Three-dimensional kinematics of the craniocervical junction of Cavalier King Charles Spaniels compared to Chihuahuas and Labrador retrievers.

Our knowledge about the underlying pathomechanisms of craniocervical junction abnormalities (CCJA) in dogs mostly derives from measurements based on tomographic imaging. These images are static and the positioning of the dogs' head does not reflect the physiological in vivo position of the craniocervical junction (CCJ). Aberrant motion patterns and ranges of motion (ROM) in sound individuals of CCJA predisposed breeds may be a pathogenetic trigger. To further extend our limited knowledge of physiological motion of the CCJ, this prospective, comparative study investigates the in vivo motion patterns and ROM of the CCJ in walk and trot in sound Cavalier King Charles Spaniels and Chihuahuas. The Labrador retriever is used as a reference breed without predisposition for CCJA. This is the first detailed description of CCJ movement of trotting dogs. Biplanar fluoroscopy images, recorded in walking and trotting dogs, were matched to a virtual reconstruction of the skull and cranial cervical spine utilising Scientific Rotoscoping. Kinematic data reveal the same motion patterns among all breeds and gaits with individual temporal and spatial differences in each dog. A stride cycle-dependent lateral rotation of the cranial cervical spine and axial rotation of the atlantoaxial joint in trot in dogs is described for the first time. The ROM of the atlantoaxial and atlantooccipital joints in walk and trot were not statistically significantly greater in the CCJA-predisposed breeds CKCS and Chihuahua. ROM values of all translational and rotational degrees of freedom were larger in walk than trot, although this is only statistically significant for the atlantoaxial joint. Until proven otherwise, a more species-specific than breed-specific general motion pattern of the CCJ in walking and trotting, clinically sound dogs must be assumed. Species-specific anatomic properties of the CCJ seem to supersede breed-specific anatomical differences in clinically sound dogs.

A Novel Dipotassium Hydrogen Phosphate Phantom for Calibrating Computed Tomographic Bone Density Measurements in Birds.

The objective of this study was to construct a calibration phantom for bone mineral density (BMD) measurements adapted to avian anatomy by quantitative computed tomography. The determination of BMD is important to assess avian osteoporosis in poultry at production facilities and to study biological features in association with flight patterns in birds. Quantitative computed tomography measured in Hounsfield units is a well-established technique for BMD measurements. Translation of Hounsfield units into the International System of Units (mg/cm3) requires the use of a calibration phantom. Although calibration phantoms for routine use in humans are commercially available, phantoms suited to avian anatomy are not. A liquid dipotassium hydrogen phosphate calibration standard was constructed out of commercially available materials, easily allowing for variations in size, bone diameter, and adaptation to avian skeletal anatomy. Periodically, quantitative computed tomography scans were performed to monitor constant correlation to the calibration standard over 3 months and to monitor for the potential influence of gas bubbling and water evaporation in the rods on BMD measurements. Finally, the calibration phantom was tested for BMD measurements with carcasses from 2 bird species, including 3 peregrine falcons (Falco peregrinus; 2 juvenile males, 1 adult female with inactive reproductive status) and 4 Eurasian kestrels (Falco tinnunculus; 1 juvenile and 2 adult males, 1 adult female with inactive reproductive status). Results demonstrated stability of the calibration phantom without the need to refill or replace rods, plus a stable correlation line (R 2 = .99) over the 3-month evaluation period. It was possible to place the phantom directly on the bird carcasses, close to the measured bones, to improve BMD analysis. As evaluated, the phantom appeared to be adaptive to avian skeletal anatomy. Moreover, it was possible to build the phantom within 24 hours from commercially available materials.

Three-Dimensional Kinematic Motion of the Craniocervical Junction of Chihuahuas and Labrador Retrievers.

All vertebrate species have a distinct morphology and movement pattern, which reflect the adaption of the animal to its habitat. Yet, our knowledge of motion patterns of the craniocervical junction of dogs is very limited. The aim of this prospective study is to perform a detailed analysis and description of three-dimensional craniocervical motion during locomotion in clinically sound Chihuahuas and Labrador retrievers. This study presents the first in vivo recorded motions of the craniocervical junction of clinically sound Chihuahuas (n = 8) and clinically sound Labrador retrievers (n = 3) using biplanar fluoroscopy. Scientific rotoscoping was used to reconstruct three-dimensional kinematics during locomotion. The same basic motion patterns were found in Chihuahuas and Labrador retrievers during walking. Sagittal, lateral, and axial rotation could be observed in both the atlantoaxial and the atlantooccipital joints during head motion and locomotion. Lateral and axial rotation occurred as a coupled motion pattern. The amplitudes of axial and lateral rotation of the total upper cervical motion and the atlantoaxial joint were higher in Labrador retrievers than in Chihuahuas. The range of motion (ROM) maxima were 20°, 26°, and 24° in the sagittal, lateral, and axial planes, respectively, of the atlantoaxial joint. ROM maxima of 30°, 16°, and 18° in the sagittal, lateral, and axial planes, respectively, were found at the atlantooccipital joint. The average absolute sagittal rotation of the atlas was slightly higher in Chihuahuas (between 9.1 ± 6.8° and 18.7 ± 9.9°) as compared with that of Labrador retrievers (between 5.7 ± 4.6° and 14.5 ± 2.6°), which corresponds to the more acute angle of the atlas in Chihuahuas. Individual differences for example, varying in amplitude or time of occurrence are reported.

Three-Dimensional Kinematics of the Pelvis and Caudal Lumbar Spine in German Shepherd Dogs.

Lumbosacral vertebral motion is thought to be a factor in the development of degenerative lumbosacral stenosis in German shepherd dogs. So far, few studies exist describing natural canine lumbosacral movement in vivo. Therefore, this investigation aims to achieve a detailed in vivo analysis of bone movement of the lumbosacral region to gain a better understanding of the origin of degenerative lumbosacral stenosis using three-dimensional non-invasive in vivo analysis of canine pelvic and caudal lumbar motion (at L6 and L7). Biplanar cineradiography of the pelvis and caudal lumbar spine of four clinically sound German shepherd dogs at a walk and at a trot on a treadmill was recorded. Pelvic and intervertebral motion was virtually reconstructed and analyzed with scientific rotoscoping. The use of this technique made possible non-invasive measurement of physiological vertebral motion in dogs with high accuracy. Furthermore, the gait patterns of the dogs revealed a wide variation both between individual steps and between dogs. Pelvic motion showed a common basic pattern throughout the stride cycle. Motion at L6 and L7, except for sagittal rotation at a trot, was largely asynchronous with the stride cycle. Intervertebral motion in all dogs was small with approximately 2-3° rotation and translations of approximately 1-2 mm. The predominant motion of the pelvis was axial rotation at a walk, whereas lateral rotation was predominant at a trot. L7 showed a predominance of sagittal rotation (with up to 5.1° at a trot), whereas lateral rotation was the main component of the movement at L6 (about 2.3° in both gaits). During trotting, a coupling of various motions was detected: axial rotation of L7 and the pelvis was inverse and was coupled with craniocaudal translation of L7. In addition, a certain degree of compensation of abnormal pelvic movements during walking and trotting by the caudal lumbar spine was evident.

Abdominal ultrasound image quality is comparable among veterinary sonographers with varying levels of expertise for healthy canine and feline patients.

Abdominal ultrasonography is increasingly used as a standard diagnostic test in veterinary practices, however, there is little published information regarding the effects of operator experience on image quality. In this prospective observer agreement study, image quality was assessed for abdominal ultrasound examinations performed by nine sonographers (three general practitioners, three credentialed veterinary technicians, and three board-certified specialists). Each sonographer independently performed abdominal ultrasound examinations on the same group of 4 sedated clinically healthy animals (3 dogs, 1 cat) using the same model machine and standardized presets. Twenty-five organs and anatomical landmarks per exam (26 for male dog) were evaluated. Still images and cine loops were recorded for each one of the organs. The final scoring of image quality for each examination was performed by two board-certified veterinary radiologists in a randomized and blinded fashion. Semiquantitative scoring system was used for each reading: 0 - not seen, 1- seen but poor quality/partial seen, 2 - average/good quality, and 3 - excellent quality. The average score for each animal and sonographer was tallied and sonographer groups and individual sonographers were compared. Scores were assessed for normality and data were ranked transformed prior to statistical analysis. No significant differences were found regarding the completeness and quality scores of sonographers of different experience levels and disciplines when measuring specific standard components of a full abdominal scan. There were no statistical differences between individual sonographers or groups of sonographers. Although not statistically significant, the general practitioner's group showed the greatest variability of their individual scores.

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.