Importance of Genetic Variation in Breeding

Annika Berner M.Sc.
The hereditary diversity of a breed refers to the variety and abundance of its gene forms (alleles).
A broad genetic base is essential for maintaining the overall health, vitality, and sustainability of a breed.
Genetic diversity ensures that individuals possess multiple versions of the same gene, leading to greater heterozygosity, which enhances resilience and helps protect against hereditary diseases and defects.
This diversity also plays a crucial role in immune system function—reducing genetic variation can lead to a higher prevalence of inflammatory conditions, autoimmune disorders, and allergies.
‍
Breeding programs and hereditary advancements rely on genetic variation within a breed.
Even in numerically large breeds, genetic diversity can be significantly restricted if only a small proportion of dogs and family lines are utilized for breeding. When specific dogs contribute disproportionately to the gene pool, harmful mutations can become widespread. Over time, this can lead to the emergence of new genetic disorders, making it increasingly challenging to find breeding candidates that do not carry these mutations.

Strategies for Maintaining Genetic Diversity
An ideal breeding strategy ensures the even representation of all lineages within a breed.
The most effective way to maintain genetic diversity is to use a broad selection of dogs from various family lines while managing the number of offspring per individual dog.
Additionally, many breeds have populations in different countries, providing an opportunity to introduce new genetic material through controlled importation.
However, it is important to recognize that genetic diversity in foreign populations is not always significantly different from domestic lines.

Recommended Breeding Limits
To preserve genetic diversity, guidelines have been established regarding the maximum number of offspring a single dog should produce in its lifetime. For small-numbered breeds, the recommended limit is 5% of the total breed registrations over a four-year period.
In larger breeds, this percentage is reduced to 2-3%. For example, if a breed has 1,000 registered dogs over four years, no single dog should have more than 20-50 offspring.
Furthermore, a dog should not contribute more than 10% of the genetic pool in small-numbered breeds and 4-6% in large-numbered breeds, based on four-year registration figures.
By adhering to these recommendations, breeders can help maintain genetic diversity, reduce the risk of inherited diseases, and ensure the long-term health and sustainability of the breed population.
‍‍