly, they then begin linebreeding. Others may be mentored by an established breeder and become an extension or tool of that breeders program goal. In my case I have established partnerships with other kennels and we have joined together with a common vision and defined the goals in our breeding program and work together to achieve these goals. I imagine that this may be a popular model in the future when the concept gets out there. It does require the partners to develop a consensus goal and contractual agreements that take into account all eventualities in the development of the program. In any case at some point a beginning breeder will become aware of the term linebreeding and choose to investigate what exactly it means. Here we will provide some additional information and even map out a line breeding plan for the beginner.
Linebreeding in a short term sense is rather easy and in most cases the novice breeder that gets good lined dogs from a good breeder and matches them, will obtain a reasonable but probably not improved or refined version of the germ line. In most cases where hobby breeders are functioning solo within an established germ line there is a continual decrease in quality in their generations… or at the very least a step sideways. You will see when comparing the quality of the original foundation dogs to the third generation that the quality has declined rather than improved. Under these conditions one must say “what is the point?” Remember this above all.
Line breeding is not a method used to improve a germ-line it is a method used to refine and set characteristics of a germ line. If you are trying to refine someone elses bloodline.. again what is the point? Can you do a better job than they did?
If you are hoping to do more than fix a few characteristics that are already present in the line and you want to instead create a dramatic change in that line then you should not be line-breeding.
To clarify the point here is one simplistic example of why one WOULD want to linebreed: You have an established germline with few health issues and a quality phenotype, high mental stability but there is very little working drive in most of the individuals, You want to add working drive to your already superior quality dogs so you seek out those individuals in your line that have more drive and use these to refine and set this trait. Take this example a bit further into complication, with the assumption that within the population that represents your germ line there are 100 individuals to choose from and only 3 of these have a significant amount of working drive, but these 3 also have an undesirable trait found within the line (eg. They may have bad tail set. In this case you would use a quality member of the germ-line that is breeding true for good tails (parents and grandparents have the desirable tails) and cross in the high drive member. Now ALL THINGS PERMITTED AND GOOD LUCK FAIRY ON YOUR SIDE you have a chance to obtain a puppy that has both drive and a good tail set. This new F1 generation with both desirable traits has the traits but still they are heterozygous thus are not “set” into the genetics of an F1 dog (overly simplified… the puppy is only have drive half good tail). Now you want to set the traits to you do another similar breeding with one of the other high drive dogs and another good tail dog and again look for the puppy with both traits. The third and final step is to breed these two F1 good drive good tail dogs to each other and pick the resultant good drive good tail set progeny. With logical breeding you can further refine the characteristics, prove you are homozygous for both traits and consider it a successful linebreeding adventure. At this point you would continue to try and refine the drive and tail traits within the line without sacrificing other traits. (This again is a simplistic example used to convey a concept. As with most inheritance there are layers of intricacy to the most mundane of examples and many other factors such as dominance of the particular alleles involved, linkage, co-dominance etc. which may or may not come into play).
As you might imagine there is an art and a strong science behind linebreeding and there are a great many methods used to accomplish these “patterns” with the ultimate goal of staying close and refining the foundation stock. It has been said that Linebreeding is similar to weaving a masterpiece tapestry and there are few that have the knowledge to be masterful and fewer still that are naturally masterful. There are a few who are lucky.
One of the best of rationales for linebreeding is as follows-
"The more superior a breeder's herd or flock is to the average merit of its breed, the more reason he has to practice linebreeding to his very best animals or to the very best of the recent ancestors."
In order to be successful at line-breeding you must have all the necessary traits and genetic tools within your germ-line, a reasonably low coefficient of inbreeding in your breeding stock, you must have an ideal firmly set in your mind, you must be prepared to ignore breeding fads and recognize that it is a long ranged plan that must be mapped out ahead of time up to 20 yrs in advance. You must also map out the desired traits up to 20 yrs in the past. Only with this chess player mentality and stringency will you ever hope to be more than a hack, lucky, a failure, or can you hope to do more than watch the continued decline of a germ-line as health problems, non-type traits, and mental instability creep into your program. At the point where this decline happens one must look at the obvious and decide to abandon the original plan and move on to another. Without serious knowledge and considerable luck such a failure will mean the demise of a breeding program. A good breeder will just pack it in at a certain point and except failure. Especially with the APBT there are too many breeders that are continually breeding the same medium quality dogs as their previous generations or breeding lower quality dogs than their foundations. These dogs lack one or more of the defining traits of our all around working breed. The breeder must use selection as a rigid tool in the process. Unless this is adhered to, the breeder will never attain his goal and the program will be doomed to failure. You may produce a beautiful APBT that wins every dog show but unless your dog can work, is intelligent, is healthy, has drive, and a wonderful temperament you have a long way to go.
One of the traits missing in many of the popular lines these days is that terrier drive and tenacity that our SUPER DOG BREED was once selected ULTIMATELY and predominantly DEFINED BY.
A beginning breeder must realize that in spite of what others are doing or saying there are very few constructive linebreeding programs and very few bloodlines that can be successfully linebred into the future. The beginner must understand all the concepts that must exist within and be maintained within a bloodline. You cannot select for show ability at the sacrifice of the other important traits of our breed. These are in order temperament (disposition, intelligence), soundness (health), fertility (females that exhibit the ability to raise healthy pups, and males that have the ability to reproduce naturally), and conformation.
If a breeder is first and foremost considering color (I only breed red noses, I only breed blues) then my bet is they will see nothing but a decline in quality over the lifetime of their breeding program.
Breeders take note: The APBT is an athlete and a sure sign that you have lost athleticism in your line is when your males are no longer able to successfully mount and breed a female. One particular and overly popular germ-line in the APBT is populated with males that require artificial assistance. They jump and hump but only a few times before having to dismount to rest. Get over your uneducated dog show judge induced need for bone and substance and big heads and get back on track with this athletic breed.
Remember the following rules (1) linebreeding (and inbreeding) are only as viable as a breeder’s knowledge of basic genetics and (2) a linebred pedigree is only as valuable as a person’s ability to determine the virtues and faults of the dogs it contains. When we add the final ingredient of rigorous and non-kennel blind selection hopefully we are on the way to producing better APBTs
The ins and outs of establishing a breeding program.
A smart breeding program always starts with selection of the highest quality foundation females. When you are forced by availability to start with a foundation female that is lesser in quality to others of her line you are immediately starting your journey by pushing the cart up hill. If your foundation females represent the best your germ-line has to offer then you are half way to the success you so desire. This cannot be stressed enough. I see too many new breeders starting with dogs that are nowhere near the quality of their siblings being used as foundation stock. In many of these cases these kennels also obtain a stud “to go along with their foundation female” and the stud also turns out to be of lesser quality than his siblings. Instead of looking at this as a problem they continue on and breed poor quality puppies. Now we are doubling up on lack of quality. Why is this? Because when you obtain a dog from a breeder typically they do not give you pick of the litter without a serious agreement in place, thus you end up with one of the "others" in the litter.
This leads us to the second step in establishing a quality breeding program. You do not need a stud in your yard at first. Outsource to the highest quality males available. Most breeders or male owners will offer stud service if the price is right. Taking this route you have to consider whether you are trying to save money or trying to produce better animals.
An addition to this approach is to utilize one of your foundation females to generate foundation studs which are utilized on other foundation females. This is a complicated strategy and beyond the scope of this discussion.
In example: I note one line-breeding kennel in particular that seems dead set on in-house breeding with no semblance of trait selection. Mearly what appears to be a “We haven’t tried this yet hope it nicks" type of selection. They also started with a low caliber female as part of their foundation. With each breeding we note one or two pups per litter with quality similar to that of the parents, which is a sad thing and is a definite signal for the end of a line-breeding program. A quality line-breeding program will at least maintain the quality of the parents in a majority of the progeny. The particular example here is experiencing inbreeding depression and hidden traits such as bad bites and kinked tails and health problems will become more prevalent in future generations.
So how can I be successful at line breeding? Well you must fully understand the principles BEFORE starting.
OK so let us make a very simple line-breeding program with a short term three generation goal. Because we are considering it a short term program by necessity this program must make use of an existing germ-line developed by some other breeder.
The first step in this example program is the identification and obtaining of the two highest quality females available within a particular germ-line. This is nearly impossible because breeders that are capable of producing the highest caliber animals are also capable of selecting out the best and keeping them (or at the very least coowning them). Thus, the beginning breeder must settle for an alliance with an established breeder, or most likely settle with at the very least the second best female from a litter as their foundation (already at a disadvantage? Maybe.. maybe not~!). Why not obtain males? Many breeders including myself, believe that the females are the strongest part of the line breeding program and the studs are providers of the necessary genes. As part of this three generation example, these females should both be closely related (neice/aunt, cousin) but not too closely related (half sibs or sibs). Then another layer of complexity is that these two foundations should be lined down from the highest quality foundation ancestors. In example do everything you can to obtain a bitch and her niece both of which descend from the highest quality female the line has ever produced.
OK so both these females mature nicely and they exceed expectations in conformation and all other criteria then you are set to start a short term linebreeding program such as I will describe (or a long term which is beyond the depths I will discuss here and does not start with line breeding for sure). BUT what if after a year one of the females does not turn out and is of lesser quality than her siblings and most of the individuals in her line? You love her and invested a ton in her BUT Do NOT attempt to begin using inferior stock or your linebreeding program. Because you product will be as described above just decline in quality compared to the rest of the original line. (You should spay her and try again). The next step in this short term line-breeding program is to select a single foundation stud. The stud should be from a more distant branch of the line, but must have all of the traits we would desire to maintain, certain desirable traits we wish to add to our females, and few if any weaknesses where our foundation females do not have weaknesses, and certainly few or hopefully none of those genetic traits we would wish to avoid. THAT IS ASKING A LOT!!!!! You would breed this stud to both of your females and select from each of these litters the highest quality male AND female puppy. Select those puppies that combine the desirable traits of both parents and have fewer of the undesirable traits. Thus you now have 4 superior puppies. These puppies mature as did their parents and exceed your expectations in conformation and other breed traits.
The final step is the mating of the half brothers and half sisters to set the traits, which are produced by mating the single foundation sire with the two foundation females. The result of the half brother and half sister mating will be the third generation with the resulting offspring being double grandsons and double granddaughters of the superior male and founded off of your superior females which also happen to be bred down from the ultimate germ-line dam. From this population we will have now produced a handful of dogs that may match or exceed the quality of the ancestors and set a few new and desirable traits. Note however you have reached what is known as a high inbreeding coefficient in your final product animals. We shall see below that the IC is an important measure of how tightly bred our germline is. Thus we have seen a basic and logical 3 generation linebreeding program now however the IC indicates that for our program to continue we must choose to outcross or outreach (distant relatives but still within the lines) to avoid inbreeding depression.
NOTE: One must not try to linebreed to more than one common ancestor except as noted above using a niece for example of your original bitch. The double grandsons and granddaughters will be genetic sons and daughters of the foundation sire.
Close linebreeding is inbreeding even if it is not mother/son, father/daughter etc. Inbreeding is most appropriately defined by the COI (coefficient of inbreeding) which we do not ever want to exceed 35-50% depending on how perfect genetically our bloodline is. Most lines out there I would not want to see above 25% COI
INBREEDING
Willis (1989) defines INBREEDING as the mating of animals "more closely related to one another than the average relationship within the breed." From the introductory table we can see that these involve brother/sister or parent/child breeding.
With all the negative connotations associated with inbreeding why discuss it as a viable breeders tool?
It is true inbreeding can create horrific genetic mistakes or it can be the best and fastest way to improve and standardize a line (set traits). IN the first sense it is a useful genetic tool to reveal hidden recessive genetic problems in your line by doubling up on them and making them express themselves (as it were LOL). Note this is a tool used to reveal hidden defects and these defectives should be culled from the breeding pool. In the second sense when your line is heterotrophic for beneficial traits you can do inbreeding to make them homozygous (set the trait). Note it must be a tremendously important trait or preferably numerous traits you are trying to set within your line to consider inbreeding as the best method to set the trait. So here inbreedings are done to verify the superiority of a particular strain or to check for recessive problems. Any weaknesses, faults, deformities, etc. are likely to show up. If a truly superior line or strain has been developed, containing only desirable qualities, these desirable qualities will be seen in the resulting offspring.
There is a great example of the result of professionally developed and planned inbreeding that against all odds has gone right (don’t EVEN CONSIDER OR HAVE A FANTASY that you can reproduce this with the APBT!) Anyways, I copied the following paragraph from another site.
Guiding Eyes For The Blind, Inc., located in San Raphael, Ca., has developed 3 strains of German Shepherd Dogs to guide the blind. One of these strains, the "Frankie line" is being inbred to produce offspring containing as much of Frankie’s genetic material as possible, some having as high as 96% of their genetic material from Frankie. And these dogs are happy, healthy, well-adjusted and successfully guiding their blind owners through city traffic, etc. (Another strain is geared to linebreeding to produce puppies that have as close to exactly 50% of Frankie’s genes as possible-linebreeding. The third strain is based on another dog [Orthos], and they are trying to increase the percentage of his genes in the puppies to the highest possible extent, while still maintaining something genetically from Frankie.)
The totality of qualities belonging to that individual AND the knowledge of the breeder will determine whether this is a horrible thing or a wonderful thing. As I mentioned previously to a geneticist linebreeding and inbreeding only differ in degree measured by the "inbreeding coefficient" which puts a number to the degree of inbreeding an animal shows relative to a random breeding population.
As animals are mated to their relatives, however distant, simple mathematics will show that the likelihood of any one gene becoming homozygous will increase. As homozygosity increases, variation among offspring decreases. The dog breeder takes advantage of this in inbreeding to produce a breed which "breeds true" and conforms to a "breed standard" and within the breed to produce offspring that are like peas in a pod. Breeders look for a "prepotent" sire or bitch ( ie one that always throws pups very similar to itself). These animals come from a "good line bred pedigree" - that is one that is inbred so that the animal is homozygous for as many as possible of the characteristics that the breeder regards as desirable.
Unfortunately this search for perfection and uniformity comes at a cost. Undesirable genes also become increasingly likely to be homozygous and so affect the health of the animal. Most of these genes have minor effects which gradually accumulate. There are many genes involved in traits like fertility, immune competence and mental stability. It is a fact that accumulation of homozygous recessive "bad" genes gradually diminishes the function of these systems no matter what.
Walkowitz & Wilcox 1994, Willis 1992, 1989, Onstott 1962 all view linebreeding and inbreeding as essentially the same and differing only in degree of intensity. Whether one considers inbreeding and linebreeding to be the same or feels they are two distinct breeding systems, quantifying the degree to which an animal is linebred (or inbred) provides important information regarding its potential genetic contribution.
If we traced our APBT pedigrees back far enough we would see that all our dogs are ultimately related and the inbreeding coefficient would be quite high. If such a dog were compared to a dog whose background is only known for a few generations, it would appear as if this dog were much less inbred. But this, of course, is not necessarily true. When we are comparing pedigrees, we must always consider for how many generations we are calculating the inbreeding coefficient.
Calculation of inbreeding coefficients will give an indication of how inbred a dog or a prospective cross is. Knowing these numbers enables the breeder to make choices that will reduce inbreeding.
COEFFICIENT OF INBREEDING (COI)
NOTE: It should be noted here that an inbreeding coefficient is of little value without a standard to which it can be compared, it would be of utmost value considering how APBT breeders are beyond many in their love of pedigree analysis and tracing. Thus I would propose the creation of a Register of Inbreeding Coefficients which would allow for calculation of a breed average for comparison.
The inbreeding coefficient is a measure of the proportion of loci that are homozygous because of the relationship between the parents. In other words, it is the percentage of probability that a particular locus is homozygous due to the relationship between the ancestors. An inbreeding coefficient of 0 % would mean that no locus is homozygous because of any relationship between the parents. If 100% then the offspring are clones of the parents.
Some comparison matings: Note these percentages do not take into account any past generational influence:
· Inbreeding:
o When a dog is mated with a sister/brother: 25 %
o When a dog is mated with a parent: 25 %
· Linebreeding
o When a dog is mated with a halfsister/halfbrother: 12.5 %
o When a dog is mated with a grandparent: 12.5 %
o When a dog is mated with a cousin: 6,25 %
The coefficient should increase by less than 0.25-0.5 percentage point per generation. If the increase is higher, the population will be at risk of health problems due to inbreeding. It might take many generations before the problems are visible, but when they arise they will be difficult to remove from the line.
Lets consider both methods by first looking at Wright’s equation for calculation of “inbreeding coefficient”.
Fx is the inbreeding coefficient of the dog in question, Fa is the coefficient of the common ancestor, n1 is the intervening generations between the sire and the common ancestor, and n2 is the intervening generations between the dam and the common ancestor. Since I will make use of the degree of inbreeding notation (x,y:a,b) for listing common ancestors, which counts actual generations instead of intervening generations, we will be using n1+n2-1.
LITTLE DOG
BAD DOG
BIG DOG
BITCHY BITCH
BIG DOG
PED A
LITTLE DOG is the result of the mating of half-brother/sister, both of the parents being out of BIG DOG. If BIG DOG carries a gene with two different alleles (e.g. the horrible red nose and black nose unrealistic example LOL), if red nose is passed to BAD DOG there is a 50% probability of being passed to LITTLE DOG. There is also a 50% probability that BITCHY BITCH will receive the same red nose allele from BIG DOG and a 50% probability of it being passed to LITTLE DOG. The probability that LITTLE DOG will be homozygous for this red nose allele is 0.5 x 0.5 x 0.5 = 0.125 or 12.5%. If Walton were the only common ancestor, the inbreeding coefficient for LITTLE DOG would be 12.5%.
LITTLE DOG’S inbreeding coefficient because of BIG DOG is calculated by ½ to the power n, where n is the number of individuals from LITTLE DOG to the common ancestor BIG DOG on the top of the pedigree (male side) and back to LITTLE DOG on the other bottom (female side) of the pedigree.. This makes n equal to BIG DOG – BAD DOG – BITCHY BITCH by BIG DOG, or 3. The calculation, therefore, is (½)³ or (½ x ½ x ½), which equals one eighth or 12.5%.
In the equation quoted above n1 = 1 (BAD DOG) and n2 = 1 (BITCHY BITCH by BIG DOG). BIG DOG, the common ancestor, is represented by 1. If BIG DOG is also inbred, or line bred, then BITCHY DOG’s inbreeding coefficient would be 12.5 x (1 plus the inbreeding coefficient of BIG DOG, the common ancestor). If the common ancestor is not inbred then Fa = 0, therefore this part of the equation can be ignored because (1+Fa) = 1. If LITTLE DOG had more than one common ancestor then calculations would be made for each and added together to give his inbreeding coefficient.
Wright’s Equation works to a certain extent but anyone who claims this is the best way to determine inbreeding coefficient needs to go back to breeder’s school because as mentioned there are definite and inherent defects in it because it does not take into account generational influence. Thus, using Wright’s COI does not take into consideration the positions of the common ancestor in the pedigree.
In the 1st Generation there are 2 dogs so 25% / 2 = 12.5% as the possible inbreeding coefficient
In the 2nd Generation there are 4 dogs = 6.25%
3rd Generation 8 dogs = 3.125%
4th Generation 16 dogs = 1.5625%
5th Generation 32 dogs = .78125%
25% 6.25% 3.125% 1.56%
LITTLE DOG
BAD DOG
BIG DOG
STUB DOG
HUGE DOG
RED DOG
HUGE DOG
BITCHY BITCH
BIG DOG
STUB DOG
HUGE DOG
RED DOG
HUGE DOG
PED B
If LITTLE DOG’s grandsire BIG DOG was inbred to HUGE DOG (2 x 2), LITTLE DOG’s inbreeding coefficient would be .125 x 1.125 = .140625 or 14.0625%.The increase of 1.5625% represents the total influence of HUGE DOG which appears four times in the fourth generation of the pedigree of LITTLE DOG. LITTLE DOG inherited 25% of his genes from HUGE DOG, which when divided by four results in an inbreeding coefficient of 6.25%. LITTLE DOG’S inbreeding coefficient should, therefore, be 12.5% + 6.25% = 18.75%. This same estimation can be derived visually by adding the numbers seen at the top of the pedigree columns x the number of times an individual appears more than once in a pedigree. So HUGE DOG = 4 x 1.56 + +BIG DOG 2 x 6.25+STUBDOG 2 x 3.125 + RED DOG 2 x 3.125 = 31.25%
THUS using Wright’s equation which consists of multiplying an inbreeding coefficient by one plus the inbreeding coefficient of a common ancestor tends to underestimate the total amount of inbreeding in a pedigree.
In fact, an inbreeding coefficient calculated using Wright's Equation is neither an estimation of the number of genes put into the homozygous state nor an estimation of the percentage of inbreeding. It is merely the probability that identical alleles will be inherited from ancestors common to both sire and dam.
Wright's Equation considers duplicated ancestors only if they are common to both sire and dam, but if the inbreeding of an individual is one half the relationship of its sire and dam, then duplicated ancestors wholly contained within the pedigrees of either the sire or the dam should also be considered because ultimately they will trace to ancestors common to both sire and dam.
PROBLEMS “InHeReNt” WITH LINEBREEDING AND INBREEDING. LOL!
A well educated opinion regarding inbreeding and modern homogeneity of dog breeds such as the APBT states that inbreedings/linebreedings time is past. This author indicated that if purebred dogs are to remain viable into the next century breeders need to rethink their strategy and work toward their goals with more emphasis on over-all health and concerted efforts to reduce the level of inbreeding in their breeds. Especially to me as a geneticist this is an important point considering three of the most prolific germ-lines in the show APBT and the health problems that are increasingly apparent.
Inbreeding and tight linebreeding typically act to reduces fertility, overall health and mental stability. Inbred animals are more prone to diseases such as infections and cancer, and more likely to be "highly strung" and nervous.
To understand why this happens we need to consider basic genetics:
All dogs carry some harmful genes. These genes are usually hidden because we have one good copy of the gene to compensate for the defective version and the good copy of the gene can perform the tasks required. If we double up on this gene through inbreeding/linebreeding we are removing the good copy and the harmful gene is the only one left. If this defective gene was the one that stabilizes our animal during stressful situations we end up with a nervous dog. If the defective gene was one that coded for genes that protect against cancer we have a dog less likely able to fight cancer. With many double defective genes the problem may be so severe that the animals die, suffer debilitating disease. Some are doubled up on defects in bone structure, reproductive anatomy, immune function, or may be blind, deaf, or plain sick all the time.
What we are seeing whether the breeder of a particular line acknowledges it or not is that when the overall homology (increased inbreeding coefficient) of a specific germ line is focused by line or inbreeding there is an exacerbated tendency toward occurrence of disorders that are ultimately controlled by multiple sets of genes. Of particular interest cosmetically in the APBT are kinked tails, underbites and serious debilitating disorders as hip dysplasia, temperament issues (such as fear or human aggression), and congenital heart anomalies. Of utmost importance to an APBT breeder is prior knowledge of abnormalities that the common ancestors have produced. Continued linebreeding within such lines can promote the fixation of these defects permanently within the line resulting in extraordinary risk of genetic defects.
The most important issue is making health a top priority when linebreeding or inbreeding for trait selection. It is obvious even to those who promote inbreeding that screening for genetic diseases and not breeding affected individuals is important. As tests become available which will detect carriers of genetic problems, they should be put to use. However, before I state the following please do not for a second use the following words to justify or rationalize breeding selection of unhealthy animals. A particularly fine individual with a multitude of high quality traits that has carrier status for a detrimental defect should not automatically be precluded from breeding but the utmost care should be taken that they aren’t bred to other carriers and more importantly those who buy puppies from a carrier parent damn well MUST be advised to screen the pup if they want to breed it. But eliminating proven carriers as breeding stock if they are anything but stellar otherwise is the only ethical approach. Defects such as dysplasia, temperament issues, congenital heart defects that are homozygous and expressed in a dog is however definitely a reason to spay/neuter. Definitely an animal that carries a trait is very different from an animal that displays the trait. (read the above again and note the difference between carrier and an animal that displays a recessive homozygous defect)
INBREEDING DEPRESSION
Research has shown that inbreeding depression, or diminished health and viability through inbreeding is directly related to the amount of detrimental recessive genes present. Some lines thrive with inbreeding, and some do not.
One of the effects of inbreeding is a decrease in the heterozygosity of important gene clusters such as those involved in immune expression. This effect places individuals and the population at a greater risk from homozygous recessive and immune related diseases. The impact of accumulating deleterious homozygous traits is called inbreeding depression. Ultimately this is considered to be a loss in progenies vigor due to loss in genetic variability or genetic options particularly those involving immune response.
Sometimes two different alleles may be better than one. Consider the major histocompatibility complex (MHC) of the immune system as indicated above. This large group of genes requires high diversity because each on of these individual genes adapts to combat a specific insult to the immune system. Having a variety of MHC alleles is vital to an animals ability to combat any given infection (for instance) or allergen. Thus, if both copies of the MHC is inherited from the same common ancestor due to inbreeding there is only half the combinations of genetic information to counteract environmental and harmful problems the immune system is geared to combat. Not only does this provide better defense against pathogens, but there is growing evidence that parents who carry different MHC haplotypes may have fewer fertility problems. This is not a universally accepted theory, but today one is hard pressed to find a conservation or zoo biologist concerned with preserving an endangered species who would not list maintaining maximum genetic diversity as one of his/her primary goals.
The MHC is very specific and in a way each gene in the MHC helps to create individual one type of cell that is specific to and capable of recognizing and killing only one kind of dangerous environmental problem. Examples of environmental insults includes such things as pollen, dust mite saliva, fly bite, insect venom, cancer cells, viruses, bacteria etc. The environment has billions upon billions of different insults that the animal may encounter in its lifetime and for each insult only one MHC gene will have the ability to counteract the insult. Now consider a very inbred individual that has two copies of same MHC that followed the limits of probability and was passed down from the same ancestor. If both chromosomes of the dog have the identical immune system gene segments, that animal has lost half of its potential antibody genes. If that animal is further inbred, it starts to lose other individual gene segments to a genetic phenomenon we noted in a previous section called "crossover." Ultimately with continued inbreeding depression we may lose billions of potential antibodies. Maybe we lost that antibody that was required to fight that particular cancer our dog died of. Our dogs may also exhibit allergies to common things due to inbreeding depression. This is often seen when
Other signs of inbreeding depression are small litter sizes or difficulty producing or rearing young. Bitches from families that consistently produce small litters may be suffering inbreeding depression. Specific with lines of the APBT signs of inbreeding depression dog is indifferent to bitches in standing heat, incapable of mounting and successfully completing ties (hop off after a couple humps), bitches that require physically restrained, bitches that kill or damage puppies through intent or neglect and signify that this animal should not be bred.
Breeders walk a tightrope between needing to reduce genetic variation to maintain uniform breed type and needing to maintain genetic diversity to avoid inbreeding depression. One of the most pervasive causes for inbreeding depression and decrease in genetic diversity is brought on voluntarily by breeders who continually breed the favored sires out to everyone that asks, while the majority of potential breeding males are never bred. The sire may not be of exceptional quality in all aspects or may be of exceptional quality. This bottleneck is made all the worse by the fact that the majority of breeding bitches are often sired by other popular studs from previous generations.
It is possible to prevent this deterioration in health and vigor by limiting linebreeding and by selecting rigorously for highly fertile, vigorous, long lived, mentally stable animals. Responsible, intelligent dog breeders do just that. Only breed the best to the best and cull the rest.
OUT CROSSING
Outcrossing brings together two APBTs that are less related than the average for the breed. By convention both the sire and dam during an outcross should have some linebreeding in their background because no matter how you slice it, breeding a scatterbred dog to a linebred dog produces a scatterbred dog (see our case study below). Many breeders feel this is outcrossing but in reality you now have only half your lines genes and no rational idea what the other half may be. Thus we usually consider outcrossing to involve two linebred or inbred animals from different bloodlines.
A reason to outbreed would be to bring in new traits that your breeding stock does not possess or to decrease the inbreeding coefficient or typically both. When you are looking for high quality traits, also termed aptitudes, that are not present in acceptable members of your germline, then the most obvious way to bring in missing aptitudes is to outcross to a line prepotent for these. Thus, if you are experiencing inbreeding depression you can seek dogs outside your lines with aptitudes that compliment your lines weaknesses. Example one would choose a mate that does not possess the same faults while phenotypically complements and hopefully maintains your dog's good traits. By convention both individuals should be linebred but share no common ancestors in 5 generation pedigree. This promotes more heterozygosity, and gene diversity within each dog by matching pairs of unrelated genes from different ancestors. Note that the key type genes that define our breed will always stay paired. Unfortunately, outbreeding can also mask the expression of recessive genes, and allow their propagation in the carrier state.
When the sire and dam may be genetically unrelated especially compared to your linebred dogs you may experience yet another outcross phenomenon known as heterosis. Heterosis is more commonly called by APBT breeders as hybrid vigor. It should be noted that hydrid vigour is more commonly used to describe mixing of different species rather than different breeds of course but it is still an apt term. What we notice sometimes when we do logical complimentary outcrosses among our breed is a burst of fertility, good health and growth that is seen in the progeny when two unrelated germlines are mated. The more divergent and unmixed these unrelated germlines are the greater the differences between them and ultimately we will see more evidence of hybrid vigour as we revert to heterotrophic on many alleles that cause inbreeding depression. Allelic diversity is a good thing in many instances even though we try when producing a germline to pair up on many others. We must always avoid inbreeding depression especially if our lines are becoming less healthy. What we seek with an outcross similar to phenotypic complementarity is to overcome defects in one or other germline - the way two bloodlines "nick" or really “mix well” in dog breeding terms.” On the other hand breeders are often turned off from outcrossing especially novice breeders because there is always a risk involved and careful and longterm goals must be established and short term problems anticipated and prepared for. Outbreeding can produce exceptional quality in the F1 generation or can produce nightmares (just like inbreeding huh?). We must carefully analyze if we can obtain from each outcross that which we are seeking and avoid bringing in those traits we cannot easily get rid of if they end up set within out lines. This is why many outcrosses fail. Contrasting aptitudes of specific germlines can definitely conflict with one another, rather than blend. However, with the APBT when we are selective for specific traits during outcrossing that are both favorable and if we also select against as many unfavorable genes as possible, the shared genetic background of the strains or homozygosity of so many alleles will help contribute to a favorable blend of their contrasting aptitudes especially as outcrosses are blended back into the germlines logically.
Outcrossing Depression (the flip side)
In some cases, inbreeding is purposely done to create a "pure line" of individuals which all have similar genes. This is the case with many lines of APBT. Breeders intentionally linebreed to create a population that has the genes for desired traits in a homozygous state, so that the offspring will perpetuate the desired phenotype. Over generations, individuals with deleterious genes are removed from the breeding population, resulting in a monomorphic, yet healthy population. (OK it is possible) These populations can actually suffer "out-breeding depression" when crossed to unrelated individuals which results in new combinations of alleles, and possible entry of deleterious genes.
BACKCROSSING
Backcrossing as we might remember from Table 1 at the top of the page is when outcrossed dogs are bred back into one of the original bloodlines. While we may not see the degree of heterosis that we might see in the original outcross we should maintain a level of this vigour in specific individuals. Here is where selection and luck are vital. Less that honest appraisal of the F2 outcrosses backcross can lead to reestablishment of traits we were trying to breed out or traits we are trying to avoid. Thus, it is this F2 or highbred individual that is the actual goal of the parental outcross and backcrossing functions.
NOTE: Usually outcrossing is done in pairs with closely related linbred individuals which allow mixing of the backcrossed progeny which would hopefully set the traits we were attempting to bring into our bloodline with the outcrossing. A double backcross (taking an outcross back into the original line F1 and the progeny F2 from this also back into the original line again (double backing). will typically reduce the original influence of the outcross such that we are virtually back to linebred status. What we would instead try to do is perform two logical outcrosses and two backcrosses and then interbreed both outcrosses. As stated the goal of outcrossing and backcrossing is to set traits without increasing the coefficient of inbreeding.
Scatterbreeding.
Scatterbreeding within the APBT may or may not be a good thing but in most cases that we see, especially in regards to your typical back yard breeder, scatter bred dogs usually end up lacking in all but the most basic of breed type, they are typically unpredictable in temperament in relation to their sire and dam (The meaning of this is not that certain scatterbred individuals look very nice and may fit the standard but ultimately because there is no consistency in their lineage there is also no consistency in their genetics. For this reason we usually see scatter bred puppies from the same litter with wide variation in regards to temperament, health, coloration, type and many other traits that are set and maintained by linebreeding.)
Consider a new kennel that has a scatterbred male they are very proud of because it is their first “papered dog” and a good quality linebred female of medium inbreeding coefficient. Rather than outsourcing to a higher quality stud of the line of the female or outcrossing to a high quality stud of another set germ-line, they took the easy route and bred to the in house scatterbred male. We must wonder to what purpose this is done. Because we really know nothing about the scatterbred sire and the consistency of traits many generations behind him we now know nothing genetically about the puppies. Breeding a linebred animal to a scatterbred animal is not outcrossing it is producing another generation of scatterbred puppies. If we bred the puppies from this litter back to the sire we would be on the road to developing a specific germline (in the long run) but in reality this should only be done if the scatterbred animal is of the utmost quality in all the traits we desire (or at least a majority) and certainly traits that are lacking in the stable germline. If this scatterbred animal is only mediocre quality then we will be developing a mediocre germline that must be improved in an uphill breeding effort.
Provided By:http://apbtconformation.com/breeding_methods.htm
