Monitoring Hip and Elbow Dysplasia Achieved Modest Genetic Improvement of 74 Dog Breeds over 40 Years in USA

Abstract

Hip (HD) and Elbow Dysplasia (ED) are two common complex developmental disorders of dogs. In order to decrease their prevalence and severity, the Orthopedic Foundation for Animals (OFA) has a voluntary registry of canine hip and elbow conformation certified by boarded radiologists. However, the voluntarily reports have been severely biased against exposing dogs with problems, especially at beginning period. Fluctuated by additional influential factors such as age, the published raw scores barely showed trends of improvement. In this study, we used multiple-trait mixed model to simultaneously adjust these factors and incorporate pedigree to derive Estimated Breeding Values (EBV). A total of 1,264,422 dogs from 74 breeds were evaluated for EBVs from 760,455 hip scores and 135,409 elbow scores. These EBVs have substantially recovered the reporting bias and the other influences. Clear and steady trends of genetic improvement were observed over the 40 years since 1970. The total genetic improvements were 16.4% and 1.1% of the phenotypic standard deviation for HD and ED, respectively. The incidences of dysplasia were 0.83% and 2.08%, and the heritabilities were estimated as 0.22 and 0.17 for hip and elbow scores, respectively. The genetic correlation between them was 0.12. We conclude that EBV is more effective than reporting raw phenotype. The weak genetic correlation suggested that selection based on hip scores would also slightly improve elbow scores but it is necessary to allocate effort toward improvement of elbow scores alone.

Canine hip dysplasia: phenotypic scoring and the role of estimated breeding value analysis

“…The small amount of genetic progress attained using selection of breeding stock based on individual extended-hip view phenotype has led several commentators to recommend the use of EBV in CHD breeding schemes (Hou et al 2013;Lewis et al 2013). Selection of breeding stock solely on the basis of their individual phenotypic hip status is not the most accurate method of identifying dogs with superior genes, because for a quantitative trait like CHD, it is possible for two dogs of identical genotypes to express very different phenotypes under differing environmental influences (Lust and Farrell 1977).…”

“…One evaluation of the OFA database showed a steady, albeit slow, increase in the proportions of dogs graded as excellent and good, whereas proportions of fair and mild/moderate/severe dysplastic grades significantly decreased over the period 1989(Kaneene et al 2009). More recently, Hou et al (2013) performed an estimated breeding value (EBV) analysis on 760,455 hip scores across 74 breeds listed in the OFA database to evaluate genetic trends between the period 1970-2009 inclusive. The study found a genetic improvement of 0.1 units of hip score during the study period, which was equivalent to 16.4% of the phenotypic standard deviation.…”

“…These values corresponded to a 0.52% decrease in incidence of CHD in the study population. Additionally, the study emphasised that while some genetic improvement was evident on the basis of the EBV analysis of the OFA database, there was a variation in the amount of genetic improvement amongst breeds (Hou et al 2013). These studies suggest that whilst the OFA system has been effective at reducing the number of severely affected dogs, there has been only limited progress towards reducing the overall impact of CHD.…”

Consequences of a screening programme on the prevalence of congenital hereditary sensorineural deafness in the Australian Cattle Dog

“…; Hou et al . ). Despite this, diligent dog breeders actively select breeding stock from phenotypically normal sires and dams and utilise pedigree information to reduce the prevalence of recessive genetic diseases.…”

Protein biomarkers in serum and urine for determining presence or absence of hip dysplasia in a canine model

“…Breeding selection in dogs based on radiographic evaluation has only led to incremental improvements in OFA hip scores in more than 50 breeds between 1970 and 2015. 15,16 One factor contributing to the lack of greater progress is that a definitive diagnosis of CHD is most often made after clinical signs are manifested and the disease process is irreversible, and often after affected dogs have reproduced. Early screening methods such as PennHIP can provide data regarding relative risk for development of CHD.…”