A total of 2114 scores of elbow arthrosis from the official screening programme of the German Rottweiler Breeding Association (ADRK) were analysed in respect of prevalence and genetic disposition. 45.8% showed no signs of arthritis, 40.6% were scored in Grade 1 with minor osteophytes and 13.6% were affected by arthritis of clinical relevance (Grade 2 and 3). REML estimates showed a heritability of 28% and a litter variance of 6.4%. The only significant environmental fixed effect was gender. 39.1% of the male and 51.5% of the female were free from ED which corresponds with 19.2% of the male and only 8.8% of the female in the critical ED classes of Grade 2 and 3. Differences between the years of examination could be explained by genetic gain. Month of birth as well as age at examination, in the range covered by this study, was not significant. It was stated that the effect of bodyweight should be tested before starting a breeding programme. ZusammenfassungVerbreitung und Erblichkeit der Ellbogendysplasie des Hundes in der Deutschen Rottweiler Population 2114 Bewertungen der Ellbogenarthrose aus dem offiziellen Screening des Allgemeinen Deutschen Rottweiler Klub (ADRK) wurden in Hinblick auf Häufigkeit und genetische Praedisposition untersucht. 45,8% der Tiere hatten keine Anzeichen von Arthrose, 40,6% wurden mit Grad 1, geringgradige Osteophythenbildung, bewertet und 13,6% waren mit Arthrosen Grad 2 und 3 von klinischer Relevanz behaftet. REML-Schätzungen zeigten eine Heritabilität von 28% und eine wurfbedingte Varianz von 6.4%. Der einzige signifikante fixe Umwelteffekt war der Einfluß des Geschlechtes. 39,1% der Rü den und 51,5% der Hü ndinnen waren ED-frei. Das korrespondiert damit, daß 19,2% der Rü den und nur 8,8% der Hü ndinnen in die kritischen ED-Klassen 2 und 3 eingestuft wurden. Unterschiede zwischen den Untersuchungsjahren konnten als genetischer Trend erklärt werden. Der Geburtsmonat sowie das Alter beim Rö ntgen, zumindest in dem Altersbereich, den diese Studie umfasste, waren nicht signifikant. Es wurde als wichtig angesehen, den Einfluß des Kö rpergewichtes näher zu prü fen, bevor ein Zuchtprogramm begonnen wird. U.S.

The elbow dysplasia scores were determined by two genetically different traits. The possibilities for selecting German shepherd dogs with respect to elbow dysplasia might be improved by taking into account these two traits in the prediction of breeding values.

We describe a mild form of disproportionate dwarfism in Labrador Retrievers, which is not associated with any obvious health problems such as secondary arthrosis. We designate this phenotype as skeletal dysplasia 2 (SD2). It is inherited as a monogenic autosomal recessive trait with incomplete penetrance primarily in working lines of the Labrador Retriever breed. Using 23 cases and 37 controls we mapped the causative mutation by genome-wide association and homozygosity mapping to a 4.44 Mb interval on chromosome 12. We re-sequenced the genome of one affected dog at 30x coverage and detected 92 non-synonymous variants in the critical interval. Only two of these variants, located in the lymphotoxin A (LTA) and collagen alpha-2(XI) chain gene (COL11A2), respectively, were perfectly associated with the trait. Previously described COL11A2 variants in humans or mice lead to skeletal dysplasias and/or deafness. The dog variant associated with disproportionate dwarfism, COL11A2:c.143G>C or p.R48P, probably has only a minor effect on collagen XI function, which might explain the comparatively mild phenotype seen in our study. The identification of this candidate causative mutation thus widens the known phenotypic spectrum of COL11A2 mutations. We speculate that non-pathogenic COL11A2 variants might even contribute to the heritable variation in height.

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Results from radiographic screening for canine hip dysplasia (CHD) and elbow dysplasia (CED) of 48 367 German shepherd dogs born in 2001-07 were used for the population genetic analyses. Available information included CHD scores for 47 730 dogs, CED scores for 28 011 dogs and detailed veterinary diagnoses of primary ED lesions for a subsample of 18 899 dogs. Quasi-continuous traits were CHD, CED and cases of CED without radiographically visible primary lesion (CED-ARTH). Binary coding was used for fragmented medial coronoid process of the ulna (FCP), borderline findings and mild to severe signs of dysplasia in hip and elbow joints. Genetic parameters were estimated in univariate threshold and multivariate linear and mixed linear-threshold models using Gibbs sampling. Correlations between univariately predicted breeding values (BV) indicated genetic differences between borderline and affected disease status for both CHD (r(BV) = 0.5) and CED (r(BV) = 0.3). Multivariate genetic analyses with separate consideration of borderline findings revealed moderate heritabilities of 0.2-0.3 for the quasi-continuous traits with positive additive genetic correlation of 0.3 between CHD and both CED and CED-ARTH. For FCP, heritability of 0.6 and additive genetic correlations of +0.1 to CHD and -0.1 to CED-ARTH were estimated. Results supported the relevant genetic determination of CHD and CED, argued for both diseases against interpretation of borderline findings as healthy and implied genetic heterogeneity of CED. Accordingly, future breeding strategies to reduce the prevalences of CHD and CED in the German shepherd dog should be most efficient when based on BV from multivariate genetic evaluation for CHD, CED-ARTH and FCP with use of the whole scale of categories for classification of CHD and CED.