What is a coefficient of inbreeding (COI) and why should we care about it?
The coefficient of inbreeding or COI (Wright’s Coefficient) is calculated from the known pedigree of an animal and represents the probability that the two alleles (from the sire and the dam) of any given gene in an individual (or a mating) are identical by descent. Usually expressed as a percentage, it may also be viewed as the probable percentage of gene loci for this individual or mating that are homozygous by descent. The COI is significant because it gives us a quantitative measure of the inbreeding that occurs in any given mating, including the mating that produced the individual dog for which we have calculated a COI. The percentage figure gives us an easy way to compare matings without attempting to analyse long pedigrees. COI is customarily calculated to ten generations of pedigree, because to calculate to only four or five generations fails to give us the full picture. A ten-generation pedigree will often show quite significant levels of inbreeding even though no repetitions o
