Computed tomography myelographic findings in dogs with cervical spondylomyelopathy

Computed tomography (CT) myelography is used occasionally in the diagnosis of cervical spondylomyelopathy, but the type of lesion found in large- versus giant-breed dogs using this modality has not been characterized. Our purpose was to report the frequency of compressive lesions in large- and giant-breed dogs with cervical spondylomyelopathy and imaged using CT myelography. Fifty-eight dogs were retrospectively studied, 23 large-breed and 35 giant-breed dogs. Multiple sites of compression were found in 12 large-breed dogs (52.2%) compared to 30 (85.8%) giant-breed dogs. The main site of compression was at C5-6 and C6-7 in both large-breed (91.3%) and giant-breed (72.4%) dogs. The main cause and direction of compression was disc-associated and ventral in 19 (82.6%) of the large-breed dogs while osseous changes were the primary cause of compression in 27 (77.2%) of the giant-breed dogs, with most compressions being lateral (51.4%), followed by dorsolateral (14.2%). Osseous compression was observed at C7-T1 in eight giant-breed dogs (22.8%), and at T1-T2 or T2 only in five dogs (14.3%). Four of 23 large-breed dogs (17.4%), and seven (20%) of 35 giant-breed dogs had spinal cord atrophy. Therefore, giant-breed dogs often have multiple compressions, usually caused by osseous changes causing lateralized compressions. In large-breed dogs most compressions are disc-associated and located ventrally. Considering the number of giant-breed dogs with compressions at C7-T1, T1-2, and T2, it is important to include the cranial thoracic region when imaging dogs suspected of having cervical spondylomyelopathy.     

Intervertebral and intravertebral ratios in Doberman pinscher dogs with cervical spondylomyelopathy

No screening method is currently available to differentiate dogs with and without cervical spondylomyelopathy. Intravertebral and intervertebral ratios are used in horses and can predict cervical vertebral malformation. Intervertebral ratios could be a useful screening method for canine cervical spondylomyelopathy. Our purpose was to compare cervical intervertebral and intravertebral ratios in normal vs. affected Doberman pinschers. Forty dogs were studied, 27 affected and 13 normal. Cervical radiographs were obtained in all dogs. The minimum intra- and intervertebral sagittal diameter ratios were established for each cervical vertebrae and disc space from C(2) to C(7) . Comparisons were made between groups and specific vertebral body and disc levels. The effect of gender, age, and method of measurement (analog or digital radiographs) was also studied. There was no difference in either the intervertebral or intravertebral ratio between normal vs. affected dogs. The ratios decreased progressively along the cervical spine, being smallest at C(6) -C(7) and C(7) , respectively. Age, gender, and method of measurement had a significant influence on both inter- and intravertebral ratios, with smaller ratios seen as dogs aged and in male dogs. Based on our results, inter- or intravertebral ratios have no value to distinguish between clinically normal Doberman pinschers and Doberman pinschers with cervical spondylomyelopathy.     

Clinical and magnetic resonance imaging (MRI) findings in 26 dogs with canine osseous-associated cervical spondylomyelopathy

The potential link between degenerative changes seen on magnetic resonance imaging (MRI) in osseous-associated cervical spondylomyelopathy (OA-CSM) and clinical signs has not been explored. Our goal was to retrospectively evaluate MRI findings, while investigating potential correlations between these changes, signalment, and clinical signs. Twenty-six dogs diagnosed with OA-CSM were included in the study. Clinical signs were converted into a Modified Frankel Score (MFS) and MRI findings were assessed and graded. Giant breeds had multiple compressed sites and presented at a younger age than large breeds, suggesting a different underlying pathophysiology. Spinal cord compression, most commonly bilateral, was present in 36.8% of intervertebral spaces. Synovial fluid loss and articular process sclerosis were the most common degenerative changes. Most dogs showed identical MFS scores, and no significant correlations were found between MFS and MRI changes. More detailed functional scales should be used to investigate this in the future.     

MRI features of cervical articular process degenerative joint disease in Great Dane dogs with cervical spondylomyelopathy

Cervical spondylomyelopathy or Wobbler syndrome commonly affects the cervical vertebral column of Great Dane dogs. Degenerative changes affecting the articular process joints are a frequent finding in these patients; however, the correlation between these changes and other features of cervical spondylomyelopathy are uncertain. We described and graded the degenerative changes evident in the cervical articular process joints from 13 Great Danes dogs with cervical spondylomyelopathy using MR imaging, and evaluated the relationship between individual features of cervical articular process joint degeneration and the presence of spinal cord compression, vertebral foraminal stenosis, intramedullary spinal cord changes, and intervertebral disc degenerative changes. Degenerative changes affecting the articular process joints were common, with only 13 of 94 (14%) having no degenerative changes. The most severe changes were evident between C4-C5 and C7-T1 intervertebral spaces. Reduction or loss of the hyperintense synovial fluid signal on T2-weighted MR images was the most frequent feature associated with articular process joint degenerative changes. Degenerative changes of the articular process joints affecting the synovial fluid or articular surface, or causing lateral hypertrophic tissue, were positively correlated with lateral spinal cord compression and vertebral foraminal stenosis. Dorsal hypertrophic tissue was positively correlated with dorsal spinal cord compression. Disc-associated spinal cord compression was recognized less frequently.     

A comparison of clinical,magnetic resonance imaging and pathological findings in dogs with gliomatosis cerebri,focusing on cases with minimal magnetic resonance imaging changes‡

The primary study objective was to determine whether clinical examination and magnetic resonance imaging (MRI) can underestimate canine gliomatosis cerebri (GC); we also investigated immunohistochemical features. Seven dogs with GC were studied; four recruited specifically because of minimal MRI changes. Neuroanatomic localization and the distribution of MRI, gross and sub‐gross lesions were compared with the actual histological distribution of neoplastic cells. In six cases, clinical examination predicted focal disease and MRI demonstrated a single lesion or appeared normal. Neoplastic cells infiltrated many regions deemed normal by clinical examination and MRI, and were Olig2‐positive and glial fibrillary acid protein‐negative. Four dogs had concurrent gliomas. GC is a differential diagnosis for dogs with focal neurological deficits and a normal MRI or a focal MRI lesion. Canine GC is probably mainly oligodendrocytic. Type II GC, a solid glioma accompanying diffuse central nervous system neoplastic infiltration, occurs in dogs as in people.     

Low‐field magnetic resonance imaging of keratomas of the hoof wall

Standing low‐field magnetic resonance imaging (MRI) was used to image the feet of 21 horses affected by keratomas. The animals had variable clinical histories including acute, chronic or recurrent lameness. Of the 21 horses, only 14 (66%) had radiological changes suggestive of keratoma. Standing low‐field MRI revealed a smoothly demarcated hoof wall lesion in all horses, with deformity of the adjacent surface of the distal phalanx in 15 cases. The signal characteristics of the keratomas varied, with most showing either hypointensity or heterogeneous mixed signal intensity in T1‐ and T2*‐weighted images and hypointensity in STIR sequences. An intermediate or high STIR signal intensity was present in the trabecular bone of the adjacent region of the distal phalanx in 5 cases. Surgical debridement was performed in 16 horses. Recurrence was common, especially in cases where the lesion was ill‐defined; the prior MRI appearance of these cases tended to be of heterogeneous signal intensity.     

One-year clinical and magnetic resonance imaging follow-up of Doberman Pinschers with cervical spondylomyelopathy treated medically or surgically

OBJECTIVE: To evaluate progression of clinical signs and magnetic resonance imaging (MRI) findings in dogs with cervical spondylomyelopathy (wobbler syndrome) treated medically or surgically. DESIGN: Prospective cohort study. ANIMALS: 12 Doberman Pinschers. PROCEDURES: Neurologic examinations and MRI were performed before medical (n = 9) or surgical treatment (ventral slot, 3) and a minimum of 12 months later. RESULTS: Mean follow-up time was 14.5 months. Clinically, 2 dogs improved after surgical treatment and 5 improved after medical treatment. Magnetic resonance imaging of surgically treated dogs revealed adequate spinal cord decompression. Spinal cord signal changes were seen in 2 dogs before surgery, both of which had new signal changes at the same and adjacent sites during follow-up examination. One dog treated surgically developed 3 new areas of spinal cord compression. In the medically treated dogs, the severity of spinal cord compression at the time of follow-up examination was unchanged in 4 dogs, worse in 2 dogs, and improved in 3 dogs, but spinal cord atrophy was observed on transverse images. Four medically treated dogs had changes in spinal cord signal initially, but none developed new signal changes or compressions. CONCLUSIONS AND CLINICAL RELEVANCE: Medical and surgical treatment improved or stabilized the clinical condition of most dogs. Surgical treatment appeared to hasten the development of additional areas of spinal cord compression and lesions in dogs with preoperative cord changes; however, the clinical importance of these changes was not determined. The progression of pathologic MRI abnormalities was notably less in medically treated dogs, compared with surgically treated dogs.     

Morphologic and morphometric magnetic resonance imaging features of Doberman Pinschers with and without clinical signs of cervical spondylomyelopathy

OBJECTIVE: To compare morphologic and morphometric features of the cervical vertebral column and spinal cord of Doberman Pinschers with and without clinical signs of cervical spondylomyelopathy (CSM; wobbler syndrome) detected via magnetic resonance imaging (MRI). ANIMALS: 16 clinically normal and 16 CSM-affected Doberman Pinschers. PROCEDURES: For each dog, MRI of the cervical vertebral column (in neutral and traction positions) was performed. Morphologically, MRI abnormalities were classified according to a spinal cord compression scale. Foraminal stenosis and intervertebral disk degeneration and protrusion were also recorded. Morphometric measurements of the vertebral canal and spinal cord were obtained in sagittal and transverse MRI planes. RESULTS: 4 of 16 clinically normal and 15 of 16 CSM-affected dogs had spinal cord compression. Twelve clinically normal and all CSM-affected dogs had disk degeneration. Foraminal stenosis was detected in 11 clinically normal and 14 CSM-affected dogs. Vertebral canal and spinal cord areas were consistently smaller in CSM-affected dogs, compared with clinically normal dogs. In neutral and traction positions, the intervertebral disks of CSM-affected dogs were wider than those of clinically normal dogs but the amount of disk distraction was similar between groups. CONCLUSIONS AND CLINICAL RELEVANCE: The incidence of intervertebral disk degeneration and foraminal stenosis in clinically normal Doberman Pinschers was high; cervical spinal cord compression may be present without concurrent clinical signs. A combination of static factors (ie, a relatively stenotic vertebral canal and wider intervertebral disks) distinguished CSM-affected dogs from clinically normal dogs and appears to be a key feature in the pathogenesis of CSM.     

Cerebrospinal fluid flow in normal beagle dogs analyzed using magnetic resonance imaging

BackgroundDiseases related to cerebrospinal fluid flow, such as hydrocephalus, syringomyelia, and Chiari malformation, are often found in small dogs. Although studies in human medicine have revealed a correlation with cerebrospinal fluid flow in these diseases by magnetic resonance imaging, there is little information and no standard data for normal dogs.ObjectivesThe purpose of this study was to obtain cerebrospinal fluid flow velocity data from the cerebral aqueduct and subarachnoid space at the foramen magnum in healthy beagle dogs.MethodsSix healthy beagle dogs were used in this experimental study. The dogs underwent phase-contrast and time-spatial labeling inversion pulse magnetic resonance imaging. Flow rate variations in the cerebrospinal fluid were observed using sagittal time-spatial labeling inversion pulse images. The pattern and velocity of cerebrospinal fluid flow were assessed using phase-contrast magnetic resonance imaging within the subarachnoid space at the foramen magnum level and the cerebral aqueduct.ResultsIn the ventral aspect of the subarachnoid space and cerebral aqueduct, the cerebrospinal fluid was characterized by a bidirectional flow throughout the cardiac cycle. The mean ± SD peak velocities through the ventral and dorsal aspects of the subarachnoid space and the cerebral aqueduct were 1.39 ± 0.13, 0.32 ± 0.12, and 0.76 ± 0.43 cm/s, respectively.ConclusionsNoninvasive visualization of cerebrospinal fluid flow movement with magnetic resonance imaging was feasible, and a reference dataset of cerebrospinal fluid flow peak velocities was obtained through the cervical subarachnoid space and cerebral aqueduct in healthy dogs.     

Correlation of motor evoked potentials with magnetic resonance imaging and neurologic findings in Doberman Pinschers with and without signs of cervical spondylomyelopathy

OBJECTIVE: To establish the reference ranges for motor evoked potential (MEP) latency and amplitude in clinically normal Doberman Pinschers, compare the MEPs of Doberman Pinschers with and without clinical signs of cervical spondylomyelopathy (CSM; wobbler syndrome), and determine whether MEP data correlate with neurologic or magnetic resonance imaging (MRI) findings. ANIMALS: 16 clinically normal and 16 CSM-affected Doberman Pinschers. PROCEDURES: Dogs were classified according to their neurologic deficits. After sedation with acepromazine and hydromorphone, transcranial magnetic MEPs were assessed in each dog; latencies and amplitudes were recorded from the extensor carpi radialis and cranial tibial muscles. Magnetic resonance imaging was performed to evaluate the presence and severity of spinal cord compression. RESULTS: Significant differences in cranial tibial muscle MEP latencies and amplitudes were detected between clinically normal and CSM-affected dogs. No differences in the extensor carpi radialis MEP were detected between groups. There was a significant correlation (r = 0.776) between the cranial tibial muscle MEP latencies and neurologic findings. Significant correlations were also found between MRI findings and the cranial tibial muscle MEP latencies (r = 0.757) and amplitudes (r = -0.453). CONCLUSIONS AND CLINICAL RELEVANCE: Results provided a reference range for MEPs in clinically normal Doberman Pinschers and indicated that cranial tibial muscle MEP latencies correlated well with both MRI and neurologic findings. Because of the high correlation between cranial tibial muscle MEP data and neurologic and MRI findings, MEP assessment could be considered as a screening tool in the management of dogs with spinal cord disease.     

Magnetic resonance imaging characteristics of suspected vertebral instability associated with fracture or subluxation in eleven dogs

The purpose of this study was to describe the magnetic resonance imaging (MRI) characteristics of suspected instability in dogs with vertebral fractures or subluxations. Eleven dogs that had MRI examinations of the spine prior to surgical stabilization of vertebral fractures and/or subluxations were included in the study. Nine dogs also had survey radiographs. Four dogs had cervical fracture or fracture-subluxation and presented with tetraplegia with intact nociception (n = 2) or nonambulatory tetraparesis (n = 2). Seven dogs had thoracolumbar fracture-subluxation or subluxation and presented with paraplegia with intact nociception (n = 5) or nonambulatory paraparesis (n = 2). A three-compartment model was applied to the interpretation of both the radiographic and MRI studies. Radiography identified compartmental disruption consistent with spinal instability in seven out of the nine cases radiographed. In MRI studies, rupture of the supportive soft tissue structures and/or fracture in at least two compartments could be visualized. Nine cases had spinal cord changes on MRI including signal intensity changes, swelling, compression, and intramedullary hemorrhage. Paravertebral muscle intensity changes were also visible at each trauma site. Magnetic resonance imaging provided helpful information on the location and extent of damage to supportive soft tissue structures and enabled assessment of spinal cord injury in this group of dogs with surgically confirmed vertebral fractures and subluxations.     

Diagnosis of laryngeal dysplasia in five horses using magnetic resonance imaging and ultrasonography

Reasons for performing study: Laryngeal dysplasia due to suspected maldevelopment of the fourth branchial arch has been reported previously in the horse and has been associated with rostral displacement of the palatopharyngeal arch and/or right laryngeal dysfunction. These studies all described the endoscopic and/or anatomical post mortem identification of the disease, but ultrasonography or magnetic resonance imaging (MRI) of this disease have not been described. Hypothesis: MRI and ultrasound findings accurately reflect the anatomical features of presumptive fourth branchial arch abnormality and allow accurate ante mortem diagnosis of this condition and, therefore, appropriate management. Methods: Between February 2008 and January 2009, all horses examined at Rood and Riddle Equine Hospital diagnosed with rostral displacement of the palatopharyngeal arch and/or right laryngeal dysfunction using upper airway endoscopy (n = 5) underwent ultrasonography and MRI of the laryngeal region. Results: All 5 horses that met the inclusion criteria were identified and all underwent laryngeal MRI and ultrasound examinations. Features consistent with laryngeal dysplasia, including lack of the cricothyroid articulation, dorsal extension of the thyroid cartilage lamina, and absence or hypoplasia of the cricopharyngeus muscle, were seen in all cases using both types of imaging. Conclusions and potential relevance: MRI and ultrasonography permit definitive premortem diagnosis of laryngeal dysplasia. Upper airway abnormalities identified using endoscopy can be more fully characterised using MRI and ultrasonography allowing more appropriate recommendations to be made. Preoperative imaging may also prevent inappropriate surgical intervention.     

Use of standing low‐field magnetic resonance imaging to diagnose middle phalanx bone marrow lesions in horses

Bone marrow lesions (BMLs) (also known as ‘bone bruises’, ‘bone oedema’, ‘bone contusions’ and ‘occult fractures’) within the middle phalanx were diagnosed by standing low field magnetic resonance imaging (MRI) in 7 horses. The lesions were characterised by low signal intensity on T1‐ and T2*‐weighted gradient echo sequences, mildly increased signal intensity on T2 fast spin echo sequences, and high signal intensity on short tau inversion recovery (STIR) sequences. Four distinct patterns of abnormal signal were identified: BML associated with osteoarthritis of either the proximal or distal interphalangeal joints; BML associated with soft tissue injury; BML associated with acute trauma; and BML unassociated with any other injury or lameness (assumed to represent bone response to biomechanical stress). Repeat MRI was undertaken in 4 cases. In most cases the BML resolved with rest and time, although lameness was persistent in 2 horses (one of which had an associated osteoarthritis of the proximal interphalangeal joint).     

Detection of spinal cord compression in dogs with cervical intervertebral disc disease by magnetic resonance imaging

The medical records and magnetic resonance images of 33 dogs with surgically confirmed Hansen type I cervical intervertebral disc disease were reviewed. Fourteen of the dogs were chondrodystrophic and 19 were not chondrodystrophic. The most common clinical sign was neck pain, which affected 28 of the dogs, and 23 of the dogs were able to walk. Fifteen of the dogs had developed clinical signs acutely, within the previous 24 hours. On cross-sectional images the median area of spinal cord compression was 26 per cent (range 11 to 71 per cent) of the normal spinal cord area. The degree of spinal cord compression was significantly associated with the dogs' presurgical neurological status but not with their postsurgical neurological status. The dogs with an acute onset of clinical signs had more severe neurological dysfunction before surgery, but their condition improved more as a result of surgery.