Objective—To determine the spectrum and frequency of abnormalities for low-field magnetic resonance imaging (MRI) examinations of clinically normal Doberman Pinschers and Foxhounds.
Animals—37 clinically normal dogs (20 Doberman Pinschers and 17 Foxhounds).
Procedures—For each dog, MRI of the cervical vertebrae (sagittal, dorsal, and transverse T1- and T2-weighted images) was performed. Variables assessed were intervertebral disk degeneration, disk-associated compression, compression of the dorsal portion of the spinal cord, vertebral body abnormalities, and changes in intraparenchymal signal intensity. Associations between these variables and age, breed, sex, and location of the assessed intervertebral disk spaces were evaluated.
Results—Severe MRI abnormalities were detected in 17 dogs, including complete disk degeneration (n = 4 dogs), spinal cord compression (3), or both (10). Vertebral body abnormalities were detected in 8 dogs, and hyperintense signal intensity was detected in 2 dogs. Severity of disk degeneration and disk-associated compression was significantly associated with increased age. There was a significant association between disk degeneration, disk-as-sociated compression, and compression of the dorsal aspect of the spinal cord and location of the assessed intervertebral disk space, with the intervertebral disk spaces in the caudal portion of the cervical region being more severely affected.
Conclusions and Clinical Relevance—Abnormalities were commonly seen on MRI examinations of the caudal portion of the cervical vertebral column and spinal cord of clinically normal Doberman Pinchers and Foxhounds. Such lesions were probably part of the typical spinal cord degeneration associated with the aging process of dogs.
Objective—To evaluate the evolution of clinical signs and their correlation with results of magnetic resonance imaging (MRI) and transcranial magnetic stimulation (TMS) and to assess potential prognostic variables after conservative medical treatment for disk-associated cervical spondylomyelopathy (DA-CSM) in dogs.
Design—Prospective cohort study.
Animals—21 client-owned dogs with DA-CSM.
Procedures—After neurologic grading, dogs underwent low-field MRI and TMS with measurement of onset latencies and peak-to-peak amplitudes from the extensor carpi radialis and cranial tibial muscles. Dimensions calculated from MRI images were remaining spinal cord area, spinal cord compression ratio, vertebral occupying ratio, vertebral canal height-to-body height ratio, vertebral canal height-to-body length ratio, and vertebral canal compromise ratio. Intraparenchymal signal intensity changes were graded. Dogs were reevaluated 1, 3, 6, 12, and 24 months after initial diagnosis.
Results—Outcome was successful in 8 of 21 dogs. Negative outcomes were characterized by rapid progression of clinical signs. All dogs with more severe clinical signs of DA-CSM 1 month after diagnosis had unsuccessful outcomes. Outcome was associated with the remaining spinal cord area and vertebral canal compromise ratio. Prognosis was not associated with severity of clinical signs or results of TMS. There were no significant correlations among clinical signs, MRI findings, and TMS results.
Conclusions and Clinical Relevance—Conservative medical treatment of DA-CSM was associated with a guarded prognosis. Selected MRI variables and clinical evolution 1 month after diagnosis can be considered prognostic indicators. The lack of correlation among clinical signs, results of diagnostic imaging, and results of electrophysiologic evaluation in dogs with DA-CSM warrants further investigation.
Objective—To evaluate the use of transcranial magnetic stimulation for differentiating between clinically relevant and clinically irrelevant cervical spinal cord compression on magnetic resonance imaging (MRI).
Animals—Clinically normal Doberman Pinschers without (n = 11) and with (6) spinal cord compression on MRI and 16 Doberman Pinschers with disk-associated wobbler syndrome (DAWS).
Procedures—After dogs were sedated, transcranial magnetic motor evoked potentials were recorded from the extensor carpi radialis muscle (ECRM) and cranial tibial muscle (CTM). Onset latencies and peak-to-peak amplitudes were measured. Magnetic resonance imaging was performed to identify spinal cord compression.
Results—There were significant differences in ECRM and CTM onset latencies between Doberman Pinschers with DAWS and each of the 2 groups of clinically normal dogs, but there were no significant differences in ECRM and CTM onset latencies between the 2 groups of clinically normal dogs. There were significant differences in CTM peak-to-peak amplitudes between Doberman Pinschers with DAWS and each of the 2 groups of clinically normal dogs, but there were no significant differences in ECRM peak-to-peak amplitudes among groups or in CTM peak-to-peak amplitudes between the 2 groups of clinically normal dogs. There was a significant correlation between severity of spinal cord compression and ECRM onset latency, CTM onset latency, and CTM peak-to-peak amplitude.
Conclusions and Clinical Relevance—Results suggested that transcranial magnetic stimulation may be a useful diagnostic tool to differentiate between clinically relevant and clinically irrelevant spinal cord compression identified on MRI alone.
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).
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.