COI Is a Useful Number — But It Cannot Choose a Mating
Fiona Robertson
COI Is a Useful Number — But It Cannot Choose a Mating
Coefficient of inbreeding, or COI, is one of the tools breeders can use to understand how closely related the parents of a proposed litter are on paper.
I naturally prefer a low COI. In one of my own Clumber Spaniel planning examples, a potential mating came out at around 2.3%. That was encouraging, but it was never the whole decision.
A low number cannot tell me whether the dogs have the temperament I want, whether their structure and movement are sound, whether important health problems sit elsewhere in the family, or whether the mating will leave useful options for the next generation.
COI also depends on pedigree depth. Two dogs can appear unrelated in a shallow pedigree while the same influential ancestors reappear further back. Genomic diversity testing adds another layer because it looks directly at DNA rather than relying only on recorded ancestry.
For vulnerable breeds, I see COI as a tool in the front pocket: visible, useful and part of the decision, but never the driver. The real question is whether the mating helps preserve healthy, functional dogs and leaves the breed with somewhere sensible to go next.
Read the full article in the Newflands Vulnerable Dog Breeds series: Coefficient of Inbreeding: What It Tells You — and What It Doesn’t.
