Coefficient of inbreeding (COI)

The coefficient of inbreeding (COI) is the probability that the two copies of a gene in a dog come from the same ancestor. It is given as a percentage and calculated from the pedigree.

What does the number tell you?

The higher the COI, the greater the chance that a dog carries two identical gene variants, including harmful recessive ones. The figure depends on how many generations the pedigree covers, so values from different sources cannot be compared unless the generation depth is stated.

What does it not tell you?

COI says nothing about which diseases a dog carries. Only DNA tests do. See DNA testing.