Functional outcome in dogs after surgical treatment of caudal lumbar intervertebral disk herniation.

Caudal lumbar disk herniations (i.e., third lumbar [L3] to seventh lumbar [L7] intervertebral spaces) represent approximately 15% of surgically treated thoracolumbar disk herniations in dogs. A retrospective case-control study was conducted to determine the postoperative outcome of this subset of dogs in the authors' neurosurgical practice. Medical records (1985 through 1996) were reviewed for dogs with caudal lumbar disk herniation confirmed at surgery. Thirty-six cases were identified. For each case, two dogs that underwent surgical treatment for upper motor neuron thoracolumbar disk herniation (tenth thoracic [T10] to L3 intervertebral spaces) were selected as controls. Probabilities of functional recovery for cases and controls were 81% and 85%, respectively (p value of 0.49). In dogs with caudal lumbar disk herniation, complete sensorimotor loss was the only significant predictor of functional recovery (p value of 0.005). Disk herniations that occur at the thoracolumbar junction and those that occur in the caudal lumbar region should not be considered to be different in terms of surgical treatment and postoperative outcome. The lower motor neuron signs that often accompany caudal lumbar disk herniation reflect the site of spinal cord injury and do not necessarily predict a poor prognosis.     

Association between various physical factors and acute thoracolumbar intervertebral disk extrusion or protrusion in Dachshunds

OBJECTIVE: To determine whether body weight, body condition score, or various body dimensions were associated with acute thoracolumbar intervertebral disk extrusion or protrusion and whether any of these factors were associated with severity of clinical signs in Dachshunds. DESIGN: Cross-sectional clinical study. ANIMALS:75 Dachshunds with (n = 39) or without (36) acute thoracolumbar intervertebral disk extrusion or protrusion. PROCEDURES: Signalment, various body measurements, body weight, body condition score, and spinal cord injury grade were recorded at the time of initial examination. RESULTS: Mean T1-S1 distance and median tuber calcaneus-to-patellar tendon (TC-PT) distance were significantly shorter in affected than in unaffected dogs. A 1-cm decrease in T1-S1 distance was associated with a 2.1-times greater odds of being affected, and a 1-cm decrease in TC-PT distance was associated with an 11.1-times greater odds of being affected. Results of multivariable logistic regression also indicated that affected dogs were taller at the withers and had a larger pelvic circumference than unaffected dogs, after adjusting for other body measurements. Results of ordinal logistic regression indicated that longer T1-S1 distance, taller height at the withers, and smaller pelvic circumference were associated with more severe spinal cord injury. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that certain body dimensions may be associated with acute thoracolumbar intervertebral disk extrusion or protrusion in Dachshunds and, in affected dogs, with severity of neurologic dysfunction.     

Fecal incontinence associated with epidural spinal hematoma and intervertebral disk extrusion in a dog

CASE DESCRIPTION: A 7-year-old castrated male Great Dane was evaluated because of a 2-month history of fecal incontinence. CLINICAL FINDINGS: On the basis of the presence of paraparesis and apparently normal spinal reflexes, the neurologic signs were localized in the region of the third thoracic to the third lumbar spinal cord segments. On the basis of the findings of magnetic resonance imaging, a presumptive diagnosis of a compressive intervertebral disk extrusion with secondary hemorrhage and epidural hematoma formation was made. TREATMENT AND OUTCOME: A right-sided hemil-aminectomy was performed (centered at the T13-L1 intervertebral space) to further characterize the lesion and decompress the spinal cord. The histopathologic diagnosis was extruded intervertebral disk material with chronic hemorrhage and inflammation. Three weeks after surgery, there was complete resolution of the dog's fecal incontinence and moderate improvements in its hind limb function. CLINICAL RELEVANCE: Thoracolumbar spinal cord injuries can result in upper motor neuron fecal incontinence in ambulatory dogs. Epidural spinal hematomas may develop secondary to intervertebral disk herniations and cause spinal cord compression resulting in neurologic deficits.     

Long-term functional outcome of dogs with severe injuries of the thoracolumbar spinal cord: 87 cases (1996-2001)

OBJECTIVE: To determine long-term (> 6 months) outcome of dogs with paraplegia and loss of hind limb deep pain perception (DPP) resulting from intervertebral disk herniation or trauma. DESIGN: Retrospective study. ANIMALS: 87 dogs. PROCEDURE: Outcome was determined as successful or unsuccessful. The association of neuroanatomic localization, breed, age, weight, sex, and (for dogs with intervertebral disk herniation) speed of onset of signs and duration of paraplegia prior to surgery with outcome was evaluated. Owners were contacted by telephone to identify long-term health problems. RESULTS: Nine of 17 dogs with traumatic injuries were treated, and 2 regained the ability to walk; none of the 17 dogs regained DPP. Sixty-four of 70 dogs with intervertebral disk herniation underwent surgery; 9 (14%) were euthanatized within 3 weeks after surgery (7 because of ascending myelomalacia), 37 (58%) regained DPP and the ability to walk, 7 (11%) regained the ability to walk without regaining DPP, and 11 (17%) remained paraplegic without DPP. Outcome was not associated with any of the factors evaluated, but speed of recovery of ambulation was significantly associated with body weight and age. Fifteen (41%) and 12 (32%) dogs that regained DPP had intermittent fecal and urinary incontinence, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the prognosis for paraplegic dogs without DPP because of trauma was guarded, while dogs with disk herniation had a better chance of recovering motor function. A third of the dogs that recovered motor function had intermittent incontinence. Persistent loss of DPP did not preclude recovery of motor function, but such dogs remained incontinent.     

Magnetic resonance imaging findings in dogs with thoracolumbar intervertebral disk disease: 69 cases (1997-2005)

OBJECTIVE: To determine magnetic resonance imaging (MRI) abnormalities in dogs with intervertebral disk disease (IVDD) and develop a classification scheme for IVDD in dogs based on MRI findings. DESIGN: Retrospective case series. ANIMALS: 69 dogs. PROCEDURE: Medical records of dogs admitted because of thoracolumbar IVDD in which MRI of T9 through L7 had been performed were reviewed. RESULTS: A total of 759 intervertebral disk spaces were examined. Of these, 342 (45.1%) were classified as having a normal MRI appearance; the remaining 417 (54.9%) had various types of IVDD. Disk degeneration was identified in 276 disk spaces in 56 dogs, bulging of the intervertebral disk was identified in 37 disk spaces in 24 dogs, disk protrusion was identified in 54 disk spaces in 32 dogs, and disk extrusion was identified in 50 disk spaces in 48 dogs. Cartilage endplate changes were identified in 35 vertebrae in 17 dogs, and increased signal intensity of the spinal cord was identified in 21 dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Four types of IVDD (disk degeneration, bulging of the intervertebral disk, disk protrusion, and disk extrusion) were identified on the basis of MRI findings in dogs with thoracolumbar IVDD. We recommend that a standardized nomenclature be adopted for the various types of thoracolumbar IVDD in dogs.     

CLINICAL AND MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF THORACOLUMBAR INTERVERTEBRAL DISK EXTRUSIONS AND PROTRUSIONS IN LARGE BREED DOGS

Treatment recommendations differ for dogs with intervertebral disk extrusion vs. intervertebral disk protrusion. The aim of this retrospective, cross‐sectional study was to determine whether clinical and magnetic resonance imaging (MRI) variables could be used to predict a diagnosis of thoracolumbar intervertebral disk extrusion or protrusion in dogs. Dogs were included if they were large breed dogs, had an MRI study of the thoracolumbar or lumbar vertebral column, had undergone spinal surgery, and had the type of intervertebral disk herniation (intervertebral disk extrusion or protrusion) clearly stated in surgical reports. A veterinary neurologist unaware of surgical findings reviewed MRI studies and recorded number, location, degree of degeneration and morphology of intervertebral disks, presence of nuclear clefts, disk space narrowing, extent, localization and lateralization of herniated disk material, degree of spinal cord compression, intraparenchymal intensity changes, spondylosis deformans, spinal cord swelling, spinal cord atrophy, vertebral endplate changes, and presence of extradural hemorrhage. Ninety‐five dogs were included in the sample. Multivariable statistical models indicated that longer duration of clinical signs (P = 0.01), midline instead of lateralized disk herniation (P = 0.007), and partial instead of complete disk degeneration (P = 0.01) were associated with a diagnosis of intervertebral disk protrusion. The presence of a single intervertebral herniation (P = 0.023) and dispersed intervertebral disk material not confined to the disk space (P = 0.06) made a diagnosis of intervertebral disk extrusion more likely. Findings from this study identified one clinical and four MRI variables that could potentially facilitate differentiating intervertebral disk extrusions from protrusions in dogs.     

Evaluation of electroacupuncture treatment for thoracolumbar intervertebral disk disease in dogs

OBJECTIVE: To evaluate use of electroacupuncture combined with standard Western medical treatment versus Western medical treatment alone for treatment of thoracolumbar intervertebral disk disease in dogs. DESIGN: Prospective controlled study. ANIMALS: 50 dogs with signs of thoracolumbar intervertebral disk disease. PROCEDURES: Dogs were randomly allocated to 1 of 2 treatment groups and classified as having grade 1 to 5 neurologic dysfunction. Dogs in group 1 received electroacupuncture stimulation combined with standard Western medical treatment; those in group 2 received only standard Western medical treatment. A numeric score for neurologic function was evaluated at 4 time points to evaluate effects of treatments. RESULTS: Time (mean +/- SD) to recover ambulation in dogs with grade 3 and 4 dysfunction in group 1 (10.10 +/- 6.49 days) was significantly lower than in group 2 (20.83 +/- 11.99 days). Success (able to walk without assistance) rate for dogs with grade 3 and 4 dysfunction in group 1 (10/10 dogs) was significantly higher than that of similarly affected dogs in group 2 (6/9 dogs). Dogs without deep pain perception (grade 5 dysfunction) had a success (recovery of pain sensation) rate of 3 of 6 and 1 of 8 in groups 1 and 2, respectively, but the difference was not significant. Overall success rate (all dysfunction grades) for group 1 (23/26; 88.5%) was significantly higher than for group 2 (14/24; 58.3%). CONCLUSIONS AND CLINICAL RELEVANCE: Electroacupuncture combined with standard Western medical treatment was effective and resulted in shorter time to recover ambulation and deep pain perception than did use of Western treatment alone in dogs with signs of thoracolumbar intervertebral disk disease.     

Endoscope‐Assisted Thoracolumbar Lateral Corpectomy

Objective: To report an endoscope‐assisted lateral approach to expose the intervertebral foramen and disk and perform lateral corpectomy of thoracolumbar disks in dogs. Study Design: Cadaver study. Animals: Fresh canine cadavers (n=6). Methods: A thoracic (T10–T11) and a lumbar (L3–L4) lateral approach were made on 6 fresh canine mixed breed cadavers. Through a limited skin incision, musculature was dissected and retracted using a neurosurgical self‐retaining retractor and lateral corpectomy performed. The approach and bone removal, both performed under endoscopic control, were assessed. Results: The foramen and intervertebral disk were clearly observed in all specimens without any iatrogenic injury of the ventral and dorsal nerve branches. Access to the foramen was possible in all specimens; in the thoracic area the head of the rib was always partially excised to observe the intervertebral disk medially. Lateral corpectomy was easily performed in all cadavers and spinal cord observation was good. Extension to foraminotomy or mini hemilaminectomy could easily be performed through the same limited approach. Conclusion: Endoscopic exploration provided a good viewing of the intervertebral disk and/or foramen. An endoscope‐assisted thoracolumbar lateral corpectomy could effectively be performed through a limited approach to the thoracolumbar disks and allowed good ventral spinal cord assessment.     

THORACOLUMBAR INTRADURAL DISC HERNIATION IN EIGHT DOGS: CLINICAL,LOW‐FIELD MAGNETIC RESONANCE IMAGING,AND COMPUTED TOMOGRAPHIC MYELOGRAPHY FINDINGS

Intradural disc herniation is a rarely reported cause of neurologic deficits in dogs and few published studies have described comparative imaging characteristics. The purpose of this retrospective cross sectional study was to describe clinical and imaging findings in a group of dogs with confirmed thoracolumbar intradural disc herniation. Included dogs were referred to one of four clinics, had acute mono/paraparesis or paraplegia, had low field magnetic resonance imaging (MRI) and/or computed tomographic myelography, and were diagnosed with thoracolumbar intradural disc herniation during surgery. Eight dogs met inclusion criteria. The prevalence of thoracolumbar intradural disc herniation amongst the total population of dogs that developed a thoracolumbar intervertebral disc herniation and that were treated with a surgical procedure was 0.5%. Five dogs were examined using low‐field MRI. Lesions that were suspected to be intervertebral disc herniations were observed; however, there were no specific findings indicating that the nucleus pulposus had penetrated into the subarachnoid space or into the spinal cord parenchyma. Thus, the dogs were misdiagnosed as having a conventional intervertebral disc herniation. An intradural extramedullary disc herniation (three cases) or intramedullary disc herniation (two cases) was confirmed during surgery. By using computed tomographic myelography (CTM) for the remaining three dogs, an intradural extramedullary mass surrounded by an accumulation of contrast medium was observed and confirmed during surgery. Findings from this small sample of eight dogs indicated that CTM may be more sensitive for diagnosing canine thoracolumbar intradural disc herniation than low‐field MRI.     

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.     

MYELOGRAPHY VS. COMPUTED TOMOGRAPHY IN THE EVALUATION OF ACUTE THORACOLUMBAR INTERVERTEBRAL DISK EXTRUSION IN CHONDRODYSTROPHIC DOGS

Myelography and/or computed tomography (CT) are commonly used to evaluate acute intervertebral disk extrusion in chondrodystrophic dogs. The purpose of this study was to evaluate the sensitivity of myelography and two different CT protocols in determining level and lateralization of acute thoracolumbar intervertebral disk extrusion in comparison with surgical findings, investigate interobserver variability, and determine examination duration times. Results of conventional CT, helical CT, and myelography were compared with surgical findings in 19 chondrodystrophic dogs with acute thoracolumbar intervertebral disk extrusion. Agreement among investigators was determined for different imaging modalities, and examination times were recorded. In the diagnosis of level of disk extrusion there was agreement of myelography, conventional CT, and helical CT with surgical findings in 94.7%, 100%, and 94.7% of dogs, respectively ( P =0.144). In the diagnosis of level and lateralization of disk extrusion there was agreement of myelography, conventional CT, and helical CT with surgical findings in 78.9%, 87.4%, and 85.3% of dogs, respectively ( P =0.328). Interobserver agreement was very good for all imaging modalities (myelography κ=0.87; conventional CT κ=0.86; helical CT κ=0.95). There were significant differences in median examination duration times between helical CT (4 min), conventional CT (8 min), and myelography (32 min) ( P <0.001). Both helical and conventional CT appear to be accurate for evaluation of acute thoracolumbar intervertebral disk extrusion in chondrodystrophic dogs and are faster to perform than myelography.     

Incidence of seizures associated with iopamidol or iomeprol myelography in dogs with intervertebral disk disease: 161 cases (2000–2002)

Objective – To compare the incidence of seizures in dogs with intervertebral disk disease after iopamidol or iomeprol myelography, and to assess whether the incidence of seizures differed between the 2 agents when severity of neurological deficits, location of cord compression, duration of anesthesia, site of myelogram, volume of contrast, and concentration of contrast were evaluated. Design – Retrospective study. Setting – Veterinary teaching hospital. Animals – One hundred and sixty‐one client‐owned dogs with intervertebral disk disease. Interventions – Subarachnoid injection of contrast medium. Measurements and Main Results – One hundred and sixty‐one dogs with intervertebral disk disease were subjected to myelography using iopamidol (n=74) or iomeprol (n=87). Cranial myelography was performed in 31 dogs, caudal myelography in 125 and both cranial and caudal myelography in 5. Seizures occurred in 23 of 161 (14%) dogs. There was no significant difference overall between iopamidol and iomeprol myelography. However, in dogs with thoracolumbar disk extrusion and paraplegia, seizures occurred more frequently after caudal myelography using iopamidol compared with iomeprol. Conclusions – Both iomeprol and iopamidol are suitable for myelography in dogs. Iomeprol is recommended for caudal myelography in paraplegic dogs with thoracolumbar disk extrusion due to the higher incidence of seizures in this group when iopamidol was used.     

EVALUATION OF MAGNETIC RESONANCE IMAGING GUIDELINES FOR DIFFERENTIATION BETWEEN THORACOLUMBAR INTERVERTEBRAL DISK EXTRUSIONS AND INTERVERTEBRAL DISK PROTRUSIONS IN DOGS

Four MRI variables have recently been suggested to be independently associated with a diagnosis of thoracolumbar intervertebral disk extrusion or protrusion. Midline intervertebral disk herniation, and partial intervertebral disk degeneration were associated with intervertebral disk protrusion, while presence of a single intervertebral disk herniation and disk material dispersed beyond the boundaries of the intervertebral disk space were associated with intervertebral disk extrusion. The aim of this retrospective, cross‐sectional study was to determine whether using these MRI variables improves differentiation between thoracolumbar intervertebral disk extrusions and protrusions. Eighty large breed dogs with surgically confirmed thoracolumbar intervertebral disk extrusions or protrusions were included. Randomized MRI studies were presented on two occasions to six blinded observers, which were divided into three experience categories. During the first assessment, observers made a presumptive diagnosis of thoracolumbar intervertebral disk extrusion or protrusion without guidelines. During the second assessment they were asked to make a presumptive diagnosis with the aid of guidelines. Agreement was evaluated by Kappa‐statistics. Diagnostic accuracy significantly improved from 70.8 to 79.6% and interobserver agreement for making a diagnosis of intervertebral disk extrusion or intervertebral disk protrusion improved from fair (κ = 0.27) to moderate (κ = 0.41) after using the proposed guidelines. Diagnostic accuracy was significantly influenced by degree of observer experience. Intraobserver agreement for the assessed variables ranged from fair to excellent and interobserver agreement ranged from fair to moderate. The results of this study suggest that the proposed imaging guidelines can aid in differentiating thoracolumbar intervertebral disk extrusions from protrusions.     

THE COMPUTED TOMOGRAPHIC APPEARANCE OF ACUTE THORACOLUMBAR INTERVERTEBRAL DISC HERNIATIONS IN DOGS

The appearance of herniated intervertebral disc material in the thoracolumbar vertebral canal was evaluated in 23 dogs using computed tomography (CT). The images were then compared with the myelographic and surgical findings. The normal spinal cord, outlined by epidural fat over intervertebral disc spaces, was of intermediate attenuation on transverse CT images. Herniated disc material was identified in all animals as a heterogeneous hyperattenuating extradural mass. The attenuation of the disc material increased with the degree of mineralization. In seven dogs, the herniated material was only slightly more attenuating than the spinal cord. In these dogs, small fragments of mineralized disc material and significant hemorrhage were found in the epidural space at surgery. In dogs with a long standing history of disc herniations, disc material identified in the vertebral canal had a more hyperattenuating and homogeneous appearance than recently herniated disc material. We conclude that mineralized, herniated disc material and hemorrhage can be identified quickly and safely in dogs using CT.     

Transplantation of adipose derived mesenchymal stem cells for acute thoracolumbar disc disease with no deep pain perception in dogs

Thirty-four dogs with no deep pain perception due to acute thoracolumbar intervertebral disc disease underwent decompression surgery within 1 week of diagnosis. All dogs underwent hemilaminectomy. Adipose derived mesenchymal stem cells (AD-MSCs) were transplanted into the injured spinal cord parenchyma for the AD-MSCs transplant dogs. Long-term outcome was evaluated at the end of the follow-up period (> 6 months). AD-MSCs combination treatment showed better recovery outcomes compared to decompression surgery alone. These results indicate that this stem cell therapy is a potential therapeutic strategy to overcome the limitations of treatment for spinal cord injury in clinical medicine.     

Intervertebral disc extrusion in six cats

Existing reports concerning intervertebral disc disease (IVDD) have focused almost exclusively on dogs, although a small number of individual case reports of IVDD of cats has been published. The medical records of six cats with IVDD were reviewed. Radiographic studies confirmed narrowed intervertebral disc spaces, mineralised intervertebral discs, and one or more extradural compressive lesions of the spinal cord in each cat. All disc extrusions were located in the thoracolumbar region. Surgical decompression of the spinal cord was achieved in all cats by means of hemilaminectomy and removal of compressive extradural material confirmed to be degenerative disc material. Good to excellent neurological recovery was noted in five of the six cats included in this report. Based on this review, it appears that IVDD of cats has many similarities to IVDD of dogs, and that healthy cats with acute intervertebral disc extrusion(s) respond favourably to surgical decompression of the spinal cord.     

Association of cerebrospinal fluid analysis findings with clinical signs and outcome in acute nonambulatory thoracolumbar disc disease in dogs

Background: Cerebrospinal fluid (CSF) pleocytosis recently was associated with the severity of neurologic signs in dogs with intervertebral disc disease (IVDD). Hypothesis/Objectives: To look for an association among CSF cell counts, total protein concentration, and severity of neurologic signs at presentation with outcome in dogs with acute thoracolumbar IVDD. Our hypothesis was that CSF total nucleated cell count (TNCC) and percentage cell types would be associated with the severity of spinal cord damage and therefore with both the presenting clinical signs and the prognosis of affected dogs. Animals: Fifty‐four dogs with acute nonambulatory thoracolumbar IVDD were evaluated. Methods: Retrospective study. Signalment, neurologic grade, CSF TNCC, protein concentration, red blood cells count and differential cell percentages, and short‐ and long‐term outcomes were evaluated. Results: CSF pleocytosis (>5 cells/μL) was present in 54% of dogs and was positively associated with neurologic grade at presentation and with postoperative time to regaining ambulation. Neutrophils were observed most frequently. The percentage of CSF macrophages and macrophage to monocyte ratio were higher (P= .001, for both) in dogs presented without deep pain sensation (DPS) that did not regain ambulation. Receiver operator characteristics curve analysis yielded a cut‐off point of 13% macrophages with a sensitivity and specificity of 100 and 83%, respectively, for prediction of a negative outcome. Conclusions and Clinical Importance: CSF pleocytosis is positively associated with the severity of spinal cord damage in dogs with thoracolumbar IVDD. The percentage of CSF macrophages can be used as a prognostic indicator for regaining ambulation in dogs that have lost DPS.     

Incidence of Spinal Compressive Lesions in Chondrodystrophic Dogs with Abnormal Recovery after Hemilaminectomy for Treatment of Thoracolumbar Disc Disease: A Prospective Magnetic Resonance Imaging Study

Objective— To investigate causes of the lack of clinical improvement after thoracolumbar disc surgery. Study Design— Case–control magnetic resonance imaging (MRI) study. Animals— Chondrodystrophic dogs with acute thoracolumbar disc disease treated by hemilaminectomy: 10 that had no short‐term clinical improvement and 12 with “normal” clinical improvement. Methods— Dogs that had surgery for treatment of intervertebral disc extrusion (2003–2008) where thoracolumbar disc disease was confirmed by MRI were evaluated to identify dogs that had lack of clinical improvement after surgery. Ten dogs with delayed recovery or clinical deterioration were reexamined with MRI and compared with 12 dogs with normal recovery and MRI reexamination after 6 weeks (control group). Results— Of 173 dogs, 10 (5.8%) had clinical deterioration within 1–10 days after surgery. In 8 dogs, residual spinal cord compression was identified on MRI. Bleeding was present in 1 dog. In 3 dogs, the cause was an incorrect approach and insufficient disc material removal. In 3 dogs, recurrence occurred at the surgical site. In 1 dog, the centrally located extruded material was shifted to the contralateral side during surgery. These 8 dogs had repeat surgery and recovery was uneventful. In 2 dogs, deterioration could not be associated with a compressive disc lesion. Hemorrhagic myelomalacia was confirmed by pathologic examination in 1 dog. The other dog recovered after 6 months of conservative management. Conclusion— Delayed postsurgical recovery or deterioration is commonly associated with newly developed and/or remaining compressive disc lesion. Clinical Relevance— We recommend early MRI reexamination to assess the postsurgical spinal canal and cord, and to plan further therapeutic measures in chondrodystrophic dogs with delayed recovery after decompressive hemilaminectomy for thoracolumbar disc disease.     

Association of spinal cord compression seen on magnetic resonance imaging with clinical outcome in 67 dogs with thoracolumbar intervertebral disc extrusion

OBJECTIVES: To determine whether there is an association between the degree of transverse spinal cord compression detected by magnetic resonance imaging following thoracolumbar Hansen type 1 intervertebral disc disease in dogs and their presenting and postsurgical neurological status. METHODS: Medical records of 67 dogs with surgically confirmed Hansen type 1 intervertebral disc disease (2000 to 2004) were reviewed to obtain the rate of onset of disease, duration of clinical signs and presurgical and postsurgical neurological grade. Percentage of spinal cord compression was determined on transverse T2-weighted magnetic resonance images. Linear regression was used to examine the association between spinal cord compression and each of the above variables. Chi-squared tests were used to examine associations among postsurgical outcome and presurgical variables. RESULTS: Eighty-five per cent (57 of 67) of dogs were chondrodystrophoid. Mean spinal cord compression was 53 per cent (sd=219.7, range 14.3 to 84.9 per cent). There was no association between the degree of spinal cord compression and the neurological grade at presentation, rate of onset of disease, duration of clinical signs or postsurgical outcome, with no difference between chondrodystrophoid and non-chondrodystrophoid dogs. CLINICAL SIGNIFICANCE: The degree of spinal cord compression documented with magnetic resonance imaging in dogs with thoracolumbar Hansen type 1 intervertebral disc disease was not associated with the severity of neurological signs and was not a prognostic indicator in this study.     

Pneumorrhachis in a rottweiler

An 8·5-year-old, female, neutered, Rottweiler was presented for investigation of progressive ataxia of one week duration. Proprioception was absent in the left pelvic limb and reduced on the right, thoracolumbar hyperalgesia was evident and pelvic limb segmental spinal reflexes were normal. Magnetic resonance imaging (MRI) demonstrated a spherical region of signal void compressing the spinal cord between the fifth and sixth thoracic vertebrae and several non-compressive degenerate intervertebral discs. Computed tomography (CT) of the region confirmed the findings and identified the lesion as gas. A dorsolateral hemilaminectomy was performed to decompress the spinal cord and achieved complete resolution of the clinical signs on examination after 3 months. This is the first known reported case of spontaneous pneumorrhachis in a veterinary patient.