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Abstract

Objective—To determine the association between the 3-dimensional (3-D) motion pattern of the caudal lumbar and lumbosacral portions of the canine vertebral column and the morphology of vertebrae, facet joints, and intervertebral disks.

Sample Population—Vertebral columns of 9 German Shepherd Dogs and 16 dogs of other breeds with similar body weights and body conditions.

Procedure—Different morphometric parameters of the vertebral column were assessed by computed tomography (CT) and magnetic resonance imaging. Anatomic conformation and the 3-D motion pattern were compared, and correlation coefficients were calculated.

Results—Total range of motion for flexion and extension was mainly associated with the facet joint angle, the facet joint angle difference between levels of the vertebral column in the transverse plane on CT images, disk height, and lever arm length.

Conclusions and Clinical Relevance—Motion is a complex process that is influenced by the entire 3-D conformation of the lumbar portion of the vertebral column. In vivo dynamic measurements of the 3-D motion pattern of the lumbar and lumbosacral portions of the vertebral column will be necessary to further assess biomechanics that could lead to disk degeneration in dogs.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To estimate genetic population variables for 6 radiographic criteria of canine hip dysplasia (CHD).

Animals—664 full- and half-siblings from a colony of Labrador Retrievers.

Procedure—Heritability estimates and genetic correlations were calculated for 6 radiographic criteria of CHD. Two evaluation protocols were compared: the grade of the most severely affected hip joint and the sum of the scores for both hip joints. The predictive performance of estimated breeding values was also evaluated.

Results—The overall prevalence of CHD (Fédération Cynologique Internationale grades C, D, and E) was 29.6%. Median age at radiographic examination was 377 days. Heritability for the total CHD grade, Norberg angle (NA), coverage of the femoral head (COV), craniodorsal acetabular rim (ACR), subchondral bone sclerosis (SUBCH), shape of the femoral head and neck (FHN), and osteoarthritic changes at the insertion site of the joint capsule (JC) was estimated as follows: 0.44, 0.43, 0.46, 0.37, 0.32, 0.21, and 0.05, respectively. Heritability estimates were slightly higher for the sum of the scores for both hip joints. If NA and COV were included as fixed effects in the model for the dependent variables ACR, SUBCH, FHN, and JC , then heritability of these traits significantly decreased (0.08 to 0.15). High scores of NA and COV lead to a significant increase of the scores of the remaining criteria.

Conclusions and Clinical Relevance—Canine hip dysplasia is heritable to a moderate degree. Signs of subluxation revealed the highest heritability estimates. The criteria ACR, SUBCH, FHN, and JC were strongly influenced by NA and COV. (Am J Vet Res 2001;62:846–852)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the possible association between facet joint geometry and intervertebral disk degeneration in German Shepherd Dogs.

Animals—25 German Shepherd Dogs and 11 control dogs of similar body weight and condition.

Procedure—Facet joint angles in the caudal portion of the lumbar region of the vertebral column (L5-S1) were measured by use of computed tomography, and the intervertebral discs were evaluated microscopically. The relationship between facet joint geometry and disk degeneration was evaluated by use of statistical methods.

Results—German Shepherd Dogs had significantly more facet joint tropism than control dogs, but an association with disk degeneration was not found. However, German Shepherd Dogs had a different facet joint conformation, with more sagittally oriented facet joints at L5-L6 and L6-L7 and a larger angle difference between the lumbar and lumbosacral facet joints, compared with control dogs.

Conclusion and Clinical Relevance—A large difference between facet joint angles at L6-L7 and L7-S1 in German Shepherd Dogs may be associated with the frequent occurrence of lumbosacral disk degeneration in this breed. (Am J Vet Res 2002;63:86f–90)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To measure concentrations of nitric oxide metabolites (nitrite-nitrate [NOt]) in cartilage, synovial membrane, and cranial cruciate ligament (CCL) in dogs and evaluate associations with osteoarthritis in dogs with CCL rupture.

Animals—46 dogs with CCL rupture and 54 control dogs without joint disease.

Procedure—Tissue specimens for histologic examination and explant culture were harvested during surgery in the CCL group or immediately after euthanasia in the control group; NOt concentrations were measured in supernatant of explant cultures and compared among dogs with various degrees of osteoarthritis and between dogs with and without CCL rupture.

Results—Osteoarthritic cartilage had significantly higher NOt concentration (1,171.6 nmol/g) than did healthy cartilage (491.0 nmol/g); NOt concentration was associated with severity of macroscopic and microscopic lesions. Synovial membrane NOt concentration did not differ between dogs with and without CCL rupture. Ruptured CCL produced less NOt than did intact ligaments. In control dogs, NOt concentrations were similar for intact ligaments (568.1 nmol/g) and articular cartilage (491.0 nmol/g). Synthesis of NOt was inhibited substantially by coincubation with inhibitors.

Conclusions and Clinical Relevance—Results suggest that NOt in canine joint tissues originates from the inducible nitric oxide synthase pathway. Nitric oxide metabolite production in cartilage was greater in dogs with osteoarthritis than in healthy dogs and was associated with lesion severity, suggesting that nitric oxide inhibitors may be considered as a treatment for osteoarthritis. The CCL produces substantial concentrations of NOt; the importance of this finding is unknown. ( Am J Vet Res 2000;61:530–536)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate pulsed-wave Doppler spectral parameters as a method for distinguishing between neoplastic and inflammatory peripheral lymphadenopathy in dogs.

Sample Population—40 superficial lymph nodes from 33 dogs with peripheral lymphadenopathy.

Procedures—3 Doppler spectral tracings were recorded from each node. Spectral Doppler analysis including assessment of the resistive index, peak systolic velocity-to-end diastolic velocity (S:D) ratio, diastolic notch velocity-to-peak systolic velocity (N:S) ratio, and end diastolic velocity-to-diastolic notch velocity ratio was performed for each tracing. Several calculation methods were used to determine the Doppler indices for each lymph node. After the ultrasonographic examination, fine needle aspirates or excisional biopsy specimens of the examined lymph nodes were obtained, and lymphadenopathy was classified as either inflammatory or neoplastic (lymphomatous or metastatic) via cytologic or histologic examination. Results of Doppler analysis were compared with cytologic or histopathologic findings.

Results—The Doppler index with the highest diagnostic accuracy was the S:D ratio calculated from the first recorded tracing; a cutoff value of 3.22 yielded sensitivity of 91%, specificity of 100%, and negative predictive value of 89% for detection of neoplasia. Overall diagnostic accuracy was 95%. At a sensitivity of 100%, the most accurate index was the N:S ratio calculated from the first recorded tracing; a cutoff value of 0.45 yielded specificity of 67%, positive predictive value of 81%, and overall diagnostic accuracy of 86.5%.

Conclusions and Clinical Relevance—Results suggested that noninvasive Doppler spectral analysis may be useful in the diagnosis of neoplastic versus inflammatory peripheral lymphadenopathy in dogs.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the 3-dimensional motion pattern including main and coupled motions of the caudal lumbar and lumbosacral portions of the vertebral column of dogs.

Animals—Vertebral columns of 9 German Shepherd Dogs (GSDs) and 16 dogs of other breeds with similar body weights and body conditions .

Procedure—Main and coupled motions of the caudal lumbar and lumbosacral portions of the vertebral column (L4 to S1) were determined by use of a testing apparatus that permitted precise application of known pure moments to the vertebral column. Motion was compared between GSDs and dogs of other breeds.

Results—All specimens had a similar motion pattern consisting of main motion and a certain amount of coupled motion including translation. Vertebral columns of GSDs had significantly less main motion in all directions than that of dogs of other breeds. Translation was similar in GSDs and dogs of other breeds and was smallest at the lumbosacral motion segment.

Conclusions and Clinical Relevance—Results indicated that motion in the caudal lumbar and lumbosacral portions of the vertebral column of dogs is complex and provided a basis for further studies evaluating abnormal vertebral columns. ( Am J Vet Res 2004;65:544–552)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine interobserver and intraobserver agreement for results of low-field magnetic resonance imaging (MRI) in dogs with and without disk-associated wobbler syndrome (DAWS).

Design—Validation study.

Animals—21 dogs with and 23 dogs without clinical signs of DAWS.

Procedures—For each dog, MRI of the cervical vertebral column was performed. The MRI studies were presented in a randomized sequence to 4 board-certified radiologists blinded to clinical status. Observers assessed degree of disk degeneration, disk-associated and dorsal compression, alterations in intraspinal signal intensity (ISI), vertebral body abnormalities, and new bone formation and categorized each study as originating from a clinically affected or clinically normal dog. Interobserver agreement was calculated for 44 initial measurements for each observer. Intraobserver agreement was calculated for 11 replicate measurements for each observer.

Results—There was good interobserver agreement for ratings of disk degeneration and vertebral body abnormalities and moderate interobserver agreement for ratings of disk-associated compression, dorsal compression, alterations in ISI, new bone formation, and suspected clinical status. There was very good intraobserver agreement for ratings of disk degeneration, disk-associated compression, alterations in ISI, vertebral body abnormalities, and suspected clinical status. There was good intraobserver agreement for ratings of dorsal compression and new bone formation. Two of 21 clinically affected dogs were erroneously categorized as clinically normal, and 4 of 23 clinically normal dogs were erroneously categorized as clinically affected.

Conclusions and Clinical Relevance—Results suggested that variability exists among observers with regard to results of MRI in dogs with DAWS and that MRI could lead to false-positive and false-negative assessments.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the prevalence of spinal cord compression subsequent to traumatic intervertebral disk (IVD) extrusion in dogs, characterize factors associated with spinal cord compression in dogs with traumatic IVD extrusion, and evaluate the outcomes of dogs with traumatic IVD extrusion with or without spinal cord compression.

Design—Retrospective case series.

Animals—31 dogs with traumatic IVD extrusion.

Procedures—Medical records and MRI findings were reviewed for dogs with a history of trauma to the spinal region. Dogs were included in the study if a neurologic examination and MRI were performed and there was a description of clinical signs and MRI findings including identification of the spinal cord segment affected by IVD extrusion, presence or absence of spinal cord compression, treatment, and outcome available for review.

Results—31 of 50 (62%) dogs had traumatic IVD extrusions without any other detectable vertebral lesions; 9 (29%) and 22 (71%) of those 31 dogs did and did not have spinal cord compression, respectively. Dogs with spinal cord compression were significantly older and more likely to be chondrodystrophic and have evidence of generalized IVD degeneration, compared with dogs without spinal cord compression. The outcome for dogs with spinal cord compression was similar to that for dogs without spinal cord compression.

Conclusions and Clinical Relevance—Results indicated traumatic IVD extrusion was common and should be considered as a differential diagnosis for dogs with trauma to the spinal region, and spinal cord compression should be evaluated, especially in older or chondrodystrophic dogs.

Full access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association