Discover your Dog's COI.
We are coming to understand the importance (and impact) of our dogs' Coefficient of Inbreeding (COI). But how do you find this out what your dog's COI is? Today, we have two choices -- one old and one new. The first choice is free. Unfortunately sometimes, we get what we pay for.
Online Pedigree Calculators are Free. Why Not Use Those?
Old School Online Pedigree Calculators. Prior to 2018, they were the only choice. Prior to 2018, we all used pedigree calculators built upon one of two math formulas to estimate our dog's level of inbreeding. They look at how many ancestors are found on both mom and dad's side and predict how inbred a dog is LIKELY to be. These calculators are all we had. Of course, math and pedigree geeks knew the resulting calculation was only an estimate for several reasons. We just didn't know how wrong the estimate could be.
Here's a real-life example of how wrong calculated pedigree COIs can be. Take the example of one Doberman ("Boone") tested through the non-profit Doberman Diversity Projec). His COI, calculated with a popular pedigree calculator using eight generations, was 7.19%. See image below on the left.
Boone had his DNA tested through the DDP (a simple cheek swab) and we learned what his actual Genetic COI was. Boone, selected by his owner in part due to his low COI, turned out to have a Genetic COI of a whopping 34%. See image below on the right. Boone's owner was shocked. Even veterinarians were taken aback by Boone's results. We all knew the pedigree calculators were inaccurate for several reasons (explained below), but we never expected our dogs' Genetic COIs to be so high. Remember the two results below are for the same dog.
Boone had his DNA tested through the DDP (a simple cheek swab) and we learned what his actual Genetic COI was. Boone, selected by his owner in part due to his low COI, turned out to have a Genetic COI of a whopping 34%. See image below on the right. Boone's owner was shocked. Even veterinarians were taken aback by Boone's results. We all knew the pedigree calculators were inaccurate for several reasons (explained below), but we never expected our dogs' Genetic COIs to be so high. Remember the two results below are for the same dog.
Pedigree Calculated COI for Boone
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Genetic COI of Boone
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What Can Make Pedigree Calculators Inaccurate?
Reason #1. Most pedigree calculators use far too few generations to calculate our dog's Pedigree COI.
Pedigree calculators that use 20 or more generations (with complete information) can be fairly accurate if their pedigree data is complete back to the founding dogs of a breed. But few calculators do this and most use a maximum of eight or ten generations. For a pedigree calculator to be close to accurate, it should incorporate into it's calculation all dogs -- back to the breed's founding dogs -- and it should calculate the COI using as many generations as possible (we like to see at least 20 generations). Unfortunately, no pedigree calculators (that we are aware of) calculate back to the founder dogs or use at least 20 generations of data. That deep of a calculation would required tremendous computing power.
Pedigree calculators that use 20 or more generations (with complete information) can be fairly accurate if their pedigree data is complete back to the founding dogs of a breed. But few calculators do this and most use a maximum of eight or ten generations. For a pedigree calculator to be close to accurate, it should incorporate into it's calculation all dogs -- back to the breed's founding dogs -- and it should calculate the COI using as many generations as possible (we like to see at least 20 generations). Unfortunately, no pedigree calculators (that we are aware of) calculate back to the founder dogs or use at least 20 generations of data. That deep of a calculation would required tremendous computing power.
Reason #2. Pedigree calculators wrongly assume Genetics are Inherited Evenly.
A pedigree COI calculator assumes that all alleles are passed to the next generation with equal probability (50/50). But, this isn't always how inheritance works. Genetics are, unfortunately, infinitely more complex than that. Each time this even distribution calculation is done (at each generation of dogs), the COI increasingly drifts.
A pedigree COI calculator assumes that all alleles are passed to the next generation with equal probability (50/50). But, this isn't always how inheritance works. Genetics are, unfortunately, infinitely more complex than that. Each time this even distribution calculation is done (at each generation of dogs), the COI increasingly drifts.
Reason #3. Pedigree calculators rely on Inaccurate pedigree database content.
We humans are imperfect. As a result, pedigrees are imperfect. Ancestors are often missing or inaccurately reported. Pedigree databases concentrate this problem because pedigree information is input by humans creating the opportunity for human error. Further, the information on our dogs' pedigrees, and input into the database, comes from varying sources -- all of different degrees of accuracy.
We humans are imperfect. As a result, pedigrees are imperfect. Ancestors are often missing or inaccurately reported. Pedigree databases concentrate this problem because pedigree information is input by humans creating the opportunity for human error. Further, the information on our dogs' pedigrees, and input into the database, comes from varying sources -- all of different degrees of accuracy.
This image represents a typical pedigree with all non-unique ancestors removed. Every ancestor that shows up more than one time in this dog's pedigree has been removed.
This illustrates the origin of the term "Genetic Bottleneck". |
Reason #4. Pedigree calculators wrongly assume a "clean slate" at the oldest generation of dogs used for the calculated COI.
Pedigree calculators wrongly assume that the dogs in the base generation are unrelated (e.g., in a pedigree calculator that uses eight generations, the base generation is that eighth generation). For this illustration (see left), the dogs at the eighth generation are far from unrelated. In fact, they all come from only THREE dogs. Take a closer look at the image on the left. It doesn't look like a normal pedigree because each ancestor who is not unique (appeared on the pedigree multiple times as a result of inbreeding), has been removed. This lets you quickly see the three unique dogs from which all of these dogs originated. Clearly the dogs at generation eight are NOT unrelated. |
Compare COI Calculation Methodologies
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Online Pedigree COI Calculator
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New Genetic COI
(available through the non-profit DDP)
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Today's Science: the Genetic COI.
Today, we can simply swab our dog's cheek, send it to the lab, and find out our dog's Genetic COI. Avoiding the problems that make pedigree COIs so inaccurate, this method not only gives you an accurate COI for your dog, but enables you to access a new, cutting-edge virtual mating tool that will let you see what the Genetic COI of a future litter will be (with opposite sex mates who have been similarly tested).
Meet the non-profit Doberman Diversity Project. They've negotiated with Embark Veterinary (the official partner laboratory of Cornell University's vet school) to give Doberman owners who consent to sharing their dog's DNA for research, access to a broad testing panel that includes Doberman genetic diseases and your dog's Genetic COI (and access to that amazing tool we mentioned). For $135 ($199 if you chose not to share your dog's genomic data with researchers), you'll learn your dog's Genetic COI and his results for vWD1, DCM1/PDK4, MDR1, DM, GPT, B-Locus (black and brown), D-Locus (dilute), and K-Locus (dominant black). Plus you'll contribute to research.
