Maternal age, paternal age, and litter size interact to affect the offspring sex ratio of German Shepherd dogs.

Several factors influence mammalian sex ratio. In this study, the effects of parental age and litter size on the offspring sex ratio in dogs were evaluated in 602 puppies born from 101 German Shepherd litters from a breeding facility. The data was obtained from recordings of the kennel and Studbook from 1996 to 2016.