Erector spinae plane block in dogs undergoing hemilaminectomy: A prospective randomized clinical trial

OBJECTIVE

To compare the perioperative cumulative opioid consumption and the incidence of cardiovascular complications in dogs undergoing hemilaminectomy in which either an erector spinae plane (ESP) block or systemic opioids were administered.

STUDY DESIGN

Prospective randomized clinical trial.

ANIMALS

A total of 60 client-owned dogs.

METHODS

Dogs were randomized to one of three groups: an ESP block (group ESP), a constant rate infusion of fentanyl (group FNT, positive control) or a single dose of methadone as premedication (group MTD, negative control). Intraoperative nociceptive response was treated with fentanyl [1 μg kg-1, intravenously (IV)] boli. Before closure of the surgical site, morphine (0.1 mg kg-1) was applied to the dura mater. The cumulative dose of opioids was recorded and compared between groups. The incidence of intraoperative bradycardia and/or hypotension and the time to extubation were compared between groups. The short form of the Glasgow Composite Pain Scale (SF-GCPS) was used to score nociception before anaesthetic induction and 1, 2, 6, 12,18 and 24 hours postoperatively. Methadone 0.2 mg kg-1 was administered IV if the SF-GCPS score was ≥ 5.

RESULTS

Group MTD required more intraoperative rescue analgesia than groups ESP (p = 0.008) and FNT (p = 0.001). The total cumulative intraoperative dose of fentanyl was higher in groups FNT (p < 0.0001) and MTD (p = 0.002) than in group ESP. The incidence of cardiovascular complications was similar between groups. Extubation time was longer in group MTD (p = 0.03). Postoperatively, the time to first rescue analgesia was longer in group ESP than in group MTD (p = 0.03). The cumulative postoperative opioid consumption and pain scores were similar between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

The ESP block resulted in a reduced intraoperative opioid consumption compared with the control positive and negative groups.

Perioperative analgesic effects of the erector spinae plane block with bupivacaine or bupivacaine-dexmedetomidine in dogs undergoing hemilaminectomy: A randomized controlled trial

Objective

To compare the perioperative opioid requirements among dogs receiving an erector spinae plane (ESP) block with bupivacaine, with or without dexmedetomidine, and a control group.

Animals and procedure

Thirty client-owned, healthy adult dogs undergoing hemilaminectomy were included in this randomized, prospective, blinded clinical study. Dogs were randomly assigned to 1 of 3 treatment groups: Group B, ESP block with bupivacaine; Group BD, ESP block with bupivacaine and dexmedetomidine; and Group C, control. Rescue intra- and postoperative analgesia consisted of fentanyl and methadone, respectively. Postoperative pain was evaluated using the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF).

Results

In Group BD, 0/10 dogs required intraoperative fentanyl, compared to 9/10 in Group C (P < 0.001), whereas 1/10 required postoperative methadone, compared to 9/10 in Group B (P = 0.003) and 10/10 in Group C (P < 0.001). The total amount of intraoperative fentanyl (μg/kg) was 0 (0 to 4) in Group B and 0 (0 to 0) in BD, compared to 6 (0 to 8) in C (P = 0.004 and P < 0.001, respectively). Postoperative methadone (mg/kg) required during the first 12 h was 0.5 (0 to 1.4) in Group B (P = 0.003) and 0 (0 to 0) in BD (P < 0.001), compared to C (P = 0.003 and P < 0.001, respectively).

Conclusion

An ESP block with bupivacaine, with or without dexmedetomidine, was associated with a reduction in perioperative opioid consumption and provided effective acute pain control.

Thoracic Vertebral Canal Stenosis and Vertebral Instability in a Young Minuet Cat

This report describes a unique case of thoracic vertebral canal stenosis and vertebral instability in a 1 yr old Minuet cat. The cat presented with a history of chronic progressive nonambulatory paraparesis. Myelography with neutral and stress positions revealed dynamic compression at T1-4. Computed tomography and MRI revealed multiple sites of vertebral endplate osteolysis, adjacent bone sclerosis, intervertebral disk space narrowing, and spondylotic bridging within the cervical and cranial thoracic vertebral bodies and pedicles, particularly at C6-T4. The cat underwent a right-sided T1-4 hemilaminectomy and C7-T4 vertebral stabilization using positively threaded profile pins and polymethylmethacrylate. The cat fully recovered without any complication. The case highlights the potential for young cats, especially those with a chondrodysplastic condition, to develop vertebral canal stenosis and vertebral instability. The surgical treatment described herein resulted in an excellent outcome.

Clinical features of early recurrence of type I thoracolumbar intervertebral disk herniation in Miniature Dachshunds

Some reports have been published on clinical features in dogs with early recurrence of type I thoracolumbar intervertebral disk herniation (TL-IVDH), but there is little understanding of the changes involved. This retrospective study describes the clinical features, including radiographic image results at the time of recurrence, of dogs with type I TL-IVDH that had undergone hemilaminectomy but then suffered early recurrence. Our medical records were searched between June 2007 and December 2022. Nine dogs showed deterioration in neurological signs within 4 to 6 weeks after surgery. All nine were Miniature Dachshunds. Radiographic images at initial onset showed calcification at the affected intervertebral disk space in all 9 dogs. Disk herniations at the initial onset were located between T11-12 and L1-2. After the first surgery, neurological function improved in all dogs. Recurrence occurred at the same site as at initial onset in all dogs. No calcification was observed at the affected intervertebral disk space on images at the time of recurrence. The extruded disk materials were surgically removed, and neurological function improved after the second surgery. In conclusion, calcification at the affected disk space at the time of initial onset is indicative of residual nucleus materials not yet fully extruded, and is a risk factor for early recurrence of type I TL-IVDH.

A feline spinal dermoid cyst treated with surgical intervention

A 5-year-old neutered female mixed cat presented with reduced activity and ataxia of the hind limbs. Computed tomography and magnetic resonance imaging revealed an extradural mass compressing the spinal cord on the dorsal aspects from the 7th to 8th thoracic vertebra. Dorsal laminectomy was performed on the 7-8th thoracic vertebra and the cyst was totally removed, giving full resolution of the clinical signs. The cyst was diagnosed as a dermoid cyst. To our knowledge, this is the first report of feline dermoid cyst compressing the spinal cord that was diagnosed antemortem. The prognosis is favorable when the cyst is completely resected.

Decompressive laminectomy with vertebral stabilization allows neurologic improvement of most Pekingese dogs with thoracolumbar vertebral instability

OBJECTIVE

To describe the diagnostic findings, surgical techniques, and outcomes of thoracolumbar vertebral instability associated with or without articular process (AP) anomalies in Pekingese dogs.

ANIMALS

11 client-owned Pekingese dogs.

PROCEDURES

Medical records (2007 to 2022) were reviewed. Inclusion criteria were Pekingese dogs with thoracolumbar vertebral instability that underwent decompressive laminectomy and vertebral stabilization. Dynamic myelographic study and/or intraoperative spinal manipulation were used to diagnose vertebral instability. Data on preoperative and postoperative neurologic status, diagnostic findings, surgical techniques, and outcomes were retrieved.

RESULTS

The dogs presented with paraparesis (n = 9) or paraplegia (2). Five dogs had caudal AP anomalies. Dynamic myelographic study demonstrated single (n = 7) or multiple (4) dynamic compressions with poststress spinal cord height reduction (median, 12.5%; IQR, 6.8% to 21.2%). Of the 17 dynamic compression lesions, 5 lesions were at the disc spaces with caudal AP abnormalities. All dogs had vertebral instability confirmed by intraoperative spinal manipulation and underwent hemilaminectomy and unilateral vertebral stabilization. One dog had adjacent segment vertebral instability and underwent vertebral stabilization 3 months after the initial operation. All but 1 dog showed successful outcomes at the last follow-up (median, 16 months; IQR, 3 to 32 months).

CLINICAL RELEVANCE

Vertebral instability associated with or without AP abnormalities is a potential cause of thoracolumbar spinal cord injury in Pekingese dogs. Dynamic myelographic studies and/or intraoperative spinal manipulation demonstrated vertebral instability. Spinal cord decompression and vertebral stabilization are effective, resulting in neurologic improvements in most dogs.

IV Versus Myelography Computed Tomography for Thoracolumbar Intervertebral Disc Extrusion Surgical Planning in French Bulldogs

Accurate diagnostic imaging is required for surgical planning of acute thoracolumbar intervertebral disc extrusion. However, data comparing the accuracy of conventional IV contrast-injected computed tomography (CT) and myelography CT for hemilaminectomy localization and size assessment are sparse. In this study, IV contrast-injected CT and myelography CT were performed in 48 French bulldogs presenting with acute disc herniation and compared with postsurgical CT. CT images were evaluated by three raters. IV contrast-injected CT erroneously identified the compressive lesion site significantly more often than myelography CT. The length of the compressive lesion was significantly higher using myelography CT compared with conventional CT, but this did not lead to relevant consequences on the surgical opening site length. Myelography CT should therefore be recommended when thoracolumbar disc disease is suspected and multiple compressive lesions are visualized on IV-injected CT in French bulldogs.

Tridimensional models and radiographic study of dorsal laminectomy and thoracolumbar hemilaminectomy in dogs

PURPOSE

To create three-dimensional anatomical models of the thoracic and lumbar portions of the canine spine that reproduce the vertebral surgical approaches of dorsal laminectomy and hemilaminectomy, and to perform the respective radiographic evaluations of each approach.

METHODS

In a digital archive of the canine spine, digitally replicate the dorsal laminectomy and hemilaminectomy in the thoracic and lumbar portions and, then, make tridimensional prints of the vertebral models and obtain radiographs in three dorsoventral, ventrodorsal and laterolateral projections.

RESULTS

The anatomical models of the surgical spinal canal accesses of the thoracic and lumbar portions showed great fidelity to the natural bones. The created accesses have the proper shape, location and size, and their radiographic images showed similar radiodensities.

CONCLUSIONS

The replicas of the dorsal laminectomy and hemilaminectomy developed in the anatomical models in the thoracic and lumbar portions are able to represent the technical recommendations of the specialized literature, as well as their respective radiographic images, which have certain radiological properties that allow to make a deep radiological study. Therefore, the models are useful for neurosurgical training.

Unique cytologic and imaging features of a lumbosacral oligodendroglioma in a cat

A 12-y-old castrated male domestic longhaired cat had progressive paraparesis and neurolocalization of L4-S3. MRI revealed a circumscribed intradural-extraparenchymal mass from L5 to S1 that was T2 and short tau inversion recovery hyperintense and strongly contrast-enhancing. Cytologic interpretation of a blind fine-needle aspirate obtained through the L5-L6 space was a tumor of probable mesenchymal origin. A pair of suspect neoplastic cells was seen on a cytocentrifuged preparation of the atlanto-occipital CSF sample, despite a normal nucleated cell count (0 × 106/L) and total protein (0.11 g/L) with only 3 RBCs × 106/L. Clinical signs progressed despite increasing doses of prednisolone and cytarabine arabinoside. Repeat MRI on day 162 demonstrated tumor progression from L4 to Cd2 vertebral segments with intraparenchymal extension. Surgical tumor debulking was attempted, but an L4-S1 dorsal laminectomy revealed diffusely abnormal neuroparenchyma. Intraoperative cryosection favored lymphoma, and the cat was euthanized intraoperatively 163 d following presentation. Postmortem examination was performed, and the final diagnosis was a high-grade oligodendroglioma. This case illustrates the cytologic, cryosection, and MRI features of a unique clinical presentation of oligodendroglioma.

[Kinetic and kinematic gait analysis of the back movement in chondrodystrophic breeds following hemilaminectomy in comparison to a healthy control population]

OBJECTIVE

To collect kinetic and kinematic data on the back movement in healthy dogs in comparison to chondrodystrophic dogs following hemilaminectomy while walking and trotting.

MATERIAL AND METHODS

Gait analysis on the back movement was obtained from 19 healthy dogs and 21 chondrodystrophic dogs following hemilaminectomy procedure in consequence to disc herniation in the thoracic or lumbar region.

RESULTS

In transverse and sagittal planes the group of surgically treated dogs showed a higher range of motion (ROM) throughout the spine while walking and trotting. The difference in back movement depended on the region of the hemilaminectomy (thoracic, thoracolumbar, or lumbar). Operated dogs showed a significantly higher weight distribution towards their front limbs. When comparing the weight distribution among the hind limbs, there was a decreased Peak Vertical Force (PVF) and Vertical Impulse (VI) on the side corresponding to the hemilaminectomy.

CONCLUSIONS

Following hemilaminectomy, dogs displayed increased instability within their spine, which - depending on the region and side of the hemilaminectomy - affected the back movement in different ways. Weight bearing was generally shifted away from the hind limb of the affected side, and towards the front limbs.

CLINICAL RELEVANCE

Even though hemilaminectomy has an effect on the back movement of dogs, it seems not to have relevant influence of quality of life.

A long survival case of spinal nephroblastoma in a dog

Background:

Dogs’ nephroblastoma of the spinal cord is a rare neoplastic disease, with few reports of long-term survival after surgery. We experienced that surgical treatment with postoperative radiation therapy for spinal nephroblastoma in a dog resulted in the long-term survival of 11 years.

Case Description:

The patient presented to our veterinary hospital because of progressive hindlimb paralysis. Based on diagnostic imaging, she was diagnosed with a thoracolumbar spinal cord tumor and was treated with surgery. The gross tumor tissue was removed after laminectomy, followed by postoperative radiation therapy using orthovoltage equipment. The histopathological features of the surgical specimen were consistent with those of previously reported spinal nephroblastoma, although infrequent mitotic figures were observed. The dog recovered well after treatment and resumed her normal walking condition. No tumor recurrence was observed on periodic follow-up magnetic resonance imaging performed 10 and 21 months after surgery. Imaging evaluation for the gradual development of hindlimb weakness was performed 9 years after surgery; however, no recurrence of tumor tissue was observed, and spondylosis deformans, probably induced after laminectomy, were identified as a possible cause. The dog died of aspiration pneumonia 11 years after surgery, independent of spinal nephroblastoma.

Conclusion:

To date, no clinical cases of canine spinal cord primary nephroblastoma that survived for 11 years after surgery have been reported. This case strongly suggests that providing intensive treatment for canine spinal nephroblastoma is very important.

Continuous hemilaminectomy of nine vertebrae can be performed safely in large breed dogs: a case report of a German Shepherd Dog with intervertebral disc extrusion and extensive extradural hemorrhage

Background:

Extended, continuous hemilaminectomy has only been reported in small to medium-sized dogs so far. It remains unclear whether excessive continuous hemilaminectomy can also be performed safely in large breed dogs.

Case Description:

We describe the surgical treatment and clinical outcome of a 5-year-old German Shepherd Dog that presented with paraplegia and deep pain perception following a short episode of bilateral hind-limb lameness, secondary to jumping off of a car. Computed tomography-myelography revealed that the paraplegia originated from extensive extradural spinal cord compression (Th6-L1), due to intervertebral disc extrusion and associated epidural hemorrhage. The dog was treated with a continuous hemilaminectomy involving nine vertebrae (Th6-L1) and recovered completely with no remaining neurological deficits, within 6 months.

Conclusion:

The rapid, uncomplicated, and complete functional recovery in the presented case emphasizes the practicability of extensive, continuous hemilaminectomies, also in large breed dogs.

Influence of peri-incisional epaxial muscle infiltration with bupivacaine pre- or post-surgery on opioid administration in dogs undergoing thoraco-lumbar hemilaminectomy

This study investigated the influence of bupivacaine infiltration before or after hemilaminectomy on peri-operative opioid requirement in dogs. Thirty dogs undergoing T3-L3 hemilaminectomy were randomly assigned to receive peri-incisional infiltration of bupivacaine 2 mg/kg into the epaxial muscles before surgery (Group A), at wound closure (Group B), or no infiltration (Group C). Anaesthesia comprised dexmedetomidine 4 mcg/kg and methadone 0.3 mg/kg IV (premedication), alfaxalone IV (induction), and isoflurane in oxygen (maintenance). All dogs received meloxicam SC/PO prior to induction of general anaesthesia. Response to surgery, defined as a change in autonomic physiological variables >20% above baseline, was treated with fentanyl 2.5 mcg/kg boluses, followed by a continuous rate infusion of fentanyl at 5 mcg/kg/h. The Glasgow Composite Pain Score-Short Form (GCPS-SF) was performed before premedication and at regular intervals until 24 h postoperatively. Methadone 0.2 mg/kg analgesia was given IV if GCPS-SF was ≥5/20. Number of intraoperative, postoperative and total analgesic interventions were recorded. Analgesic interventions were analysed using a chi-squared test using a Pocock approach and statistical significance was set at P < 0.029. The number of intra-operative analgesic interventions in Group A (median, 0; range, 0-2), was significantly lower than in Group B (median, 3; range, 0-5) and Group C (median, 3; range, 0-5; P = 0.019). Regarding postoperative interventions, there were significantly fewer in Group A (median, 0; range, 0-1) and Group B (median, 0; range, 0-1) than in Group C (median, 1; range, 0-2; P = 0.047). Group A (median, 0; range, 0-3), had significantly fewer total analgesic interventions than Group B (median, 3; range, 0-6) and Group C (median, 4; range, 1-7; P = 0.014). Bupivacaine reduced peri-operative opioid administration and pre-surgical peri-incisional infiltration yielded the greatest benefit.

Long-term postoperative pain evaluation in dogs with thoracolumbar intervertebral disk herniation after hemilaminectomy

BACKGROUND

Chronic neuropathic pain is a common complication in people with spinal cord injury (SCI) but has not been investigated in dogs.

OBJECTIVE

To determine the reliability of measuring spinal mechanical sensory thresholds (MSTs) in dogs and to compare MSTs of healthy dogs and dogs with SCI caused by acute thoracolumbar intervertebral disk extrusion after hemilaminectomy over a 1-year period.

STUDY DESIGN

Prospective study.

ANIMALS

Thirty-two healthy and 40 SCI dogs.

METHODS

Dogs were divided into group 1 (healthy Dachshunds), group 2 (healthy dogs including several breeds), and SCI group. The MSTs were measured using algometry at an incision (thoracolumbar) and control site. Dogs in group 1 were tested once; those in group 2 were tested for 5 consecutive days; and SCI dogs were tested on days 7, 14, 28, 42, 180, and 365 postoperatively. The MSTs were compared among days in healthy and SCI dogs and between SCI and healthy dogs using mixed effect models. P < .05 was considered significant.

RESULTS

At the incision site of SCI dogs, MST was significantly lower than in healthy dogs for 42 days postoperatively, but not subsequently. However, 4/27 dogs had control site MST below the reference range 1 year after surgery.

CONCLUSIONS AND CLINICAL IMPORTANCE

Mechanical sensory thresholds normalize by 6 months after surgery in most dogs with SCI. Approximately 15% of SCI dogs may develop chronic neuropathic pain. Improving long-term pain assessment of SCI dogs is important for offering treatment options and advising owners.

Effects of intervertebral distraction screw fixation of the lumbosacral joint on the adjacent lumbar segments in Beagles

OBJECTIVE

To investigate the effects of intervertebral distraction screw (IDS) fixation of the lumbosacral joint (LSJ) on the intervertebral foraminal area (IFA) and intervertebral stabilization of the LSJ and adjacent lumbar segments in dogs.

ANIMALS

7 healthy Beagles.

PROCEDURES

Dorsal laminectomy was performed at the LSJ in each dog to expose the intervertebral disk. The IDS was then inserted into the L7-S1 disk. Computed tomography was performed before and after laminectomy and after IDS insertion (intact, laminectomy, and IDS conditions, respectively) to measure the intervertebral range of motion (ROM) and intervertebral distance (ID) at L7-S1, L6-7, and L5-6 with the LSJ in a flexed and extended position. The intervertebral foramina stenosis rate was calculated from the intervertebral foramina area in entrance, middle, and exit zones. Results were compared among conditions.

RESULTS

The ROM at L7-S1 after IDS insertion was lower than that observed before and after laminectomy; no other differences were identified among conditions. With the LSJ in the flexed position, the ID at L7-S1 was larger after IDS insertion than before and after laminectomy; no other differences in ID were identified. In all evaluated zones, the stenosis rate was lower after IDS insertion than before and after laminectomy. No differences in ROM, ID, and stenosis rate were identified among conditions at L6-7 or L5-6.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that IDS fixation of the LSJ restricted lumbosacral ROM and prevented decreases in lumbosacral ID and IFA in healthy dogs. There were no changes at L6-7 and L5-6.

Sacrocaudal (sacrococcygeal) intervertebral disc protrusion in 2 cats

One cat was presented for investigation of urinary retention and constipation and a second cat was presented with decreased appetite, reluctance to jump, reduced level of activity, and constipation. Magnetic resonance imaging revealed dorsal bulging of the hypo-intense intervertebral disc at S3-Cd1 on fast spin echo T2. Dorsal laminectomy was performed and both cats recovered with resolution of neurological signs.

Lumbar hemilaminectomy for treatment of diskospondylitis in an aardvark (Orycteropus afer)

CASE DESCRIPTION A 17-year-old sexually intact male aardvark (Orycteropus afer) was evaluated because of hind limb proprioception deficits and ataxia. CLINICAL FINDINGS Results of examination and CT suggested a diagnosis of intervertebral disk disease and diskospondylitis at the L2-3 intervertebral space. Magnetic resonance imaging of the vertebral column also indicated intervertebral disk rupture with spinal cord compression and inflammation of the adjacent epaxial musculature TREATMENT AND OUTCOME Hemilaminectomy was performed according to the technique described for dogs. Anatomic variations encountered intraoperatively limited the ability to completely remove the affected disk material; however, adequate decompression of the spinal cord was achieved. Microbial culture and susceptibility testing of surgical biopsy specimens yielded a multidrug-resistant Enterococcus faecalis that was treated with a 10-week course of linezolid. Intensive postoperative care required constant rate infusions for adequate sedation, analgesia, and antimicrobial treatment. Dehiscence of the surgical site occurred 3 weeks after surgery and was treated with negative pressure wound therapy. Physical rehabilitation initiated 5 days after surgery progressed from passive range of motion to the use of an underwater treadmill. Despite initial improvement, acute deterioration occurred 5.5 months after surgery. Repeated CT revealed progression of diskospondylitis, which prompted euthanasia. CLINICAL RELEVANCE Postoperative hind limb paresis and paralysis in this species presented considerable challenges for care and rehabilitation. Patient demeanor, size, and anatomy required development of custom mechanical devices. Despite the inability to eliminate the multidrug-resistant bacterial osteomyelitis that resulted in the death of this aardvark, information gained may benefit treatment of subsequent patients.

Surgical treatment of a paraspinal abscess with osteomyelitis and spinal cord compression in a rabbit

CASE DESCRIPTION A 16-month-old neutered male Continental Giant rabbit (Lepus curpaeums) was referred for evaluation of a 7-day history of acute-onset, progressive, symmetric paraparesis. CLINICAL FINDINGS On initial examination, the rabbit was nonambulatory, and results of neurologic examination were consistent with a lesion affecting the T3-L3 spinal cord segments. Thoracic radiography showed irregular widening of the left T11-12 articular process joint. Marked dorsolateral and lateral extradural spinal cord compression with contrast enhancement of the adjacent epaxial muscles was evident on MRI images of the spine. TREATMENT AND OUTCOME A left-sided T11-T12 hemilaminectomy was performed, which revealed an abnormal and hypertrophic T11-12 articular process joint and an osteolytic lesion communicating with the vertebral canal. Copious purulent material causing marked spinal cord compression was evident, and the surgical site was lavaged extensively with sterile (0.9% NaCl) saline solution. Results of aerobic, anaerobic, and enriched bacteriologic cultures of swab specimens obtained from the surgical site were negative. Histologic analysis of biopsy samples revealed chronic purulent osteomyelitis, myositis, and fasciitis with necrosis, fibrosis, and dystrophic mineralization. The rabbit was discharged 48 hours after surgery. Ten weeks after surgery, the rabbit was ambulatory with mild paraparesis. On telephone follow-up 21 months after surgery, the owners indicated that the rabbit was healthy and expressed satisfaction with the treatment and outcome. CLINICAL RELEVANCE Paraspinal abscess with vertebral canal involvement should be considered as a differential diagnosis for rabbits with clinical signs of progressive T3-L3 myelopathy. Outcome for the patient of the present report suggested that surgical treatment including decompression and debridement can result in a favorable long-term outcome.

Use of a non-invasive surgical skin closure device in dogs following dorsolateral hemilaminectomy

The ZipLine 16 surgical skin closure device (ZipLine 16; Zipline Medical, Campbell, California, USA) provides noninvasive surgical wound closure. This prospective study investigated its use in dogs undergoing a dorsolateral hemilaminectomy. Although the device produced normal appositional healing compared with controls, unacceptable traumatic dermatitis that is likely related to the device adhesive was noted after removal.

Preliminary evaluation of the effects of photobiomodulation therapy and physical rehabilitation on early postoperative recovery of dogs undergoing hemilaminectomy for treatment of thoracolumbar intervertebral disk disease

OBJECTIVE To evaluate the effects of postoperative photobiomodulation therapy and physical rehabilitation on early recovery variables for dogs after hemilaminectomy for treatment of intervertebral disk disease. ANIMALS 32 nonambulatory client-owned dogs. PROCEDURES Dogs received standard postoperative care with photobiomodulation therapy (n = 11), physical rehabilitation with sham photobiomodulation treatment (11), or sham photobiomodulation treatment only (10) after surgery. Neurologic status at admission, diagnostic and surgical variables, duration of postoperative IV analgesic administration, and recovery grades (over 10 days after surgery) were assessed. Time to reach recovery grades B (able to support weight with some help), C (initial limb movements present), and D (ambulatory [≥ 3 steps unassisted]) was compared among groups. Factors associated with ability to ambulate on day 10 or at last follow-up were assessed. RESULTS Time to reach recovery grades B, C, and D and duration of postoperative IV opioid administration did not differ among groups. Neurologic score at admission and surgeon experience were negatively associated with the dogs' ability to ambulate on day 10. The number of disk herniations identified by diagnostic imaging before surgery was negatively associated with ambulatory status at last follow-up. No other significant associations and no adverse treatment-related events were identified. CONCLUSIONS AND CLINICAL RELEVANCE This study found no difference in recovery-related variables among dogs that received photobiomodulation therapy, physical rehabilitation with sham photobiomodulation treatment, or sham photobiomodulation treatment only. Larger studies are needed to better evaluate effects of these postoperative treatments on dogs treated surgically for intervertebral disk disease.

Canine Intraneural Perineurioma

A 6-year-old castrated German Shepherd Dog was presented with a 6-month history of progressive, nonpainful, left pelvic limb paresis. Magnetic resonance imaging revealed atrophy of left-sided epaxial and hypaxial muscles from L5–L7 and an enlarged L5 spinal nerve. Exploratory hemi-laminectomy revealed focally and cylindrically thickened L5 and L6 nerve roots. Histologic evaluation of a surgical biopsy specimen from the L6 dorsal nerve root, and the L5 nerve roots after later amputation revealed distended hypercellular fascicles. This distension was due to widely separated axons surrounded by concentric lamellations formed by neoplastic perineurial cells and their processes. These pseudo-onion bulbs were separated from each other by a basophilic myxoid stroma. The perineurioma cell processes were immunonegative for S-100 (a and b chains) and collagen IV, but were immunoreactive for laminin. The central axons were also immunoreactive for NF-200 and S-100. The proliferative index of the perineurioma cells, as determined by MIB-1 immunoreactivity, was about 3%. Ultrastructurally, the widely separated, interdigitating perineurioma cell processes were connected by desmosomal-like junctional complexes to form continuous circles. Their processes were covered by a discontinuous basal lamina. Each centrally placed axon was normally, thinly, or completely unmyelinated and was surrounded by a normal Schwann cell. These morphologic and immunologic features distinguish this lesion from hypertrophic neuropathy and were consistent with intraneural perineurioma.

Presence of residual material following mini-hemilaminectomy in dogs with thoracolumbar intervertebral disc extrusion

Presence of residual material following mini-hemilaminectomy in dogs (n = 9) with spontaneous thoracolumbar intervertebral disc extrusion was prospectively investigated. Volume of extruded disc material within the vertebral canal and the proportion of residual material were determined using pre- and post-operative magnetic resonance imaging. The degree of spinal cord compression, proportion of extradural material considered hemorrhage, and invasion of the articular facets were also determined. Residual material was identified in 44% of the mini-hemilaminectomies. The median percentage of residual material calculated was 7.7% of the preoperative volume. No observed effect of surgical side or site, proportion of extradural material considered hemorrhage, patient weight, and duration of clinical signs was detected.

Comparison of the access window created by hemilaminectomy and mini-hemilaminectomy in the thoracolumbar vertebral canal using computed tomography

Hemilaminectomy and mini-hemilaminectomy were performed on opposite sides of the spine at T11-T12, T13-L1, and L2-L3 in 11 canine cadavers in order to report differences in the access provided to the thoracolumbar vertebral canal. Measurements of the vertebral canal height, defect height, and dorsal and ventral remnants of the vertebral arch were obtained after computed tomography. A median of 7% to 20% of the vertebral canal height was not removed dorsally after mini-hemilaminectomy compared to 1% to 2% in hemilaminectomy. Thirteen to 25% of the vertebral canal height was left ventrally in mini-hemilaminectomy and 11% to 27% in hemilaminectomy. Potential for a restricted exposure of thoracolumbar lesions should be considered if lesions are located in the ventral 11% to 27% vertebral canal height when performing either procedure or in the dorsal 7% to 20% of the canal height when performing a mini-hemilaminectomy.

Spontaneous intradural disc herniation with focal distension of the subarachnoid space in a dog

Myelo-computed tomography of a paraparetic 14-year-old dog revealed subarachnoid distension with an intradural filling defect above the T13-L1 disc space. T12-L1 hemilaminectomy followed by durotomy allowed removal of a large piece of degenerated disc material that compressed the spinal parenchyma. Full return to function was achieved 10 days post-surgery. The distension was likely secondary to the intradural herniation, and is a rare and distinct finding.

[Intraoperative sonography for examination of intervertebral disk extrusion in the dog]

OBJECTIVE

It has been shown that the components of the vertebral canal (dura mater, pia mater, subarachnoid space, spinal cord parenchyma and central canal) can be visualized intraoperatively with the help of ultrasonography. This study was conducted to document the intraoperative sonographical findings of disc extrusion and to determine imaging criteria for the localisation of the extrusion and the consecutive changes of the spinal cord parenchyma.

MATERIAL AND METHODS

43 dogs of different breeds with a diagnosed disc extrusion were sonographically examined immediately after establishing the surgical decompression (hemilaminectomy, laminectomy, ventral slot) (examination 1) and again after removal of disc material (examination 2).

RESULTS

In all 34 patients the extruded disc material could be imaged sonographically appearing as inhomogenous, hyperechoic areas of moderate echogenicity. There was a distal shadowing dependent on the grade of calcification in 53% of the patients in examination 1 and in 79% at examination 2. Furthermore, a tendency towards a central localisation of the disc prolapse (67.6% in examination 1 and 57.1% examination 2) was observed. Intraoperative identification of disc extrusion could be accomplished in 79% of the cases. Intraoperative haemorrhage highly significantly impaired the assessment of the spinal cord (p<0.0001).

CONCLUSION

Intraoperative spinal ultrasonography using a linear probe with a frequency from 5 to 10 MHz is a valuable tool for the visualization of spinal structures. It provides information for intraspinal navigation and evaluation of the extent of spinal lesions as well as the state of decompression. Bleeding has a negative influence on the visualization of the spinal canal.

Concurrent occipital hypoplasia, occipital dysplasia, syringohydromyelia, and hydrocephalus in a Yorkshire terrier

Magnetic resonance imaging of a 7.5-year-old neutered male Yorkshire terrier with mild generalized ataxia and intermittent neck scratching led to a diagnosis of caudal occipital malformation and syringohydromyelia. Surgical exploration led to a diagnosis of occipital dysplasia with concurrent occipital hypoplasia. Following a dorsal laminectomy of the first cervical vertebra there was no progression or improvement a month later.

Asymmetric lumbosacral transitional vertebra and subsequent disc protrusion in a cocker spaniel

A 10-year-old cocker spaniel bitch presented with severe lumbosacral pain and acute onset left pelvic limb lameness. A diagnosis of asymmetric lumbosacral transitional vertebra with disc protrusion at L6-L7 was made by computed tomography. The cauda equina and left L6 nerve root were surgically decompressed with a dorsal laminectomy and lateral foraminotomy, which led to rapid resolution of the clinical signs.

Canine thoracolumbar invertebral disk disease: diagnosis, prognosis, and treatment

Thoracolumbar intervertebral disk disease (IVDD) is a common, important cause of paraspinal hyperesthesia, pelvic limb ataxia, paraparesis, paraplegia, and urinary and fecal incontinence in dogs. A companion article reviewed pathophysiology, epidemiology, physical examination, and emergency medical therapy. This article addresses the diagnosis, prognosis, and treatment of dogs with thoracolumbar IVDD.

Evaluation of topical epidural morphine for postoperative analgesia following hemilaminectomy in dogs

A randomized prospective study was conducted in dogs undergoing hemi-laminectomy procedures for Hansen type I disk protrusion to compare postoperative analgesia achieved with topical spinal application of morphine versus saline. An absorbable gelatin sponge was placed in the defect next to the dura and soaked with either preservative-free morphine (0.1 mg/kg) or saline (0.1 ml/kg) just before wound closure. For 48 hours after surgery, dogs were monitored for pain using visual analog and numeric descriptive scales and given rescue analgesia according to study guidelines. A Kaplan-Meier survival analysis revealed that dogs in the morphine group had a longer (13.3 +/- 3.6 hours) duration of postoperative analgesia than those in the control saline group (5.3 +/- 1.8 hours), and dogs in the morphine group also required fewer doses of additional pain medication. Preservative-free morphine administered topically via an absorbable gelatin sponge appears to be a promising method to alleviate postoperative pain in dogs undergoing hemilaminectomy procedures.

The effects of fasting and general anesthesia on serum chemistries in KCG miniature pigs

Investigators are obligated to optimize the perioperative care of experimental animals, but little is known about the effects of anesthesia and surgery on serum chemistries in KCG pigs. The objective of this study was to examine the influence of fasting and surgery under general anesthesia on 27 serum chemistries in KCG miniature pigs to improve management. Crossbred KCG minipigs were used at a mean of 12.3 mo of age (range, 8.6 to 14.9) and 33.4 kg of body weight (range, 24.0 to 40.2). Serum chemistries were evaluated at the start and end of a 24 h fasting period in fasted animals (n = 6). No significant differences were observed between the starting and postfasting studies. Partial hemilaminectomy of the lumbar spine was carried out in 2 groups of animals. Those given sevoflurane anesthesia (n = 7) had significant decreases in serum albumin, potassium, inorganic phosphorus, gamma-glutamyltransferase peptidase, cholinesterase, and glucose postoperatively compared with preoperative values. Animals given isoflurane (n = 7) anesthesia had significantly decreased total protein, albumin, triglyceride, phospholipids, sodium, potassium, calcium, alanine aminotransferase, alkaline phoshatase and glucose after surgery compared with levels before surgery. In a separate experiment (n = 7), serum glucose and insulin also decreased during the postoperative period after isoflurane anesthesia. These results demonstrate that select serum electrolytes, glucose, and insulin of KCG miniature pigs are altered after general anesthesia. Investigators must be aware of the effects of anesthetic agents on experimental animals to provide optimal care and for interpretation of experimental data.

Partial lateral corpectomy for ventral extradural thoracic spinal cord compression in a cat

A 7-year-old, female spayed, domestic shorthair cat was presented for ambulatory paraparesis. No trauma history was reported. Myelography and subsequent computed tomography revealed multiple ventrally located extradural spinal cord compressive lesions possibly due to intervertebral disc disease. Compression at the level of Th3-Th4 intervertebral disc space was considered responsible for the paraparesis. The lesion was approached via a right-sided lateral partial corpectomy as described for dogs. Complete spinal decompression was achieved, as documented intraoperatively by visual inspection and palpation of the spinal canal. No surgery related complications were encountered and the cat improved gradually within 8 weeks after the procedure. At 1 year follow-up only a slight proprioceptive deficit in the right hind limb could be noted. This is the first report of partial lateral corpectomy in a cat and should encourage the use of this technique even in small patients.

Review and retrospective analysis of degenerative lumbosacral stenosis in 156 dogs treated by dorsal laminectomy

The medical records of 156 dogs with degenerative lumbosacral stenosis (DLS) that underwent decompressive surgery were reviewed for signalment, history, clinical signs, imaging and surgical findings. The German Shepherd Dog (GSD) was most commonly affected (40/156, 25.6%). Pelvic limb lameness, caudal lumbar pain and pain evoked by lumbosacral pressure were the most frequent clinical findings. Radiography showed lumbosacral step formation in 78.8% (93/118) of the dogs which was associated with elongation of the sacral lamina in 18.6% (22/118). Compression of the cauda equina was diagnosed by imaging (epidurography, CT, or MRI) in 94.2% (147/156) of the dogs. Loss of the bright nucleus pulposus signal of the L7-S1 disc was found on T2-weighted MR images in 73.5% (25/34) of the dogs. The facet joint angle at L7-S1 was significantly smaller, and the tropism greater in GSD than in the other dog breeds. The smaller facet joint angle and higher incidence of tropism seen in the GSD may predispose this breed to DLS. Epidurography, CT, and MRI allow adequate visualization of cauda equina compression. During surgery, disc protrusion was found in 70.5% (110/156) of the dogs. Overall improvement after surgery was recorded in the medical records in 79.0% (83/105) of the dogs. Of the 38 owners that responded to questionnaires up to five years after surgery, 29 (76%) perceived an improvement.

Surgical Treatment of Lumbosacral Foraminal Stenosis Using a Lateral Approach in Twenty Dogs with Degenerative Lumbosacral Stenosis

OBJECTIVES

To describe clinical signs, magnetic resonance imaging (MRI) and surgical findings using a lateral approach to the lumbosacral intervertebral foramen and to evaluate clinical outcomes in dogs with or without concurrent dorsal decompression and annulectomy.

STUDY DESIGN

Retrospective study.

ANIMALS

Dogs (n=20) with degenerative lumbosacral stenosis (DLSS).

METHODS

Medical records (2002-2006) of dogs that had lumbosacral lateral foraminotomy alone or in combination with dorsal decompression were reviewed. Degree of dysfunction was assessed separately for each pelvic limb; dogs with unilateral signs were included in group A, those with bilateral signs in group B. Retrieved data were: signalment, history, neurologic status on admission, 3 days, 6 weeks, and 6 months postoperatively, duration of clinical signs, results of MRI, surgical site(s), intraoperative findings, and outcome.

RESULTS

Based on the clinical and MRI findings unilateral foraminotomy was performed in 8 dogs, bilateral foraminotomy in 1 dog, unilateral foraminotomy with concurrent dorsal decompression in 7 dogs, and bilateral foraminotomy with concomitant dorsal decompression in 4 dogs. Surgery confirmed the presence of foraminal stenosis in all dogs, with osteophyte formation and soft tissue proliferations being the most common lesions. Outcome was good to excellent in 19 dogs and poor in 1 dog. Mean follow-up was 15.2 months (range, 6-42 months).

CONCLUSION

Lateral foraminotomy addresses compressive lesions within exit and middle zones of the lumbosacral foramen.

CLINICAL RELEVANCE

Successful surgical management of DLSS is dependent on recognition and correction of each of the compressive lesions within the lumbosacral junction.

Evaluation of the success of medical management for presumptive thoracolumbar intervertebral disk herniation in dogs

OBJECTIVE

To determine the success of medical management of presumptive thoracolumbar disk herniation in dogs and the variables associated with treatment outcome.

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs (n=223) with presumptive thoracolumbar disk herniation.

METHODS

Medical records from 2 clinics were used to identify affected dogs, and owners were mailed a questionnaire about success of therapy, recurrence of clinical signs, and quality of life (QOL) as interpreted by the owner. Signalment, duration and degree of neurologic dysfunction, and medication administration were determined from medical records.

RESULTS

Eighty-three percent of dogs (185/223) were ambulatory at initial evaluation. Successful treatment was reported for 54.7% of dogs, with 30.9% having recurrence of clinical signs and 14.4% classified as therapeutic failures. From bivariable logistic regression, glucocorticoid administration was negatively associated with success (P=.008; odds ratio [OR]=.48) and QOL scores (P=.004; OR=.48). The duration of cage rest was not significantly associated with success or QOL. Nonambulatory dogs were more likely to have lower QOL scores (P=.01; OR=2.34).

CONCLUSIONS

Medical management can lead to an acceptable outcome in many dogs with presumptive thoracolumbar disk herniation. Cage rest duration does not seem to affect outcome and glucocorticoids may negatively impact success and QOL. The conclusions in this report should be interpreted cautiously because of the retrospective data collection and the use of client self-administered questionnaire follow-up.

CLINICAL RELEVANCE

These results provide an insight into the success of medical management for presumptive thoracolumbar disk herniation in dogs and may allow for refinement of treatment protocols.

Thoracolumbar dorsolateral laminectomy with osteotomy of the spinous process in fourteen dogs

OBJECTIVE

To describe outcome after an alternative unilateral approach to the thoracolumbar spine for dorsal laminectomy.

STUDY DESIGN

Retrospective clinical study.

ANIMALS

Dogs (n=14) with thoracolumbar spinal cord compression.

METHODS

Thoracolumbar spinal cord compression was lateral (6 dogs), dorsal (4), and dorsolateral (4) caused by subarachnoid (7) and synovial cysts (2) and intradural-extramedullary neoplasia (5). All dogs were treated by dorsal laminectomy with osteotomy of the spinous process using a unilateral paramedian approach. The contralateral paraspinal muscles were not stripped from the spinous process and the osteoligamentous complexes were preserved. Retraction of the spinous process and muscles to the contralateral side resulted in complete visualization of the dorsal vertebral arch thereby allowing dorsal laminectomy to be performed.

RESULTS

No technique complications occurred. Approximately 75% exposure of the spinal cord (dorsal and lateral compartments) was achieved providing adequate visualization and treatment of the lesions. Transient deterioration of neurologic state occurred in 5 dogs because of extensive spinal cord manipulation. At long-term follow-up, 6 dogs were normal, 6 had clinical improvement, and 2 were unchanged.

CONCLUSION

Dorsal laminectomy after osteotomy and retraction of the spinous process may be considered in canine patients with dorsal, dorsolateral, or lateral compression to facilitate adequate decompression of the spinal cord.

CLINICAL SIGNIFICANCE

This surgical technique offers an alternative approach to the thoracolumbar spine and spinal cord by a modified dorsal laminectomy that preserves the paraspinal muscle integrity on the contralateral side.

Recurrent spinal arachnoid cyst in a cat

Spinal arachnoid cysts (SACs) are uncommon expanding lesions in the spinal canal. They are rarely diagnosed in dogs, and there are only four published cases in cats. We report a case of a 12-year-old cat with recurrent signs of intermittent urinary incontinence and hind limb ataxia 2 years after surgical marsupialisation of a spinal arachnoid cyst at T11/12. Recurrence of a cyst was diagnosed by myelography. Repeated marsupialisation after laminectomy was successful and the cat recovered satisfactorily although intensive physical therapy was necessary. SACs are very rare in cats and seem to occur mainly as a secondary lesion to spinal and meningeal trauma or irritation due to bony changes of the vertebrae.

Closed Fluoroscopic-Assisted Spinal Arch External Skeletal Fixation for the Stabilization of Vertebral Column Injuries in Five Dogs

OBJECTIVE

To evaluate outcome after closed fluoroscopic-assisted application of spinal arch external skeletal fixators in dogs with vertebral column injuries.

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs with traumatic vertebral column injuries (n=5).

METHODS

Medical records of dogs with vertebral column fractures and/or luxations stabilized with spinal arch external skeletal fixator frames applied using a closed fluoroscopic-assisted technique were reviewed. Owners were contacted to obtain long-term clinical outcomes.

RESULTS

Five dogs (age range, 6-72 months; weight, 10-54 kg) had traumatic vertebral column injuries stabilized with spinal arch external skeletal fixators applied in closed fashion. Injuries involved vertebral segments of the thoracolumbar junction, lumbar spine, and lumbosacral junction. Immediately postoperatively, 4 dogs had anatomic alignment of their vertebral fracture/luxation; 1 dog had 1 mm of vertebral canal height compromise. Time to fixator removal ranged from 65 to 282 days (141+/-87 days). All dogs had regained satisfactory neurologic function by 3 months. At long-term follow-up (range, 282-780 days; mean 445+/-190 days) all dogs were judged to have good to excellent return of function by their owners.

CONCLUSION

Successful closed fluoroscopic-assisted application of external skeletal fixators using spinal arches provided satisfactory reduction with few complications in 5 dogs. Return to function was judged to be good to excellent in all dogs at long-term evaluation.

CLINICAL RELEVANCE

Closed fluoroscopic-assisted application of ESF using spinal arches provided satisfactory reduction and effective stabilization of spinal fractures with few complications and should be considered as a treatment approach.

Vertebral Stabilization Using Positively Threaded Profile Pins and Polymethylmethacrylate, with or Without Laminectomy, for Spinal Canal Stenosis and Vertebral Instability Caused by Congenital Thoracic Vertebral Anomalies

OBJECTIVE

To describe diagnostic findings, surgical technique, and outcome in dogs with thoracic spinal canal stenosis and vertebral instability secondary to congenital vertebral anomalies.

STUDY DESIGN

Retrospective clinical study.

ANIMALS

Dogs (n=9) with thoracic spinal canal stenosis.

METHODS

Medical records (1995-1996; 2000-2006) of 9 dogs with a myelographic diagnosis of spinal canal stenosis and/or vertebral instability secondary to congenital vertebral anomaly that were surgically managed by vertebral stabilization with or without laminectomy were reviewed. Data on pre- and postoperative neurologic status, diagnostic findings, surgical techniques, and outcomes were retrieved. Follow-up evaluations were performed at 1, 2, and 6 months. Long-term outcome was assessed by means of clinical examination or owner telephone interviews.

RESULTS

Spinal cord compression was confirmed by myelography, and in 2 dogs, dynamic compression by stress myelography. Eight dogs regained the ability to ambulate postoperatively. One dog with a partial recovery regained voluntary movement but did not become ambulatory.

CONCLUSIONS

Spinal cord injury secondary to congenital vertebral anomaly may have a good outcome when treated by vertebral stabilization with or without laminectomy. Adequate stabilization of the vertebrae and improved neurologic outcome were achieved in most dogs.

CLINICAL RELEVANCE

Vertebral stabilization using positively threaded profile pins and polymethylmethacrylate with or without laminectomy is an effective treatment for spinal canal stenosis and vertebral instability secondary to congenital thoracic vertebral anomalies.

Use of intraoperative ultrasonography in canine spinal cord lesions

The purpose of this retrospective study was to describe the intraoperative appearance of various spinal cord conditions, and to investigate how intraoperative ultrasonography assisted in modification of surgical and postoperative treatment plans. Intraoperative ultrasonography (B-mode, and power Doppler mode) was used in 25 dogs undergoing spinal surgery. The neurologic conditions included cervical spondylomyelopathy, intervertebral disc (IVD) protrusion, IVD extrusion, spinal tumors, nerve sheath mass, granulomatous myelitis, and discospondylitis. All of these diagnoses were supported by histopathologic and/or cytologic evaluation. It was possible to visualize the spinal cord and the abnormal spinal tissue in all of the patients. Power Doppler imaging allowed assessment of the spinal cord microcirculation, and assisted in judgment of the degree of decompression. Ultrasound imaging directly impacted the surgical and the medical treatment plans in four patients. Owing to the intraoperative imaging, two hemilaminectomies were extended cranially and caudally, and additional disc spaces were fenestrated, one hemilaminectomy site was extended dorsally to retrieve the disc material from the opposite side, and one intramedullary cervical spinal cord lesion was discovered, aspirated, and consequently diagnosed as granulomatous inflammation, which altered the long-term medication protocol in that dog. This study suggests that intraoperative sonographic spinal cord imaging is a useful and viable technique.

Tri-level surgical treatment of cervical spinal cord compression in a Thoroughbred yearling

A Thoroughbred yearling was presented with neurological, radiographic, and myelographic abnormalities consistent with cervical vertebral stenotic myelopathy. Surgical correction was performed by using ventral cervical interbody fusion at 3 intervertebral spaces. The patient recovered uneventfully from surgery. The neurological status remained unchanged initially; however, significant improvement was noted 37 weeks postoperatively.

Extradural spinal juxtafacet (synovial) cysts in three dogs

Three dogs were presented for investigation of spinal disease and were diagnosed with extradural spinal juxtafacet cysts of synovial origin. Two dogs that were presented with clinical signs consistent with pain in the lumbosacral region associated with bilateral hindlimb paresis were diagnosed using magnetic resonance imaging. Both cysts were solitary and associated with the L6-7 dorsal articulations; both the dogs had a transitional vertebra in the lumbosacral region. A third dog that was presented with progressive paraparesis localised to T3-L3 spinal cord segments and compression of the spinal cord at T13-L1 was diagnosed using myelography. A solitary multiloculated cyst was found at surgery. Decompressive surgery resulted in resolution of the clinical signs in all three dogs. Immunohistological findings indicated that one to two layers of vimentin-positive cells consistent with synovial origin lined the cysts.

Treatment of thoracolumbar spinal cord compression associated withHistoplasma capsulatuminfection in a cat

CASE DESCRIPTION

A 7-year-old domestic shorthair cat with a 2-month history of decreased appetite and weight loss was examined because of paraparesis of 1 week's duration that had progressed to paraplegia 3 days earlier.

CLINICAL FINDINGS

Neurologic examination revealed normo- to hyperreflexia and absence of deep pain sensation in the hind limbs and thoracolumbar spinal hyperesthesia. Neuro-anatomically, the lesion was located within the T3 through L3 spinal cord segments. Biochemical analysis and cytologic examination of CSF revealed no abnormalities. Radiography revealed narrowing of the T11-12 intervertebral disk space and intervertebral foramen suggestive of intervertebral disk disease. Myelography revealed an extradural mass centered at the T12-13 intervertebral disk space with extension over the dorsal surfaces of T11-13 and L1 vertebral bodies.

TREATMENT AND OUTCOME

A right-sided hemilaminectomy was performed over the T11-12, T12-13, and T13-L1 intervertebral disk spaces, and a space-occupying mass was revealed. Aerobic bacterial culture of samples of the mass yielded growth of a yeast organism after a 10-day incubation period; histologically, Histoplasma capsulatum was identified. Treatment with itraconazole was initiated. Nineteen days after surgery, superficial pain sensation and voluntary motor function were evident in both hind limbs. After approximately 3.5 months, the cat was ambulatory with sling assistance and had regained some ability to urinate voluntarily.

CLINICAL RELEVANCE

In cats with myelopathies that have no overt evidence of fungal dissemination, differential diagnoses should include CNS histoplasmosis. Although prognosis associated with fungal infections of the CNS is generally guarded, treatment is warranted and may have a positive outcome.

INTERVERTEBRAL DISC EXTRUSION AND SPINAL DECOMPRESSION IN A BINTURONG (ARCTICTIS BINTURONG)

A 10-yr-old binturong (Arctictis binturong) developed an acute onset of hind limb paralysis. Neurological examination revealed sensorimotor paraplegia. Myelography and computed tomography demonstrated a ventrolateral extradural compression of the spinal cord centered over the L3-L4 intervertebral disc space. Spinal decompression was performed via hemilaminectomy and excision of degenerate nucleus pulposus, confirmed by histopathologic examination. The binturong regained slight motor function by day 8 postoperatively but succumbed to pancreatitis 19 days postoperatively.

Epidural Spinal Myelolipoma in a Dog

Epidural spinal myelolipoma was diagnosed in a 13-year-old, male Siberian husky that was referred for evaluation of progressive pelvic limb paresis and urinary incontinence. An epidural mass was detected by magnetic resonance imaging and computed tomography. The mass was removed and identified histopathologically as an epidural myelolipoma. Pelvic limb paresis improved after surgery, but urinary retention associated with neurological bladder dysfunction persisted.

Imaging diagnosis--infiltrative lipoma causing spinal cord compression in a dog

An 11-year-old, 43 kg neutered female Labrador retriever dog developed acute pelvic limb paraparesis. In magnetic resonance images there was a T1- and T2-hyperintense extradural at the fifth thoracic intervertebral space that was causing marked compression of the spinal cord. In short tau inversion recovery and fat suppressed T1-weighted images the signal from the mass was decreased indicating it was of fatty origin. The mass was removed via a dorsal hemilaminectomy in the thoracic area. Histopathologic analysis confirmed the mass was an infiltrative lipoma. The dog recovered and is fully ambulatory 24 months after surgery. This report provides additional evidence that lipomas in the vertebral canal may be the source of pelvic limb neuropathy and also illustrates the value of magnetic resonance imaging in establishing the fatty nature of some soft tissue masses.

Influence of surgical approach on the efficacy of the intervertebral disk fenestration: a cadaveric study

OBJECTIVES

To investigate the influence of different approach angles on the amount of nucleus pulposus removed during intervertebral disc fenestration in dogs.

METHODS

Twenty cadavers of beagle dogs were randomly divided into four groups: a control group and three treatment groups in which intervertebral fenestration was performed using either a dorsal, dorsolateral or lateral approach between the 12th thoracic and second lumbar spaces. The volume of nucleus pulposus, the weight of the residual nucleus pulposus and the angle of the working sector were measured. The ratio of the residual nucleus pulposus weight to the nucleus pulposus volume was used to evaluate the efficacy of the performed fenestration. Data were analysed with Kruskal-Wallis analysis of variance between groups on ranks with correction for ties and Bonferroni correction for multiple comparisons. Correlation between ratio and working angle was calculated using a Spearman's rank test (P<0.05).

RESULTS

The calculated ratio of nuclear weight to volume was significantly less in the lateral approach group than that in the other groups. The working sector was widest in the dorsolateral approach group, but this did not correlate with efficient fenestration.

CLINICAL SIGNIFICANCE

Using the lateral approach for intervertebral disc fenestration may increase the efficiency of the fenestration procedure.

Imaging findings and surgical treatment of hemivertebrae in three dogs

CASE DESCRIPTION

3 immature screw-tailed dogs were evaluated because of progressive pelvic limb paraparesis.

CLINICAL FINDINGS

Each dog had marked ataxia and paresis of the pelvic limbs and a palpable deformity of the midthoracic portion of the vertebral column. Pain perception in the pelvic limbs was considered normal, and there was no evidence of fecal or urinary incontinence in any of the 3 dogs. Radiography and magnetic resonance imaging revealed hemivertebrae with severe dorsoventral stenosis of the vertebral canal resulting in spinal cord compression in 2 dogs and lateral compression in the other.

TREATMENT AND OUTCOME

Each dog underwent decompressive surgery consisting of dorsal laminectomy or hemilaminectomy and vertebral stabilization by use of combinations of Kirschner wires or threaded external fixator pins plus polymethylmethacrylate bone cement. All dogs regained strong locomotor function with minimal residual pelvic limb ataxia.

CLINICAL RELEVANCE

Little detailed information regarding surgical treatment of hemivertebrae in dogs is available; results of treatment in these 3 dogs suggest that spinal cord decompression and stabilization of the vertebral column can achieve a satisfactory, functional outcome.