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

Automated Assessment of Pelvic Longitudinal Rotation Using Computer Vision in Canine Hip Dysplasia Screening

Canine hip dysplasia (CHD) screening relies on accurate positioning in the ventrodorsal hip extended (VDHE) view, as even mild pelvic rotation can affect CHD scoring and impact breeding decisions. This study aimed to assess the association between pelvic rotation and asymmetry in obturator foramina areas (AOFAs) and to develop a computer vision model for automated AOFA measurement. In the first part, 203 radiographs were analyzed to examine the relationship between pelvic rotation, assessed through asymmetry in iliac wing and obturator foramina widths (AOFWs), and AOFAs. A significant association was found between pelvic rotation and AOFA, with AOFW showing a stronger correlation (R2 = 0.92, p < 0.01). AOFW rotation values were categorized into minimal (n = 71), moderate (n = 41), marked (n = 37), and extreme (n = 54) groups, corresponding to mean AOFA ± standard deviation values of 33.28 ± 27.25, 54.73 ± 27.98, 85.85 ± 41.31, and 160.68 ± 64.20 mm2, respectively. ANOVA and post hoc testing confirmed significant differences in AOFA across these groups (p < 0.01). In part two, the dataset was expanded to 312 images to develop the automated AOFA model, with 80% allocated for training, 10% for validation, and 10% for testing. On the 32 test images, the model achieved high segmentation accuracy (Dice score = 0.96; Intersection over Union = 0.93), closely aligning with examiner measurements. Paired t-tests indicated no significant differences between the examiner and model's outputs (p > 0.05), though the Bland-Altman analysis identified occasional discrepancies. The model demonstrated excellent reliability (ICC = 0.99) with a standard error of 17.18 mm2. A threshold of 50.46 mm2 enabled effective differentiation between acceptable and excessive pelvic rotation. With additional training data, further improvements in precision are expected, enhancing the model's clinical utility.

The markers of the predictive DNA test for canine hip dysplasia may have a stronger relationship with elbow dysplasia

Canine hip and elbow dysplasias, which are prevalent orthopedic conditions rooted in developmental and hereditary factors are yet to be comprehensively assessed. This study aimed to address this gap by exploring the prognostic significance of five markers linked to canine hip dysplasia using available genome-wide association studies (GWAS) data. The influence of these markers on both hip and elbow dysplasia was examined in dogs exposed to standardized environmental conditions. We made a groundbreaking discovery using custom primers, qPCR assays, and evaluation of fluorescent resonance energy transfer (FRET) probes. Three specific SNPs previously associated with the risk of canine hip dysplasia demonstrated a potentially stronger correlation with elbow dysplasia. Notably, the SNP at nucleotide position 22691322, located near the canine CHST3 gene, displayed significance as a marker in multivariable logistic regression analysis. Surprisingly, none of the initially targeted SNPs showed a direct association with hip dysplasia. The genomic positions of these SNPs reside within a region conserved across mammals. In silico analyses suggested that the relevant variant might be positioned in a region linked to bone and muscle structures. Our findings revealed a remarkable relationship between SNP2 genotypes and methylation patterns, shedding light on the underlying mechanism that partially explains the genotype-phenotype correlation in canine CHST3. These groundbreaking findings offer essential insights for future, more extensive investigations into canine orthopedic health. This research significantly contributes to our understanding of the molecular foundations of hip and elbow dysplasia in dogs by charting a course for advancements in veterinary medicine and the overall well-being of canine companions.

Genome wide association study in Swedish Labrador retrievers identifies genetic loci associated with hip dysplasia and body weight

Genome wide association studies (GWAS) have been utilized to identify genetic risk loci associated with both simple and complex inherited disorders. Here, we performed a GWAS in Labrador retrievers to identify genetic loci associated with hip dysplasia and body weight. Hip dysplasia scores were available for 209 genotyped dogs. We identified a significantly associated locus for hip dysplasia on chromosome 24, with three equally associated SNPs (p = 4.3 × 10-7) in complete linkage disequilibrium located within NDRG3, a gene which in humans has been shown to be differentially expressed in osteoarthritic joint cartilage. Body weight, available for 85 female dogs, was used as phenotype for a second analysis. We identified two significantly associated loci on chromosome 10 (p = 4.5 × 10-7) and chromosome 31 (p = 2.5 × 10-6). The most associated SNPs within these loci were located within the introns of the PRKCE and CADM2 genes, respectively. PRKCE has been shown to play a role in regulation of adipogenesis whilst CADM2 has been associated with body weight in multiple human GWAS. In summary, we identified credible candidate loci explaining part of the genetic inheritance for hip dysplasia and body weight in Labrador retrievers with strong candidate genes in each locus previously implicated in the phenotypes investigated.

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.

Radiographic Diagnosis of Hip Laxity in Rottweilers: Interobserver Agreement at Eight- and Twelve-Months of Age

Hip laxity is one of the predisposing factors of canine hip dysplasia. The early diagnosis of hip laxity allows veterinarians to prevent the participation of dysplastic dogs in breeding programs, which could lower the disease's prevalence due to its genetic background. Furthermore, it allows them to plan preventive/therapeutic procedures for mild/near-normal hips to reduce the symptoms of the disease at older ages. A reliable screening program must be repeatable and reproducible, and intra- and inter-observer studies can help us to determine the best methods. In this study, we aimed to evaluate the radiographic parameters used for the early diagnosis of hip dysplasia in Rottweilers at 8 and 12 months of age with five observers to assess the interobserver agreements. According to our findings, there were high interobserver agreements at both ages for the quantitative values, such as the center edge angle (CEA), dorsal acetabular rim slope (DARS), distraction index (DI), and Norberg angle (NA), whereas we recorded from poor to moderate agreements for the qualitative values, such as the grading of the dorsal acetabular rim (GDAR), grading of the degenerative joint disease (GDJD), location of the center of the femoral head (LCFH), and sclerosis of the cranial acetabular rim (SCAR).