Fokken van gezonde rashonden

Health of dogs is key in each Dutch dog breeding association. Health of their dogs is of great concern for their owners. The “Science shop” of Wageningen University has set up this project in answer to questions from three breeding organisations, with the aim to provide knowledge on how to better breed for healthy dogs ans use the latest insights from scientific developments. Next to dealing with health problems, genetic management to preserve genetic diversity and prevent high inbreeding rates is essential. A high inbreeding rate caused by using too few and too related dogs in breeding will harm the health of the dogs. Consequently, excluding too many dogs for health reasons will restrict the genetic pool and may cause a too high rate of inbreeding with subsequent health problems. A balance between breeding for health and restricting inbreeding must be found. This has led to the central question of this research: How to set up breeding for healthy pedigreed dogs? A healthy dog is the aim both of dog owners, breeding organisations and society in general. In this report 4 questions are treated: • How to deal with a multitude of hereditary health problems in a breed? • Can breeding value estimation help to reduce health problems in dogs and how to design it? • What is the value of DNA genotyping for estimation of kinships and inbreeding and thereby improving the health of dogs? • When and how to set up an outcross, and what does it contribute to the health of the dogs? Tackling health problems is not easy, because the problems are complex and knowledge of genetics is often scarce. Although the task ahead is considerable, there are clear starting points. To manage inbreeding rates the use of mean kinships is most effective and recommended. Additional to that, this report provides specific recommendations on how to deal with the four subjects mentioned above: • Dealing with a multitude of genetic diseases: Start with prioritising diseases to be bred against, based on their severity, frequency and date of onset. Monitoring them is essential, next to unravelling their genetic background. Cooperation between veterinarians, population geneticists and breeding organisations is needed. Use of the expertise in livestock breeding and of Wageningen University & Research (WUR) will help to develop a “weighted health index”. • Breeding value estimation will contribute to decrease the prevalence of genetic diseases, especially polygenic diseases such as hip-dysplasia. This should start with education to increase the acceptance in the breeding organisations. Next it is recommended to investigate the possibility to join forces with foreign initiatives such as developed in the UK. • DNA genotyping theoretically improves estimating inbreeding and relatedness. However, inbreeding estimates provided by commercial companies are at an individual basis while a population approach is needed. Furthermore, results of genotype based inbreeding estimates depend on the marker set used and the methot of calculation, both of which are not clear for commercial providers. A central database where all genotype results per breed are gathered is needed. More research on how best to estimate inbreeding and relatedness from genotype results is needed as well. • Outcrossing can improve the genetic health of breeds, especially if fertility is strongly reduced. It is important to develop a plan with a clear goal. Outcrossing cannot replace other measures for reducing inbreeding rates. As soon as an outcross is finished former inbreeding rates will return. This implies that either outcrossing should be performed on a continuous base, or it must be combined with other measures. Genotyping can help to select dogs for breeding when look-a-likes are used for an outcross. Most important, information and education in close collaboration with breed organisation is essential to organise support for each of the different measures to be taken.