The issue of inbreeding between stud dogs and bitches is not entirely easy to identify, however, in order to avoid it happening it is critical that pedigree dogs that go back at least eight generations are accurately analysed.
Stud dogs that appear out-crossed, with no individual ancestor appearing more than once amongst three generations of pedigree, may descend from only four of the same dogs, and are therefore likely to be highly inbred.
Coefficient inbreeding is the percentage estimate of all variable gene pairs which are homozygous (identical), due to the inheritance of common ancestors. Coefficients pinpoint key ancestors which feature any inbreeding and provide estimates of their overall genetic contribution.
The breeding and mating of an unrelated half-brother stud dog and their half-sister produces inbreeding co-efficiency of 12.5%, whilst stud dogs and bitches that are brother and sister or father and daughter will produce co-efficient inbreeding of 25%.
Stud dogs with inbreeding co-efficiency are substantially higher and over 20% inbreeding will be prevalent at third generation, rising to more than 27% at their eighth generation – which is of course far from ideal.
At first glance, stud dogs and bitches may not appear as particularly inbred but this is because they are only as genetically diverse as the offspring of their father and daughter combinations.
Whilst this type of coefficient inbreeding between stud dogs and bitches has resulted in puppies of a top class standard, when dog breeding the breeder should always be aware that this type of inbreeding is taking place in order to make informed and fundamental choices.