What is COI?
The Coefficient of Inbreeding (COI) measures the probability that two alleles at any given locus are identical by descent (IBD) from a common ancestor shared by both the sire and dam. Mathematically, Wright's coefficient of inbreeding is expressed as:
$COI = \sum \left( \frac{1}{2} \right)^{n_1 + n_2 + 1} (1 + F_A)$
Where n1 and n2 represent the number of generations from the sire and dam to the common ancestor A, and FA is the inbreeding coefficient of that common ancestor.
What Should COI Be?
Ideally, breeders aim for low COI values to maintain long-term genetic health, vitality, and breed longevity across generations. A lower COI helps prevent the rapid expression of detrimental genetic disorders.
Test Mating Integration
You can try potential matings within the database to instantly calculate the resulting litter coefficient before breeding takes place, allowing you to simulate and plan genetic outcomes safely.
Evaluating Breeding Pairs
Comparing multiple potential pairings helps breeders make informed, scientifically backed decisions for future litters, balancing bloodline traits with genetic diversity preservation.
Why Track COI?
Tracking COI helps prevent the rapid unmasking of deleterious recessive genetic traits, minimizes inbreeding depression (loss of fertility, vigor, and lifespan), and preserves overall immune system resilience.
Pedigree Example
An animal with common ancestors appearing multiple times on both sire and dam sides will reflect an elevated inbreeding coefficient because genetic material is being funneled through fewer unique channels.
Other Genetic Factors
While COI is a critical compass, it should never be looked at in isolation. It must always be evaluated alongside physical health clearances, stable temperament, structural soundness, and breed type.
Common Misconceptions
A low COI does not automatically guarantee a healthy or perfect puppy, just as a slightly higher COI does not spell instant disaster if managed carefully within a thoughtful breeding program.
How COI is Calculated
Calculations use multi-generational pedigree depth (up to 25 generations) to trace common ancestors back through historical lines, identifying overlapping branches down to the individual allele level.
Managing High COI
When high COI is unavoidable due to breed population bottlenecks or historical pool limitations, careful outcrossing with genetically diverse lines can help reintroduce healthy variation.
Why Bother with Metrics?
Modern pedigree analysis tools protect future generations and give breeders clear, quantifiable, data-driven insight into bloodline health rather than relying on guesswork.
Find Out More
Explore our comprehensive documentation and database features to learn more about advanced canine genetic indices and how to apply them ethically.
What is AVK?
The Ancestor Loss Coefficient (AVK), sometimes called the Coefficient of Ancestral Loss, measures the ratio between the number of unique ancestors and the total possible number of ancestors in a pedigree up to a given depth. The formula is:
$AVK = \frac{\text{Number of Unique Ancestors}}{\text{Total Possible Ancestors in Generation } n} \times 100$
It highlights how much ancestral collapse has occurred due to the same individuals appearing repeatedly in the family tree.
Why AVK Matters
An AVK close to 100% indicates high genetic diversity with minimal ancestral collapse. When AVK drops significantly, it means fewer unique dogs are contributing genetic material, raising the risk of silent genetic bottlenecks.
Calculating AVK Depth
Deep pedigree analysis tracks ancestral loss across successive generations (typically evaluated at 10 generations or deeper) to expose hidden saturation and repetitive use of popular sires or dams in historical lines.
Interpreting Results
Combining AVK ratios with COI metrics provides a complete, balanced picture: COI tells you how likely genes are to match by descent, while AVK tells you how wide or narrow the actual pool of ancestors was that supplied those genes.
Find Out More About Breeding Indices
Equivalent Founder Genome Number (FGE) :
FGE measures the number of equally contributing founders that would be required to produce the genetic diversity found in the population or individual, accounting for potential allele loss from drift. The formula is:
$FGE = \frac{1}{\sum p_i^2}$
Where pi is the proportional genetic contribution of each founder, tracking how evenly genetic material has distributed down the line.
Effective Founder Number (FE) :
FE (Effective Founder Number) calculates the number of equally-contributing founders that would account for the genetic diversity in an individual's pedigree by mapping pathway probabilities. Calculated via:
$FE = \frac{1}{\sum q_j^2}$
Where qj represents the fractional probability weight of each founder path. Unlike raw founder counts, FE weights how heavily those genetic lines actually survived and propagated.
Ancestor Loss Coefficient (ALC) :
ALC measures the proportional loss of ancestral representation in a pedigree due to common ancestors filling multiple slots across different branches. It is evaluated as:
$ALC = \left(1 - \frac{\text{Unique Ancestors}}{\text{Total Filled Ancestor Slots}}\right) \times 100$
This directly captures the degree of duplication across the lineage structure.
Pedigree Completeness Index (PCI) :
PCI evaluates how thoroughly a pedigree is documented across generations, ensuring that calculations for inbreeding and genetic diversity are built upon complete data rather than missing branches. The standard index for generation $k$ is calculated as:
$PCI_k = \frac{2}{\left( \frac{1}{PCI_{sire}} + \frac{1}{PCI_{dam}} \right)}$
This ensures unrecorded parents do not falsely deflate inbreeding scores due to data gaps.
Founder Count & Ancestral Depth :
Founder Count & True Generation Depth track the foundational base of a pedigree over deep multi-generational analysis (up to 25 generations), providing insights into the historical bedrock and absolute generation boundaries of the bloodline.
Total Ancestors & True Depth :
Tracking the Total Ancestors and true generational depth ensures breeders can accurately compare how deep their pedigree records reach across registries, separating well-documented lines from sparse regional files.
Breed Quality Score :
The Breed Quality Score combines completeness, balance of bloodlines, and genetic health indices into a single unified formula to assist breeders in evaluating overall lineage strength:
$Score = \frac{((100 - COI) \times 0.25) + (AVK \times 0.20) + (FGE \times 0.20) + (ALC \times 0.15) + (PCI \times 0.10) + (Depth \times 0.10)}{MaxPossibleScore} \times 100$
Mean Ancestor Generation (MAG) :
The Mean Ancestor Generation (MAG) calculates the average depth (generation number) where all known ancestors actually appear in the pedigree. The formula is:
$MAG = \frac{\sum (d_i)}{\text{Total Ancestor Occurrences}}$
Where di is the generation depth of each ancestor occurrence. A higher MAG indicates that your recorded pedigree reaches deep into historical bloodlines, while a lower MAG implies that ancestors are clustered tightly in recent generations.
Maximum Individual Founder Contribution (%) :
Maximum Individual Founder Contribution measures the exact percentage of a dog's genetic makeup that traces back to its single most dominant historical ancestor. Calculated as:
$MaxFounder = \left( \frac{\text{Occurrences of Top Founder}}{\text{Total Ancestor Slots}} \right) \times 100$
This metric instantly flags genetic bottlenecks where a single popular ancestor over-contributes to a bloodline.
Inbreeding Rate per Generation ($\Delta F$) :
The Inbreeding Rate per Generation measures the speed at which inbreeding accumulates per generation, normalizing the lifetime COI against the pedigree depth. Approximated via:
$\Delta F = 1 - \exp\left( \frac{\ln(1 - F)}{t} \right)$
Where F is the coefficient of inbreeding and t is the completed generation depth. This helps breeders distinguish between slow, steady linebreeding over many generations and rapid inbreeding crammed into a few recent steps.
