Passive hip laxity in Estrela Mountain Dog - distraction index, heritability and breeding values
ABSTRACT Two hundred and fifteen Estrela Mountain Dogs (EMD) were examined using the PennHIP method between 2002 and 2006. Passive hip laxity (PHL) was estimated calculating the distraction index (DI). Pedigree information was obtained from the Portuguese Kennel Club. The heritability and breeding values were estimated using the linear Animal Model. The DI, using as reference the worst joint of each animal, ranged from 0.15 to 1.12 (0.55 +/- 0.19). The PHL was equal in right and left sides, and was higher in females than in males (P > 0.05 and P <0.01 in the t-test, respectively). The estimated heritability was 0.83 +/- 0.11. The mean breeding values for PHL were stable in EMD born between 1991 and 2003, and showed an improvement in 2004 and 2005. The data confirm high PHL in breeds with high prevalence and severity of canine hip dysplasia. The high heritability indicates that the DI could be reduced in the breed if PHL were used as a selection criterion. The early favourable evolution of DI breeding values could be related with the increase of voluntary radiographic hip screening in the last years, and the subsequent introduction of hip quality as a breeding criterion.
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ABSTRACT: To assess the reproducibility of the Fédération Cynologique Internationale (FCI) classification over time, and between assessors and to evaluate the benefit of computer-assisted measurement of the Norberg angle and of its percentile ranking by breed for the diagnosis of canine hip dysplasia, and for the selection of couples for breeding. During the time period of 2006 to 2010, 5094 hip radiographs were evaluated according to the FCI rules, and 4400 have been submitted for statistical analysis. A system of computer-assisted image analysis (Digimizer(®) , MedCalc Software Ltd, Mariakerke, Belgium) was used to measure the Norberg angle. The Norberg angle value of individual dogs was expressed as percentile rank by breed. The agreement between individual assessors was highly significant (P<0·001), but there were important variations over time of the ratio of classes A or B. The Norberg angle and the percentile rank accurately discriminated between dogs with or without canine hip dysplasia, with positive and negative likelihood ratios of 6·31 and 0·21, respectively, for the Norberg angle at criterion value of 102·2°, and 4·21 and 0·18 for the percentile rank at criterion value of the 25th percentile. The percentile rank of the Norberg angle may be a valuable tool for breeding selection.Journal of Small Animal Practice 10/2011; 52(10):536-42. DOI:10.1111/j.1748-5827.2011.01105.x · 0.91 Impact Factor
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ABSTRACT: To critically review the different screening systems used for canine hip dysplasia (CHD) and their impact on the prevalence of the disease. Critical literature review. Literature search through PubMed (November 1959-October 2011) and the Orthopedic Foundation for Animals (OFA), Fédération Cynologique Internationale (FCI), British Veterinary Association/Kennel Club (BVA/KC), and Pennsylvania Hip Improvement Program (PennHIP) websites. The OFA, FCI, and BVA/KC screening methods, which use the hip-extended radiographic projection, have had relatively minor success on CHD prevalence. These screening approaches are prone to conflicting data regarding interobserver agreement. The PennHIP and Dorsolateral Subluxation (DLS) systems, both distraction methods, have not reported on prevalence but seem to be important heritable traits in genomic screening of dysplastic dogs. A shift towards genome screening yields a promising future combating CHD, although further investigation towards fine-mapping in the search for genes, responsible for CHD, is necessary.Veterinary Surgery 01/2012; 41(1):10-9. DOI:10.1111/j.1532-950X.2011.00929.x · 0.99 Impact Factor
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ABSTRACT: Canine hip dysplasia (CHD) is a serious and common musculoskeletal disease of pedigree dogs and therefore represents both an important welfare concern and an imperative breeding priority. The typical heritability estimates for radiographic CHD traits suggest that the accuracy of breeding dog selection could be substantially improved by the use of estimated breeding values (EBVs) in place of selection based on phenotypes of individuals. The British Veterinary Association/Kennel Club scoring method is a complex measure composed of nine bilateral ordinal traits, intended to evaluate both early and late dysplastic changes. However, the ordinal nature of the traits may represent a technical challenge for calculation of EBVs using linear methods. The purpose of the current study was to calculate EBVs of British Veterinary Association/Kennel Club traits in the Australian population of German Shepherd Dogs, using linear (both as individual traits and a summed phenotype), binary and ordinal methods to determine the optimal method for EBV calculation. Ordinal EBVs correlated well with linear EBVs (r = 0.90-0.99) and somewhat well with EBVs for the sum of the individual traits (r = 0.58-0.92). Correlation of ordinal and binary EBVs varied widely (r = 0.24-0.99) depending on the trait and cut-point considered. The ordinal EBVs have increased accuracy (0.48-0.69) of selection compared with accuracies from individual phenotype-based selection (0.40-0.52). Despite the high correlations between linear and ordinal EBVs, the underlying relationship between EBVs calculated by the two methods was not always linear, leading us to suggest that ordinal models should be used wherever possible. As the population of German Shepherd Dogs which was studied was purportedly under selection for the traits studied, we examined the EBVs for evidence of a genetic trend in these traits and found substantial genetic improvement over time. This study suggests the use of ordinal EBVs could increase the rate of genetic improvement in this population.PLoS ONE 10/2013; 8(10):e77470. DOI:10.1371/journal.pone.0077470 · 3.53 Impact Factor