What is COI?

Both Parents Contribute One Allele

COI is short for Coefficient of Inbreeding. It's simply a number that tells you how inbred your dog is.

• Example: A 5% COI means your dog is 5% inbred (5% of his genome is the same -- he inherited the same thing from mom and dad).

Remember high school biology?  Dogs have 39 CHROMOSOMES. Each Chromosome hosts many GENES (each coding for something specific like eye color, or the blood's ability to clot). Each Gene has two ALLELES. And each parent dog contributes one Allele to each puppy. In our example 5% COI dog, 5% of these Genes received the same thing from both parent dogs. 

If a dog has a high COI (is very inbred), it has inherited the same genes from mom and dad in many locations. And when a disease is caused only when two mutations are present, that's a problem. When two genetically similar dogs are bred, the chances are much higher that puppies will receive the same mutated gene from both parents.

This image shows one Chromosome and three Genes. The Eye Color Gene shows how one parent contributed an allele coding for blue eyes and the other parent contributed an allele for green eyes. 

How Does COI Matter?

The higher the COI is, the higher the risk of genetic disease and early death. 
A recent study found an inverse correlation between COI and Longevity, demonstrating that for each one percent a dog's COI rises, there is a loss of about one month of longevity. Example: Compared to a 1% COI dog, a 52% COI dog is statistically expected to die a fully four years and three months earlier. Remember that COI describes how inbred a dog is. Google "results of inbreeding".

Read COI 201