A DNA COI test (typically SNP chip technology) scans the genome and identifies runs of homozygosity (ROH) — stretches where both maternal and paternal copies are identical because they were inherited from the same ancestor. The total ROH length as a proportion of the genome gives the genomic COI. This is a direct measurement of what actually happened.
Pedigree COI uses Wright's formula to calculate the expected probability of homozygosity from shared ancestry. It traces the pedigree, finds every ancestor on both sides, and sums inheritance probabilities through each path. This is a statistical prediction based on family tree structure.
Neither result is "wrong" — they measure the same thing from different angles, and some divergence is expected.
Use pedigree COI as your everyday breeding tool. Available for every dog, rich in detail, directly supports mating decisions. Check the PCI to understand reliability.
DNA test when you need confirmation or when pedigree data is limited. For dogs with incomplete pedigrees, DNA fills in what the pedigree can't show. For breeding stock, DNA adds confidence.
Add DNA results to Dog Breeder Pro. Enter your DNA-tested COI on any dog's profile — it will display alongside the calculated Wright's COI. The system continues calculating pedigree-based COI because the additional analyses it enables cannot come from a DNA number alone.
Dog → Genealogy → Inbreeding Analysis
Wright's COI is the headline number. If a DNA COI has been entered, it appears on the dog's pedigree view alongside the calculated value.