Clinical outcomes of 20 brachycephalic dogs with thoracolumbar spinal deformities causing neurological signs treated with spinal stabilization using 3D-printed patient-specific drill guides.

OBJECTIVE: To describe the clinical outcomes for pugs and French bulldogs with congenital vertebral malformations, undergoing thoracolumbar spinal stabilization surgery using 3D-printed patient-specific drill guides. To evaluate the accuracy of pedicle screw placement in this group of dogs. STUDY DESIGN: Retrospective descriptive study. ANIMALS: Twenty dogs (12 pugs and eight French bulldogs). METHODS: Medical records searched between August 2018 and March 2021 for pugs and French bulldogs diagnosed with congenital vertebral abnormalities via magnetic resonance imaging (MRI) scan and computed tomography (CT) scan causing T3-L3 myelopathy signs that underwent spinal stabilization surgery using 3D-printed patient-specific drill guides followed by a postoperative CT scan. The short-term outcome was based on the neurological grade (modified Frankel score-MFS) on the day after surgery, day of discharge, and at the follow-up examination at 4 to 6 weeks after surgery. The mid-term outcome was obtained via an online questionnaire (or direct examination in one case). RESULTS: Twenty dogs met the inclusion criteria (19/20 grade 2 MFS, 1/20 grade 4 MFS). No complications were reported in the immediate postoperative period and optimal pedicle screw placement was obtained in 169/201 of screws. Twenty-four hours after surgery 16/20 dogs displayed an unchanged neurological grade. Short-term outcomes revealed a static (17/20) or improved (2/20) neurological grade. Ten owners participated in the online questionnaire. All patients were reported to be ambulatory; however, 7/10 dogs displayed abnormal gait. Neurological signs had remained static (6/10) or improved (3/10) in comparison with the dogs' preoperative status at a median of 883.5 days from the surgery. CONCLUSION: Dogs in this study had a favorable short-term outcome and mid-term outcome evaluation revealed a static/improved neurological status. CLINICAL SIGNIFICANCE: Thoracolumbar spinal stabilization surgery using 3D-printed patient-specific drill guides showed a favorable outcome in brachycephalic breeds affected by vertebral deformities.

Significance of intramedullary T2* signal voids in the magnetic resonance imaging of paraplegic deep pain-negative dogs following intervertebral disc extrusion at short-term follow-up.

Introduction: Dogs presenting as paraplegic without nociception due to a thoracolumbar intervertebral disc extrusion provide a difficult decision to both the clinician and the owner. The prognosis when performing surgical decompression remains guarded. Aside from significant extradural compression, these dogs often have a significant secondary spinal cord injury, which has shown to be an important factor in determining both the likelihood of developing progressive myelomalacia and the return to ambulation. Materials and methods: This is a retrospective, observational, single centre study including 82 dogs presenting as paraplegic with absent nociception diagnosed with an intervertebral disc extrusion. Patients underwent MRI of the thoracolumbar spine, including a gradient echo sequence which was evaluated for the presence of intramedullary signal void artefacts. Decompressive surgery was performed, and patients were evaluated for the presence of nociception at short term follow up (at least four weeks post-surgery). Results: Overall, 59.8% of patients regained nociception within the study period. This number was significantly reduced to 33.3% when multiple gradient echo signal voids were present (compared to 67.3% of dogs without signal voids). There was no significant difference in the rate of developing progressive myelomalacia between groups. Conclusions: This paper adds to the existing literature and suggests that the gradient echo sequence may be of use when assessing acute spinal cord injury in the context of intervertebral disc extrusion and how it relates to prognosis.

Clinical features, treatment and outcome of discospondylitis in cats.

OBJECTIVES: There is a paucity of information on feline discospondylitis. This study aimed to describe the signalment, clinical and laboratory findings, aetiological agents, treatment and outcome in cats affected by discospondylitis. METHODS: This was a retrospective review of the medical records of cats diagnosed with discospondylitis at four referral institutions. RESULTS: A total of 17 cats were identified. Most were domestic shorthair cats (76.5%) and male (58.8%), with a median age of 9 years (range 0.9-14) and a median duration of clinical signs of 3 weeks (range 0.3-16). All cats presented with spinal hyperaesthesia; 3/17 had pyrexia. Neurological dysfunction was found in 64.7% of cats, which was indicative of a T3-L3 or L4-S2 spinal segment, associated nerve root or associated nerve neurolocalisation. Haematology, serum biochemistry and urinalysis revealed occasional inconsistent non-specific changes. All cats underwent urine culture; 9/17 cats also had a distinct tissue cultured. Positive bacterial cultures were obtained in two cats (11.8%) for Staphylococcus species (urine, blood and intradiscal fine-needle aspirate) and Escherichia coli (urine); both presented with multifocal discospondylitis. Treatment was non-surgical in all cats, with sustained antibiotic therapy for a median of 3 months (range 1-9). Analgesia provided included non-steroidal anti-inflammatory drugs, alone or in combination with gabapentin. Restricted exercise was advised for a minimum of 4 weeks. Outcome information available in 12 cats was excellent in terms of pain control and neurological function in 10 cats (83.3%) at the time of stopping antibiotics. Recurrence occurred in one case, which had received a single antibiotic for 6 weeks, and relapsed 4 months after presentation. One other case failed to improve and was euthanased during the course of hospitalisation. CONCLUSIONS AND RELEVANCE: Feline discospondylitis is uncommon and no obvious signalment predisposition was found in this study. Spinal hyperaesthesia was universally present, with neurological dysfunction also highly prevalent. Bacterial culture was unrewarding in most cases. Amoxicillin-clavulanic acid or cephalosporins are reasonable choices for first-line antibiotics. Prognosis was favourable, with no long-term evidence of recurrence in cats on sustained antibiotic therapy, for a mean duration of 3 months.

Intracranial meningioma in two coeval adult cats from the same litter.

CASE SUMMARY: In this report we describe the occurrence of intracranial meningioma in two adult cats from the same litter. The location of the meningioma varied: one tumour was at the level of the brainstem, and the other was affecting the temporal and piriform lobes. The cat with the brainstem meningioma was treated with radiotherapy and the littermate had a rostrotentorial craniectomy for tumour removal. Both cats had a histopathological diagnosis of grade I meningioma of a predominantly fibrous subtype. RELEVANCE AND NOVEL INFORMATION: Cases of familial meningioma in cats have not previously been described in the veterinary literature. However, familial meningioma is well described in humans and it is possible that cases are underestimated in animals. We discuss the possible genetic background and other causes, as well as challenges we may face in veterinary medicine in identifying these associations.

Lumbosacral intervertebral disk extrusions in 13 dogs.

OBJECTIVE: To describe the clinical presentation, magnetic resonance imaging (MRI) findings, and outcome of dogs treated surgically for lumbosacral intervertebral disk extrusion (IVDE). STUDY DESIGN: Retrospective study. ANIMALS: Thirteen dogs. METHODS: Records and MRI studies of dogs with intraoperatively confirmed lumbosacral IVDE were reviewed. MRI features of thoracolumbar IVDE were applied to all cases. Postoperative outcome was subjectively assessed as excellent, good, or poor. RESULTS: All dogs had an acute or subacute onset of lumbosacral pain and nerve root signature. Seven dogs had neurological deficits. MRI revealed lateralized herniated disk material and partial to complete disk degeneration in all cases; the extradural material extended cranial and/or caudally from the disk space in 10 cases. All dogs underwent L7-S1 dorsal laminectomy and removal of extruded disk material. In six dogs, surgery was complicated by inflammatory changes, including one case of epidural steatitis. On reexamination 4-6 weeks postsurgery, outcome was judged as excellent in 11 dogs and poor in the remaining 2 due to contralateral nerve root signature in one case and nonambulatory paraparesis and urinary incontinence in the case with steatitis. CONCLUSION: Lumbosacral IVDE in dogs was characterized by acute/subacute onset of lumbosacral pain and nerve root signature and lateralized and often dispersed extradural material over a degenerated L7-S1 intervertebral disk on MRI. Early decompressive dorsal laminectomy generally resulted in excellent clinical outcome. CLINICAL SIGNIFICANCE: Observation of these clinical and imaging features in dogs should prompt clinical suspicion of lumbosacral IVDE.

Accuracy of Placement of Pedicle Screws in the Lumbosacral Region of Dogs Using 3D-Printed Patient-Specific Drill Guides.

OBJECTIVE: The aim of this study was to report the accuracy of pedicle screw placement using three-dimensional (3D)-printed, patient-specific drill guides in the lumbosacral region of dogs. STUDY DESIGN: This was a retrospective study. Thirty-two pedicle screws were placed in five dogs. Medical records were reviewed between November 2015 and November 2018 for dogs showing clinical signs associated with cauda equina syndrome. Inclusion criteria included preoperative magnetic resonance imaging, pre- and postoperative computed tomography (CT) and dorsal stabilization, with pedicle screws placed using 3D-printed, patient-specific drill guides and polymethylmethacrylate. Screw placement was evaluated for medial or lateral breaching on postoperative CT. RESULTS: Five dogs met the inclusion criteria. Four had degenerative lumbosacral stenosis and one had discospondylitis. All dogs had failed medical management prior to surgery. Of 32 bicortical pedicle screws placed, 30 were fully contained inside the pedicle and 2 were partially breaching the vertebral canal (less than one-third of the screw diameter). Postoperative CT revealed good alignment of L7-S1 in all planes. CONCLUSION: This technique enabled an accurate and safe placement of pedicle screws in the lumbosacral region of dogs with lumbosacral disease. Three-dimensional, printed patient-specific drill guides are a safe and effective method of placing pedicle screws in dogs with lumbosacral disease.

Imaging features of discospondylitis in cats.

OBJECTIVES: This study describes the imaging features of feline discospondylitis on MRI, comparing them with CT and radiographic findings where available. METHODS: The medical records of cats diagnosed with discospondylitis, presented to three referring institutions, were reviewed. MRI, CT and radiographic features were assessed by two of the authors independently. RESULTS: Fourteen sites of discospondylitis were retrospectively identified in 13 cats. The L7-S1 intervertebral disc space (IVDS) was affected in 7/14 (50%) cases. Characteristic MRI features included a hyperintense nucleus pulposus signal on T2-weighted (T2W) imaging (n = 10/14 [71%]) and short tau inversion recovery (STIR) imaging (n = 11/13 [85%]), with contrast enhancement in all (n = 11/11); involvement of adjacent vertebral endplates (n = 11/14 [79%]) and hyperintense neighbouring soft tissue on T2W (n = 11/14 [79%]) and STIR (n = 10/13 [77%]), with contrast enhancement in all (n = 11/11); and the presence of spondylosis deformans (n = 10/14 [71%]). Other features included narrowed or collapsed IVDS (n = 8/14 [57%]), contrast enhancement of vertebral bodies (n = 5/11 [46%]), epidural space involvement (n = 5/14 [36%]), compression of the spinal cord or nerve roots (n = 5/14 [36%]), paraspinal abscessation (n = 3/14 [21%]) and meningeal signal intensity abnormalities with contrast enhancement (n = 5/6 [83%]). These latter findings may indicate secondary focal meningitis. Radiographs were available covering five sites (in four cats) and CT covering three sites (in two cats). The most common radiological features were collapse or narrowing of the affected IVDS (80%) and endplate erosion (60%). No changes suggestive of discospondylitis were identifiable on radiography or CT in two sites (one cat), despite being identifiable on MRI. Repeated radiography in one case did not reveal complete radiological resolution following 9 months of treatment. CONCLUSIONS AND RELEVANCE: The results of this study indicate consistent MRI features of feline discospondylitis that should be considered in the diagnosis of this condition.

Accuracy of placement of pedicle screws in the thoracolumbar spine of dogs with spinal deformities with three-dimensionally printed patient-specific drill guides.

OBJECTIVE: To determine the accuracy of pedicle screw placement in the thoracic spine of dogs with spinal deformities with three-dimensionally (3D) printed patient-specific drill guides. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Six dogs in which sixty pedicle screws were placed in the thoracolumbar spine. METHODS: Medical records were searched between June 2017 and June 2018 for dogs with clinical signs associated with a thoracolumbar vertebral malformation. Inclusion criteria included MRI and computed tomography (CT) data that were used to create 3D printed patient-specific drill guides. All dogs were stabilized dorsally with guided bicortical pedicle screws and polymethylmethacrylate. Accuracy of screw placement was assessed by immediately postoperative CT according to a modified Zdichavsky classification. RESULTS: Five pugs and one French bulldog met the inclusion criteria. Sixty bicortical pedicle screws were placed; 96.7% were graded as I (optimal placement), and 3.3% were classified as IIa (partial penetration of the medial pedicle wall) according to a modified Zdichavsky classification. CONCLUSION: Three-dimensionally printed patient-specific drill guides allowed safe and accurate placement of pedicle screws in the thoracolumbar spine in dogs with vertebral malformation. CLINICAL SIGNIFICANCE: Three-dimensionally printed patient-specific drill guides are a safe and effective method of placing pedicle screws in dogs with thoracolumbar vertebral malformations.

Clinical presentation, magnetic resonance imaging features, and outcome in 6 cats with lumbar degenerative intervertebral disc extrusion treated with hemilaminectomy.

OBJECTIVE: To describe the clinical presentation, magnetic resonance imaging features, and outcome of cats treated with hemilaminectomy for intervertebral disc extrusion (IVDE). STUDY DESIGN: Short case series. ANIMALS: Six cats. METHODS: Medical records were reviewed for signalment, onset, duration, and severity of clinical signs, magnetic resonance imaging features, surgical findings, and clinical outcome with a minimum postoperative follow-up of 4 weeks. RESULTS: Our population included 6 cats with a median age of 8.6 years, consisting predominantly of males (n = 5) and purebred cats (n = 4). An acute onset and short duration of progressive clinical signs of myelopathy was the most common presentation; spinal hyperesthesia was present in 3 cats. A large volume of extradural material was identified by MRI within the lumbar vertebral column of each cat, causing marked spinal cord compression. The most common sites affected were L2-L3 (n = 2) and L6-L7 (n = 2). Follow-up after hemilaminectomy was available in 5 cats: 4 had normal voluntary motor function, and 1 had recurrence of acute paraplegia, compromised nociception, and an extensive T2w hyperintense intramedullary lesion according to MRI. All 4 cats with preoperative urinary incontinence remained incontinent for at least 1 week despite good voluntary motor function of pelvic limbs. CONCLUSION: Intervertebral disc extrusion was diagnosed by MRI in all 6 cats, most commonly at L2-3 and L6-7. Hemilaminectomy resulted in a good to excellent outcome in 4 of 5 cats. CLINICAL SIGNIFICANCE: Feline IVDE can be diagnosed by MRI and carry a good prognosis after surgical decompression, although urinary continence may be delayed despite good pelvic limb voluntary motor function.

Accuracy of a patient-specific 3D printed drill guide for placement of cervical transpedicular screws.

OBJECTIVE: To develop a patient-specific 3-dimensional (3D) printed drill guide for placement of cervical transpedicular screws and to assess its accuracy. STUDY DESIGN: Prospective case-series. SAMPLE POPULATION: Thirty-two cervical pedicle screws (CPS) placed in 3 large breed dogs. METHODS: Computed tomographic (CT) data of the cervical vertebrae were exported to a medical image processing software and 3D virtual vertebral models were created for each vertebra. These models were processed in a computer aided design (CAD) software to determine the optimal trajectory and size of the CPS. Virtual drill guides were created for each patient, 3D-printed, and used intraoperatively. Locking titanium screw heads were bonded with polymethylmethacrylate cement to stabilize affected vertebral segments. Postoperative CT was used to assess the radiological accuracy of CPS placement in each dog. For each screw, CAD files were analyzed to determine a screw-diameter-to-pedicle-width-ratio (SDPWR) at the narrowest point of the pedicle. RESULTS: A total of 32 CPS were placed, measuring 3.5 mm (n = 20), 2.7 mm (n = 11), and 2.4 mm (n = 1) in diameter. The majority (29/32) of these screws were placed without evidence of vertebral canal breach (grade 0), whereas a vertebral canal breach <2 mm (grade 1) was detected in 3/32 screws. This outcome was achieved despite a mean SDPWR of 0.75 (range 0.58-0.93). CONCLUSION: The use of a 3D-printed patient-specific drill guide permitted accurate placement of 32 bicortical pedicle screws in the caudal cervical vertebrae of 3 dogs. This technique may improve clinical outcome through superior biomechanical properties of screws, reduced surgical time, and reduced morbidity. These results warrant evaluation of patient outcome in a larger population.

Outcome comparison in dogs with a presumptive diagnosis of thoracolumbar fibrocartilaginous embolic myelopathy and acute non-compressive nucleus pulposus extrusion.

Dogs with fibrocartilaginous embolic myelopathy (FCEM) or acute non-compressive nucleus pulposus extrusion (ANNPE) are reported to have a fair prognosis; however, persistent motor/autonomic deficits are possible. Specific MRI patterns have been suggested to differentiate these diseases although never been validated with histopathology in large studies. The aim of this retrospective study was to evaluate if these MRI patterns are associated with different clinical outcomes in dogs with peracute non-progressive T3-L3 myelopathy. Two hundred and one dogs were included. Outcome data were obtained via medical records and telephone questionnaires. MRIs were blindly reviewed by three board-certified observers, obtaining substantial to almost perfect interobserver agreement on diagnoses (κ=0.635-0.828). Presumptive ANNPE and FCEM were diagnosed in 157 and 44 dogs , respectively. Ambulatory function was regained in 99 per cent of cases, with persistent motor deficits in 83.6 per cent and 92.5 per cent of dogs with presumptive ANNPE and FCEM, respectively. The presumptive diagnosis was not associated with motor function recovery, recovery times or urinary continence. Faecal incontinence was five times more likely in dogs with presumptive ANNPE (23 per cent) compared with presumptive FCEM (7.5 per cent).Distinguishing between MRI patterns of presumptive ANNPE or FCEM in dogs with peracute non-progressive T3-L3 myelopathy may help predict the risk of developing faecal incontinence.

Retrograde migration and subcutaneous coiling of the peritoneal catheter of a ventriculoperitoneal shunt in a cat.

Case summary Ventriculoperitoneal shunt placement is the most commonly utilised surgical treatment for hydrocephalus in human and veterinary patients. Migration of the peritoneal catheter is an uncommon but well-documented complication in people, usually occurring within the first 3 months postoperatively, although only a single feline case report exists. A ventriculoperitoneal shunt was placed in a domestic shorthair cat, aged 4 years and 10 months, following a diagnosis, with MRI, of unilateral, non-communicating hydrocephalus. Diarrhoea, increased vocalisation and pruritus were reported within the first 3 months postoperatively. A shunt-associated seroma developed, which was aspirated under ultrasound guidance. Within 3 days, the entire peritoneal catheter was subcutaneously coiled at the level of the seroma. The peritoneal catheter was replaced within the abdomen via a new subcutaneous tunnel. No further complications had occurred 24 months following revision surgery. Relevance and novel information This is the second report describing peritoneal catheter migration in a cat. Repetitive head and neck movements during self-grooming, raised intra-abdominal pressure secondary to vocalisation and tenesmus, and negative pressure exerted during seroma aspiration may have contributed to ventriculoperitoneal shunt migration. Excessive loose skin and increased activity may further increase the risk of migration in cats. Diagnostic imaging should be offered prior to and following aspiration of shunt-associated swellings, and minimal negative pressure should be exerted. Attempts to reduce the frequency of postoperative self-grooming, prevention and prompt treatment of conditions predisposing to raised intra-abdominal pressure and moderate exercise restriction, particularly within the first 3 months, may help reduce the risk of peritoneal catheter migration.

High resolution protein electrophoresis of 100 paired canine cerebrospinal fluid and serum.

This study was performed to investigate the diagnostic relevance of cerebrospinal fluid (CSF) high resolution electrophoresis. The laboratory technique was applied to 100 paired samples of canine CSF and serum, with paired samples tested during the same analytical run, as recommended in human medicine. Ninety four of the dogs had a neurological disease and 6 healthy dogs served as a control group. A strong linear correlation between CSF total protein concentration and the albumin quota (AQ) was found in the control group and in the inflammatory (infectious or noninfectious), neoplastic, and miscellaneous groups: AQ = 0.015 CSF total protein--0.102, r = 0.990. This correlation suggests that an increased CSF total protein concentration can be an indicator of blood brain barrier dysfunction. The highest median AQ value was found in the aseptic suppurative meningitis group, but no statistical differences were found between this and the other groups. The AQ, calculated with this technique, did not provide any additional information. Moreover, although unexpected, the electrophoretic profiles were not characteristic of any particular disease. In conclusion, this study did not confirm high resolution electrophoresis of paired CSF and serum samples to be a valuable ancillary diagnostic tool for canine neurological diseases.