IMAGING FEATURES OF DISCOSPONDYLITIS IN TWO HORSES

Two horses with discospondylitis are described with emphasis on the imaging modalities used and their contribution to the final diagnosis and outcome. Radiographic findings were vertebral endplate lysis with sclerosis in both horses, with additional vertebral subluxation and ventral spondylosis in one horse. Ultrasonographic findings included vertebral malalignment and obliteration of the intervertebral disc by spondylotic bone in one horse and irregular endplates, a widened disc space, a hypoechoic paravertebral abscess and hypoechoic, atrophic adjacent musculature with loss of linear fiber pattern in the other horse. Bone scintigraphy excluded additional affected sites. A systematic approach is recommended when performing an ultrasound examination of the spine.     

Magnetic resonance imaging characterization of vertebral endplate changes in the dog

Spinal MR images acquired from canine patients over a 7-year period were reviewed for the presence of vertebral endplate changes. Seventy-five dogs with 76 distinct lesions were identified. Presumptive diagnoses fell into five categories: reactive endplate changes (10 dogs/13.2%), discospondylitis (29 dogs/38.2%), vertebral osteochondrosis (7 dogs/9.2%), intravertebral disc herniation (Schmorl's nodes) (4 dogs/5.3%), and fatty infiltration (26 dogs/34.2%). Fatty infiltration occurred significantly more often in small breed dogs (P < 0.001) and tended to be multifocal. The following features were observed in discospondylitis as well as in other nonfatty endplate pathologies: irregular endplates, endplate hyperintensity in T2w or STIR images, reduced endplate signal intensity in T1w SE, variable T1w GRE signal intensity, and endplate contrast enhancement. Overlap between MR characteristics of nonfatty endplate changes should prompt cautious evaluation of adjacent structures.     

DISCOSPONDYLITIS IN A CAT

The incidence and causative agents of discospondylitis in cats are unknown. This report describes a cat with radiologic changes consistent with discospondylitis and concurrent urinary tract infection. As in dogs, discospondylitis should be the primary rule out for vertebral end plate lysis in cats.     

Surgical treatment of lumbosacral instability caused by discospondylitis in four dogs

OBJECTIVE: To describe a surgical technique involving distraction and stabilization of the lumbo-sacral vertebral segment using an external skeletal fixator in dogs with lumbosacral instability caused by discospondylitis. STUDY DESIGN: Retrospective clinical study. ANIMALS: Four client-owned dogs. METHODS: Medical records of all dogs diagnosed with discospondylitis from 1994 to 1997 were identified and reviewed. Four dogs with lumbosacral discospondylitis requiring surgical treatment were then specifically studied. Surgical technique, clinical signs, preoperative diagnostic investigation, radiographic findings, and the results of short-term and long-term reevaluations were recorded. RESULTS: Twelve dogs with discospondylitis were identified, 4 of which had lumbosacral discospondylitis. These 4 dogs underwent surgical distraction and stabilization because they failed to respond to medical treatment. Three dogs received a cancellous bone graft between L7 and S1 and had rapid interbody fusion of this vertebral segment. The dog that did not receive a graft did not have interbody fusion at the time of fixator removal. This did not affect the final clinical outcome. Lumbosacral pain and neurological deficits present before surgery rapidly subsided after the procedure. All dogs received concurrent antibiotic treatment for a minimum of 4 weeks. All dogs were clinically normal at the time of fixator removal and all continued to do well during the follow-up period (8-48 months; mean, 27.5 months). CONCLUSION AND CLINICAL RELEVANCE: Lumbosacral discospondylitis may not respond well to conservative treatment because of the mobility of the affected space. Surgical treatment involving distraction and stabilization to obtain intervertebral fusion is very effective in treating lumbosacral instability caused by discospondylitis.     

Computed tomographic myelography of a foal with discospondylitis and extradural spinal cord compression due to a vertebral abscess

A one‐month‐old Quarter Horse colt presented with progressive gait abnormalities and weakness. The foal was ataxic at presentation. Radiography identified focal endplate irregularities and lysis at C6–7. Radiographic diagnosis was discospondylitis. Computed tomographic myelography was performed immediately following euthanasia and identified an extradural compressive spinal cord lesion corresponding to the site of discospondylitis. Post mortem examination findings included abscess formation at the C6–7 intervertebral space with osteomyelitis extending into the adjacent physes and subchondral bone of caudal C6 and cranial C7. The vertebral abscess extended into the ventral spinal canal at C6–7 and was identified as the cause of extradural spinal cord compression. Salmonella sp. was cultured and isolated from purulent exudate at the intervertebral space. Computed tomographic myelography has not been previously reported for assessment of discospondylitis in horses and was successful at accurately characterising spinal cord compression in addition to osteolytic changes associated with discospondylitis.     

Cervical Spine Locking Plate Fixation for Treatment of Cervical Spondylotic Myelopathy in Large Breed Dogs

Objective— To describe indirect decompression by means of cervical spine locking plate (CSLP) fixation with vertebral distraction, discectomy, and cancellous block bone grafting in large breed dogs with single caudal cervical dynamic spondylotic lesions diagnosed by myelography with linear traction to the cervical spine, and contrast-enhanced computed tomography.
Study Design— Prospective clinical study.
Animals— Dogs (n=12) with caudal cervical spondylotic myelopathy because of a single dynamic, traction-responsive lesion.
Methods— Single, traction-responsive, caudal cervical spondylotic lesions were treated by vertebral distraction, discectomy, cancellous block bone grafting, and CSLP fixation. Follow-up was obtained by sequential recheck examination by the author or referring veterinarian or by telephone inquiries.
Results— Ten dogs had neurologic improvement after surgery. Indirect decompression by maintained distraction with cancellous block grafting and CSLP fixation was readily accomplished with less risk of blood loss or iatrogenic spinal cord injury than that associated with direct (ventral) decompression. There were no complications of graft intrusion, extrusion or subsidence, implant loosening, foraminal impingement, or end-plate failure. Two dogs that had satisfactory short-term recoveries developed clinical signs associated with adjacent segment disease and were euthanatized. At long-term follow-up, 8 dogs had satisfactory function, either a normal gait or one with slight to moderate proprioceptive deficits.
Conclusions— CSLP fixation with cancellous block interbody grafting is an effective and perhaps safer method of treating single-level, traction-responsive cervical spondylosis in large breed dogs.
Clinical Relevance— CSLP fixation with interbody bone grafting is a viable alternative to other techniques for treatment of single-level, traction-responsive cervical spondylosis.     

The diagnosis and treatment of cauda equina lesions in the dog

The case details of 46 dogs with cauda equina syndrome are reviewed. The causes were variable and included lumbosacral spondylosis, disc protrusion, discospondylitis, fractures, dislocations and neoplasia. Dogs with discospondylitis generally responded well to prolonged antibiotic therapy but the response to conservative treatment of lumbosacral spondylosis or disc protrusion was transient or incomplete. Ten dogs with cauda equina syndrome were treated surgically; the techniques are described and results presented.     

RADIOGRAPHIC FINDINGS DURING RECOVERY FROM DISCOSPONDYLITIS

The diagnosis of discospondylitis is based on radiographic changes in the vertebrae. The limitations of this method are the time gap between the onset of clinical signs and the first appearance of the radiographic findings, as well as the disassociation between the clinical and radiographic signs during recovery. It is known that the radiographic changes appear only two to four weeks after the onset of clinical signs, but the characteristics of radiographic changes during recovery has yet to be documented, thus making follow-up radiographs difficult to interpret. A prospective and retrospective study was designed to document typical radiographic changes during recovery from discospondylitis. We reviewed 12 dogs that had complete and uneventful recovery with antibiotic therapy alone. Periodic follow-up radiographs and clinical examinations were conducted up to five months after the onset of clinical signs to correlate between the clinical status and radiographic changes during recovery. Although the clinical signs improved within the first 10 days of antibiotic therapy, the radiographic deterioration continued before regression and signs of radiographic recovery were noticed. This radiographic deterioration, despite successful antibiotic therapy, appeared shorter in young dogs (less than one year old) and lasted three to nine weeks in older dogs.     

COMPARISON BETWEEN COMPUTED TOMOGRAPHIC AND SURGICAL FINDINGS IN NINE LARGE-BREED DOGS WITH LUMBOSACRAL STENOSIS

In a three-year prospective study, computed tomographic (CT) and surgical findings were compared for nine large breed dogs with lumbosacral stenosis. Surgically-excised tissue was examined histologically in seven dogs and additional necropsy evaluation was performed in one dog. The CT abnormalities observed at sites of confirmed cauda equina compression were: loss of epidural fat, increased soft tissue opacity, bulging of the intervertebral disc margin, spondylosis, thecal sac displacement, narrowed intervertebral foramen, narrowed vertebral canal, thickened articular process, articular process subluxation, articular process osteophyte, and telescoped sacral lamina. The CT characteristics of lumbosacral degenerative disease and discospondylitis were similar to those described in humans. In three dogs, CT findings at the site of cauda equina compression were consistent with congenital or developmental spinal stenosis, but the method of surgical exposure precluded confirmation. Epidural fibrosis (eight dogs) and multi-level CT abnormalities (six dogs) were identified but the cause(s) and significance were unknown.     

The value of the determination of anti-Aspergillus IgG in the serodiagnosis of canine aspergillosis: comparison with galactomannan detection

Diagnosis of canine aspergillosis is difficult using currently available methods. It often passes unnoticed or is diagnosed in the later phases of the disease. We developed an ELISA technique to detect anti-Aspergillus antibodies in canine serum using an Aspergillus antigenic mycelial extract, which could then be used for the diagnosis of canine aspergillosis. We used a cut-off of X + 3SD obtained from 20 control sera. The test was performed on 46 dogs with lesions indicating possible aspergillosis and gave nine positive results: one systemic mycosis, two discospondylitis, one uveitis, two bronchopulmonary processes and three rhinitis. We compared this methodology with the PLATELIA technique in the follow-up of the affected dogs, obtaining the same limitations as in the diagnosis of human aspergillosis. We consider our ELISA technique using sera samples a speedy, safe and reliable method which enables us to follow up the evolution of the disease and the efficacy of the therapy chosen. A definitive diagnosis must still take into account the results of other tests such as clinical examination, radiographic studies, endoscopy and biopsy.     

MAGNETIC RESONANCE, COMPUTED TOMOGRAPHIC AND RADIOLOGIC FINDINGS IN A DOG WITH DISCOSPONDYLITIS

Magnetic resonance (MR), computed tomographic and radiographic imaging were conducted in a dog with discospondylitis. The MR findings were increased T2 and decreased T1 signal intensity of the soft tissues ventral to vertebral bodies, the end plates of the same vertebral bodies and the intervertebral disc, and are similar to those described in human with discospondylitis.     

Radiographic and scintigraphic evaluation of spondylosis in the equine thoracolumbar spine: A retrospective study

Reasons for performing study: Clinical, radiographic and scintigraphic signs associated with spondylosis of the equine thoracolumbar spine have been poorly documented. Objectives: To establish an objective radiographic and scintigraphic grading system for spondylosis lesions; to estimate the prevalence of spondylosis in a population of horses with back pain; and to compare the results of radiography and scintigraphy Methods: Radiographic images of the thoracolumbar spine from 670 horses with clinical signs of back pain were graded. Scintigraphic images from horses with spondylosis lesions underwent subjective and objective analysis. Sensitivity and specificity of scintigraphy for detection of spondylosis relative to radiography for identification of spondylosis were calculated, and Chi‐squared analysis was performed to test for an association between location and severity of lesions. Results: Twenty‐three of 670 horses (3.4%) with back pain had radiographic evidence of spondylosis. Of these horses, 14 (61%) had more than one lesion and 44% (n = 22) of lesions occurred between T11‐T13 vertebral bodies. Only 33% (n = 28) of locations with radiographic changes had increased radiopharmaceutical uptake. Conclusion: Spondylosis occurs at a low prevalence in horses with back pain. It may be present alone or in association with other osseous abnormalities. The clinical significance of spondylosis needs further investigation. Potential relevance: Spondylosis is uncommon but may be a contributor to back pain in the horse.     

MAGNETIC RESONANCE IMAGING FEATURES OF DISCOSPONDYLITIS IN DOGS

The diagnosis of discospondylitis is based mainly on diagnostic imaging and laboratory results. Herein, we describe the magnetic resonance imaging (MRI) findings in 13 dogs with confirmed discospondylitis. In total there were 17 sites of discospondylitis. Eleven (81.1%) of the dogs had spinal pain for >3 weeks and a variable degree of neurologic signs. Two dogs had spinal pain and ataxia for 4 days. Radiographs were available in nine of the dogs. In MR images there was always involvement of two adjacent vertebral endplates and the associated disk. The involved endplates and adjacent marrow were T1‐hypointense with hyperintensity in short tau inversion recovery (STIR) images in all dogs, and all dogs also had contrast enhancement of endplates and paravertebral tissues. The intervertebral disks were hyperintense in T2W and STIR images and characterized by contrast enhancement in 15 sites (88.2%). Endplate erosion was present in 15 sites (88.2%) and was associated with T2‐hypointense bone marrow adjacent to it. In two sites (11.8%) endplate erosion was not MR images or radiographically. The vertebral bone marrow in these sites was T2‐hyperintense. Epidural extension was conspicuous in postcontrast images at 15 sites (88.2%). Spinal cord compression was present at 15 sites (88.2%), and all affected dogs had neurologic signs. Subluxation was present in two sites (11.8%). MRI shows characteristic features of discospondylitis, and it allows the recognition of the exact location and extension (to the epidural space and paravertebral soft tissues) of the infection. Furthermore, MRI increases lesion conspicuity in early discospondylitis that may not be visualized by radiography.     

The Value of the Determination of Anti‐Aspergillus IgG in the Serodiagnosis of Canine Aspergillosis: Comparison with Galactomannan Detection

Diagnosis of canine aspergillosis is difficult using currently available methods. It often passes unnoticed or is diagnosed in the later phases of the disease. We developed an ELISA technique to detect anti‐Aspergillus antibodies in canine serum using an Aspergillus antigenic mycelial extract, which could then be used for the diagnosis of canine aspergillosis. We used a cut‐off of X + 3SD obtained from 20 control sera. The test was performed on 46 dogs with lesions indicating possible aspergillosis and gave nine positive results: one systemic mycosis, two discospondylitis, one uveitis, two bronchopulmonary processes and three rhinitis. We compared this methodology with the PLATELIA technique in the follow‐up of the affected dogs, obtaining the same limitations as in the diagnosis of human aspergillosis. We consider our ELISA technique using sera samples a speedy, safe and reliable method which enables us to follow up the evolution of the disease and the efficacy of the therapy chosen. A definitive diagnosis must still take into account the results of other tests such as clinical examination, radiographic studies, endoscopy and biopsy.     

QUANTITATIVE SURVEY RADIOGRAPHIC EVALUATION OF THE LUMBOSACRAL SPINE OF NORMAL DOGS AND DOGS WITH DEGENERATIVE LUMBOSACRAL STENOSIS

Survey radiographic studies of the lumbosacral region for 93 normal dogs and for 26 dogs with confirmed degenerative lumbosacral stenosis were reviewed. Normal dogs were divided into 9 groups based on age and body weight. For normal dogs, increasing age and body weight were associated with a decreased ability to extend the lumbosacral joint and with increased incidence and severity of spondylosis. Transitional lumbosacral vertebrae and evidence of lumbosacral disc space collapse were very infrequent findings, and the pivot point for lumbosacral motion was consistently centered over the lumbosacral disc space. Relative to an age/weight matched sub-population of normal dogs, dogs with degenerative lumbosacral stenosis had similar mean normalized lumbosacral vertebral canal height, larger mean neutral lumbosacral angle, decreased extension of the lumbosacral joint, increased flexion of the lumbosacral joint, reduced lumbosacral range of motion, increased lumbosacral dynamic malalignment, higher incidence and severity of spondylosis, higher incidence of transitional vertebrae, and higher incidence of lumbosacral disc space collapse. A logistic model based strictly on radiographic parameters was able to discriminate normal from affected dogs with an overall accuracy rate of 86%.     

COMPARISON OF RADIOGRAPHY AND COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF CANINE NASAL ASPERGILLOSIS

To compare the radiographic and computed tomographic (CT) findings and to evaluate the sensitivity of radiography and CT for diagnosis of nasal aspergillosis in dogs, the radiographic and CT studies of 48 dogs with chronic nasal disease were reviewed separately. The radiographic and CT findings were recorded, and a diagnosis was made. The results obtained in the dogs with nasal aspergillosis (n = 25) were used. Based on definite aspergillosis as diagnosis, CT had a sensitivity of 88% and radiography of 72%. Considering definite and probable aspergillosis as equivalent, CT had a sensitivity of 92% and radiography of 84%. The sensitivity was higher in dogs with lesions affecting the entire nasal cavity and frontal sinus on at least one side (n = 20) with a sensitivity of 100% for CT and 90-95% for radiography than in dogs with lesions restricted to the nasal cavities (n = 5) where CT had a sensitivity of 60-80% and radiography of 0-40%. CT was superior to radiography for evaluation of the nasal cavities (mucosal thickening along the nasal bones, surrounding bone hyperostosis/lysis), frontal sinuses (mucosal thickening along the frontal bone, fluid/soft tissue, frontal bone hyperostosis/lysis), and differentiation between a cavitated-like or a mass-like process. This study suggests that CT is more sensitive than radiography for diagnosis of nasal aspergillosis in the dog because of a better demonstration of some changes suggestive of nasal aspergillosis. A diagnosis of a nasal aspergillosis restricted to the nasal cavities or associated with an FB is challenging, even with the use of CT.     

IMAGING FINDINGS IN DOGS WITH CAUDAL INTERVERTEBRAL DISC HERNIATION

The radiographic and magnetic resonance imaging (MRI) findings for four dogs with herniation of the Cd1–Cd2 intervertebral disc are described. All dogs were 7 years of age at the time of presentation, with one neutered male and three neutered females. Breeds included one Beagle, one Bassett hound, and two large, mixed breed dogs. All dogs had tail pain on manipulation, two had pain during defecation, and two maintained an abnormal tail position. Three dogs had radiographs in which mineralization within the disc space was apparent. Two of these dogs also had mineralization within the vertebral canal. Three dogs underwent MRI, which was characterized by varying degrees of disc herniation and nerve root compression at Cd1–Cd2. Mobility may be a factor predisposing to disc herniation in the cranial aspect of the caudal spine. We documented that caudal disc herniation does occur occasionally in dogs and that radiography and MRI may be used to identify this disease. Caudal intervertebral disc herniation should be considered as a differential for dogs with caudal vertebral pain, pain with tail manipulation, pain during defecation, or abnormal tail carriage.     

MAGNETIC RESONANCE IMAGING OF THE CAUDAL LUMBAR AND LUMBOSACRAL SPINE IN 13 DOGS (1990–1993)

The caudal lumbar and lumbosacral spine of 13 dogs with pain or neurologic deficits were evaluated using magnetic resonance imaging (MRI). Spin echo T1, proton density, and T2 weighted and gradient echo T2* imaging sequences were utilized. MRI permitted direct, multiplanar, tomographic visualization of the spine facilitating evaluation of all components of degenerative caudal lumbar and lumbosacral stenosis. Abnormalities detected included intervertebral disc degeneration, intervertebral disc protrusion involving both the vertebral canal and intervertebral foramina, articular process osteophytosis, articular process fracture, nerve root impingement by spondylosis deformans, and the presence of low signal material within the vertebral canal of 2 dogs with recurrent pain following previous spinal surgery. In all 7 dogs treated surgically, MRI findings were consistent with surgical findings.     

Dysplasia of the caudal vertebral articular facets in four dogs: results of radiographic, myelographic and magnetic resonance imaging investigations

Congenital anomalies of the vertebral column associated with aberrations of one of the primary vertebral ossification centres have been frequently described in the veterinary literature, but clinically significant abnormalities of secondary vertebral ossification centres, particularly involving the caudal articular processes, are much less frequently reported. This paper describes three dogs with aplasia and one dog with hypoplasia of the caudal vertebral articular processes. Thoracolumbar spinal cord compression and ataxia was evident in the three dogs with aplasia but no clinical signs were evident in the dog with hypoplasia. The radiographic appearance was similar in all four cases, with aplasia or hypoplasia of the caudal articular facets at one or more intervertebral joints in the thoracolumbar region. Bone proliferation was evident secondary to an associated degenerative joint disease. Compensatory hyperplasia of the adjacent cranial articular facets and ligamentum flavum protruded into the vertebral canal, resulting in a compressive myelopathy observed by myelography and magnetic resonance imaging.     

DISCOGRAPHY AND EPIDUROGRAPHY FOR EVALUATION OF THE LUMBOSACRAL JUNCTION IN DOGS WITH CAUDA EQUINA SYNDROME

Cauda equina syndrome in the dog is a common neurologic disorder caused by compression of the spinal cord, nerve roots and spinal nerves caudal to the fifth lumbar vertebra. This paper describes the clinical signs, radiographic findings of discography and/or epidurography, and comparison with surgery or necropsy of 21 dogs with cauda equina syndrome. Discograms were performed by using a 20- or 22-gauge spinal needle introduced in a sagittal plane into the lumbosacral (LS) disc space under fluoroscopic guidance. Epidurograms were performed following discography by injecting contrast medium after repositioning the tip of the needle into the ventral epidural space at the level of the LS junction. Direct examination of the LS junction was performed in all dogs by surgical exploration and/or necropsy. On survey radiographs, the most common findings were spondylosis, malalignment of the sacrum to the last lumbar vertebra, collapse of the LS disc space, stenosis of the vertebral canal at the LS junction, and transitional vertebral segments. Discography was considered of diagnostic quality in 19/21 (90%) of the dogs, showing disc protrusion in 14/21 (67%). Epidurography was of diagnostic quality in 18/18 (100%) dogs, showing abnormal findings in 14/18 (78%). No adverse reaction was noted to the radiographic procedure when dogs were allowed to recover from anesthesia before surgery. Based on macroscopic findings, combination of survey radiographs and disco-epidurography was correctly positive in 16/18 dogs (89%). It is concluded that discography associated with epidurography is a valuable procedure for evaluation of the LS junction in the dog. A combination of both procedures reduces the possibility of technical artifacts by outlining both sides of the compressive lesion, i.e., the disc and the epidural space.