Dogs exhibit a high number of recognized genetic diseases and this can be partly explained by the loss of genetic variability induced by mating of related animals. The breeding strategy in dogs needs therefore to be optimized. Increasing the number of reproducers can be one of the solutions. Therefore, we want to start an open canine semen bank with frozen semen, based on semen donations like in humans. Frozen semen has several advantages: it can be thawed and inseminated whenever necessary, it can be stored for an unlimited time and can be imported from other continents in order to improve genetic diversity in a given breed. However, many male dogs produce semen that is not suitable for freezing. To improve the process of canine semen freezing, we will investigate i) if there are differences in the composition (in proteins or small vesicles) of dog semen in relation to their ability to withstand freezing, ii) if these differences can be used to improve the extenders used for cryopreservation, iii) if we can remove dead spermatozoa that secrete harmful compounds affecting the survival of the living sperm cells with a clean-up method and iv) if these improvements can increase the pregnancy and whelping rates after insemination of bitches. The best combination (with low inbreeding) between bitches and studs will be made based on a mate-select program set up by the kennel club. The long-term goal of this project is to breed puppies carrying less genetic diseases.