Remember that when the Quarter Horse first appeared in the US it was a “type” of horse and it took many years before the breed was established. If you go to the History page will see info on the very first Quarter “Type” Horse his name was Janus. The early breeders bred him to his daughters, granddaughters etc etc and because of this, his offspring and beyond could not run any further than a Quarter of a Mile but boy they could do it real fast!

This inbreeding is believed to have been started by a bloke in England by the name of Robert Bakewell. Bakewell believed in the philosophy of "breed the best to the best to get the best." So he assembled the "best" animals he could find and then set out to develop the "type" of animal he wanted. He closed his herd and that meant he had to retain only the genetically superior individuals to obtain the desired "type." So he had to inbreed to set that type. Bakewell's success led others to develop "breeds" that bred true or "pure" for certain characteristics when mated within the herd. Through proper selection, he retained the desired animals, making his herd "homozygous" for the desired traits.

Homozygosity is the basis for breeds passing on the same traits generation after generation. To simplify lets take a horses color for example. If all the foals of a Grey stallion turn out to be Grey in color, this means that he is probably homozygous for the Grey gene and that gene masks all other colors when passed on by the homozygous Grey parent. In other words it's dominant. Many of the undesirable colors are recessive. This is the same with other traits, like conformation, and the horses performance ability.

Inbreeding when done carefully can be and has been extremely successfu, but when done haphazardly can be extremely detrimental to a breed. Not only are you increasing the chance of passing on the good traits from generation to generation but you are also at risk of crossing a Stallion with some recessive bad traits to a mare with the same recessive traits. That is why using closed herds are essential and also not breeding the horses with undesirable traits again.

The other downfall to inbreeding is the loss of vigor in the herd. There could be a lower reproduction success rate, low resistance to disease and a loss of size. Also inbred mares have a tendency to be poor mothers and abandon their foals at birth or have a lower than normal milk production. If the breeder sticks to stringent selection methods and does not breed with horses that shows signs of inferiority then Vigor and Fertility can actually be increased by ALWAYS using the superior breeding stock.

Examples of successful inbreeding are Leo and King Glo to name a few. Leo was the result of crossing a half brother to a half sister. Both his sire and dam were by the Stallion Joe Reed. This cross actually means that Leo could have possibly had 50% blood of his grand sire. Leo was a successful racehorse in his own right where he won 20 out of 22 match races and in the fifties was the leading sire of Racing Futurity winners. In the Cutting Arena he sired Holey Sox and Leo Bingo.

King Glo is the result of crossing King with a Grand daughter of King, this cross gave King Glo 62.5% King blood. King Glo was the sire of three of the first four NCHA Futurity Champions. Money's Glo, Chickasha Glo and Chickasha Dan.

So apart from using inbreeding to develop a particular Breed it can also be used to put a particular stamp on a family. These two Stallions are examples where inbreeding has been used to establish two separate family's.

It is advisable that if anyone is considering using a stallion in an Inbreeding program, then that breeder should do some progeny testing first. One method is to cross the stallion with his own daughters and study the offspring to determine whether they carry any undesirable traits. Inbreeding is a very time consuming and expensive breeding program, to do it properly you need a very large number of breeding stock and be brutally honest in your assessment of the offspring.

In 1922 Sewell Wright came up with a formula to give an outline of the genetic make up of animals. It was called the inbreeding coefficient. Research has shown that the majority of Quarter Horses has an inbreeding coefficient of 1.7%. Values above this could be considered as desirable in that it would increase the predictability of breedings. The argument for this is that an inbred animal will consistently reproduce itself and if that animal is superior then he should out produce the other animals. An inbreeding co-efficient of 3.33% or higher would give the animal the ability to throw back to himself.

This co-efficient can be combined with the percentage of blood in a horse. If you have a particular horse that you would like "stamped" into your horses bloodlines then a figure of 10% or higher blood of that particular horse would be needed. So if you want King blood in your horses and his characteristics, to get those King traits in your horse it needs to have at least 10% King blood. Remebering if you cross your mare to stallion with 10% King blood and your mare has no King blood then the resulting foal will only have 5% King Blood. Of course there are always exceptions to the rule but the idea of breeding is to maximise the chances of success.