B-mode ultrasonography and ARFI elastography of articular and peri-articular structures of the hip joint in non-dysplastic and dysplastic dogs as confirmed by radiographic examination.

BACKGROUND: Canine hip dysplasia is a common orthopedic disease in veterinary practice. The diagnosis is made by radiographic examinations that evaluate bone alterations associated with hip dysplasia. Although radiographic examination is the gold standard for diagnosis, it does not allow a detailed evaluation of soft tissues such as the joint capsule and periarticular muscles. This study aimed to evaluate the accuracy of B-mode ultrasonography and acoustic radiation force impulse (ARFI) elastography in assessing the joint capsule and periarticular muscles of dogs using the Orthopedic Foundation of Animals (OFA) classification and the distraction index (DI) in the early and late diagnosis of hip dysplasia. This study sought to propose a protocol for the ultrasonographic evaluation of the structures involved in canine hip dysplasia. METHODS: Radiographic and ultrasonographic evaluations were performed on 108 hip joints of 54 dogs. Thirty dogs were older than 2 years and 24 were aged between 4 and 10 months. RESULTS: It was verified that an increase in pectineus muscle stiffness (cutoff value > 2.77 m/s) by elastography in some dysplastic dogs and an increase in the thickness of the joint capsule (cutoff value > 0.9 mm) in B-mode ultrasonography, were associated with a distraction index > 0.5, with both having a positive correlation. In B-mode ultrasonographic evaluation, the presence of signs of degenerative joint disease, such as irregularities of the cranial edge of the acetabulum and femoral head, were associated with a distraction index > 0.5 in canines, with a specificity of 94%. In adult dogs, the findings of degenerative joint disease on ultrasound were associated with a diseased OFA classification (P < 0.05). Measurement of the joint capsule > 1.10 mm was diagnostic for dysplasia in unhealthy dogs by OFA. CONCLUSIONS: ARFI elastography has shown that the pectineus muscle may experience changes in stiffness in dysplastic animals. Additionally, changes in joint capsule thickness can be identified in B-mode in young and adult dogs with dysplastic joints, which contributes to the diagnosis of hip dysplasia.

Breed-specific evaluation of serum biochemical markers in canine hip dysplasia observed in a Tornjak dog population.

OBJECTIVE: Canine hip dysplasia (CHD) is a global disease and an improved diagnostic approach to this orthopedic condition is needed, with an emphasis on inexpensive and minimally invasive techniques. This research aimed to determine the differentiating potential of selected biochemical markers in serum between healthy dogs and dogs with hip dysplasia in a breed-specific study that involved the Tornjak dog population. ANIMALS: 99 Tornjak dogs radiographically categorized (Federation Cynologique Internationale procedure and scoring scheme) between December 2019 and April 2021, as having no sign of hip dysplasia or near normal hip joints (nondysplastic group; n = 51) vs mild, moderate, or severe hip dysplasia (dysplastic group; 48). METHODS: Serum concentrations and enzyme activity of the biochemical markers hyaluronic acid (HA), procollagen II C-terminal propeptide (PIICP), and metalloproteinase 9 (MMP9) were compared among adult dogs with or without radiographic hip dysplasia. Statistical tests used to examine the differentiating potential of biochemical markers in Tornjak dog groups were assessed using the Mann-Whitney U test, logistic regression, and receiving operating characteristics (ROC) analysis. RESULTS: Tornjak dogs with radiographic CHD had significantly lower serum concentrations of HA and higher concentrations of PIICP and MMP9 activity compared to dogs with radiographically normal hips (P < .05). Selected biochemical markers could distinguish dogs with radiographic CHD from those without CHD with high sensitivity and specificity. CLINICAL RELEVANCE: These data suggest that the diagnostic technique of measuring serum concentrations of HA, PIICP, and MMP9 activity has a selective ability to distinguish dogs with dysplastic from dogs with normal hips.

Femoral Neck Thickness Index as an Indicator of Proximal Femur Bone Modeling.

The alteration in the shape of the femoral neck is an important radiographic sign for scoring canine hip dysplasia (CHD). Previous studies have reported that the femoral neck thickness (FNT) is greater in dogs with hip joint dysplasia, becoming progressively thicker with disease severity. The main objective of this work was to describe a femoral neck thickness index (FNTi) to quantify FNT and to study its association with the degree of CHD using the Fédération Cynologique Internationale (FCI) scheme. A total of 53 dogs (106 hips) were randomly selected for this study. Two examiners performed FNTi estimation to study intra- and inter-examiner reliability and agreement. The paired t-test, the Bland-Altman plots, and the intraclass correlation coefficient showed excellent agreement and reliability between the measurements of the two examiners and the examiners' sessions. All joints were scored in five categories by an experienced examiner according to FCI criteria. The results from examiner 1 were compared between FCI categories. Hips that were assigned an FCI grade of A (n = 19), B (n = 23), C (n = 24), D (n = 24), and E (n = 16) had a mean ± standard deviation FNTi of 0.809 ± 0.024, 0.835 ± 0.044, 0.868 ± 0.022, 0.903 ± 0.033, and 0.923 ± 0.068, respectively (ANOVA, p < 0.05). Therefore, these results show that FNTi is a parameter capable of evaluating proximal femur bone modeling and that it has the potential to enrich conventional CHD scoring criteria if incorporated into a computer-aided diagnosis capable of detecting CHD.

Development and validation of a device to measure the force applied to the coxofemoral joint during stress radiography for early diagnosis of canine hip dysplasia.

Hip dysplasia is a common orthopaedic condition in dogs and stress radiography is the best diagnostic tool for early diagnosis. Objective force guidelines are lacking, leaving room for errors and fraud during screening. Our objective was to develop an accurate and validated measuring device that allows quantification of the applied force in vivo in real-time during stress radiographic imaging. A two-step approach was followed. First, four load cells were incorporated in the original Vezzoni Modified Badertscher Distension Device (VMBDD) and a dedicated computer program was developed. In vitro evaluations of the accuracy demonstrated a trueness of 0.19 N (0.1%FS) and precision of 0.26 N (0.2%FS) for the individual loadcells. The trueness and precision of the assembled VMBDmD were 0.02 N (0.02%FS) and 0.52 N (0.38%FS). Secondly, the modified device was tested on several cadavers. The device was similar in use as the VMBDD, did not interfere with radiographic acquisition, gave the operator real-time feedback, and linked the force with the radiograph. Altogether, we describe the accuracy of the VMBDmD and have evaluated its use in cadavers. We saw that the device successfully quantified and stored the applied force in real-time during stress radiography.

Selección contra displasia de cadera canina en el ovejero alemán / Breeding against canine hip dysplasia in the german shepherd dog

RESUMEN La displasia de cadera canina o displasia coxo-femoral (DCF) es un desorden progresivo e incapacitante en perros de razas grandes, como el Ovejero Alemán. La selección de reproductores libres de displasia es la única forma de reducir su incidencia. Se han desarrollado varios métodos de diagnóstico basados en el examen radiográfico, en base a los cuales se seleccionan los reproductores para la cría. La DCF tiene una base hereditaria poligénica e influencia ambiental, con una heredabilidad media a baja (alrededor de 0,20 a 0,40), por lo que el progreso de la selección fenotípica ha sido lento. En Argentina la prevalencia de la displasia en la raza sigue siendo alta (>25%) y es imposible prever su incidencia en la progenie del plantel de cría. Algunos países han implementado la selección basada en el valor estimado de cría, obteniendo un importante avance. Los estudios de asociación del genoma completo han revelado numerosos marcadores asociados a la DCF y se han encontrado varios genes candidatos que señalan la posibilidad de implementar una selección genómica en un futuro cercano.

ABSTRACT Canine hip dysplasia (CHD) is a progressive and disabling disorder in large dog breeds, such as the German Shepherd dog. Breeding sires and dams free of dysplasia is the only way to reduce its incidence. Several diagnostic methods have been developed based on radiographic examination, on the basis of which dogs are selected for breeding. CHD has a polygenic hereditary basis and environmental influence, with a median to low heritability (ca. 0,20 to 0,40), so the progress in phenotypic selection has been slow. In Argentina, the prevalence of dysplasia in German Shepherd dogs remains high (> 25%) and it is impossible to predict its incidence in the offspring of the breeding stock. Some countries have implemented a selection based on the estimated breeding value, obtaining an important advance. Genomewide association studies have revealed numerous CHD-associated markers and several candidate genes have been found that point to the possibility of implementing genomic selection in the near future.

Inter-Observer Agreement in Radiographic Diagnosis of Coxofemoral Joint Disease in a Closed Cohort of Four-Month-Old Rottweilers.

Canine hip dysplasia is a complex and multifactorial disease. The early diagnosis of dysplastic dogs under one year of age helps veterinarians to plan proper preventive/therapeutic methods. Having an accurate screening method increases the chance of the early detection of dysplasia. The goal of our study was to assess the inter-observer reliability of eight radiographic parameters in four-month-old Rottweilers. Radiographs of the 28 Rottweilers were investigated by five experienced observers. The radiographs were taken in ventrodorsal view with extended legs, frog-leg ventrodorsal view, distraction view, and dorsal acetabular rim view. Four quantitative parameters such as Norberg angle (NA), distraction index (DI), dorsal acetabular rim slope (DARS), and center edge angle (CEA) and four qualitative parameters such as sclerosis of the cranial acetabular rim (SCAR), location of the center of the femoral head (LCFH), grading of the degenerative joint disease (GDJD), and grading of the dorsal acetabular rim (GDAR) were evaluated. High inter-observer agreements were recorded for quantitative values, whereas the inter-observer agreement of the qualitative parameters was low. It can be deduced that the evaluated quantitative parameters are reliable, and a combination of these methods with clinical examinations might increase the accuracy of the examinations.

Early hip laxity screening and later canine hip dysplasia development.

Background and Aim: Passive hip laxity (PHL) is considered the primary risk factor for canine hip dysplasia (HD) and is estimated, in stress hip radiographs, using the distraction index (DI). The study aimed to associate the early PHL using the hip Distractor of University of Trás-os-Montes and Alto Douro (DisUTAD) and the late HD grades. Materials and Methods: A total of 41 dogs (82 hips) were submitted to a follow-up study. First, between 4 and 12 months of age, dogs were radiographed using the DisUTAD hip distractor and were determined the DI for each hip joint. Then, after 12 months of age, dogs were reevaluated for HD using the conventional hip ventrodorsal projection and hips were evaluated for HD using the Fédération Cynologique Internationale (FCI) scoring system. Results: Hips of dogs' in the second examination with FCI grades of A (n=28), B (n=11), C (n=22), and D and E (n=21) had an early DI of 0.32±0.1, 0.38±0.08, 0.50±0.12, and 0.64±0.11, respectively. Statistical analysis using the general linear model univariate, with the DI as dependent variable and the FCI grades, side and sex as fixed factors, and the post hoc Bonferroni correction test showed significant differences among FCI grades (p<0.05). Conclusion: These results show the association between early DI and the late FCI HD grades and the DisUTAD is recommended for the early canine HD diagnosis.

Center of pressure and ground reaction forces in Labrador and Golden Retrievers with and without hip dysplasia at 4, 8, and 12 months of age.

Canine hip dysplasia (CHD) is a common orthopedic disease. Owing to the importance of CHD in affected dogs, both clinically and for their use in breeding or work, increasing attention is being given to early diagnosis. Therefore, early clinical and radiological examination of young animals is increasingly in demand, whereas common CHD screening according to the Fédération Cynologique Internationale (FCI) is usually performed at the age of 12 months or even older in Europe. One way to objectively evaluate gait pattern is to measure the ground reaction forces (GRFs) and center of pressure (COP). In this study, we used a pressure plate to evaluate the GRF and COP parameters for 32 Labrador Retrievers and 17 Golden Retrievers at 4, 8, and 12 months of age. The dogs also underwent radiological examination of the hip joints following the FCI rules at the age of at least 12 months, which were grouped as sound (FCI grade A or B) and diseased (FCI grade C or worse). The results revealed significantly higher COP values in both breeds in the diseased limb groups at any measurement point during walking, with the most pronounced results obtained at 8 months of age. Furthermore, COP values during walking were significantly higher at 4 months than at 8 and 12 months in both the sound and diseased limb groups, indicating an increased stability of the gait pattern. Except for COP-Speed, the values of all COP parameters were higher during walking than during trotting at 4 months of age (i.e., COP-Speed was higher when trotting), indicating that the 4-beat gait in walk is more difficult to control for puppies than the 2-beat gait in trot. Overall, our results support the early evaluation of CHD in growing animals using non-invasive methods.

Early Diagnosis of Canine Hip Laxity: Correlation between Clinical Orthopedic Examinations and the FCI Scoring Method in a Closed Cohort of Rottweilers.

Canine hip dysplasia is a multifactorial disorder characterized by hip laxity and osteoarthritis. The early diagnosis of hip laxity is an important topic in small animal orthopedics. This study aimed to evaluate the correlation between clinical orthopedic examinations and the Fédération Cynologique Internationale (FCI) scoring method. Thirty purebred Rottweilers were examined at approximately four (20 ± 2 weeks), eight (35 ± 2 weeks), and twelve months of age (54 ± 1 weeks), respectively. The Ortolani, Barlow, and Bardens tests and reduction/subluxation angle measurements were performed at each time. FCI scoring was conducted at the third examination time. Positive correlations were recorded between the reduction angle and Ortolani test, reduction angle and FCI score, and Ortolani test and FCI score for the second and third examination dates. No correlation was observed between the subluxation angle and other methods. Despite previous studies reporting 16-20 weeks as the earliest age for diagnosing hip laxity in dogs, in our study, early diagnosis was possible from the age of 35 ± 2 weeks. This difference might originate from the small sample size, low number of the dogs with severe grades of laxity, and breed differences.

The slope of the pelvis is variable in dogs but does not show correlation with femoral subluxation.

The aim of this study was to investigate the variability of the slope of the pelvis in different dog breeds and the correlation between pelvic slope and femoral subluxation. The sacrum-pelvis angle (SPA), the angulation between the sacrum and the axis of the ilium was created to represent the differences in the slope of the pelvis on lateral pelvic radiographs. The Norberg angle (NA) was used to quantify the femoral subluxation on hip-extended radiographs. Archived standard ventrodorsal hip radiographs and lateral lumbosacral radiographs of the same dogs were retrieved and a single observer measured the SPA and the NA in each case. A total of 180 dogs from six different breeds were sampled. The SPA varied between 40° and 71.5° and the NA between 71.2° and 113.9°. The findings indicated that there are significant individual and interbreed variations in the slope of the pelvis. However, no significant relationship between the slope of the pelvis and femoral subluxation could be identified.

Hands-Free Conventional Radiographic Ventrodorsal Hip Extended View.

Hip dysplasia (HD) is an important hereditary orthopedic disease in the dog associated with osteoarthritis and inadequate welfare for affected animals. The radiographic ventrodorsal hip extended (VDHE) view is used worldwide to select the better animals for breeding. This view normally is performed with manual restraining of the dog to obtain radiographs with acceptable technical quality. The veterinarian exposition to ionizing radiation is inevitable. In this study, the technical quality of VDHE radiographs and hip measurements was compared in 65 dogs radiographed twice, one with the common veterinarian manual restraining and the other obtained using a hind limb holder device, without the veterinarian within the X-ray room. The variables studied were pelvic tilting, patella displacement index, Norberg angle (NA), and subluxation hip category. The results showed a random distribution of right and left pelvic tilting, patella lateral or medial displacement, and hip subluxation categories in both samples (P > 0.05). The holder device positioning showed a better pelvic symmetry (P < 0.05) and a similar patellar displacement (P > 0.05). The mean ± standard deviation of NA was 101.1° ± 6.2° and 100.9° ± 6.1° in the manual and holder device hind limb restraining, respectively (P > 0.05), and the lower limit of 95% confidence interval of intraclass correlation coefficient was >0.75. These results showed statistical reproducibility of NA measurements by the hind limb holder device, and the examiner was protected from exposure to ionizing radiation within the X-ray room.

Genome-wide association study to identify canine hip dysplasia loci in dogs.

Korean army dogs are raised for special purposes and have contributed much to society. However, several diseases occur in dogs. Canine hip dysplasia (CHD) is a musculoskeletal disorder that occurs frequently in Korean army dogs and interferes with their activities. If we could control CHD, this would have a positive effect on their performance. This study performed a genome-wide association study (GWAS) in 69 Korean army dogs to find significant loci for CHD using 170K single nucleotide polymorphisms (SNPs). CHD was classified according to the Norberg angle criterion. The control group comprised 62 dogs classified as relatively normal, and 7 dogs with severe CHD formed the case group. From the GWAS analysis, we concluded that SNPs present on chromosome 4 might have a significant impact on the overall expression of canine hip dysplasia.

Validation of DNA test for hip dysplasia failed in Danish Labrador Retrievers.

Canine hip dysplasia is characterized by poor hip joint conformation and laxity. The disease is a complex trait influenced by both genetics and environment. Diagnosis and quantification of hip dysplasia are performed by radiographic examination of the hip joint and the diagnosis is used for making breeding decisions in many breeds. A prognostic genetic test (the Dysgen test) based on seven associated SNPs has been developed in a study based on Spanish Labrador Retrievers. In our study this test has been evaluated in 39 Danish Labrador Retrievers with known radiographic hip score: 14 with hip dysplasia (grade D or E) and 25 without hip dysplasia (grade A or B). There was no significant correlation between the Dysgen test results and the radiographic hip status (P = 0.3203) in these dogs, indicating that Dysgen test results obtained for Danish Labrador Retrievers have no prognostic value.

Canfam_GSD: De novo chromosome-length genome assembly of the German Shepherd Dog (Canis lupus familiaris) using a combination of long reads, optical mapping, and Hi-C.

BACKGROUND: The German Shepherd Dog (GSD) is one of the most common breeds on earth and has been bred for its utility and intelligence. It is often first choice for police and military work, as well as protection, disability assistance, and search-and-rescue. Yet, GSDs are well known to be susceptible to a range of genetic diseases that can interfere with their training. Such diseases are of particular concern when they occur later in life, and fully trained animals are not able to continue their duties. FINDINGS: Here, we provide the draft genome sequence of a healthy German Shepherd female as a reference for future disease and evolutionary studies. We generated this improved canid reference genome (CanFam_GSD) utilizing a combination of Pacific Bioscience, Oxford Nanopore, 10X Genomics, Bionano, and Hi-C technologies. The GSD assembly is ∼80 times as contiguous as the current canid reference genome (20.9 vs 0.267 Mb contig N50), containing far fewer gaps (306 vs 23,876) and fewer scaffolds (429 vs 3,310) than the current canid reference genome CanFamv3.1. Two chromosomes (4 and 35) are assembled into single scaffolds with no gaps. BUSCO analyses of the genome assembly results show that 93.0% of the conserved single-copy genes are complete in the GSD assembly compared with 92.2% for CanFam v3.1. Homology-based gene annotation increases this value to ∼99%. Detailed examination of the evolutionarily important pancreatic amylase region reveals that there are most likely 7 copies of the gene, indicative of a duplication of 4 ancestral copies and the disruption of 1 copy. CONCLUSIONS: GSD genome assembly and annotation were produced with major improvement in completeness, continuity, and quality over the existing canid reference. This resource will enable further research related to canine diseases, the evolutionary relationships of canids, and other aspects of canid biology.

Prevalence of Canine Hip Dysplasia in Switzerland Between 1995 and 2016-A Retrospective Study in 5 Common Large Breeds.

Canine hip dysplasia (CHD) is a genetic disease, modulated by epigenetic and environmental factors. To decrease the prevalence of CHD, the hip joints of many pure breed dogs are radiographed to identify dysplastic dogs not qualified for breeding. It has been shown that both, prevalence and severity of CHD may be reduced on the basis of phenotypic i.e., radiographic selection of breeding animals. The method has been used in many countries for over 50 years. In the present study, severity and prevalence of CHD in five common large breeds in Switzerland were evaluated since 1995. Both, prevalence and severity of CHD dropped in each breed between the periods 1995-1999 and 2010-2016. The prevalence decreased in Golden Retrievers from 25 to 9% and in Labrador Retrievers from 16 to 3%, respectively. In the Flat-Coated Retriever, prevalence in general was low, decreasing from 6 to 3%. In the Bernese mountain dog and the German shepherd dog, a decrease from 21 to 12% and from 46 to 18%, respectively, was observed. However, the rather low overall rate of radiographed dogs (Retrievers: 11 to 18%, Bernese Mountain dogs: 23% and German Shepherd dogs: 31%) does not allow to draw reliable conclusions regarding the true prevalence of CHD for the entire population of these breeds in Switzerland.

Acetabular ventroversion using the sacroiliac wedge, with or without pelvic osteotomies in dogs: an ex vivo study / Ventroversão acetabular associada ou não a osteotomias pélvicas por meio da utilização de cunha sacroilíaca em cães: estudo ex-vivo

Canine hip dysplasia (CHD) is a common condition observed in the surgical clinics for small animals. Among the surgical techniques for management of CHD, triple pelvic osteotomy and sacroiliac wedge promote acetabular lateral axial rotation (ventroversion), increasing acetabular coverage and joint stability. The present study aimed to evaluate radiographically, by measuring the Norberg angle (NA) and the acetabular coverage percentage (ACP), the acetabular ventroversion induced by the sacroiliac wedge technique, with or without pelvic osteotomies; we also checked the feasibility of wedges made of polyamide with an angulation of 20° and 30°. The software used to measure NA and ACP was AutoCAD® 2009. Pelves from 10 canine corpses were evaluated radiographically at four time-points: M0 (Control Group), M1 (wedges of 20° and 30°), M2 and M3 (wedges associated with bilateral pubis and ischium osteotomies, respectively). There was no significant increase in the acetabular ventroversion at M1, M2, and M3. The polyamide sacroiliac wedge technique proved to be feasible, stable, and easy to apply. Further, the software proved to be efficient and easy to use for NA and ACP measurements. In the present study, even in the cases of non-dysplasic adult canine corpses, it was concluded that the sacroiliac wedge technique does not require to be accompanied by pubis and ischial osteotomies because they did not significantly increase the NA and ACP.(AU)

A displasia coxofemoral (DCF) é afecção comum na clínica cirúrgica de pequenos animais. Entre as técnicas cirúrgicas para controle da DCF, a osteotomia pélvica tripla (OPT) e a cunha sacroilíaca (CSI), promovem rotação lateral acetabular no eixo axial (ventroversão), aumentando a cobertura acetabular e a estabilidade da articulação. Desta forma, o presente estudo objetivou avaliar radiograficamente, por meio da aferição do ângulo de Norberg (NA) e da porcentagem de cobertura acetabular (PCA), a ventroversão acetabular induzida pela técnica da cunha sacroilíaca, associada ou não às osteotomias pélvicas, além de verificar a exequibilidade das cunhas confeccionadas de poliamida com angulação de 20ο e 30ο. O software utilizado para aferir o AN e o PCA foi o AutoCAD® 2009. Dez pelves de cadáveres caninos foram avaliadas radiograficamente em quatro momentos: MO (Grupo Controle), M1 (cunhas de 20ο e 30ο), M2 e M3 (cunhas associadas à osteotomia bilateral do púbis e ísquio, respectivamente). Não houve aumento significativo da ventroversão em M1, M2 e M3. A técnica de cunha sacroilíaca de poliamida mostrou-se exequível, estável e de fácil aplicação. Não obstante, o software utilizado mostrou-se eficiente e de fácil utilização nas aferições do AN e PCA. Neste estudo, mesmo tratando-se de cadáveres de cães adultos e de maioria não displásicos, concluiu-se que a utilização da técnica de cunha sacroilíaca não necessita de associação à ostectomia púbica e a osteotomia do ísquio por não promoverem aumento significativo do AN e da PCA.(AU)

Provisional heritability estimates of four distraction index traits in a breeding population of German Shepherd dogs.

AIM To obtain provisional estimates of the heritability (h2 ) 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 h2 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 h2 of the DI of the left hip (0.81, SE 0.40) was higher than the h2 of the DI of the right hip (0.35, SE 0.36). The h2 for the worse-hip DI (0.15, SE 0.28) in each dog was lower than the h2 of the individual hip DI, or the h2 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 h2 estimates for the left, right and mean DI traits were moderate to high, whereas the h2 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 h2 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.

Joint Genomic Prediction of Canine Hip Dysplasia in UK and US Labrador Retrievers.

Canine hip dysplasia, a debilitating orthopedic disorder that leads to osteoarthritis and cartilage degeneration, is common in several large-sized dog breeds and shows moderate heritability suggesting that selection can reduce prevalence. Estimating genomic breeding values require large reference populations, which are expensive to genotype for development of genomic prediction tools. Combining datasets from different countries could be an option to help build larger reference datasets without incurring extra genotyping costs. Our objective was to evaluate genomic prediction based on a combination of UK and US datasets of genotyped dogs with records of Norberg angle scores, related to canine hip dysplasia. Prediction accuracies using a single population were 0.179 and 0.290 for 1,179 and 242 UK and US Labrador Retrievers, respectively. Prediction accuracies changed to 0.189 and 0.260, with an increased bias of genomic breeding values when using a joint training set (biased upwards for the US population and downwards for the UK population). Our results show that in this study of canine hip dysplasia, little or no benefit was gained from using a joint training set as compared to using a single population as training set. We attribute this to differences in the genetic background of the two populations as well as the small sample size of the US dataset.

Canine hip dysplasia: A natural animal model for human developmental dysplasia of the hip.

Developmental dysplasia of the hip (DDH) in humans is a common condition that is associated with hip pain, functional limitations, and secondary osteoarthritis (OA). Surgical treatment of DDH has improved in the last decade, allowing excellent outcomes at short- and mid-term follow-up. Still, the etiology, mechanobiology, and pathology underlying this disease are not well understood. A pre-clinical animal model of DDH could help advance the field with a deeper understanding of specific pathways that initiate hip joint degeneration secondary to abnormal biomechanics. An animal model would also facilitate different interventional treatments that could be tested in a rigorous and controlled environment. The dog model exhibits several important characteristics that make it valuable as a pre-clinical animal model for human DDH. Dogs are naturally prone to develop canine hip dysplasia (CHD), which is treated in a similar manner as in humans. Comparable to human DDH, CHD is considered a pre-OA disease; if left untreated it will progress to OA. However, progression to OA is significantly faster in dogs than humans, with progression to OA within 1-2 years of age, associated with their shorter life span compared to humans. Animal studies could potentially reveal the underlying biochemical pathway(s), which can inform refined treatment modalities and provide opportunities for new treatment and prevention targets. Herein, we review the similarities and differences between the two species and outline the argument supporting CHD as an appropriate pre-clinical model of human DDH. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1807-1817, 2018.

Canine Hip Dysplasia Screening Within the United States: Pennsylvania Hip Improvement Program and Orthopedic Foundation for Animals Hip/Elbow Database.

Canine hip dysplasia (CHD) is a complex, polygenic disease radiographically associated with hip subluxation and development of osteoarthritis. Screening programs have been established with the goal of hip improvement, with the most common in the United States being OFA hip scoring and the PennHIP method. When evaluating the single hip-extended view used by OFA versus the 3 radiographic views and associated distraction index (DI) used by PennHIP for CHD screening, the scientific evidence supports the use of the DI and PennHIP method. OFA scoring can be used to effect hip improvement, especially when incorporated into estimated breeding values.