Vertebral Fracture and Luxation in Small Animals

Accuracy and safety of freehand vs. end-on fluoroscopic guided drill-hole placement in canine cadaveric thoracic, lumbar and sacral vertebrae

Objective

To develop and evaluate the safety and accuracy of an open, end-on fluoroscopic guided (EOFG) drill hole position technique in canine cadaveric spinal surgery, in comparison to a traditional free-hand (FH) drilling technique.

Study design

Cadaveric comparison study.

Animals

Canine cadaveric vertebral columns (n = 4).

Methods

Computed tomography (CT) scans were performed for in-silico planning. Ideal implant purchase depth and angulations were determined from previously published data. Plans for end-on fluoroscopic guided drill holes included angled reconstructions in thick slab mode to mimic fluoroscopic images. Following surgical preparation of T8 to S2, holes were drilled by one of two experienced surgeons randomized evenly by operated side, surgeon, and technique. C-arm fluoroscopy was utilized for the end-on technique. CT was repeated after the procedures. Safety was determined categorically using a modified Zdichavsky classification and "optimal" placement was compared between techniques. Continuous data for drill-hole accuracy was calculated as angle and depth deviations from the planned trajectories. Data sets were analyzed at both univariable and multivariable levels with logistic regression analysis.

Results

Drill hole safety was categorized as optimal (modified Zdichavsky classification 1) in 51/60 (85%) of drill holes using EOFG and 33/60 (55%) using FH (P < 0.001) techniques. There were no "unsafe" holes (modified Zdichavsky classification 3a). Optimal drill hole placement was significantly associated with the EOFG technique and use of the largest cadaver, and was significantly less likely within the thoracic region. Mean angle and depth deviations were significantly lower with the EOFG technique. Angle deviations were significantly lower for EOFG in the lumbar region, whereas bone purchase deviations were significantly lower for EOFG in both the thoracic and lumbar regions. The mean time taken to drill the hole was significantly longer for the EOFG technique.

Conclusion

Optimal drill hole placement was significantly more likely with the EOFG technique and improved the accuracy of bone purchase in the thoracic region.

Clinical significance

The EOFG technique shows promise for translation into a clinically setting, potentially improving implant purchase and therefore stabilizing construct strength, whilst potentially reducing the likelihood of neurovascular injury and need for surgical revision.

Spinal Neuronavigation for Lumbar Plate Fixation in Miniature Breed Dogs

OBJECTIVE

 The main aim of this pilot study was to assess the feasibility of spinal neuronavigation for plate fixation of lumbar vertebrae in miniature breed dogs using a surgical navigation system in combination with a custom-made reference array.

STUDY DESIGN

 This was an experimental cadaveric study in five miniature breed dogs.

METHODS

 A 4-hole locking plate with four 2.0-mm locking screws was placed on two adjacent lumbar vertebrae using a neuronavigation system consisting of a mobile cone beam computed tomography linked to a navigation system. The procedure was performed by a novice surgeon. The plate and screw positions were assessed for surgical safety using predefined criteria. Surgical accuracy was determined by the deviation of entry and exit points between pre- and postoperative images.

RESULTS

 A total of five plates and 20 screws were placed. In 85% (17/20), screws were placed appropriately. The median entry point deviation was 1.8 mm (range: 0.3-3.7) and the median exit point deviation was 1.6 mm (range: 0.6-5).

CONCLUSION

 Achievement of surgical accuracy in the placement of screws for fixation of lumbar vertebral plates in small breed dogs using neuronavigation with a custom-made reference array by a novice surgeon resulted in surgical safe plate placement in four of the five cadavers. Therefore, we judge the method as promising, however, further studies are necessary to allow the transfer of image-guided navigation for lumbar plate fixation into the clinic.

MRI and CT features of a disc herniation through a fractured lumbar vertebra causing lumbar spinal cord compression in a dog

A 5-year-old intact male Saint Bernard was presented for paraparesis following a fall down the stairs. Magnetic resonance imaging revealed a chronic fragmentation of the dorsocaudal aspect of the second lumbar vertebral body (L2). Material migrated from the L2 to L3 intervertebral space through the fractured caudal vertebral endplate into the vertebral body and reached the vertebral canal, resulting in a severe extradural compressive myelopathy. Computed tomography confirmed the vertebral fragmentation. Histology of surgically removed compressive material revealed fibrocartilaginous material. The uncommon route of the extruded disc material through a fractured vertebral body makes this case of traumatic disc extrusion unusual.

Unusual lesions seen in the caudals of the hadrosaur, Edmontosaurus annectens

The study of pathologies in the fossil record allows for unique insights into the physiology, immunology, biomechanics, and daily life history of extinct organisms. This is especially important in organisms that have body structures dissimilar to those of extant organisms as well as transitional groups whose extant relatives may have very dissimilar physiologies. Comparisons between modern groups and their fossil ancestors are further complicated by the fact that fossil groups may have experienced unique biomechanical stresses as well as possessing a mixture of anatomical features seen in their related extant groups. In this study, we present lesions in the caudal vertebrae of the hadrosaur, Edmontosaurus annectens from the Ruth Mason Dinosaur Quarry of South Dakota, which exhibit unique morphologies. X-ray microtomography was performed on the most extreme example of this morphology to allow for both a detailed and more accurate diagnosis of the pathologic condition as well as virtual conservation of the specimen. Based on the location, the overall morphology of the lesion, and the relative "normal" appearance of the internal microstructure, the most probable cause is postulated as long-term biomechanical stresses exerted on this section of the tail by both lateral and dorsoventral motions of the tail. This deduction was based on a process of elimination for a variety of known osteological conditions; however, future work is needed to determine the nature of the stresses and why this condition has not been recorded in more hadrosaurian specimens.

Diagnostic traction and dorsal locking plate stabilization of a fifth and sixth thoracic vertebral fracture/luxation in a golden retriever: Case report

Traction was used to diagnose instability of a T5-T6 traumatic luxation that was stabilized with locking plates in the laminae and dorsal pedicles. A two-year-old, 27 kg, female spayed golden retriever was presented to a veterinary teaching hospital after being referred for possible mandibular and spinal fractures after being hit by a car. The dog presented non-ambulatory paraparetic with intact pain perception. Computed tomographic (CT) imaging showed a fifth and sixth thoracic vertebral fracture/luxation, with and without manual traction. Surgical stabilization of the spine was performed with bilateral dorsally placed locking plates (String-of-Pearls, Orthomed, UK) in the laminae and dorsal aspects of the vertebral pedicles. The dog recovered well, and neurologic status improved significantly overnight and continued to improve up until discharge, which was 6 days postoperatively. Upon recheck exam at 8 weeks postoperatively, the dog appeared neurologically normal with no obvious surgical complications. This case demonstrates that diagnostic traction-the process of pulling, during imaging, on the dog's pelvis while the forelimbs are secured in extension-demonstrated instability of the spine which was not readily apparent on initial CT imaging. Additionally, the dorsal locking plate stabilization is a viable fixation option that provided acceptable stabilization of the mid-thoracic vertebrae.

Diagnostic and Treatment of Spinal Fracture and Luxation in Italian Wolves (Canis lupus italicus)

The medical records of 14 Italian wolves (Canis lupus italicus) with a vertebral fracture or luxation (SFL) between C1 and L7 treated at Ospedale Veterinario San Michele from 2017 and 2022 were reviewed. The most common cause of SFL was “road traffic accident”. Neurological signs were graded from 0 to 6 using a modified Frankel scale. Spinal fractures occurred in C1–C5 in 1 case, in T3–L3 in 11 cases and in L4–L7 in 2 cases. Six wolves were euthanized without treatment because they presented paraplegia without deep pain perception (DPP). Two animals with motor function were treated conservatively, and later on one of them was euthanized because of neurological impairment. Six wolves were surgically treated. Seven wolves had good neurological recovery, and six of them were released into the wild. Our results suggest that wolves with DPP before surgery may have a good functional recovery.

Computed tomography features of discospondylitis in dogs

BACKGROUND

Computed tomography (CT) findings of dogs with discospondylitis have not been widely described despite increased availability of this imaging modality.

OBJECTIVES

Describe the CT features of discospondylitis in a population of clinically affected dogs with discospondylitis diagnosed by magnetic resonance imaging (MRI).

ANIMALS

Forty-one dogs (63 affected discs) with MRI-identified discospondylitis presented to a single referral hospital between 2012 and 2022.

METHODS

Retrospective, single center, descriptive case series with analysis of MRI-identified discospondylitis sites and concomitant CT imaging. Computed tomographic features of MRI-affected sites including intervertebral disc space (IVDS), endplates, vertebral body, epidural space and paraspinal tissues were described.

RESULTS

The most frequently found changes were: (1) endplate involvement (87.3%) most frequently bilateral (94.5%), with erosion (61.9%) and multifocal osteolysis (67.3%); (2) periosteal proliferation adjacent to the IVDS (73%) and spondylosis (66.7%); and (3) vertebral body involvement (66.7%) involving one-third of the vertebra (85.7%) with multifocal osteolysis (73.5%). Other less prevalent features included an abnormal IVDS (narrowed or collapsed), sclerosis of the adjacent vertebral body or endplates, presence of disseminated idiopathic skeletal hyperostosis or vacuum artifact.

CONCLUSIONS AND CLINICAL IMPORTANCE

We determined that bilateral endplate erosion and periosteal proliferation were very common in dogs with discospondylitis. Careful evaluation of CT in all 3 planes (dorsal, sagittal, transverse) is necessary to identify an affected IVDS. These described CT features can aid in the diagnosis of discospondylitis in dogs but equivocal cases might still require MRI.

Long-Term Follow-Up of Dogs and Cats after Stabilization of Thoracolumbar Instability Using 2-0 UniLock Implants

Traumatic vertebral fracture or luxation often results in spinal instability requiring surgical stabilization. This study describes the long-term outcome of spinal stabilization using a unilateral 5-hole 2-0 UniLock implant in eight dogs and two cats with trauma-induced thoracolumbar vertebral luxation/subluxation and presumed instability, as assessed by a combination of preoperative radiographs and MRI using a 3-compartment method. The UniLock plate was secured with four monocortical locking screws in adjacent vertebral bodies. Additional pins and facet screws were used in several patients. Postoperative radiographs and MRI studies showed restoration of the main spinal axis in all patients and satisfactory implantation of the screws in the vertebral bodies, with no intrusion in the vertebral canal or in the adjacent intervertebral disc spaces. Neurological status improved in nine patients six weeks postoperatively. Partial implant failure was detected in three patients with no long-term consequences. After 12 months, seven patients reached full recovery with no neurological deficit, two patients were euthanized (including one owing to an unrelated condition), and one remained paraparetic. The results of this study demonstrate that using a 2-0 UniLock implant to stabilize the thoracolumbar spine results in satisfactory long-term recovery in most dogs and cats with traumatic spinal luxation/subluxation and presumed instability. Complications may occur but do not require revision surgery and do not affect clinical outcomes.

Canine Seventh Lumbar Vertebra Fracture: A Systematic Review

Simple Summary

The aim of this paper is to review the available literature about canine seventh vertebra lumbar fracture. According to PRISMA guidelines, the authors detected data about the clinical presentation, surgical techniques, and the outcome of this rare traumatic injury that is poorly reported and described. The major problem addressed was the lack of prospective studies with a large study population and univocal data collection about complications, outcome, and post-surgical treatment.

Abstract

(1) Background: Lumbosacral traumatic injuries are reported as 39% of canine vertebral lesions. This area is prone to fracture and luxation. Several surgical techniques were described from 1975 to 2021 to stabilize the traumatic injuries of the lumbosacral junction. This report aims to critically review the available literature focused on clinical presentation, surgical techniques, and follow-up of the lumbar vertebra fracture. (2) Methods: Three bibliographic databases: PubMed, Google Scholar, and Scopus were used with a board search of Lumbosacral junction fracture AND, of L7 fracture AND (canine OR dog). The Joanna Briggs Institute (JBI) Critical Appraisal Checklist for case reports and case series was applied for the studies included. (3) Results: A total of 432 reports yielded only nine that met the inclusion criteria. Non-ambulatory paraparesis/plegia, sciatic nerve involvement, faecal/urinary incontinence, and severe back lumbar pain were the most reported signs. Survey radiographs were the most reported technique to confirm the diagnoses. The surgical treatment was reported in all reports examined with a good long-term prognosis. (4) Conclusions: The seventh lumbar vertebra fracture, despite the different surgical techniques performed, had a favourable prognosis for long-term outcome and neurological recovery.

Successful Nonsurgical Management of a Traumatic Dens Fracture in a Cat with Clinical and Radiographic Resolution

An adult domestic shorthair presented with obtundation, vestibular ataxia, head tilt, and visible evidence of facial injury following motor vehicle trauma. Plain radiographs and computed tomography imaging revealed a complete minimally displaced transverse fracture of the caudal aspect of the dens of the C2 vertebra and multiple minimally displaced cranial fractures. The dens fracture was managed with 8 wk of strict rest, followed by 4 wk of supervised activity at home. No external immobilization was performed. Neurological examinations at 8 days, 10 wk, and 9 mo following initial presentation were normal. Repeat radiographic and computed tomography examinations at 10 wk and 9 mo following the traumatic event demonstrated progressive and eventual complete osseous union of the fractured dens. To the authors’ knowledge, this is the first report of successful nonsurgical management of a traumatic dens fracture in an adult cat with documented radiographic and clinical resolution. This report suggests that nonsurgical management can be considered in such cats and that complete resolution with osseous union is feasible.

Subaxial cervical articular process subluxation and dislocation: Cervical locked facet injuries in dogs

OBJECTIVE

To describe neurologic signs, diagnostic imaging findings, potential treatments, and outcomes in dogs with subaxial cervical articular process subluxation and dislocation, or a "locked facet."

STUDY DESIGN

Retrospective case series.

ANIMALS

Ten client-owned dogs.

METHODS

Dogs with a diagnosis of cervical locked facets were identified through medical records and imaging reports searches. Data on presenting signs, diagnostic findings, treatment, and outcome were recorded.

RESULTS

All cases were small or toy-breed dogs with preceding trauma. Four dogs were tetraplegic with intact pain perception, five were nonambulatory tetraparetic, and one was ambulatory tetraparetic, with half of the tetraparetic dogs having worse motor function in the thoracic limbs. The only sites affected were C5/6 (n = 6) and C6/7 (n = 4). All dogs had unilateral dorsal displacement of the cranial articular process of the caudal vertebra relative to the caudal articular process of the cranial vertebra at the luxation site. Five dogs were treated surgically, three by external coaptation, one by restriction, and one was euthanized the day after diagnosis. All dogs with outcome data (n = 8) became ambulatory. Nonambulatory dogs returned to ambulation in a median of 4 weeks (IQR 1-12; range 1-28).

CONCLUSION

In these dogs, locked facet injuries affected the caudal cervical vertebrae in small breeds and could be identified on imaging through the presence of dorsal displacement of a cranial articular process. Our small cohort had a functional recovery regardless of treatment.

CLINICAL SIGNIICANCE

Locked facet injuries should be a differential for small or toy-breed dogs with a cervical myelopathy secondary to trauma.

Dystocia and cesarean section in a free-ranging ocelot (Leopardus pardalis) after traumatic spinal cord injury resulting from dog (Canis familiaris) attack

Background:

Ex situ breeding programs are essential to establish genetic resource banks and produce offspring to strengthen the in situ conservation of endangered species. However, many programs fail to maintain viable ex situ populations due to reproductive problems, including dystocia in pregnant females. Dystocia encompasses different emergency obstetric situations for the lives of dams and fetuses that require urgent intervention. This condition has been studied in domesticated species but published records in wildlife, specifically in felines species, are scarce.

Case Description:

An adult female ocelot (Leopardus pardalis) was referred to the wildlife hospital of the Universidad San Francisco de Quito after being attacked by dogs (Canis familiaris). Neurological tests revealed traumatic spinal cord injury at a thoracolumbar level. Complementary tests (laboratory exams, radiographs, and ultrasound) revealed a full-term pregnancy, failure in the labor progress, and critical fetal stress. A cesarean section was performed, and the newborns received resuscitation care after assessing their viability using the Apgar score system. The neonate with the lowest Apgar score died within the first hour after birth, while the second one showed an increase in Apgar score after resuscitation care and survived the procedure.

Conclusion:

We provide new obstetric data that could be relevant to save the lives of dams and newborns in related cases for ocelots and other species of wild felids. Furthermore, this study confirms the adverse effects that domestic dogs have on wildlife species.

Pedicle screws implantation in polymethylmethacrylate construct to stabilise sixth lumbar vertebral body fracture in dogs: 5 cases (2015-2018)

OBJECTIVES

To assess the feasibility and outcome of pedicle screw implantation on sixth lumbar vertebral body fractures.

MATERIALS AND METHODS

Dogs with sixth lumbar vertebral body fractures stabilised using L6 and L7 (±L5) pedicular implantation via a dorsal approach preferentially and conventional vertebral body implantation otherwise were reviewed. Coaptation was made with bone cement. Complete neurological examination, pre and postoperative imaging consistent with L6 body fracture (radiographs ± CT scan) and follow up including clinical examination and radiographs 3 to 5 weeks post-operatively were required as inclusion criteria. When available, owner interview and/or clinical examination and imaging (radiographs ± CT scan) at least 1 year after surgery were reported.

RESULTS

Five dogs met the inclusion criteria. Dorsal pedicle screws implantation was feasible in all L7 vertebrae and in four L6 vertebrae. Adequate implantation was observed in all of the post-operative radiographs and on all of the three CT scans available. At 3 to 6 weeks after surgery, neurological status and locomotion were normal in four dogs, while one dog suffering from severe sciatic neuropathy did not regain normal locomotion. At least 1 year after surgery, clinical outcome was excellent for four dogs and imaging by radiography and CT scan were available for three dogs and showed complete healing of the fracture and correct positioning of the implants. The dog suffering from sciatic neuropathy had a further trauma and was euthanased 7 weeks after the surgery.

CLINICAL SIGNIFICANCE

In this case series, pedicle screw implantation achieved stabilisation of L6 vertebral body fractures, with full recovery observed in four out of five dogs. Further studies are required to confirm the safety and the effectiveness of this intervention.

Accuracy and Safety of Image-Guided Freehand Pin Placement in Canine Cadaveric Vertebrae

OBJECTIVE

 The aim of this study was to validate an imaging technique for evaluation of spinal surgery accuracy and to establish accuracy and safety of freehand technique in the thoracolumbar spine of large breed dogs.

STUDY DESIGN

 After thoracolumbar spine computed tomography (CT), 26 drilling corridors were planned then drilled to receive 3.2 mm positive profile pins using a freehand technique. After pin removal, CT was repeated. All entry points, exit points and angles of the preoperative planned trajectories were compared with postoperative ones using an image registration and fusion technique by three observers. Corridor coordinates for entry and exit points were evaluated in three dimensions and angles were measured in one plane. Intraclass correlation coefficient (ICC) was used to establish the imaging technique reliability and descriptive statistics were used to report on the freehand technique accuracy. Safety was evaluated using a vertebral cortical breach grading scheme.

RESULTS

 Intraclass correlation coefficient for the entry points, exit points and angle were 0.79, 0.96 and 0.92 respectively. Mean deviations for the entry points, exit points and angle were 3.1 mm, 6.3 mm and 7.6 degrees respectively. Maximum deviations were 6.3 mm, 11.0 mm and 16.4 degrees. Most deviations were lateral and caudal. All corridors were judged as safe.

CONCLUSION

 The imaging technique reliability was good to excellent to study spinal surgery accuracy. Implant deviations should be anticipated when planning stabilization surgery in large breed dogs using the freehand-guided technique.

Accuracy and safety of three-dimensionally printed animal-specific drill guides for thoracolumbar vertebral column instrumentation in dogs: Bilateral and unilateral designs

OBJECTIVE

To evaluate the safety and accuracy of a unilateral three-dimensionally printed animal-specific drill guide (3DASDG) design for unilateral stabilization in the thoracolumbar vertebral column of dogs compared to a bilateral design.

STUDY DESIGN

Cadaveric study.

SAMPLE POPULATION

Fifty-two corridors in one canine cadaver.

METHODS

Two 3DASDG designs with 2 drilling tubes each were created from T8 to L7 vertebrae. Fifty-two corridors were drilled on the right and the left sides by using unilateral and bilateral designs, respectively. Planned and postoperative trajectories (entry point, exit point, angle) were compared to establish the accuracy. Statistical analysis was used for accuracy comparison between designs. Safety was evaluated by using Zdichavsky classification.

RESULTS

Unilateral and bilateral drill guide designs were not different for entry point and angle deviations; however, they were different for the exit point deviations. Two corridors breached outside the vertebra. For all guides, mean entry and exit point deviations were less than 1 and 2 mm, respectively. The maximum entry or exit point deviation in both groups was 4.7 mm. The mean angle deviation was <3.5°, and the maximum angle deviation was 9.3°.

CONCLUSION

No difference was detected in accuracy of entry points and angle deviations between drill guide designs tested in normal vertebrae. The technique was classified as highly safe.

CLINICAL SIGNIFICANCE

A unilateral drill guide design may be a safe alternative to bilateral guides for unilateral stabilization of the thoracolumbar vertebral column in dogs.

Comparison of the biomechanical performance of a customized unilateral locking compression plate with and without an intervertebral spacer applied to the first and second lumbar vertebrae after intervertebral diskectomy in canine cadaveric specimens

OBJECTIVE

To determine whether a customized unilateral intervertebral anchored fusion device combined with (vs without) an intervertebral spacer would increase the stability of the L1-L2 motion segment following complete intervertebral diskectomy in canine cadaveric specimens.

SAMPLE

Vertebral columns from T13 through L3 harvested from 16 skeletally mature Beagles without thoracolumbar disease.

PROCEDURES

Complete diskectomy of the L1-2 disk was performed in each specimen. Unilateral stabilization of the L1-L2 motion segment was performed with the first of 2 implants: a unilateral intervertebral anchored fusion device that consisted of a locking compression plate with or without an intervertebral spacer. The resulting construct was biomechanically tested; then, the first implant was removed, and the second implant was applied to the contralateral side and tested. Range of motion in flexion and extension, lateral bending, and torsion was compared among intact specimens (prior to diskectomy) and constructs.

RESULTS

Compared with intact specimens, constructs stabilized with either implant were as stable in flexion and extension, significantly more stable in lateral bending, and significantly less stable in axial rotation. Constructs stabilized with the fusion device plus intervertebral spacer were significantly stiffer in lateral bending than those stabilized with the fusion device alone. No significant differences in flexion and extension and rotation were noted between implants.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings did not support the use of this customized unilateral intervertebral anchored fusion device with an intervertebral spacer to improve unilateral stabilization of the L1-L2 motion segment after complete L1-2 diskectomy in dogs.

Canine models of spine disorders

Neck and low back pain are common among the adult human population and impose large social and economic burdens on health care and quality of life. Spine-related disorders are also significant health concerns for canine companions with etiopathogeneses, clinical presentations, and diagnostic and therapeutic options that are very similar to their human counterparts. Historically, induced and spontaneous pathology in laboratory rodents, dogs, sheep, goats, pigs, and nonhuman primates have been used for study of human spine disorders. While each of these can serve as useful preclinical models, they all have inherent limitations. Spontaneously occurring spine disorders in dogs provide highly translatable data that overcome many of the limitations of other models and have the added benefit of contributing to veterinary healthcare as well. For this scoping review, peer-reviewed manuscripts were selected from PubMed and Google Scholar searches using keywords: "intervertebral disc," "intervertebral disc degeneration," "biomarkers," "histopathology," "canine," and "mechanism." Additional keywords such as "injury," "induced model," and "nucleus degeneration" were used to further narrow inclusion. The objectives of this review were to (a) outline similarities in key features of spine disorders between dogs and humans; (b) describe relevant canine models; and (c) highlight the applicability of these models for advancing translational research and clinical application for mechanisms of disease, diagnosis, prognosis, prevention, and treatment, with a focus on intervertebral disc degeneration. Best current evidence suggests that dogs share important anatomical, physiological, histological, and molecular components of spinal disorders in humans, such that induced and spontaneous canine models can be very effective for translational research. Taken together, the peer-reviewed literature supports numerous advantages for use of canine models for study of disorders of the spine when the potential limitations and challenges are addressed.

Evaluation of prognostic factors for return of urinary and defecatory function in cats with sacrocaudal luxation

OBJECTIVES

The aim of this study was to evaluate outcomes and prognostic factors for cats with sacrocaudal luxation.

METHODS

Medical records and radiographs were reviewed for cats with sacrocaudal luxation. Information obtained from the clinical records included signalment, clinical presentation, concurrent traumatic injuries, treatment details, outcome and survival time. Severity of neurological signs was graded from 1 to 5, based on previous grading systems for cats with sacrocaudal luxation. Degree of vertebral displacement was calculated on survey radiographs. Outcomes were collected from serial neurological examinations and telephone interviews. Cats had to be given a minimum of 30 days to regain urinary function to be included in the study.

RESULTS

Seventy cats were included. Fifty-five of 61 cats (90%) regained voluntary urinary function. A higher neurological grade was associated with a decreased likelihood (P = 0.01) and longer duration (P = 0.0003) of regaining urinary function. No significant associations were found between urinary outcome and age, sex, anal tone, perineal sensation, tail base sensation, degree of craniocaudal or dorsoventral sacrocaudal displacement, concurrent orthopaedic injury, tail amputation, defecatory function at diagnosis and survival. Cats that regained defecatory function had longer survival times than those that did not recover defecatory function (P = 0.03). Defecatory outcome was not significantly associated with any other variables.

CONCLUSIONS AND RELEVANCE

In agreement with previous studies, neurological grade is the most important prognostic indicator for cats with sacrocaudal luxation. Determination of the severity of neurological signs can also aid in advising owners the time frame in which urinary function is expected to return. Faecal incontinence may be a more important prognostic factor than previously suspected.

Biomechanical comparison of ex vivo lumbar vertebral fracture luxations stabilized with tension band or polymethylmethacrylate in cats

OBJECTIVE

To evaluate spinal stabilization with tension band stabilization (TS) in cats compared to screw and polymethylmethacrylate fixation (SP).

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Sixteen feline thoracolumbar spinal specimens.

METHODS

The intact specimens were mounted in a six-degree-of-freedom biaxial testing machine for nondestructive testing to obtain the neutral zones (NZ) and range of motion (ROM) in flexion and extension. Thereafter, nondestructive testing was consecutively performed after destabilization by disc fenestration and partial L1 corpectomy and after treatment with either TS or SP. Load to failure was compared after surgical treatment in flexion. Significance was assessed by Student's t test or Wilcoxon signed-rank test.

RESULTS

Range of motion was 26.4° ± 2.2° in TS constructs and 13.4° ± 2.1° in SP constructs (P = .0005). When flexion and extension were analyzed separately, no difference was found for ROM in flexion (SP, 7.0° ± 3.7°; TS, 8.3° ± 2.1°; P = .38). In extension, the mean displacement was 6.4° ± 2.7° and 18.1° ± 5.1° in SP and TS constructs, respectively (P = .0001). Neutral zone was 2.9° ± 0.6° and 7.5° ± 0.8° for the SP and TS groups, respectively (P = .0003). Screw and polymethylmethacrylate fixation constructs were two times stiffer (P = .045).

CONCLUSION

Tension band stabilization provided stability comparable to SP in flexion. In extension, ROM of SP constructs was half that of TS constructs. The mode of failure of TS was related to the limited dorsal bone stock of feline lumbar vertebrae.

CLINICAL SIGNIFICANCE

Surgeons should be aware of the limited stability in extension provided by TS when it is used to stabilize thoracolumbar spinal injuries. Our results provide evidence to justify additional studies to clarify the type of fractures amenable to TS.

Ex-vivo evaluation of the three-column concept in canine thoracolumbar fractures

ABSTRACT Traumatic events such as a motor vehicle accident or falling from heights are very common in veterinary medicine and often lead to vertebral fracture-luxation with concomitant spinal cord injuries, mostly in the thoracolumbar spine. The purpose of this cadaveric biomechanical study was to determine the feasibility of the three-column concept in canine thoracolumbar segments with induced fractures. Eighteen Functional Spinal Units (FSU) of the thoracolumbar segments (T12-L2) were collected from 18 medium-sized adult dog cadavers and were subjected to flexion-extension and lateral bending tests so that range of motion (ROM) was recorded with a goniometer. Fractures were induced by compressive loads applied by a universal testing machine (EMIC®). After this, specimens were screened using computed tomography (CT) and the fractures were graded as affecting one, two or three columns, and divided into groups A, B, and C, respectively. Post-fracture range of motion (ROM) was compared with the previous results. Groups B and C (with fractures in two or three columns) had instability in the two axes evaluated (P<0.05). The outcomes of this study support the applicability of the three-column theory to thoracolumbar spines of dogs, as the FSUs that suffered fractures in two or more columns showed axial instability.

Determination of whether morphometric analysis of vertebrae in the domestic cat (Felis catus) is related to sex or skull shape

In many mammals, gender and skull shape are related to the bone morphology of the entire body; however, this has not been well established in the domestic cat (Felis catus). This study aims to find a relationship between cervical, thoracic and lumbar vertebrae morphometrics with regard to the sex and skull shape of domestic cats. A total of 79 samples obtained from 92 dried bones of domestic cats were used to determine morphometric measurements for a total of 29 parameters. Hierarchical clustering was used to cluster the vertebral bones found in three groups: C3-T1, T2-T11 and T12-L7. The skull shape identification process employed discriminative analysis and revealed the highest training data accuracy rate at up to 86.20% in T4 followed by L1 (86.04%) Axis (85.71%) and C5 (85.18%). Sex identification employed discriminative analysis and displayed the highest training data accuracy rate at up to 75.58% in L1 followed by, T7 (71.87%) and C6 (71.79%). Moreover, we found that 14% of the samples had one vertebra missing (T13 or L1). In conclusion, domestic cat vertebral morphometrics were found to be more related to skull shape than gender. In addition, bone clustering employed morphometric data and yielded a result that was similar to that of traditional cluster analysis involving body regions.

MRI has limited agreement with CT in the evaluation of vertebral fractures of the canine trauma patient

Complete assessment of vertebral trauma in dogs currently requires CT and MRI for evaluation of the osseous and soft tissue structures that contribute to vertebral stability. Some studies in people have suggested that MRI may be sensitive and specific at detecting vertebral fractures making this potentially a single modality that could be used in spinal trauma evaluation. This study aimed to assess the ability for observers to evaluate vertebral fractures using MRI when compared to CT, which was used as the reference standard. Twenty-nine dogs with previously diagnosed acute vertebral fractures and four dogs with no vertebral fracture that had undergone sequential CT and MRI were included into the study. One hundred twenty-eight vertebrae were evaluated for the presence of fractures. Imaging studies were read by two observers blinded to the history. While both observers had similarly high sensitivity and specificity for simple detection of any fractured vertebrae, interobserver agreement was only moderate (κ = 0.584). When evaluations were specifically limited to detection of structurally unstable fractured vertebrae both observers showed improved specificity and interobserver agreement became substantial (κ = 0.650). Complete agreement for exact fracture location between MRI and CT results was only achieved in 14.3-32.6% of fractured vertebra with up to 79% of fractures being missed in some vertebral structures. This suggests that although MRI may be able to detect the presence of fractured vertebrae, it is not able to replace CT for the complete evaluation of the traumatized spine and documentation of fracture morphology.

Traumatic atlantoaxial subluxation in dogs: 8 cases (2009-2016)

OBJECTIVE

To demonstrate the utility of advanced imaging in dogs with traumatic atlantoaxial subluxation (TAAS), and to report the presentation, treatment, and outcome for these dogs.

DESIGN

Retrospective study (2009-2016).

SETTING

University teaching hospital.

ANIMALS

Eight dogs diagnosed with TAAS with magnetic resonance imaging (MRI), computed tomography (CT), or both.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Eight dogs met criteria for inclusion. Of these, 6 were male, median age was 4 years (range, 1.5-11 years), and median body weight was 4.9 kg (range, 3.0-25.0 kg). On presentation, 6/8 (75%) dogs were nonambulatory tetraparetic and the most common injury was trauma inflicted by another animal 5/8 (62.5%). Diagnosis of TAAS was made using a combination of imaging modalities including vertebral column radiographs in 7/8 (87.5%) (of which 71.4% were suspicious for TAAS), CT in 7/8 (87.5%), and MRI in 7/8 (87.5%). In 7/8 (87.5%) dogs, CT and/or MRI offered additional information regarding the extent of injuries. Vertebral fractures were identified in 62.5% (5/8) of dogs. The majority of dogs underwent surgical repair (7/8 [87.5%]). The most common complication was aspiration pneumonia (3/8 [37.5%]). All 8 dogs survived to discharge. At the time of discharge, 4/8 (50%) were ambulatory tetraparetic. The 4 dogs that were nonambulatory tetraparetic at discharge progressed to being ambulatory within 2 months of surgery.

CONCLUSIONS

Although TAAS is an uncommon occurrence it should be considered a differential for any trauma patient that is presenting with signs of a cranial cervical myelopathy. CT and MRI have been shown to be useful to identify the extent of injuries and to facilitate surgical planning. With appropriate care, these dogs can have an excellent prognosis.

Optimal safe implantation corridors in feline cervical vertebrae (C2-T1): CT study in 16 domestic shorthair cats

OBJECTIVES

The objective of this study was to define safe corridors for the optimal placement of bicortical implants in the feline cervical spine (C2-T1) using CT.

METHODS

CT images of feline cervical spines (n = 16) were reviewed retrospectively. Multiplanar reconstructions were used to define the optimal safe corridors. Safe corridors were defined by their angle of insertion, width and length. The insertion point within the vertebral body was also described. Vertebral measurements were compared between vertebrae using multilevel linear regression, and left and right measurements within vertebrae were compared with the paired samples Wilcoxon signed-rank test. A P value <0.05 was considered significant for all analyses.

RESULTS

The safe corridor insertion points were located within the caudal third of the vertebral body in C2 (mean cranial vertebral ratio 0.73) and in the cranial third of the vertebral bodies from C3-T1 (mean cranial vertebral ratios 0.34-0.38). Mean safe corridor widths ranged from 1.04 mm in C2 to 2.30 mm in C7 and T1. The mean right and left optimal angles of implantation were, respectively, 21.79° and 21.49° for C2, 45.26° and 46.19° for C3, 51.48° and 51.04° for C4, 53.52° and 54.30° for C5, 56.36° and 56.65° for C6, 63.40° and 64.92° for C7, and 53.90° and 52.90° for T1. There were statistically significant differences between vertebrae in almost every measurement.

CONCLUSIONS AND RELEVANCE

Cervical vertebral safe corridors in cats are narrow and differ to those reported in dogs. Safe corridors are located in the caudal third of C2 and cranial third of the C3-T1 vertebral bodies. Current recommendations for implant sizes should be reviewed, as 1.5-2 mm implants would be oversized for bicortical implantation in most of the feline cervical vertebrae.

Use of Three-Dimensional Printing Models for Veterinary Medical Education: Impact on Learning How to Identify Canine Vertebral Fractures

Vertebral fractures and luxations are common causes of neurological emergencies in small-animal patients. The objective of this study was to evaluate the impact of three-dimensional printing (3Dp) models on how veterinary students understand and learn to identify canine spinal fractures and to compare 3Dp models to computed tomography (CT) images and three-dimensional CT (3D-CT) reconstructions. Three spinal fracture models were generated by 3Dp. Sixty first-year veterinary students were randomized into three teaching module groups (CT, 3D-CT, or 3Dp) and asked to answer a multiple-choice questionnaire with 12 questions that covered normal spinal anatomy and the identification of vertebral fractures. We used four additional questions to evaluate the overall learning experience and knowledge acquisition. Results showed that students in the 3Dp group performed significantly better than those in the CT (p < .001) and the 3D-CT (p < .001) groups. Students in the 3Dp and 3D-CT groups answered all questions more quickly than the CT group (3Dp versus CT, p < .001; 3D-CTversus CT, p < .001), with no significant differences between the 3Dp and 3D-CT groups (p = .051). Only the degree of knowledge acquisition that the students considered they had acquired during the session showed significant differences between groups (p = .01). In conclusion, across first-year veterinary students, 3Dp models facilitated learning about normal canine vertebral anatomy and markedly improved the identification of canine spinal fractures. Three-dimensional printing models are an easy and inexpensive teaching method that could be incorporated into veterinary neuroanatomy classes to improve learning in undergraduate students.

Ventral Stabilization of a T2-T3 Vertebral Luxation via Median Sternotomy in a Dog

An 8-year-old neutered male miniature Poodle presented for evaluation of a suspected T3-L3 lesion with cervical component following vehicular trauma. Magnetic resonance imaging and computed tomography revealed a T2-T3 luxation with right displacement of T3. A T2 caudal endplate fracture was present as well as multifocal noncompressive bulges of cervical intervertebral discs. Conservative management failed and ventral stabilization of C7-T4 was performed via a median sternotomy. Paired String-of-Pearls plates were placed on the ventral aspect of vertebrae. Eight weeks postoperatively, the dog was ambulatory with moderate pelvic limb paraparesis. A luxation of T2-T3 is uncommon in small animals and surgical stabilization is poorly described in literature. This case report demonstrates the use of a ventral approach to cranial thoracic vertebral stabilization with a successful outcome.

Usefulness of spinal unenhanced computed tomography and CT-myelography in the age of multidetector CT technology and magnetic resonance imaging - Preliminary considerations

Over the last decade, magnetic resonance imaging (MRI) and multidetector computed tomography (MDCT) have revolutionized diagnostic potential in small animal practice, providing adequate assessment of spinal diseases at levels comparable to that achieved in human radiology. T2-weighted MRI images are extremely sensitive to intramedullary parenchymal disorders, while balanced steady-state free precession sequences provide high-quality myelographic images of the spine without the need of intrathecal contrast medium administration. Multidetector computed tomography, with its near-isotropic spatial resolution and multiplanar reformatting of the acquired datasets, provides sufficient stratigraphic details of the spinal cord and the epidural space, facilitating the detection of compressive pathologies without the need of subarachnoid opacification. Nowadays, MDCT and low-field (LF) MRI have become fairly standard and available in academic institutions and private veterinary facilities, appearing to be valuable, complementary, and non-invasive diagnostic tools for imaging the spine. In this scenario, this clinical communication provides a series of preliminary observations that may help to reconsider the usefulness of CT-myelography in the light of its invasiveness and actual diagnostic advantages compared to MRI and unenhanced MDCT for the assessment of compressive and non-compressive spinal diseases in small animals.

Computed tomographic study of the optimal safe implantation corridors in feline thoraco-lumbar vertebrae

Objective: To define the implantation corridors in feline thoraco-lumbar vertebrae (T10-L7) using computed tomography (CT) for optimal safe placement of the implants (screws/pins) in spinal column stabilization.

Study design: Computed tomographic study.

Materials and methods: Computed tomography images of feline spinal column (n = 10) were used to define the optimal safe implantation corridors (OSIC) in the transverse plane. The OSIC were defined as corridors allowing the greatest amount of bone purchase with safe margins for implantation of the bicortical implants. They were characterized by their insertion point, optimal angle (from the midsagital plane), maximum and minimum safe angles (from the same insertion points), length, and width.

Results: The OSIC are located within the vertebral bodies. Insertion points were situated at the level of the vertebro-costal joint or the base of the transverse process of the vertebral body for thoracic and lumbar vertebrae, respectively. The mean optimal angle of the OSIC was 90.2° with a maximum deviation angle from optimal angle of 10° dorsally and 8.8° ventrally in thoracic vertebrae, and 90.5° with a maximum deviation angle from the optimal angle of 8.4° dorsally and 7.6° ventrally in lumbar vertebrae.

Conclusion and clinical relevance: Corridors drilled in the vertebral body perpendicular to the midsagital plane (90°) or with a small angle (≤10°) of deviation from the optimal angle provide an optimal safe placement of bicortical implants. However, perpendicular implant placement may not always be feasible due to surrounding soft tissue structures.

Surgical repair of thoraco-lumbar vertebral fracture-luxations in eight cats using screws and polymethylmethacrylate fixation

Objective: To report our clinical experience in the surgical treatment of feline thora-columbar vertebral fracture-luxations using optimal safe implantation corridors as previously described in vitro.

Study design: Retrospective clinical study.

Materials and Methods: Medical records and radiographs of cats with vertebral fracture- luxations stabilized by screws and polymethylmethacrylate (PMMA) using optimal safe implantation corridors between 2009 and 2011 were reviewed. For each patient the data included: signalment, cause of vertebral fracture-luxations, presence of concurrent injuries, pre- and postoperative neurological grade, surgical treatment, imaging findings, and clinical outcome with short-term (2 weeks) and long-term (12 months) follow-up.

Results: Eight cats with vertebral fracture-luxations involving the lumbar (L)(n = 5), the thoracic (T) spinal segments (n = 2), or the thoraco-lumbar junction (n = 1) were included in the study. Screws and PMMA were used bilaterally in five cats and unilaterally in three cats. No surgical intra-operative complications using the defined corridors were recorded. Implant failure followed by spontaneous recovery was recorded in one case. Two cats died in the postoperative period (≤4 days). The short-term and long-term clinical outcome was excellent in four out of eight cats and satisfactory in two out of eight cats.

Conclusion and Clinical relevance: This pilot study demonstrates the clinical applicability of optimal safe implantation corridors for stabilization of feline thoraco-lumbar vertebral fracture-luxations with screws and PMMA. This technique can be used with limited risks of iatrogenic injuries for stabilization of vertebral fracture-luxation localized between T11-L4.

Biomechanical comparison between pins and polymethylmethacrylate and the SOP locking plate system to stabilize canine lumbosacral fracture-luxation in flexion and extension

OBJECTIVE

To determine the stability of a simulated complete L7-S1 fracture-luxation immobilized with SOP locking plate system, compared to pins and polymethylmethacrylate (PMMA).

STUDY DESIGN

In vitro biomechanical study.

ANIMALS

Cadaver specimens of 18 skeletally mature large-breed dogs.

MATERIALS AND METHODS

Specimens were randomly stabilized with one of the two fixation techniques. Lumbosacral spine specimens (L5-S3) were subjected to a bending moment applied to the caudal and cranial ends of the specimen. The biomechanical parameters (ie, range of motion [ROM], neutral zone [NZ], and elastic zone stiffness [EZS]) were compared between fixation techniques.

RESULTS

No difference was found between the means of the NZ in flexion (P = .3458), extension (P = .1255), and total value (P = .3458) of L7-S1 stabilized with the two fixation techniques. Mean ROM in flexion (P = .2386), extension (P = .1255), and mean of EZS in extension (P = .4094) did not differ between fixations. The only significant differences were in the means of total ROM and means of the EZS in flexion, with the means being smaller with SOP fixation.

CONCLUSION

The stability of the two fixation techniques in flexion and in extension was similar for the L7-S1 and adjacent L5-L6 junctions, while the mean of ROM of L6-L7 in flexion was smaller with SOP fixation.

CLINICAL RELEVANCE

Stability of the resulting construct should be considered when selecting an implant. Our results provide evidence that fixation via pin-PMMA or SOP provide similar stability for L7-S1 fracture-luxation. In this context, other factors become more important in selecting the fixation method.

Uso do Clamp and Rod Internal Fixation pedicular na estabilização da coluna lombossacra em felino: relato de caso

RESUMO Objetivou-se reportar, pela primeira vez descrita até então, a fixação de uma fratura de sétima vértebra lombar (L7) com luxação de L7-S1, por meio de fixação pedicular, utilizando-se Clamp and Rod Internal Fixation (CRIF) em um gato. Um felino de um ano de idade, macho, SRD, foi atendido com histórico de atropelamento havia sete dias, apresentando paraparesia não ambulatória secundária à fratura da sétima vértebra lombar e compressão da cauda equina. Após avaliação geral do paciente, no dia seguinte, ele foi submetido à cirurgia descompressiva por meio de laminectomia dorsal e posterior estabilização pedicular entre L7 e S1, utilizando-se CRIF bilateralmente. O paciente apresentou evolução favorável com deambulação normal após 15 dias do procedimento cirúrgico.

The use of autologous neurogenically-induced bone marrow-derived mesenchymal stem cells for the treatment of paraplegic dogs without nociception due to spinal trauma

The aim of this study was to investigate the effects of percutaneous transplanted autologous neurogenically-induced bone marrow-derived mesenchymal stem cells (NIBM-MSCs) in paraplegic dogs without deep pain perception (DPP) secondary to external spinal trauma. Thirteen client owned dogs that had failed in improvement neurologically at least 42 days after conservative management, decompression and decompression-stabilization were included in the study. Each dog received two doses of autologous 5.0 × 10⁶ NIBM-MSCs suspension, which were positive to 2',3'-Cyclic-nucleotide-3'-phosphodiesterase (CNPase) and Microtubule-associated protein 2 (MAP-2), as well as to Glial fibrillary acidic protein (GFAP) and beta III tubulin. The cells were injected into the spinal cord through the hemilaminectomy or laminectomy defects percutaneously with 21 days interval for 2 times. The results were evaluated using Texas Spinal Cord Injury Scale (TSCIS), somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) at the admission time, cell transplantation procedures and during 2, 5, 7 and 12th months after the second cell transplantation. Improvement after cell transplantation in gait, nociception, proprioception, SEP and MEP results was observed in just 2 cases, and only gait score improvement was seen in 6 cases, and no improvement was recorded in 5 cases. All progresses were observed until 2nd month after the second cell transplantation, however, there was no improvement after this period. In conclusion, percutaneous transplantation of autologous NIBM-MSCs is a promising candidate modality for cases with spinal cord injury after spinal trauma and poor prognosis.

Usefulness of multidetector computed tomography in the evaluation of spinal neuro-musculoskeletal injuries

Spinal trauma is commonly diagnosed in small animal practice. Although the first approach to the patient with spinal trauma includes survey spinal radiographs, an accurate evaluation of the injury often requires advanced imaging. Multidetector computed tomography has revolutionized computed tomography technology, providing near-isotropic volumetric representation of the complete body with exquisite anatomical detail in a brief scan time. This review aims to discuss the technical background, indications, and limitations of multidetector computed tomography in the assessment of spinal trauma with particular reference to skeletal, muscular and nervous spinal components.

Observações clinicocirúrgicas em fraturas e luxações vertebrais toracolombares em cães

Objetivou-se avaliar as implicações e os resultados obtidos frente aos tratamentos conservativo e cirúrgico em 37 cães sem distinção de sexo, raça ou idade, que apresentaram fraturas e luxações vertebrais (FLV) toracolombares. Cada paciente passou por anamnese, seguida por exames clínico, neurológico e radiográficos para se obter o diagnóstico neuroanatômico e a severidade da lesão. Os cães foram submetidos ao tratamento conservativo ou cirúrgico de acordo com as características de cada caso. Dos 37 animais deste estudo, 37,7% tinham percepção de dor profunda (PDP) intacta. Vinte animais foram submetidos ao tratamento conservativo, 14 ao tratamento cirúrgico e três animais faleceram antes do tratamento. Dos animais que mantiveram a PDP intacta, a taxa de recuperação foi de 100%, com tempo de recuperação total variando de sete a 75 dias, ao passo que, dos animais que perderam a PDP, nenhum recuperou a deambulação voluntária. Dos 14 animais operados, 42,8% apresentaram alterações vertebrais não visibilizadas ao exame radiográfico convencional, sendo necessária mudança na técnica cirúrgica planejada em 14,2% desses casos. Nos animais que mantiveram a PDP, não houve diferença significante nas taxas nem no tempo de recuperação da deambulação voluntária, independentemente do tipo de tratamento. Entretanto, houve diferença altamente significante entre os graus que mantiveram a PDP intacta com os animais que perderam a percepção de dor profunda em relação à taxa de recuperação. A taxa de eutanásia foi menor que em outros trabalhos descritos na literatura. Dos animais sem PDP submetidos ao tratamento conservativo ou cirúrgico, 31,25% readquiriram a capacidade de caminhar sem recuperar a PDP, sendo essa deambulação involuntária atribuída ao caminhar espinal.

Traumatic odontoid process synchondrosis fracture with atlantoaxial instability in a calf: clinical presentation and imaging findings

A 6-week-old female Simmental calf was evaluated for acute non-ambulatory tetraparesis. Physical and laboratory examinations revealed no clinically relevant abnormalities. Neurological findings were consistent with acute, progressive and painful cervical myelopathy. Radiographs displayed a fractured odontoid process (dens axis) and vertebral step misalignment at the fracture site. A traumatic origin was suspected. Advanced diagnostic imaging was considered to allow better planning of potential surgical stabilisation and to exclude any additional lesions of the cervical vertebral column. However, during trailer transportation to the advanced diagnostic imaging and surgery site, the calf deteriorated neurologically and was humanely euthanised. Magnetic resonance imaging (MRI) and computed tomography (CT) were performed immediately post-mortem for scientific reasons. The MRI examination reflected the radiographic findings and confirmed severe spinal cord compression at the fracture site. In addition, a T2W-hyperintense signal change within the paravertebral soft tissue dorsal to the fracture site was indicative of a traumatic event. CT identified the fracture site at the synchondrosis between the odontoid process and the body of the axis, and this finding was confirmed by post-mortem examination. Advanced diagnostic imaging and post-mortem examination did not identify any other cervical lesion. In summary, this calf was diagnosed with a traumatic odontoid process synchondrosis fracture, which has not been reported previously in calves but presents a challenging and well-known fracture type in young children. This case report indicates that the odontoid process synchondrosis is a potential predisposed injury site and that traumatic odontoid process synchondrosis fractures should be considered as a potential differential in calves with acute cervical pain and/or signs of a cervical myelopathy.

Multiple subluxations and comminuted fracture of the cervical spine in a sheep

A 5-month-old, 13.5 kg, female Corriedale sheep was referred to the Veterinary Medicine Teaching Hospital, with a history of traumatic injury of the cervical spine followed by non-ambulatoric tetraparesis that occurred 2 weeks before being admitted to the hospital. At admission, malalignment of the cervical spine with the cranial part of the neck deviating to the right was noted. Neurological examinations identified the absence of postural reactions in both forelimbs, mildly decreased spinal reflexes, and normal reaction to pain perception tests. Radiography revealed malalignment of the cervical vertebrae with subluxations at C1-C2 and C2-C3, and a comminuted fracture of the caudal aspect of C2. The sheep was euthanized due to a presumed poor prognosis. Necropsy and histopathological findings confirmed injuries of the cervical spine from C1 to C3, which were consistent with the clinical finding of tetraparesis in this case. This paper presents a rare case of multiple subluxations of the cervical spine caused by blunt force trauma in a young sheep. These results highlight the importance of an astute clinical diagnosis for such an acute cervical spine trauma and the need for prompt surgical correction for similar cases in the future.

Acute spinal cord injury: tetraplegia and paraplegia in small animals

Spinal cord injury (SCI) is a common problem in animals for which definitive treatment is lacking, and information gained from its study has benefit for both companion animals and humans in developing new therapeutic approaches. This review provides an overview of the main concepts that are useful for clinicians in assessing companion animals with severe acute SCI. Current available advanced ancillary tests and those in development are reviewed. In addition, the current standard of care for companion animals following SCI and recent advances in the development of new therapies are presented, and new predictors of recovery discussed.

Total vertebrectomy for stabilisation of chronic spinal lumbar luxation in a paraplegic dog without nociception

An adult male crossbred dog was referred with a history of a road traffic accident that took place 1 month earlier. Neurological examination revealed paraplegia with absent nociception in the pelvic limbs. On epaxial palpation, significant curvature of the anatomical axis of the spine between the third and fourth lumbar vertebrae was observed, with the presence of a bone end almost piercing the dog's skin. Survey radiographs of the lumbar spine revealed severe dislocation between L3 and L4 vertebrae. During surgery, the spinal cord was not visible between the dislocated segments. Because of difficulties in reducing the lumbar luxation during surgery, vertebrectomy and vertebral shortening were performed. After alignment between vertebrae L3 and L5, eight cortical orthopaedic screws and bone cement were used for fixation. After 30 days, the dog started to use a wheelchair and was considered by its owner to have a good quality of life with no evidence of pain. To the authors' knowledge, this is the first case of severe luxation treated by total vertebrectomy and spine shortening in a dog. This surgery can be considered as an option in the management of severe spine luxation when the spinal cord is physically transected.

Updates in the management of the small animal patient with neurologic trauma

Neurologic trauma, encompassing traumatic brain injury (TBI) and acute spinal cord injury (SCI), is a cause of significant morbidity and mortality in veterinary patients. Acute SCIs occurring secondary to trauma are also common. Essential to the management of TBI and SCI is a thorough understanding of the pathophysiology of the primary and secondary injury that occurs following trauma. This article reviews the pathophysiology of this primary and secondary injury, as well as recommendations regarding clinical assessment, diagnostics, pharmacologic and nonpharmacologic therapy, and prognosis.

Mechanisms of injury and emergency care of acute spinal cord injury in dogs and cats

OBJECTIVES

To review the literature in regards to the pathophysiology of acute spinal cord injury, and to describe current concepts in regards to patient assessment, diagnostic, and therapeutic measures with a special emphasis on emergency and critical care considerations.

ETIOLOGY

Acute spinal cord injury occurs in 2 phases. The primary injury occurs at the time of initial injury and may include intervertebral disk herniation, vertebral fracture or luxation, penetrating injury, and vascular anomalies such as fibrocartilaginous embolic myelopathy. Secondary injury occurs following primary injury and is multifactorial encompassing numerous biochemical and vascular events that result in progression of injury.

DIAGNOSIS

The diagnosis is based on history and physical examination findings. A neurologic examination should be performed following initial patient assessment and stabilization. Further diagnostics to characterize acute spinal injury include radiographs and advanced imaging modalities such as myelography, computed tomography, or magnetic resonance imaging.

THERAPY

Initial treatment should focus on addressing the patient's cardiovascular and respiratory system. Supportive measures to support systemic perfusion are vital to minimizing secondary injury. Specific therapy toward minimizing secondary injury in veterinary medicine remains controversial, especially in regards to the utilization of methylprednisolone. Other therapies are either in need of additional research or have failed to document clinical difference.

PROGNOSIS

The prognosis for acute spinal injury is varied and is dependent upon the presence of concurrent trauma, location, and type of primary injury sustained, and extent of neurologic impairment at the time of initial presentation. The etiology of the underlying trauma is of great importance in determining prognosis and outcome. Loss of deep pain is generally accepted as a poor prognostic indicator; however, even these patients can recover depending on their response to treatment.

Traumatismo da medula espinhal em cães e gatos: estudo prospectivo de 57 casos

O traumatismo da medula espinhal é uma causa comum de disfunção neurológica em cães e gatos. Lesões nestas espécies ocorrem devido a vários tipos de acidentes, podendo ocasionar sequelas que prejudicam o paciente como animais de estimação ou lesões que comprometam a vida. O objetivo principal deste estudo foi a monitoração intensiva de animais com lesão medular atendidos entre 8/2009 e 11/2010 no Hospital Veterinário da Universidade Estadual de Londrina, estudando os fatores epidemiológicos e etiológicos, fatores de risco, segmentos medulares mais afetados, resultados dos tratamentos conservativo ou cirúrgico, relação entre o tempo de atendimento e a recuperação do animal, eficácia e efeitos colaterais do succinato sódico de metilprednisolona, complicações, sequelas e evolução do quadro. Durante este período foram acompanhados 57 animais (48 cães e nove gatos). Observou-se predominância de animais machos (68%) e domiciliados (79%). A principal causa de lesão foi o atropelamento (66%). O tempo entre o trauma e o atendimento foi menos de oito horas em 42% dos casos e mais de um dia em 51%. O segmento medular mais atingido foi o toracolombar (52%). Vinte animais foram submetidos à eutanásia após o atendimento inicial devido ao prognóstico reservado. O tratamento conservativo com repouso e/ou imobilização externa foi realizado em 29 animais e um bom resultado com esta modalidade foi obtida em 72,4% dos casos: houve recuperação funcional total em 17 (58,6%) animais e parcial em quatro (13,8%). Quatro animais não se recuperaram e quatro animais morreram. Oito pacientes foram submetidos ao tratamento cirúrgico, sendo que três animais recuperaram-se, um paciente não apresentou recuperação e quatro morreram ou foram submetidos a eutanásia devido a complicações no trans ou pós-operatório. O tratamento conservativo foi viável, principalmente em cães com lesão medular cervical.

Acute Spinal Cord Injury in the Cat: Causes, Treatment and Prognosis

Practical relevance Acute spinal conditions are a common emergency presentation in general veterinary practice and have the potential to cause devastating spinal cord injury (SCI) and consequent severe neurological deficits. SCI can be divided into two subgroups: exogenous SCI (vertebral fracture and/or luxation/subluxation) and endogenous SCI (intervertebral disc extrusion and ischaemic myelopathy).

Clinical challenges The majority of cats with SCI have concurrent injuries. The clinician must perform a thorough physical examination and prioritise and then stabilise the life-threatening problems before focusing on the neurological examination. The possibility of multiple sites of SCI and spinal shock can make interpretation of the neurological examination challenging. While plain radiographs or myelography are usually diagnostic, they do not give direct information about the integrity of the spinal cord parenchyma or the severity of any damage. If facilities or experienced staff capable of performing the necessary surgery are not available, or advanced imaging is indicated, referral to a specialist veterinary institution should be considered.

Audience This review is aimed at clinicians dealing with feline SCI in the emergency setting or at first-opinion level, and discusses causes, initial management, specific treatment and prognosis.

Patient group While any cat may potentially be affected by SCI, there is a tendency for exogenous SCI to be more common in younger individuals and, in the authors' experience, pure-breed cats are very rarely presented. Endogenous SCI can be seen in any breed and is typically a condition of adult cats.