Chapter 8 - Breeding Systems

In broad terms the dog breeder is, by definition, a breeder of purebred stock. Thus the many advantages of crossbreeding are not available to him or her. He or she can, in fact, breed either from related animals within the same breed (,inbreeding) or from unrelated animals (outbreeding). In a sense all dogs within a given breed will show some degree of relationship since all will have descended from the same source animals. This apart, close relationships may be relatively low in dogs that are widely separated in terms of location (different countries) or are members of numerically large breeds. Relationships will be closer in numerically small populations.

Inbreeding, which in its less extreme form may he called linebreeding, is a powerful tool that carries with it certain difficulties. The more that dogs are inbred (i.e., the closer the relationships between breeding stock) the greater the risks that arise. These risks involve firstly the occurrence of hidden anomalies. If a breeder mates together dogs that closely relate to some famous ancestor and that ancestor carried some deleterious recessive (known or unknown to the breeder) then the chances of puppies which carry a double dose of this recessive, and thus exhibit the problem, is increased. The same is true of more polygenic traits. For example, if the famous ancestor was poor in shoulder placement then inbreeding to that ancestor might increase the chances of poor shoulder placement in the puppies.

Thus, inbreeding should only be undertaken in very outstanding animals with few faults and, as far as one can tell, no major deleterious Mendelian features. However, even with this proviso there are still risks attached to inbreeding. Traits concerned with fitness (reproduction) which are low heritability but may be controlled by combinations of genes do have problems with inbreeding. Inbred dogs are, among other things, likely to be less fertile and give rise to smaller litters as a consequence, although this is not necessarily inevitable.

Inbreeding is something that should not be done lightly and dogs should preferably not be bred too closely. However the nature of some breeds means that breeders cannot avoid mating distantly related animals together because all members of the breed will have specific ancestors way back in their pedigrees. Boxers all trace back to Lustig v Dom, Bernese Mountain Dogs all go back to the Newfoundland Pluto v Erlengut and German Shepherd Dogs all go through Erich v Grafenwerth. These ancestors are unavoidable in all specimens of these breeds.

Most breeders will try to mate dogs that look alike - type to type mating. This is a sound policy but because dogs do have flaws it is important to try to avoid mating dogs that both have the same flaws. if a dog is too short in the foreleg then it should not he mated to an animal that is also short in foreleg. In this instance, there should be an attempt to use a longer-legged mate in the hope that this compensatory mating will give a more acceptable leg length in the progeny.

Chapter List