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Understanding Heterozygosity Scores in Pedigree Dogs and Cats
Heterozygosity is a measure of genetic diversity. In simple terms, it refers to the presence of different gene variants (alleles) at a specific location in an animal's DNA. When an individual has two different alleles at a gene location, it is called "heterozygous." The more heterozygous sites an animal has throughout its genome, the higher its "heterozygosity score."
Why Heterozygosity Matters for Pedigree Animals
Pedigree dogs and cats are bred from a limited gene pool and often have more closely related ancestors than mixed-breed animals.
This can lead to increased homozygosity (having two identical alleles), which reduces genetic diversity.
Low heterozygosity scores indicate high inbreeding, which can increase the risk for inherited diseases and reduce the population's overall robustness.
High heterozygosity scores suggest a broader mix of genes, usually associated with better health and a lower risk of genetic disorders.
Interpreting Heterozygosity Scores
In studies of pedigree dog breeds, heterozygosity scores typically range from about 0.49 to 0.69, depending on the breed and the specific genes tested[1][2].
This can lead to increased homozygosity (having two identical alleles), which reduces genetic diversity[3].
These scores can be compared within and between breeds to identify which populations are at higher risk of genetic issues due to inbreeding.
Veterinary genetic tests often report an individual pet's heterozygosity score as a percentage. A score on the lower end means the animal has less genetic diversity, while a higher score is more favorable.
Why Breeders and Owners Should Care
Monitoring heterozygosity helps breeders maintain the long-term health of pedigree lines by avoiding excessive inbreeding.
It can guide outcrossing strategies (breeding with less-related animals) to increase diversity.
For owners, understanding these scores can help when choosing a puppy or kitten, especially if concerned about inherited diseases typical of some breeds.
Key Points
Higher heterozygosity = more genetic diversity = healthier population
Lower heterozygosity = more inbreeding = greater risk of genetic problems
References
Studies on multiple dog breeds report heterozygosity scores as a measure of genetic diversity within pedigree lines[1][2].
Case studies on Border Collies and other breeds directly link heterozygosity scores to risk of inherited conditions and effective population management[3].
Variation in breeding practices and geographic isolation contribute significantly to differences in heterozygosity across pedigree breeds[4].
For a healthy pedigree population, keeping an eye on heterozygosity scores is a practical tool to ensure strong, resilient animals over generations.