Basic Information on Coefficient of Inbreeding
Like people, dogs have two copies of each gene.  The Coefficient of Inbreeding, or COI, indicates the likelihood that both copies of any of a dog's genes comes down from the same ancestor. The higher the value, the more times ancestors appear on both the mother's and father's side of the pedigree. This occurs when relatives mate - for example, the pups from mated cousins will have the same great-grandparents on both the mom's side and the dad's side.  Line breeding or inbreeding is done to help fix characteristics of breed type. Excessive line breeding, which has a high COI, leads to inbreeding depression and is associated with a loss of genetic diversity: decreased lifespan, fertility problems, reduced litter sizes and birth weight, increased incidence of cancer and autoimmune diseases.

Based on our calculations done at the end of October, 2011, the average COI for dogs in the Berner-Garde database is as shown in the following table. Breeding for a COI of less than the breed average would be ideal. But as with any breeding selection, COI is just one aspect of the whole dog that can be taken into consideration. This also makes three numbers important, the COI, the total number of dogs in the evaluated pedigree, and the number of complete generations.
Comp Gens Ave COI
8 or more 8.2
7 7.6
6 7.7
5 6.6
4 5.9
Berner-Garde is implementing the calculation of the COI with a base year instead of a fixed number of generations like the 10 generations that are sometimes used. All of the calculations go back as far as 1966 to the same group of ancestors. It provides a better estimate of the COI for use in comparing different dogs than using a fixed number of generations.

Percent Blood is an estimate of the percentage of possible contribution of genes from any given ancestor.

As you can see from the table, the COI can vary based on the completeness of the pedigree. That is why it is very important to look at those other numbers when considering any specific COI value. Everyone can help make the pedigree's and COI's more complete by submitting data to fill in missing information.