- What is a "good" or "safe" COI for dogs and cats?
- There is no universal threshold, but most geneticists and breed health organizations use these benchmarks as guides: under 6.25% (equivalent to cousins sharing one common grandparent) is generally considered low risk; 6.25–12.5% is moderate and common in many registered breeds; above 12.5% (equivalent to half-sibling or closer matings) carries meaningfully elevated risk of expressing recessive diseases and reduced immune diversity. Some rare or numerically small breeds may accept higher values due to limited gene pools. Always combine COI with health-test results and breed-specific guidance from your kennel or cat fancy club.
- How many generations should I include?
- A 4-generation pedigree captures roughly 85–90% of the total COI in most breeds; 5 generations catches around 95%. Including more generations increases accuracy but requires more information. If a distant ancestor is unknown, leave that field blank — the calculator treats unknown ancestors as unrelated, which slightly understates the true COI rather than overstating it. For health breeding decisions, filling in as many known ancestors as possible in generations 4 and 5 gives the most reliable result.
- Does a higher COI always mean worse health?
- Not automatically, but the statistical risk rises. A higher COI increases the probability that both copies of a gene locus are identical by descent — which amplifies the expression of recessive disorders the breed may carry (hip dysplasia, heart defects, immune conditions, etc.) and tends to reduce heterozygosity in immune system genes (MHC/DLA). However, COI is one tool among several: genetic health panels, OFA/PennHIP certifications, and breed-specific DNA tests remain equally important. Some breeders intentionally use line-breeding at moderate COI to fix desirable traits while monitoring health outcomes closely.
- My ancestors repeat across many positions — is that correct?
- Yes. In line-breeding, a single prominent ancestor (e.g. a famous champion stud) may appear 4, 6, or even 8 times in a 5-generation pedigree. The Wright formula correctly accounts for all independent paths through a repeated ancestor — each occurrence contributes to COI separately. The calculator identifies every position where a name appears, finds every distinct connecting path, and sums their contributions. If you see a name highlighted in yellow across multiple input fields, that individual is driving COI.
- Why does this calculator require exact name matching?
- The path coefficient method depends on correctly identifying which individuals appear on both the sire's side and the dam's side of the pedigree. The calculator normalises names by trimming spaces and ignoring capitalisation, but it cannot infer that "Ch Buddy v Haus" and "Champion Buddy vom Haus" are the same dog. Use a consistent registered name or a short nickname that you type identically in every position. If you use a breed registry database (AKC, FCI, GCCF, TICA, etc.), copying the exact registered name avoids ambiguity.