The Role of Femoral Head Size and Femoral Head Coverage in Dogs with and without Hip Dysplasia.

The subject of hip dysplasia in dogs is still current and preoccupies both animal owners and veterinarians. Major factors affecting the development of the disorder are hip laxity and incongruent joints. Many studies on etiology, pathogenesis, and early diagnosis have been performed to reduce prevalence and select healthy dogs for breeding. The purpose of the present study was to investigate a possible relationship between dysplasia and femoral head area (FHA), femoral coverage by the acetabulum (CFH) and cranio-caudal distance of the dorsal acetabular rim (CrCdAR). Radiographs of a total of 264 skeletally mature dogs with similar physical characteristics (German wirehaired pointers (GWP), German shepherd dogs (GSD) and Labrador retrievers (LAB)) presented for routine hip dysplasia screening were recruited for the study. FHA, CFH and CrCdAR were measured and related to dysplasia status. Evaluations of FHA (p = 0.011), CFH (p < 0.001) and CrCdAR length (p = 0.003) measurements revealed significant interactions between breed, sex and FCI scores, so they had to be assessed separately. The results revealed that FHA tends to decrease as the hip dysplasia score worsens. There was no significant relationship between FHA and dysplasia assessment. FHA is breed-specific and is larger in normal and near-normal male (p = 0.001, p = 0.020) and female (p = 0.001, p = 0.013) GWP compared to GSD, respectively. FHA is greater in normal male GWP (p = 0.011) and GSD (p = 0.040) compared to females. There was a significant and strong positive correlation between FHA and CrCdAR in all breeds and sexes. Additionally, FCI scoring had a medium (GWP, GSD) to strong (LAB) negative correlation with CFH.

Computed Tomography Enhances Diagnostic Accuracy in Challenging Medial Coronoid Disease Cases: An Imaging Study in Dog Breeding Appeal Cases.

OBJECTIVES: The aim of this study was to determine the radiographic sensitivity in detecting medial coronoid disease (MCD), using computed tomography (CT) as reference in dogs presented for an official second opinion, and to compare the medial coronoid process (MCP) in fragmented and fissured MCP as well as those unaffected by MCD. MATERIALS AND METHODS: The data of dogs, presented for official second opinion radiographs and CT, were reviewed by three board-certified observers and in accordance with the International Elbow Working Group guidelines regarding MCD. Radiographic delineation, radiopacity and Hounsfield Units (HU) of the MCP were recorded additionally and the correlation between radiography and CT was investigated. RESULTS: Sensitivity and specificity of radiography compared with CT yielded values of 83.6% for the former and 83.5% for the latter. False-negative grading in radiography correlated significantly (p = 0.0001) with a present fissure line in CT. The mean delineation (p = 0.03) and mean HU of fragmented MCP (p = 0.0045) were significantly reduced compared with fissured MCP and no significant differences in measured HU for fissured MCP were detected in comparison to elbows unaffected by MCD. CONCLUSION: The results of the present study show substantial agreement between radiography and CT in second opinion cases. However, sensitivity is reduced compared with not preselected cases. A present fissure line in CT was significantly associated with a false-negative grading in radiography. Therefore, CT imaging of the elbows is strongly recommended in cases of appeal.

Prospective evaluation of a patented DNA test for canine hip dysplasia (CHD).

Genetic testing has been propagated as a suitable means to specify individual risks for canine hip dysplasia (CHD). However, the current lack of validation of most genetic CHD tests has left dog owners and breeders in the dark about their practical utility. Therefore, the Society for German Shepherd Dogs (Verein für Deutsche Schäferhunde, SV) initiated a prospective study of 935 animals to assess independently the value of a genetic CHD test (European Patent Specification EP 2 123 777 B1) that was developed by Distl et al. (2009) on the basis of the SV animal stock. Dogs were followed-up for 3 years after birth, classified regarding their CHD phenotype using the scheme of the Fédération Cynologique Internationale, and genotyped for the 17 single nucleotide polymorphisms (SNPs) constituting the CHD test in question. Individual SNP genotypes were combined into animal-specific genomic breeding values (GBVs), calculated as the weighted sum of SNP-wise scores as laid down in the patent specification. Logistic regression analysis revealed that, unexpectedly, the odds ratio for CHD decreased, rather than increased, by a factor of 0.98 per unit increase of the GBV. Nevertheless, since this effect was not statistically significant (95% CI: 0.93-1.03), and the area-under-curve of the test was only 0.523, it must be concluded that the genetic test patented by Distl et al. (2009) is unsuitable for individual CHD risk assessment.

A COL11A2 mutation in Labrador retrievers with mild disproportionate dwarfism.

We describe a mild form of disproportionate dwarfism in Labrador Retrievers, which is not associated with any obvious health problems such as secondary arthrosis. We designate this phenotype as skeletal dysplasia 2 (SD2). It is inherited as a monogenic autosomal recessive trait with incomplete penetrance primarily in working lines of the Labrador Retriever breed. Using 23 cases and 37 controls we mapped the causative mutation by genome-wide association and homozygosity mapping to a 4.44 Mb interval on chromosome 12. We re-sequenced the genome of one affected dog at 30x coverage and detected 92 non-synonymous variants in the critical interval. Only two of these variants, located in the lymphotoxin A (LTA) and collagen alpha-2(XI) chain gene (COL11A2), respectively, were perfectly associated with the trait. Previously described COL11A2 variants in humans or mice lead to skeletal dysplasias and/or deafness. The dog variant associated with disproportionate dwarfism, COL11A2:c.143G>C or p.R48P, probably has only a minor effect on collagen XI function, which might explain the comparatively mild phenotype seen in our study. The identification of this candidate causative mutation thus widens the known phenotypic spectrum of COL11A2 mutations. We speculate that non-pathogenic COL11A2 variants might even contribute to the heritable variation in height.

Skeletal morphology and morphometry of the lumbosacral junction in German shepherd dogs and an evaluation of the possible genetic basis for radiographic findings.

The aim of this study was to identify skeletal variations in the lumbosacral junction (LSJ) of the German shepherd dog (GSD) compared with other large breeds. The radiographic traits of the LSJ were investigated in a group of 733 GSDs and a control group of 334 dogs of other breeds that were matched in terms of size. Nine morphological and 17 morphometric traits were recorded and analysed. Furthermore, the possibility of a genetic basis for these radiographic features was evaluated by calculation of genetic variance components. Five of the morphological and 14 of the morphometric traits varied significantly between the GSD group and the control group (P<0.05). Osteochondrosis of the sacral endplate (SOC) had a higher prevalence in the GSDs (10.1%) compared with controls (5.7%). The majority of LSJ degenerative changes recorded from the radiographs occurred in the GSDs. The extent and relative proportion of lumbosacral step formations were greater in the GSD group compared with controls (P<0.001). The lumbosacral vertebral canal height was reduced in the GSD compared with the control dogs (P<0.001) suggesting a primary stenosis. This was accentuated by an abrupt tapering of the vertebral canal at the level of the LSJ indicated by a lumbosacral ratio of 1.51 in the GSD. The skeletal morphology and morphometry of the LSJ in the GSD seem to be different from that found in other large dogs. For multiple traits frequently observed in GSD such as SOC, step formations, and LSJ stenosis, moderate to high non-zero heritabilities were noted. As these features are also assumed to promote lumbosacral disease, selection against these traits is suggested.

MR-imaging of lumbosacral intervertebral disc degeneration in clinically sound German shepherd dogs compared to other breeds.

German shepherd dogs are overrepresented in the group of dogs with cauda equina compression syndrome due to degenerative lumbosacral stenosis. A congenital predisposition for early degeneration of the lumbosacral intervertebral disc has been suspected. Our aims were to assess the morphologic appearance of the lumbosacral intervertebral disc and the lumbosacral junction in healthy German shepherd dogs compared to other breeds and to evaluate for an early onset of degenerative changes. The lumbosacral spine of 110 clinically sound German shepherd dogs and 47 healthy dogs of other large breeds was examined using magnetic resonance (MR) imaging. The degeneration of every intervertebral disc was graded using an established classification system. Signal intensity of the entire lumbosacral disc and the nucleus pulposus was determined independently. Lumbosacral malalignment was assessed according to a previously described method. The findings for the German shepherd dogs were compared to those of the other breeds. Although most dogs were younger than 18 months at the date of examination, significantly higher grades of degeneration were detected for the lumbosacral intervertebral disc of German shepherd dogs (P < 0.003). Degeneration of the lumbosacral intervertebral disc was independent from findings in the other lumbar discs. We conclude that the German shepherd dog has a predisposition for degenerative changes in the lumbosacral intervertebral disc.

[Estimation of population genetic parameters and breeding values for elbow dysplasia in Rottweilers]. / Schätzung von populationsgenetischen Parametern und Zuchtwerten für Ellbogengelenkdysplasie beim Rottweiler.

We analysed scores of elbow dysplasia following the IEWG protocol from the official screening programme of the Allgemeiner Deutscher Rottweiler Club (ADRK). The data set included X-rays from 5100 Rottweiler dogs born between 1995 and 2004. Out of these 5,100 dogs, 46.9% were free from ED, 9.8% showed borderline signs (ED-UG), 31.8% ED-grade 1 (mild ED), 10% ED-grade 2 (moderate ED) und 1.6% ED-grade 3 (severe ED). Male dogs were more often affected by ED-grade 2 and 3 than female dogs. Traits analysed were ED-grade (dogs free from ED and dogs with ED-grades 1 to 3) and borderline ED (ED-UG). Birth year, birth season and inbreeding coefficient were significant for ED-grade. Higher inbreeding coefficients were associated with higher ED scores. ED-UG was significantly influenced by birth year and the interaction of birth year and birth season. A bivariate linear animal model was employed to estimate heritabilities using Residual Maximum Likelihood (REML) for ED-grade and ED-UG. Heritability estimates and their standard errors were 0.387 +/- 0.028 for ED-grade and 0.017 +/- 0.009 for ED-UG. The additive genetic correlation between ED-grade and ED-UG was -0.5. Heritabilities for ED-grade in female and male dogs were 0.350 +/- 0.033 and 0.497 +/- 0.047. We do not recommend use of ED-UG in breeding work because of the low heritability estimate and the negative additive genetic correlation with ED-grade.

Influence of femoral head and neck conformation on hip dysplasia in the German Shepherd dog.

We investigated the prevalence of an anatomic variant of the proximal femur, termed the broomstick-like femoral head and neck formation, and its influence on the Féderation Cynologique Internationale (FCI) hip dysplasia score in 294 German Shepherd dogs. One-hundred and eighty (61%) of the 294 dogs in our study had this anatomic variant. The calculated area of the femoral heads in dogs with a broomstick-like conformation was 4.5 +/- 0.6 cm2 on the hip-extended view. In dogs with a normal femoral head, the calculated area of the femoral head was significantly larger at 4.8 +/- 0.6 cm2 (P < 0.05). In the frog-leg view, there was no significant difference in femoral head area between dogs with the broomstick-like conformation and normal dogs. There was no difference in the antetorsion angle between dogs with broomstick-like conformation and normal dogs. There was also no difference in the distraction ratio between the two phenotypes. The official FCI hip score was similar in dogs with and without the broomstick-like conformation. The average heritability of the broomstick-like conformation was 0.3 +/- 0.1, suggesting heritable influence. We conclude that the broomstick-like conformation is a common finding in the German shepherd dog and has genetic base. The broomstick-like conformation does not appear to be associated with the presence of canine hip dysplasia and it can therefore be assumed to be a normal anatomic variant.

[Comparative evaluation of six different body regions of the dog using analog and digital radiography]. / Vergleichende Untersuchungen von sechs verschiedenen Körperregionen des Hundes mit der analogen und digitalen Radiographie.

In this study the quality of digital and analog radiography in dogs was compared. For this purpose, three conventional radiographs (varying in exposure) and three digital radiographs (varying in MUSI-contrast [MUSI = MUlti Scale Image Contrast], the main post-processing parameter) of six different body regions of the dog were evaluated (thorax, abdomen, skull, femur, hip joints, elbow). The quality of the radiographs was evaluated by eight veterinary specialists familiar with radiographic images using a questionnaire based on details of each body region significant in obtaining a radiographic diagnosis. In the first part of the study the overall quality of the radiographs was evaluated. Within one region, 89.5% (43/48) chose a digital radiograph as the best image. Divided into analog and digital groups, the digital image with the highest MUSI-contrast was most often considered the best, while the analog image considered the best varied between the one with the medium and the one with the longest exposure time. In the second part of the study, each image was rated for the visibility of specific, diagnostically important details. After summarisation of the scores for each criterion, divided into analog and digital imaging, the digital images were rated considerably superior to conventional images. The results of image comparison revealed that digital radiographs showed better image detail than radiographs taken with the analog technique in all six areas of the body.