Litter size

General Information: The size of a dog's litter can be influenced by various genetic and environmental factors. One such genetic factor is a mutation in the GDF9 gene, which plays a crucial role in ovarian function and fertility. This gene is responsible for encoding a protein that regulates the development and quality of ovarian follicles, directly impacting the reproductive potential of female dogs. Dogs carrying certain variants in the GDF9 gene may experience reduced fertility and smaller litter sizes. The condition is inherited in an Autosomal Recessive manner, meaning that two copies of the mutated gene (one from each parent) are required for the dog to be affected.

Impacted dogs may show signs of subfertility, including smaller litter sizes compared to breed averages. In more severe cases, affected females may struggle to conceive or have fewer viable embryos. Environmental factors, such as diet and overall health, can also influence reproductive outcomes, but the presence of the GDF9 mutation remains a significant genetic contributor.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected (smaller litter sizes expected)

One Variant Detected: Carrier (no effect on litter size but may pass the mutation to offspring)

No Variants Detected: No Effect

Gene / Testing Information: Genetic testing for the GDF9 gene variant can help predict potential fertility challenges in female dogs. Since this condition is inherited in an Autosomal Recessive manner, a dog must inherit two copies of the mutation to be affected. Carriers with one copy of the mutation will not experience fertility issues but can pass the mutated gene to their offspring. Identifying carriers through genetic testing is essential for informed breeding decisions, as breeding two carriers has a 25% chance of producing affected puppies with reduced litter sizes.