Duurzame fokkerij van rashonden

Breeding practices in purebred dogs are highly criticized since the BBC documentary in 2008. Selection for morphological extreme traits has resulted in various anatomical abnormalities and disorders in the pedigree dog population. Furthermore, selection for breed conformity further increased the number of disorders present in these breeds as a result of inbreeding practices and the use of few popular sires. As most dog breeds are closed populations, these problems will only enhance over the years. This PhD project made an assessment of the current state of the genetic diversity of pedigree dogs in Belgium. This was investigated in 23 pedigree dog breeds, including 14 native Belgian breeds (Bichon frisé, Bloodhound, Bouvier des Ardennes, Bouvier des Flandres, Griffon Belge, Griffon Bruxellois, Petit Brabançon, Laekenois shepherd, Malinois shepherd, Tervueren shepherd, Groenendael shepherd, Papillon, Phalène and Schipperke), and 9 other popular breeds (Australian shepherd, Border Collie, Boxer, Cavalier King Charles spaniel, German shepherd, Golden retriever, Labrador retriever, Irish setter and Rottweiler). Both genealogical and microsatellite information were used to calculate genetic diversity parameters, including inbreeding and effective population size. Both methods reveal low genetic diversity, especially in native Belgian breeds with small population sizes. Eight of the Belgian breeds are at risk of extinction, as measured by the low effective population size under 50. These breeds include the Bouvier des Ardennes, Petit Brabançon, Griffon Belge, Griffon Bruxellois, Laekenois shepherd, Phalène, Schipperke and Bichon frisé. For these breeds measures such as optimal contribution selection or genetic rescue should be applied to augment their genetic diversity. All breeds should be monitored continuously, and specially breeding practices such as the extensive use of popular sires should be avoided. Varieties of breeds resulting from selection based on phenotype only, and their effect on the genetic diversity have been studied as well. Using clustering techniques and principle component analysis, 4 breed groups were studied: the Belgian shepherds comprising Laekenois-, Groenendael-, Tervueren- and Malinois shepherd, the Belgian Griffons comprising Griffon Belge, Griffon Bruxellois and Petit Brabançon, the Bouviers comprising Bouvier des Ardennes and Bouvier des Flandres and the Continental Toy spaniels comprising Phalène and Papillon. The Continental Toy spaniels and Belgian Griffons were not distinguishable from each other, confirming their common breed history. As they belong to the endangered breeds, encouragements should be made to cross between these breed varieties, in order to ensure their future. In the Belgian shepherds, two main groups were identified (Malinois-Laekenois and Tervueren-Groenendael), confirming their common ancestors. These large subpopulations can be maintained as long as their genetic diversity stays at a high level. In the Belgian Bouviers, complete separation was shown, despite their common breed history. However, the Bouvier des Ardennes has been a recently reestablished breed with very low genetic diversity, and therefore, we advised to maintain an open-breed policy, allowing crosses with related breeds such as the Bouvier des Flandres or Picardy shepherd. A major consequence of inbreeding and the use of popular sires is the appearance of genetic disorders. Many of these are of complex inheritance, with both genetics and environment playing its role. Removing all affected animals of the breeding pool would only augment the problems, and therefore, this PhD project investigated alternative strategies, such as selection based on estimated breeding values (EBVs). Hip- and elbow dysplasia (HD and ED) are two highly prevalent disorders in many large dog breeds. An analysis was made in 9 breeds (Labrador retriever, Golden retriever, German shepherd, Rottweiler, Malinois shepherd, Tervueren shepherd, Irish setter, Boxer and Border Collie), and their genetic correlation was assessed. Results indicated that both disorders were indeed heritable, and found a positive genetic correlation. Heritability estimates for HD ranged between 0.01 and 0.67, and for ED between 0.40 and 0.81. However, analysis indicated that the estimations of ED heritability resulted in very high standard errors, demonstrating that selection based on EBVs is not yet possible. For HD, estimations of heritability were possible if over 400 screening results were available, which was the case in the Golden retriever, Labrador retriever, Border Collie, Rottweiler and German shepherd. Other disorders that were studied within this PhD project were syringomyelia and chiari-malformation (SM/CM) in the Cavalier King Charles spaniel. Here, 12 years of screening were evaluated in mainly Dutch and Belgian dogs. Analysis demonstrated the overall presence of CM in the population, making it a breed specific trait, probably through selection on specific characteristics such as a short muzzle length. This indicated that selection was not possible. SM on the other hand was shown to be heritable. Our PhD project indicated that current screening procedure could be ameliorated by using the width of the syrinx as a direct measure instead of the division into classes. This was demonstrated by the higher heritability of the width of the syrinx (0.301) compared to the classes (0.127). Lastly, mitral valve disease (MVD) was studied within an international population of Cavalier King Charles spaniels. This PhD project used two different estimation methods, namely a linear model and a threshold model. Analysis indicated that MVD was heritable, with degree of heritability ranging between 0.24 and 0.30, and that it was highest when analyzed using a threshold model. This indicated that selection based on EBVs was possible for MVD as well. When selecting a breeding animal, a breeder has to consider multiple traits and disorders, and not exclude all affected animals from the breeding pool. This PhD project investigated the relative preference of traits in the Cavalier King Charles spaniel, including health traits and conformation traits, as well as inbreeding and price of the dog. This was accomplished by means of a choice experiment, and indicated an overall preference for health characteristics. The price of the dog seemed not to be of any importance. As a result of this PhD, awareness has been raised among breeders and the Belgian Kennel Club KMSH (Koninklijke Maatschappij Sint-Hubertus). This resulted in a number of measures to augment the health status and genetic diversity of the Belgian pedigree dogs, such as for example the setup of an advice tool similar to the mate select program. This tool will assist breeders in the choice of their ideal breeding animal. A large step has been covered towards healthier pedigree dogs.status: publishe