Dog Breeding Systems

The first stage of any breeding program is selecting the dog, the second deciding which dog to mate to which. Cross-breeding is the most effective for farm livestock, but dog-breeding is greatly influenced by pedigree. In pure breeding, mating is between unrelated animals of the same breed (out bred) or with closely related animals 'of the same breed (inbred). It is commonly but erroneously thought that all dog breeds are highly inbred, with consequent character failings. While a purebred animal is more inbred than a crossbred, not all purebreds are highly inbred. Taking o per cent as a totally out bred dog and 100 per cent as purely inbred (brother/sister matings for many generations), man y dog breeds would have average inbreeding levels of 4-5 per cent and below. In numerically small breeds, the levels may reach 12-14 per cent, equivalent to having the same grandparent on both sides of a pedigree.

Inbreeding is a powerful tool for fixing certain features and is almost always undertaken in the establishment of breeds of any species. However, it does bring to the surface hidden defects, usually recessive, and at high levels (in excess of zo-30 per cent) can bring about serious problems usually affecting viability  traits. Experiments with Beagles have shown  that  at extreme inbreeding levels some 75 per cent of all pups die before ten days old; high inbreeding in a Foxhound colony led to reduced litter size largely due to reduced sperm count in the males.Similar problems would be expected in other breeds. On the plus side, inbreeding can increase uniformity when combined with selection, and it has minimal effect on traits which are highly inherited in an additive fashion. However, inbreeding is best left to experienced breeders with knowledge of their breed and its pedigrees. Novice breeders often mate dogs on the evidence of their pedigrees, but this is an unwise policy: a pedigree is only as good as the dog which bears it.