Canine hip dysplasia (CHD) is a developmental orthopaedic disease of the coxofemoral joints with a multifactorial mode of inheritance. Multiple gene effects are influenced by environmental factors; therefore, it is unlikely that a simple genetic screening test with which to identify susceptible individuals will be developed in the near future. In the absence of feasible methods for objectively quantifying clinical CHD, radiographic techniques have been developed and widely used to identify dogs for breeding which are less affected by the disease. A hip-extended ventrodorsal view of the pelvis has been traditionally used to identify dogs with subluxation and/or osteoarthritis of the coxofemoral joints. More recently, there has been emphasis on the role of coxofemoral joint laxity as a determinant of CHD and methods have been developed to measure passive hip laxity. Though well-established worldwide, the effectiveness of traditional phenotypic scoring schemes in reducing the prevalence of CHD has been variable. The most successful implementation of traditional CHD scoring has occurred in countries or breeding colonies with mandatory scoring and open registries with access to pedigree records. Several commentators have recommended that for quantitative traits like CHD, selection of breeding stock should be based on estimated breeding values (EBV) rather than individual hip score/grade. The EBV is a reflection of the genetic superiority of an animal compared to its counterparts and is calculated from the phenotype of an individual and its relatives and their pedigree relationship. Selecting breeding stock on the basis of a dog's genetic merit, ideally based on a highly predictive phenotype, will confer the breeder with greater selection power, accelerate genetic improvement towards better hip conformation and thus more likely decrease the prevalence of CHD.
Takahashi Korekiyo is remembered as a wise finance minister saving Japan from the Great Depression. The contribution of his policy measures however remains to be rigorously measured, with proper control of other forces also driving the recovery. Structural vector autoregression analysis of previously unexploited monthly data confirms the pivotal role of Takahashi's debt-financed fiscal expansion. Monetizing the public debts, the Bank of Japan maintained a neutral stance. The recovery was aided by exchange-rate shocks generated during the transition from the gold standard to the floating-exchange-rate regime and, to a smaller extent, by the world recovery.
AIM To obtain provisional estimates of the heritability (h ) of passive laxity of the coxofemoral joints of a breeding colony of German Shepherd dogs, measured using the PennHIP distraction index (DI). METHODS Records were obtained of the PennHIP DI of right and left hips of 195 German Shepherd dogs (377 DI records) from the dog breeding colony of the New Zealand Police Dog Breeding Centre between 2003 and 2016, as well as pedigree records of 884 animals over four generations. Estimates of h and variance components for the log transformed DI data were obtained using restricted maximum likelihood procedures with a single trait sire model. Four DI traits for each dog were analysed: left hip, right hip, mean and worse-hip DI. The model included the fixed effects of sex and year of birth, with the age at scoring as a covariable, the random sire effect and residual error for each observation. RESULTS The h of the DI of the left hip (0.81, SE 0.40) was higher than the h of the DI of the right hip (0.35, SE 0.36). The h for the worse-hip DI (0.15, SE 0.28) in each dog was lower than the h of the individual hip DI, or the h for the mean of the two hips (0.53, SE 0.36) in each dog. The low number of generations prevented a meaningful analysis of the genetic trend. CONCLUSIONS AND CLINICAL RELEVANCE The h estimates for the left, right and mean DI traits were moderate to high, whereas the h estimates for the worse-hip DI (as used by the PennHIP programme for ranking of dogs) was low, but all estimates had large SE due to the small sample size. This provisional estimate of the h of four distraction index traits suggests that the mean DI could be useful as a selection tool against canine hip dysplasia in German Shepherd dogs, whereas the worse-hip DI may be less effective. Heritability estimates from a population with a greater number of DI measures is needed to validate this finding given the large SE in our study.
A small but favourable response to selection was achieved by three of the four breeds in the study period; during which selection for elbow traits has been largely voluntary. While the magnitude of genetic change in terms of elbow units per annum may appear small, it must be remembered that elbow scoring grades only range from 0-3. Greater improvement may be possible if compulsory screening was a requirement for pedigree breeding stock, and if greater selection pressure were applied on the basis on an individual's EBV, rather than the worst-elbow score alone. The maintenance of an open registry, with transparency of EBV information made available to all breeders, may enhance selection intensity opportunities and potentially assist with the process and progress of breeding selection.
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