The Wetterhoun population is affected by its small founder population caused by World War II and also by historical use of “popular sires” where individual famous Champion dogs were over-selected as sires.  But the major current limit to genetic diversity in the Wetterhoun is the small population of dogs available to contribute to the next generation.  This is further reduced if owners are unwilling or unable to place their own dogs into the breeding population. 

One method to improve genetic diversity in an endangered breed is the introduction of fresh genetic information from another dog breed in an outcross programme. The first outcross requires a donor breed where the health of the selected sire and his descendants is well known and documented.  From these puppies, both males and females with suitable health characteristics are chosen to enter the breeding programme. The next generations are produced by crossing back with full members of the original breed.  Outcross programmes have also  been developed for the Irish Red and White Setter and the highly endangered Norwegian Lundehund.