How far can you go with inbreeding?
By Ralph Gillum, BraceBeagling Columnist
September 04, 2004







I assume the question is to what extreme can inbreeding in beagles be taken before problems occur to stop the process. To start with, let us acknowledge that all breeds of livestock, including dogs, were created by inbreeding and careful selection of the offspring. As we know, inbreeding concentrates and intensifies all traits and characteristics, both good and bad. It also brings to the surface traits and characteristics caused by recessive genes. The more closely related the beagles mated, the greater the chance that a recessive gene carried by one breeding partner will find a matching recessive gene in the other parent. When considering all the above, we have to say that the degree to which inbreeding can be taken is dependent upon a number of factors.

The most important ingredient in any inbreeding program is always the individuals selected to be inbred. Ideally, you start with a male and two or more females which are genetically homozygous or pure for most desirable health traits, as well as for the running characteristics you desire. The first crosses will often show few physical problems that need to be culled, but will usually result in some pups that must be culled for unfavorable running characteristics. When you inbreed the offspring, brother/sister, father/daughter, mother/son, or half brother/half sister, you usually start seeing some of the undesirable recessive physical traits. If you cull these from the inbreeding program regardless of how well they perform in the field, you should be able to continue further inbreeding.

It is especially important to cull any offspring that possess traits that affect reproduction. These are fertility of the males, regular heat cycles and fertility of the females (good sized litters of strong, healthy pups), easy whelpers, good milkers and mothers, and normal thyroid function. Physical traits such as good conformation and a normal immune system are also critical to have in your keeper pups, in order to be able to continue inbreeding.

Most beaglers are not fortunate enough to start with genetically pure or almost pure foundation stock. In that case, you simply go with the best you can obtain and follow the same process of inbreeding and culling. You will just have more faults you will have to cull, especially in the first generations, in order to continue inbreeding.

There are strains of mice used in cancer research that have been extremely inbred for many generations with no end in sight. I do not believe that beagles can be directly compared to these mice. Beagles’ longer life spans and reproductive cycles limit the number we can keep and work with in a breeding program. However, it does show that the possibility is there for extreme inbreeding over a long period of time. That is, if we select foundation beagles that carry no seriously limiting genetic faults, and diligently cull all offspring that show any traits that would negatively affect reproduction.