Sexual dimorphism in limb long bones of the German Shepherd Dog.

The study of sexual dimorphism in dog anatomy, especially with regard to skeletal elements, has received little attention. The present work focuses on elements of the canine stylo- and zeugopodium, less documented than the skull or pelvis in the literature. In order to identify only sex-dependent effects, we analysed a single breed: the German Shepherd Dog. Data come from 25 dogs, with a balanced sex ratio (12 males and 13 females). Four skeletal elements of the forelimb and hindlimb (humerus, radius, femur, tibia) were each measured using seven linear morphometric variables. Univariate and multivariate analyses were then performed on these 28 variables. For all measurements, males are on average larger than females, with a mean sexual dimorphism ratio of 1.07. Sexual dimorphism is significant for 92.8% of the variables. Except of femoral measurements, diaphyseal values show the highest grade of sexual dimorphism. The mean level of disparity is higher in the forelimb (1.08) than in the hindlimb (1.05). A significant dimorphism is shown for the first component of principal component analyses conducted on each skeletal element, and for the second component with humerus measurements. Discriminant functions for sex identification give success rates included between 82% for the radius and 93% for the femur, the latter providing the highest reported score for sex identification in dogs from any skeletal element. These complementary statistic methods highlight a more dimorphic forelimb in size and a more dimorphic hindlimb in shape.

An experimental animal model for percutaneous procedures used in trigeminal neuralgia.

OBJECT: This study describes an experimental rabbit model that allows the reproduction of percutaneous operations that are used in patients with trigeminal neuralgia (TN). Attention was given to an exact anatomical description of the rabbit's middle cranial fossa as well as the establishment of conditions for a successful procedure. METHODS: Morphometric measurements were taken from 20 rabbit skulls and CT scans. The anatomy of the trigeminal nerve, as well as its surrounding structures, was assessed by bilateral dissection of 13 New Zealand white rabbits (NWR). An ideal approach of placing a needle through the foramen ovale to reach the TG was sought. Validation of correct placement was realized by fluoroscopy and confirmed by dissection. RESULTS: Precise instructions for successful reproduction of percutaneous procedures in NWR were described. According to morphological measurements, for balloon compression of the trigeminal ganglion (TG) the maximal diameter of an introducing cannula is 1.85 mm. The diameter of an empty balloon catheter should not exceed 1.19 mm, and the length of the inflatable part of the balloon can range up to 4 mm. For thermocoagulation the needle electrodes must not exceed an external diameter of 1.39, mm and the length of the non-insolated tip can range up to 4 mm. Glycerol rhizolysis can be achieved because the trigeminal cistern in the NWR is a closed space that allows a long dwelling time (>10 min) of the contrast agent. CONCLUSIONS: An experimental NWR model intended for the reproduction of percutaneous procedures on the TG has been meticulously described. This provides a tool that enables further standardized animal research in the field of surgical treatment of TN.

Dispersal pattern of injectate following CT-guided perineural infiltration in the canine thoracolumbar spine: a cadaver study.

An increasing proportion of canine patients are presented with chronic thoracolumbar back pain and without compressive spinal lesions. In humans, spinal perineural infiltrations have been reported to have a favorable effect on pain control. The purpose of this prospective cadaver study was to describe the dispersal pattern of injectate following CT-guided spinal perineural infiltration in the canine thoracolumbar region. Seven fresh canine cadavers were first scanned using multislice CT and then CT-guided spinal perineural infiltration was performed at 42 sites from T13/L1 to L6/L7. The injectate for each site was a mixture of new methylene blue and iodinated contrast medium. Immediately following CT-guided injection, cadavers were frozen, cut, and dissected macro- and mesoscopically (using a magnifying glass) to identify anatomic structures that were infiltrated. In the majority of sites (64.3%), complete epidural and hypaxial staining of spinal nerve components (including the spinal ganglion, trunk, and ventral branch) was successfully achieved. However, no (11.9%) or unpredictable staining (9.5%) of nervous tissue occurred in some sites despite careful CT guidance and the application of relatively large volumes of injectate. Optimal results were achieved when the needle tip was positioned periforaminally ventral to the cranial contour of the cranial articular process. Findings from this ex vivo study indicated that CT-guided spinal perineural infiltration is feasible for testing in the canine thoracolumbar region and that successful nerve tissue infiltration would likely occur in the majority of sites. Future in vivo studies are needed to determine the safety and efficacy of this technique.

Use of a 3D laser scan technique to compare the surface geometry of the medial coronoid process in dogs affected with medial compartment disease with unaffected controls.

Subchondral bone surface geometry of the medial coronoid process was examined in 20 grossly normal elbow joints of adult German Shepherd dogs (GSDs) and compared with results obtained from 10 joints of adult GSDs and 12 joints of adult Rottweilers affected with bilateral fragmentation of the medial coronoid process (FMCP). Additionally, seven dogs (4 GSDs and 3 Rottweilers) with unilateral FMCP were investigated. The subchondral contour of the ulnar trochlear notch was digitised to obtain the 3D coordinates of its surface points. Geometry was investigated in two defined section planes along the longitudinal and transverse axes of the medial coronoid process. The coordinates of the surface points in the section planes were normalised along one axis and geometry was estimated by the position of the surface points along its third coordinate and by calculation of the angle of inclination of the medial coronoid process. Subchondral bone surface geometry was not related to the type of fragmentation (i.e. single sagittal versus multiple sagittal or transverse fragmentation). No differences were noted when comparing joints of dogs affected unilaterally with FMCP and their contralateral normal joints. In addition, no differences in geometry were seen between GSDs affected with fragmentation and normal GSDs. The most evident differences were found between Rottweilers affected with FMCP and normal GSDs as well as FMCP affected GSDs. The results suggest that subchondral bone geometry (geometric incongruity) plays no role in the development of FMCP. Geometric differences between breeds were more prevalent than differences between normal joints and those affected with FMCP within one breed.

Effect of the recently established admissions procedure on success in the first-year exams at the University of Veterinary Medicine Vienna, Austria.

RATIONALE FOR THIS STUDY: The purpose of this study was to compare the success during the first academic year of students who underwent an admissions procedure (class 2005) and students of the three previous classes (2002-2004), who did not undergo an admissions procedure but took their exams under the same curricular framework. METHODOLOGY: Exam results of 802 students of the 2002-2004 classes were compared with those of 181 students from the 2005 class. RESULTS: Students of the 2005 class were more likely to pass all three exams given in the first academic year than students of the 2002-2004 classes (p < 0.001; OR = 3.2), and the quality of two of the three exams (indicated by individual scores) was also significantly better in 2005 than in the preceding classes (p < 0.001). In unselected classes, 25% to 31% of students showed no successful attempts to pass any of the three exams currently administered. CONCLUSION: The implementation of an admissions procedure measuring, among other indicators, academic ability has significantly improved first-year exam performance. Incoming students presenting with higher scores on academic standards are more likely to complete their courses successfully.

Admissions procedures at the University of Veterinary Medicine Vienna, Austria.

RATIONALE FOR THIS STUDY: The admission procedure implemented in fall 2005 in consequence of new laws passed in summer 2005 is described and evaluated. The general set-up, the underlying considerations, and the changes resulting from the establishment of this procedure are presented. METHODOLOGY: Admission variables and demographic information (sex, age, nationality) for 172 students who entered their first academic year at the University of Veterinary Medicine Vienna (VUW) and their academic performance measured according to their results in the three first-year examinations (successful versus unsuccessful) were assessed. Logistic regression was used to examine the relationship between predictor and outcome. RESULTS: Regression analysis indicates that Austrian students were more likely to be unsuccessful than German students (R(2) = 0.366, p < 0.001). Previous school performance was the best predictor for success in the Austrian cohort (R(2) = 0.196; p < 0.001), whereas the personal interview scores provided the best predictor in the German cohort (R(2) = 0.122; p < 0.05). CONCLUSION: This study supports our existing selection practices relating to cognitive and non-cognitive skills. The number of strugglers may be reduced on the basis of an admissions procedure, but struggling may not be excluded by the existing selection practices, which do not assess a specific threshold but are related to a score-ranking system and a predefined number of available openings in the program.

Arteriogenesis depends on circulating monocytes and macrophage accumulation and is severely depressed in op/op mice.

It has been suggested that monocytes/macrophages represent the pivotal cell type during early adaptive growth of pre-existent arterial anastomoses toward functional collateral arteries (arteriogenesis) upon arterial occlusion. This hypothesis was supported by previous studies providing evidence that elevation of the peripheral monocyte count, increased monocyte survival (e.g., granulocyte macrophage-colony stimulating factor), as well as enhanced attraction or adhesion (e.g., monocyte chemoattractant protein 1; intercellular adhesion molecule 1) of the latter cells correlates directly with the arteriogenic response to restore tissue perfusion. However, the experimental proof of the essential role of monocytes/macrophages remains to be given. We therefore hypothesized that arteriogenesis is reduced in a genuine, nonpharmocologically induced monocyte/macrophage-deficient model of femoral artery occlusion in osteopetrotic (op/op) mice. Total leukocyte count did not differ between op/op mice and control (B6C3Fe a/a-Csf1(+/+)) mice. op/op mice show a significant monocytopenia (0.67%+/-0.38% vs. 1.53%+/-0.32%), granulocytosis (33.66%+/-6.67% vs. 22.83+/-7.47%), and a concomitant, relative lymphopenia (65.67%+/-6.58% vs. 75.65%+/-7.31%). Microsphere-based perfusion measurement 7 days after femoral artery occlusion demonstrated a significantly reduced perfusion restoration upon femoral artery occlusion in op/op mice as compared with controls (28.19%+/-0.91% vs. 47.88%+/-2.49%). The application of a novel method of high resolution (microfocus X-ray system) angiography revealed a reduction of proliferation and diameter of collateral arteries. Quantitative immunohistology showed significantly lower numbers of macrophages in the surrounding tissue of proliferating arteries. This study provides additional evidence for the preeminent role of monocytes/macrophages during arteriogenesis in a genuine model of monocyte deficiency, i.e., without pharmacological intervention.

Assessment of the geometry of the cubital (elbow) joint of dogs by use of magnetic resonance imaging.

OBJECTIVE: To assess joint geometry and highlight potential evidence of physiologic incongruity in cubital (elbow) joints of large, small, and chondrodystrophic breeds of dogs. SAMPLE POPULATION: Nonarthritic elbow joints obtained from cadavers of mature dogs of large breeds (n = 19), small breeds (14), or chondrodystrophic breeds (8). PROCEDURE: Magnetic resonance imaging was used to quantify interosseous gaps at 6 defined positions and 2 sagittal planes of the humeroantebrachial region by use of a fat-suppressed 3-dimensional gradient-echo sequence. RESULTS: Interosseous gaps in the more medially located sagittal plane were significantly narrower at the level of the anconeal process than at any other position of the joint in large-breed dogs, compared with results for small- or chondrodystrophic-breed dogs. In both sagittal planes, the gaps were significantly wider at the center of the ulnar trochlear notch than at any other position. Significant correlation between body weight and width of the interosseous gaps was found only in large-breed dogs and was found in both sagittal planes at the center of the ulnar trochlear notch (r, 0.834 and r, 0.680, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: In large-breed dogs, the interosseous gap was especially narrow at the level of the anconeal process and its diametric position. This suggests less ability to compensate intra-articular steps in dogs with short ulna syndrome, which predisposes to failure of the union between the anconeal process and olecranon. Geometric incongruity may be regarded as clinically normal in nonarthritic humeroulnar joints. The degree of geometric incongruity increases with body weight.

Comparative assessment of bone mineral measurements obtained by use of dual-energy x-ray absorptiometry, peripheral quantitative computed tomography, and chemical-physical analyses in femurs of juvenile and adult dogs.

OBJECTIVE: To compare bone mineral measurements obtained by use of dual-energy x-ray absorptiometry (DEXA), peripheral quantitative computed tomography (pQCT), and chemical-physical analyses and determine effects of age and femur size on values obtained for the various techniques. SAMPLE POPULATION: Femurs obtained from 15 juvenile and 15 adult large-breed dogs. PROCEDURE: n each femur, 7 regions of interest were examined by use of DEXA to measure the bone mineral content (BMC) and bone mineral density (BMD), and 5 were examined by use of pQCT to measure BMD. Among these, 1 region was examined by both noninvasive methods and an invasive method. Volume of the femur was determined by water displacement. Volumetric bone density (VBD) was calculated. Calcium (Ca), phosphorus (P), total Ca, and total P contents were determined. RESULTS: DEXA- and pQCT-derived results revealed that all values increased with age in juvenile dogs. In adults, VBD and pQCT-derived BMD decreased significantly and DEXA-derived BMD increased with increasing femur length. The pQCT-derived BMD correlated well with VBD and Ca content, whereas DEXA-derived BMC was strongly correlated with Ca content. In juveniles, values correlated regardless of the technique used, whereas in adult dogs, DEXA-derived BMD did not correlate with pQCT-derived BMD, Ca concentration, or VBD unless data were adjusted on the basis of femur length. CONCLUSIONS AND CLINICAL RELEVANCE: DEXA-derived BMD adjusted for femur length yields approximately the same percentage variability in VBD as for pQCT-derived BMD. However, pQCT-derived BMD is still more sensitive for determining variability BMD in Ca concentration, compared with DEXA-derived BMD adjusted for femur length.

Appearance and incidence of sacroiliac joint disease in ventrodorsal radiographs of the canine pelvis.

Ventrodorsal (VD) radiographs of cadaveric pelves of large and giant breeds (n = 40) and of the corresponding bone specimens were made. Gross changes seen in the specimens were marked with metal wire or radiopaque paint to relate radiographic changes to the postmortem appearance of degenerative sacroiliac (SI) joint lesions. Two positioning techniques were used, resulting in two radiographs for each specimen. The techniques used were: (1) pulling the pelvic limbs caudally, with gentle traction producing a view of the sacrum in almost parallel alignment between the sacrum and the X-ray film (we have termed this a "central SI view") and (2) pulling the pelvic limbs caudally with greater traction than above, resulting in maximal inclination of the sacrum with respect to the X-ray film (we have termed this an "angled SI view"). Lesions of the supportive soft connective tissue could be imaged on the central and angled SI views, whereas angled SI views allowed better identification of lesions of the synovial SI joint. The insights gained in the above study were then used in a retrospective examination of 145 routine ventrodorsal radiographs of the pelvis (i.e., 290 sacroiliac joints) to determine the incidence of degenerative changes of the SI joint in large dogs. The lesions most commonly observed were calcification of the supportive soft connective tissue (n = 184/290), whereas lesions of the synovial SI joint were less frequent (n = 86/290). The degree of central or angled projection obtained in standard ventrodorsal radiographs was noted to be significantly (P < 0.05) associated with age, body conformation, anesthetic status, and the presence of spondylosis deformans at the lumbosacral junction. In contrast, SI joint disease and the gender of the animal did not affect the SI view achieved in VD radiographs.

Appearance of the sacroiliac joint in ventrodorsal radiographs of the normal canine pelvis.

Radiology of the canine sacroiliac (SI) joint was investigated by obtaining ventrodorsal radiographs of cadaveric pelves and bone specimens (n = 40) marked with solder wire or radiopaque paint to demonstrate the orientation of the sacroiliac joint in various radiographic views. In the following retrospective radiographic study (n = 94 survey sacroiliac joint radiographs), central projections of the sacrum were noted to ease identification of the dorsal, middle and ventral joint components, whereas angled projections of the sacrum had advantages when assessing the cranial joint components. Radiographic assessment was already successful in juvenile dogs older than 5 months. Failure in tracing the outlines of the joint space of the sacroiliac joints is not consistent with alteration of the SI joint. Rather, it was felt that alterations would have assisted in identifying the contours of the SI joints because of an increase in mineralization.

Use of routine ventrodorsal radiographic views of the pelvis to assess inclination of the wings of the sacrum in dogs.

OBJECTIVE: To determine the ratio of ventral-to-dorsal transverse diameters between the wings of the sacrum on ventrodorsal radiographic views of the pelvis in large dogs and to validate the reliability of this morphometric analysis for functional interpretation. SAMPLE POPULATION: Pelvic specimens from 40 large-breed dogs and radiographs of 113 large-breed dogs. PROCEDURE: In an anatomic and radiographic evaluation, the transverse dorsal diameter (TVDS) and transverse ventral diameter (TVV) between the wings of the sacrum were evaluated in sacrum specimens and on corresponding radiographs of the pelvis and sacrum. The ratio between TVV and TVDS (VD ratio) was calculated. Intraobserver reliability was determined by calculation of the coefficient of variation. In a retrospective radiographic evaluation, the VD ratio was determined in Rottweilers, Golden Retrievers, and German Shepherd Dogs. Correlations between VD ratio and breed, age, and sex were tested. RESULTS: The VD ratio was significantly higher in Rottweilers than in Golden Retrievers and German Shepherd Dogs, denoting an oblique alignment of the sacral wings in Rottweilers (ie, the dorsal aspects of the sacral wings were located more medially than the ventral aspects) and an almost sagittal alignment in the other breeds. The VD ratio was significantly associated with age but not with sex. CONCLUSIONS AND CLINICAL RELEVANCE: Sagittal alignment of the wings of the sacrum is considered to be biomechanically less efficient. These results provide a basis for further studies to evaluate radiographic assessment of the sacroiliac joints similar to the evaluation for hip dysplasia.

Functional adaptations of facet geometry in the canine thoracolumbar and lumbar spine (Th10-L6).

The shape, size and transverse distance between contralateral caudal articular processes of caudal thoracic and lumbar vertebrae were evaluated in a sample of 140 macerated canine spines to contribute to the understanding of the development of vertebral misalignment. Dogs were grouped as large, chondrodystrophic, and small breeds. In large dogs, caudal articular surfaces were adapted to higher body-weight by the presence of larger articular surfaces. Additionally, caudal articular surfaces not only covered the lateral, but also the ventral (i.e. ventral facet) and/or caudal aspects (i.e. caudal facet) of the caudal articular processes. Ventral facets, which increase loading capacity of the zygapophyseal joints in normally aligned vertebrae, were more frequently observed in large breeds (p < 0.001) than in small and chondrodystrophic breeds. With some exceptions, caudal facets primarily were present in large dogs, especially at the vertebral levels L3-L5. Their formation is induced by extension of the normal lykphotic thoracic and lumbar spine causing lumbar lordosis and denotes loss in elasticity of the bow-and-string-construction of the trunk. Because ventral and caudal facets are consistent with convexity of the caudal articular surfaces, which to a great degree was noted to result in formation of ball-and-socket joints, spinal stability is supposed to be decreased under such conditions.

The diameter of the vertebral canal in dogs in cases of lumbosacral transitional vertebrae or numerical vertebral variations.

From Th1 to L7 midsagittal and interpedicular vertebral canal diameters were measured in macerated spines of 162 dogs to determine, whether the presence of lumbosacral transitional vertebrae or numerical vertebral variations are associated with dislocation of the maximal enlargement of the lumbar vertebral canal. Relative to dogs with a regular number of 27 presacral vertebrae (C7/Th13/L7), the maximal enlargement of the lumbar vertebral canal was more frequently ( P < 0.05) located at vertebra 24 in dogs with 26 presacral vertebrae (C7/Th13/L6), and more frequently at vertebra 25 in dogs with 28 presacral vertebrae (C7/Th13/L8). However, in dogs with 26 presacral vertebrae, maximal agreement in the spinal position of maximal lumbar vertebral canal diameters was achieved relative to dogs with 28 presacral vertebrae by adding one additional thoracic (Th6, 7, or 8) segment. Therefore, the present findings strongly suggest that relative to the regular (C7/Th13/L7) condition, decrease in the number of presacral vertebrae (C7/Th13/L6) is associated with incorporation of a midthoracic segment, whereas increase in the number of presacral vertebrae (C7/Th13/L8) is not related to the presence of an additional vertebral segment. When using Th1 as landmark, the difference in the position of the maximal enlargement of the lumbar vertebral canal between dogs with 26 and dogs with 28 presacral vertebrae in average was only one segment. It is known from previous reports that the maximal enlargement of the lumbar vertebral canal corresponds with the maximal enlargement of the lumbar spinal cord. When using S1 or the transitional vertebra as the landmark for determination of the appropriate site for subarachnoid cannulation, this site is expected to range within the same limits regardless of the vertebral formula.