Novel Calcium Phosphate Promotes Interbody Bony Fusion in a Porcine Anterior Cervical Discectomy and Fusion Model.

STUDY DESIGN: Experimental porcine anterior cervical discectomy and fusion (ACDF) model: a proof-of-concept study. OBJECTIVE: The effect of monetite synthetic bone graft containing calcium pyrophosphate (Ca-PP) and ß-tricalcium phosphate (ß-TCP) on cervical spinal fusion in a non-instrumented two-level large animal model. SUMMARY OF BACKGROUND DATA: ACDF is the gold standard surgical technique for the treatment of degenerative cervical spinal diseases. However, pseudarthrosis associated with increased patient morbidity occurs in approximately 2,6% of the surgeries. Synthetic bone graft (SBG) may enhance bony fusion and subsequently decrease the risk of pseudarthrosis. Recent studies on monetite-based synthetic bone grafts for use in large cranial defects in humans have shown promising bone healing results, necessitating further investigation of their use in cervical spinal fusion. METHODS: Four adult female Danish Göttingen mini-pigs received partial cervical anterior discectomy and intervertebral defects at an upper and lower level. One defect was filled with SBG and the other was left empty. Bony fusion was evaluated using computed tomography (CT) at three-month intervals for 12 months. Fifteen months post-surgery, the animals were euthanized for further ex vivo qualitative histopathological and micro-CT evaluations. Fusion rates were compared using Fisher´s exact test at each time point. RESULTS: Increased interbody bony fusion rates were observed at synthetic bone graft levels (4/4) compared with control levels (0/4) evaluated by CT at 6- and 9-months post-surgery ( P = 0.029). Fusion was observed at all synthetic bone graft levels 12 months post-surgery and at only one control level. Histopathological evaluation confirmed high-quality interbody bony fusion at all synthetic bone graft levels, and fusion by spondylosis at one control level. CONCLUSION: This proof-of-concept study provides preliminary evidence of a novel, Ca-PP -and ß-TCP-containing monetite SBG that promotes bony fusion compared to a negative control in a clinically relevant porcine model of ACDF. LEVEL OF EVIDENCE: N/A.

Clinical Evaluation of a New Surgical Augmentation Technique for Transarticular Atlantoaxial Fixation for Treatment of Atlantoaxial Instability.

The feasibility of a newly developed augmentation of ventral fixation technique for surgical stabilization of atlantoaxial instability was clinically evaluated in a cohort of eleven dogs, and long-term clinical outcomes were retrospectively analyzed. The new technique combines wire/suture fixation through a transverse hole in the axis anchored by two screws placed in the alae atlantis or at the cranial end of plates used to bridge the atlantoaxial joint ventrally. A previous biomechanical study demonstrated good stability of this technique during shear loading, comparable to the stability achieved with other standard techniques. Ten dogs improved clinically after surgery and returned to a normal life within 3-6 months of surgery. One dog developed aphonia, dysphagia, and died of aspiration pneumonia three days after surgery. The augmentation of conventional ventral atlantoaxial fixation with the transverse bony corridor of the proximal axis body may be a valuable way to enhance stabilization of the atlantoaxial joint.

Endoscopy-assisted resection of a sphenoid-wing meningioma using a 3D-printed patient-specific pointer in a dog: A case report.

A 9-year-old female mixed-breed dog presented for treatment of a presumed sphenoid-wing meningioma. Clinical signs included tonic-clonic seizures lasting <1 min, which had started 3 months previously. The physical examination results were unremarkable. An eccentrically located neoplastic cystic structure in the right sphenoid bone region suggestive of a meningioma and peritumoural brain oedema was observed in pre-operative magnetic resonance imaging (MRI). Prior to surgery, a three-dimensional (3D) patient-specific pointer (PSP) was designed using computed tomography (CT) images and computer-aided 3D design software. After a targeted approach and exposure of the lateral part of the right temporal lobe by a craniectomy guided by the 3D-PSP, complete macroscopic piecemeal resection of the meningioma could be performed using endoscopy-assisted brain surgery. Post-operative MRI confirmed complete excision of the tumor. Anticonvulsive therapy was discontinued after 90 days, and the dosage of anticonvulsants was tapered 2 weeks after surgery. At a follow-up examination 225 days post-operatively, recurrence of seizures was not observed, and the absence of tumor recurrence was confirmed by a repeat MRI examination. To the best of our knowledge, this is the first report in veterinary medicine describing a successful resection of a sphenoid-wing meningioma using a 3D-PSP. 3D-PSP-assisted craniectomy may be a surgical option for some canine skull-based tumors, such as sphenoid wing meningiomas.

Preliminary Studies on the Intrahepatic Anatomy of the Venous Vasculature in Cats.

Hepatic surgeries are often performed in cats to obtain a disease diagnosis, for the removal of masses, or for the treatment of shunts. Whereas the vascular anatomy of the liver has been studied in dogs, such evidence is lacking in cats. The current study used corrosion casts of portal and hepatic veins and computed tomography (CT) analysis of the casts to identify and describe the intrahepatic anatomy in healthy cat livers (n = 7). The results showed that feline livers had a consistent intrahepatic portal and venous anatomy, with only minor disparities in the numbers of secondary and tertiary branches. The feline portal vein consistently divided into two major branches and not three, as previously described in the literature for cats. The finding of a portal vein originating from the right medial lobe branch leading to the quadrate lobe in 4/7 specimens is a novelty of the feline anatomy that was not previously described in dogs. Partial to complete fusion of the caudate process of the caudate and the right lateral lobe, with a lack of clear venous separation between the lobes, was present in two specimens. These findings allowed a detailed description of the most common intrahepatic venous patterns in cats. Further anatomical studies should be encouraged to confirm the present findings and to investigate the utility of this information in surgical settings.

Determination of cutoff values on computed tomography and magnetic resonance images for the diagnosis of atlantoaxial instability in small-breed dogs.

OBJECTIVE: To determine cutoff values for the diagnosis of atlantoaxial instability (AAI) based on cross-sectional imaging in small-breed dogs. STUDY DESIGN: Retrospective multicenter study. SAMPLE POPULATION: Client-owned dogs (n = 123) and 28 cadavers. METHODS: Dogs were assigned to three groups: a control group, a "potentially unstable" group, and an AAI-affected group, according to imaging findings and clinical signs. The ventral compression index (VCI), cranial translation ratio (CTR), C1-C2 overlap, C1-C2 angle, atlantoaxial distance, basion-dens interval, dens-to-axis length ratio (DALR), power ratio, and clivus canal angles were measured on CT or T2-weighted magnetic resonance (MR) images. Receiver operating characteristic (ROC) analysis was performed to define cutoff values in flexed (≥25°) and extended (<25°) head positions. RESULTS: Cutoff values for the VCI of ≥0.16 in extended and ≥0.2 in flexed head positions were diagnostic for AAI (sensitivity of 100% and 100%, specificity of 94.54% and 96.67%, respectively). Cutoff values for the other measurements were defined with a lower sensitivity (75%-96%) and specificity (70%-97%). A combination of the measurements did not increase the sensitivity and specificity compared with the VCI as single measurement. CONCLUSION: Cutoff values for several imaging measurements were established with good sensitivity and specificity. The VCI, defined as the ratio between the ventral and dorsal atlantodental interval, had the highest sensitivity and specificity in both head positions. CLINICAL SIGNIFICANCE: The use of defined cutoff values allows an objective diagnosis of AAI in small-breed dogs. The decision for surgical intervention, however, should remain based on a combination of clinical and imaging findings.

Novel immortalization approach defers senescence of cultured canine adipose-derived mesenchymal stromal cells.

In the last decades, the scientific community spared no effort to elucidate the therapeutic potential of mesenchymal stromal cells (MSCs). Unfortunately, in vitro cellular senescence occurring along with a loss of proliferative capacity is a major drawback in view of future therapeutic applications of these cells in the field of regenerative medicine. Even though insight into the mechanisms of replicative senescence in human medicine has evolved dramatically, knowledge about replicative senescence of canine MSCs is still scarce. Thus, we developed a high-content analysis workflow to simultaneously investigate three important characteristics of senescence in canine adipose-derived MSCs (cAD-MSCs): morphological changes, activation of the cell cycle arrest machinery, and increased activity of the senescence-associated ß-galactosidase. We took advantage of this tool to demonstrate that passaging of cAD-MSCs results in the appearance of a senescence phenotype and proliferation arrest. This was partially prevented upon immortalization of these cells using a newly designed PiggyBac™ Transposon System, which allows for the expression of the human polycomb ring finger proto-oncogene BMI1 and the human telomerase reverse transcriptase under the same promotor. Our results indicate that cAD-MSCs immortalized with this new vector maintain their proliferation capacity and differentiation potential for a longer time than untreated cAD-MSCs. This study not only offers a workflow to investigate replicative senescence in eukaryotic cells with a high-content analysis approach but also paves the way for a rapid and effective generation of immortalized MSC lines. This promotes a better understanding of these cells in view of future applications in regenerative medicine.

Safety of a Novel Listeria monocytogenes-Based Vaccine Vector Expressing NcSAG1 (Neospora caninum Surface Antigen 1).

Listeria monocytogenes (LM) has been proposed as vaccine vector in various cancers and infectious diseases since LM induces a strong immune response. In this study, we developed a novel and safe LM-based vaccine vector platform, by engineering a triple attenuated mutant (Lm3Dx) (ΔactA, ΔinlA, ΔinlB) of the wild-type LM strain JF5203 (CC 1, phylogenetic lineage I). We demonstrated the strong attenuation of Lm3Dx while maintaining its capacity to selectively infect antigen-presenting cells (APCs) in vitro. Furthermore, as proof of concept, we introduced the immunodominant Neospora caninum (Nc) surface antigen NcSAG1 into Lm3Dx. The NcSAG1 protein was expressed by Lm3Dx_SAG1 during cellular infection. To demonstrate safety of Lm3Dx_SAG1 in vivo, we vaccinated BALB/C mice by intramuscular injection. Following vaccination, mice did not suffer any adverse effects and only sporadically shed bacteria at very low levels in the feces (<100 CFU/g). Additionally, bacterial load in internal organs was very low to absent at day 1.5 and 4 following the 1st vaccination and at 2 and 4 weeks after the second boost, independently of the physiological status of the mice. Additionally, vaccination of mice prior and during pregnancy did not interfere with pregnancy outcome. However, Lm3Dx_SAG1 was shed into the milk when inoculated during lactation, although it did not cause any clinical adverse effects in either dams or pups. Also, we have indications that the vector persists more days in the injected muscle of lactating mice. Therefore, impact of physiological status on vector dynamics in the host and mechanisms of milk shedding requires further investigation. In conclusion, we provide strong evidence that Lm3Dx is a safe vaccine vector in non-lactating animals. Additionally, we provide first indications that mice vaccinated with Lm3Dx_SAG1 develop a strong and Th1-biased immune response against the Lm3Dx-expressed neospora antigen. These results encourage to further investigate the efficiency of Lm3Dx_SAG1 to prevent and treat clinical neosporosis.

Investigation of timing of surgery and other factors possibly influencing outcome in dogs with acute thoracolumbar disc extrusion: a retrospective study of 1501 cases.

BACKGROUND: Intervertebral disc extrusions in the thoracolumbar region are a common spinal neurologic disorder in dogs and usually considered a neurological emergency. Several factors, like timing of surgery, have previously been analysed in order to determine the effect on outcome and time of recovery. Most studies have investigated one defined population of dogs and the influence of a single factor on the overall outcome. In this retrospective study, a large cohort of dogs and the influence of one or combinations of several factors on outcome and time of recovery were analysed. RESULTS: The bivariate analysis demonstrated a significant association between the following variables and the time of recovery: the time span between the onset of clinical signs and surgery (Cramers Phi [Formula: see text] = 0.14; P = 0.003), the grade of severity ([Formula: see text] = 0.23; P < 0.001) and the implementation of physical rehabilitation ([Formula: see text] = 0.2; P < 0.001). However, the analysis of a multivariable regression model demonstrated that a significant correlation only exists between the time span between the onset of clinical signs and surgery and the overall outcome (P = 0.007), as well as between the grade of severity and the time of recovery (P < 0.001). The percentage of dogs with lacking deep pain perception (DPP) that had to be euthanised due to their neurological condition, decreased from 20.0 to 2.9% when physical rehabilitation was implemented. Additionally, the proportion of dogs (same group) that improved to reach an ambulatory status increased from 80.0 to 91.4%. CONCLUSION: The results of the bivariate analysis demonstrated several correlations between some variables and overall outcome or time of recovery, whereas the multivariable regression model demonstrated only two associations. The time span between the onset of clinical signs and surgery was significantly associated with the overall outcome. We therefore suggest that a surgical intervention should be performed without unreasonable delay. Due to the correlation between the grade of severity and time of recovery, owners of dogs with more severe neurological deficits prior to surgery should be informed about the presumably prolonged time of recovery.

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.

Influence of the Head Neck Position on Imaging Measurements Used to Assess the Craniovertebral Junction in Small Breed Dogs: A Cadaveric Study.

OBJECTIVE: The study aimed to determine the influence of head neck position on imaging measurements used to assess the craniovertebral junction (CVJ) and to recommend the most appropriate position for the evaluation of the CVJ. STUDY DESIGN: A cross-sectional sample of adult dogs' cadavers was subjected to a computed tomography scan of the cranium and the cranial cervical region in three standardized head positions. Imaging measurements often used to assess the CVJ were measured. The influence of the head neck position, breed, weight and gender on imaging measurements was tested using repeated measures analysis of variance. RESULTS: Twenty-eight cadavers of small breed dogs were enrolled in the study. All cadavers examined had occipital dysplasia. All transarticular imaging measurements were dependent on the head neck position. In addition, the breed, weight and gender had an influence on several measurements. CONCLUSION: We recommend a standardized head neck position of 50 degrees flexion if quantitative imaging measurements of the CVJ are used to diagnose pathologies in this region. Future studies should focus on the definition of cut-off values for quantitative imaging measurements of the CVJ to differentiate between healthy and diseased small breed dogs. Regarding atlantoaxial instability, a combination of six parameters (C1-C2 angle, C1-C2 overlap, atlantoaxial distance, dens-to-axis length ratio, ventral compression index and clivus canal angle) is promising for its diagnosis.

Feasability of a Frameless Brain Biopsy System for Companion Animals Using Cone-Beam CT-Based Automated Registration.

The aim of the present study was to evaluate the use of a novel intraoperative cone-beam computed tomography (CBCT)-based automated registration system for frameless stereotactic brain biopsy in companion animals. An experimental cadaveric study evaluated thalamic and piriform lobe target site needle placement error in three dogs and three cats without a history of intracranial disease. Diagnostic accuracy and diagnostic yield were prospectively evaluated in twenty-four client-owned dogs and four cats with intracranial disease. Twenty-one procedures were performed post mortem (eighteen dogs and three cats), and seven biopsy procedures were performed in alive patients (six dogs and one cat). Procedural duration was evaluated in ten post mortem and four living patients. Outcome was evaluated in six dogs and one cat. In dogs, the calculated median needle placement error was 1.8 mm (range 0.71-2.84 mm) and 1.53 mm (range 1.45-1.99 mm) for piriform lobe and thalamus target sites, respectively. In cats, the calculated median needle placement error was 0.79 mm (range 0.6-1.91 mm) for the piriform lobe target site and 1.29 mm (range 0.47-2.69 mm) for the thalamic target site. The diagnostic yield was 96.4% (95% CI 0.81-0.99), the diagnostic accuracy was 94.4% (95% CI 0.72-0.99). Median total procedural duration for post mortem biopsies was 57.5 min (range 41-69 min). Median total procedural duration for intra vitam biopsies was 122.5 min (range 103-136 min). Three dogs were discharged 1 day after biopsy and one dog after 6 days. Two dogs and one cat were euthanized 24 and 48 h after biopsy. Intraoperative CBCT-based automated image registration for frameless stereotactic biopsies in companion animals is capable of providing diagnostic brain biopsy specimens independent of skull size and morphology with diagnostic yield and accuracy comparable to published values for diverse frameless and frame-based stereotaxy systems used in veterinary medicine. Duration of the procedure is not negatively affected and within the published range with other systems. Mobile intraoperative CBCT-based registration combined with neuronavigation delivers diagnostic brain biopsies in companion animals.

Fibronectin Fragments and Inflammation During Canine Intervertebral Disc Disease.

Background: Canine intervertebral disc disease (IVDD) represents a significant clinical problem in veterinary medicine, with similarities to the human pathology. Host-derived damage-associated molecular patterns like fibronectin fragments (FnF) that develop during tissue dysfunction may be of specific relevance to IVD pathologies by inducing an inflammatory response in resident cells. Aim: This project aimed to determine the presence and pathobiological role of FnF during IVD herniation in dogs, with a focus on inflammation. Methods: Herniated nucleus pulposus (NP) material from five dogs as well as non-herniated adjacent NP material from three dogs was collected during spinal surgery required due to acute IVD herniation. The presence of different types of FnF were determined by Western blot analysis. NP cells isolated from six herniated canine IVDs were then exposed to 30 kDa FnF. NP cell inflammation and catabolism was examined by investigating the expression of IL-1ß, IL-6, IL-8, and COX-2, as well as MMP-1 and MMP-3 by qPCR (all targets) and ELISA (IL-6, PGE2). Results: Amongst multiple sized FnF (30, 35, 45, and >170kDa), N-terminal fragments at a size of ~30 kDa were most consistently expressed in all five herniated IVDs. Importantly, these fragments were exclusively present in herniated, but not in non-herniated IVDs. Exposure of canine NP cells to 500 nM 30 kDa FnF caused a significant upregulation of IL-6 (62.5 ± 79.9, p = 0.032) and IL-8 (53.0 ± 75.7, p = 0.031) on the gene level, whereas IL-6 protein analysis was inconclusive. Donor-donor variation was observed in response to FnF treatment, whereby this phenomenon was most evident for COX-2, with three donors demonstrating a significant downregulation (0.67 ± 0.03, p = 0.003) and three donors showing upregulation (6.9 ± 5.5, p = 0.21). Co-treatment with Sparstolonin B, a TRL-2/TRL-4 antagonist, showed no statistical difference to FnF treatment alone in all tested target genes. Conclusion: Given the presence of the 30 kDa FnF in canine herniated IVDs and the proinflammatory effect of 30 kDa FnF on NP cells, we concluded that the accumulation of FnF may be involved in the pathogenesis of canine IVDD. These results correspond to the findings in humans with IVDD.

A complex histopathological challenge: suspicion of an osteoblastoma-like osteosarcoma arising from the second thoracic vertebra in a cat.

BACKGROUND: Reports of osteoblastic tumours are limited to a few case reports in veterinary medicine. Osteoblastoma-like osteosarcoma has been accepted by the World Health Organization as an intermediate form between an osteosarcoma and osteoblastoma. This type of tumour indicates an osteosarcoma, that may resemble osteoblastoma clinically, histologically, and radiologically and have the capability for metastasis. Osteoblastoma-like osteosarcoma has not been described in veterinary medicine so far. CASE PRESENTATION: An eight-year old cat was presented due to progressive ataxia and paraparesis of the pelvic limbs. Imaging confirmed a well-defined, extradural mass originating from the spinous process of the second thoracic vertebra (T2) leading to severe compression of the spinal cord. Decompressive cytoreduction was achieved by removal of the mass after dorsal laminectomy of T1. After recovering from an acute worsening 3.5 weeks after surgery, the cat had an improved neurological status and the dorsal compression was resolved at follow-up 8 months later. A focal contrast enhancing lesion was still evident at the base of T2 spinous process and lung metastasis was additionally suspected. Based on histopathological, radiographic, and clinical features, an "osteoblastoma-like osteosarcoma" was suspected. CONCLUSIONS: To the best of our knowledge, this is the first description of this tumour in veterinary medicine. In addition, this case report highlights the difficulty in the diagnosis and definition of osseous neoplasia in cats and provides a literature review.

Polarization of Macrophages in Epidural Inflammation Induced by Canine Intervertebral Disc Herniation.

Introduction: Canine interverterbral disc (IVD), although physiologically acellular, displays an inflammatory cell population consisting almost exclusively of macrophages (Mϕ) when acutely herniated. Mϕ encompass a heterogenous cell population, roughly divided into classically (M1) or alternatively activated (M2)Mϕ. Polarization into M1 Mϕ leads to strong antimicrobial activity and pro-inflammatory response. In contrast, M2Mϕ exibit anti-inflammatory function and regulate wound healing. The purpose of this study was to characterize the phenotype of the Mϕ population present in naturally occurring IVD herniation. Materials and Methods: IVD material of dogs with IVD disease was collected during standard decompressive surgery. A negative control consisting of IVD material of dogs without IVD degeneration and a positive control consisting of canine liver and lymph node samples were also included. All samples were embedded in OCT and shock frozen. Eight micrometer cryostat sections were prepared, air dried and immunostained without prefixation or permeabilization. CD14 was used as marker Mϕ, MHCII for M1Mϕ and CD206 for M2Mϕ. Results: Fifteen samples of dogs with IVD herniation, 10 negative, and 5 positive control samples were obtained. No positive cell was found in the negative control group. The positive control group displayed several MHCII and CD206 positive cells, all of them being simultaneously positive to CD14. All herniated samples displayed a mixed population of M1Mϕ and M2Mϕ, and some sparse Mϕ displaying markers for both M1 and M2Mϕ simultaneously. Conclusion: The mixed phenotype encountered shows the plasticity and dynamism of Mϕ and evidences the chronic component of IVD disease despite its acute clinical presentation.

[The nerve root syndrome in small animals - A review focussing on pathophysiology and therapy in the dog]. / Das Nervenwurzelsyndrom beim Kleintier.

A large variety of etiologies is considered to be the cause of nerve root syndrome in dogs. Lateralized disc herniation, foraminal stenosis and malignant as well as benign nerve sheath tumors are some of the most important triggers described. The clinical signs of a nerve root syndrome are characterized by monoparesis in combination with progressive lameness, which may be accompanied by an elevation of the affected limb. Although the problem is well known among clinicians, there is no review article in the veterinary literature that specifically covers the subject of "nerve root syndrome in small animals". Mostly, this is merely mentioned as a symptom of its potential etiologies, as the so-called "nerve root sign" or "nerve root signature". In the pathophysiology of nerve root compression or irritation, a number of biomechanical and biochemical factors play a role. These occur individually or in combination and may lead to the same changes. The pathophysiology of the syndrome seems to focus around changes in microcirculation. These microcirculation disorders not only lead to pathomorphological changes such as edema formation, demyelination and axon death, but also initiate a cascade of reactions at the site of damage as well as in the central nervous tissue. This leads to the release of various neuropeptides, modulation of nerve excitability and impulse transmission. Different pathomechanisms therefore often lead to a uniform damage pattern, which makes it difficult to point out the original triggering factors. The body's response to these factors determines whether a nerve root syndrome actually develops or not. The treatment of the cause, if found, and an individual and multimodal pain therapy seem to be the most successful therapeutic approaches for nerve root syndrome in dogs.

Prospective Validation of Facial Nerve Monitoring to Prevent Nerve Damage During Robotic Drilling.

Facial nerve damage has a detrimental effect on a patient's life, therefore safety mechanisms to ensure its preservation are essential during lateral skull base surgery. During robotic cochlear implantation a trajectory passing the facial nerve at <0.5 mm is needed. Recently a stimulation probe and nerve monitoring approach were developed and introduced clinically, however for patient safety no trajectory was drilled closer than 0.4 mm. Here we assess the performance of the nerve monitoring system at closer distances. In a sheep model eight trajectories were drilled to test the setup followed by 12 trajectories during which the ENT surgeon relied solely on the nerve monitoring system and aborted the robotic drilling process if intraoperative nerve monitoring alerted of a distance <0.1 mm. Microcomputed tomography images and histopathology showed prospective use of the technology prevented facial nerve damage. Facial nerve monitoring integrated in a robotic system supports the surgeon's ability to proactively avoid damage to the facial nerve during robotic drilling in the mastoid.

[Outcome of intervertebral disk disease surgery depending on dog breed, location and experience of the surgeon: 1113 cases]. / Postoperatives Ergebnis bei Diskopathien des Hundes in Abhängigkeit von Rasse, Lokalisation und Erfahrung des Chirurgen: 1113 Fälle.

OBJECTIVE: Intervertebral disc disease (IVDD) is a common neurological condition in dogs that can be treated surgically in many cases. Following surgical disc treatment, possible influencing factors, including signalment, localisation and severity of the IVDD and the surgeon's experience, were investigated to determine their impact on the long-term outcome of the treatment. MATERIAL AND METHODS: Data from 1113 dogs that had undergone surgical treatment for one or more herniated discs between January 2008 and July 2013 were evaluated. RESULTS: In particular, there was a disposition for the chondrodystrophic (CD) breeds Dachshund, Jack Russell Terrier and French Bulldog to suffer from herniated discs much earlier than non-chondrodystrophic (NCD) breeds, with significant differences in localisation and neurological severity. Unneutered male dogs were disproportionately more frequently affected, whereas the patient weight did not correlate with IVDD occurrence. The postoperative outcome was affected by the neurological severity and localisation of the IVDD, but not by the breed of dog or the surgeon's level of experience. Similarly, there was no correlation between the surgical procedure used and convalescence or recurrence rate. CONCLUSION AND CLINICAL RELEVANCE: CD breeds were more prone to IVDH and on average earlier than NCD breeds, with French Bulldogs as the youngest patients. Most incidents occurred in the thoracic spine (peak in Th12/13), with the fewest in the cervical spine, with race-specific differences: Beagles were mainly affected in the cervical spine, small NCD breeds, Dachshund and Jack Russell Terriers in the thoracic spine and French Bulldogs and large NCD breeds in the lumbar spine. An increasing neurological type and an IVDH in the thoracic spine had a negative impact on the clinical outcome: Small NCD breeds with type IV IVDH in the thoracic spine had the longest convalescence, whereas French Bulldogs with the same type of IVDH in the lumbar spine were quicker able to walk again.

Short-Term Clinical and Radiographical Outcome after Application of Anchored Intervertebral Spacers in Dogs with Disc-Associated Cervical Spondylomyelopathy.

OBJECTIVES: The purpose of this study was to assess the short-term outcome of a new intervertebral anchored fusion device (C-LOX) for the treatment of disc associated cervical spondylomyelopathy (DA-CSM) in dogs, based on clinical and radiographical follow-up data. MATERIALS AND METHODS: To be included in the study, dogs had to be clinically affected by DA-CSM treated with surgical distraction/stabilization using the anchored intervertebral spacer (C-LOX). Neurological signs, as well as diagnostic imaging performed pre-, immediately postoperatively, and after 6 weeks and 3 months were assessed. If available, clinical follow-up after 3 months was documented. RESULTS: Thirty-seven cases were enrolled in the study. Outcome at 3 months was available in 25 dogs; improvement of neurological status was documented in 25/25 cases.The most common postoperative complication was screw loosening and/or breakage (n = 22), followed by subsidence (n = 15). Four dogs required revision surgery. CLINICAL SIGNIFICANCE: Distraction/stabilization of DA-CSM in dogs with the C-LOX device resulted in short-term clinical improvement in 33/37 treated cases. The high incidence of screw loosening was taken into consideration and modification of the implant with a new locking system and new screw dimensions was required. The C-LOX device seems to be a valuable alternative to more complicated distraction-fusion techniques.

In Vitro Biomechanical Comparison of Four Different Ventral Surgical Procedures on the Canine Fourth-Fifth Cervical Vertebral Motion Unit.

INTRODUCTION: Biomechanical properties of four different ventral surgical procedures at the canine fourth-fifth cervical (C4-C5) vertebral motion unit (VMU) were assessed and compared with the intact C4-C5 VMU. MATERIALS AND METHODS: The third-sixth cervical vertebral column from 24 skeletally mature Beagle cadavers were randomly allocated to four groups (standard ventral slot, slanted slot, inverted cone slot and intervertebral disc fenestration). Standardized tests were performed for each specimen in flexion/extension, lateral bending and axial rotation. The specimens were tested intact and after completion of one of the three slots techniques or fenestration. Pre-testing, cadaver specimens were confirmed to be free of disease by computed tomography (CT) examination. Post-testing, dimensions of slots and fenestration were determined based on a second CT examination. RESULTS: All ventral surgical procedures increased range of motion (ROM) at the C4-C5 VMU compared with intact specimens. The only significant difference in the increase in ROM was observed between slanted slot and fenestration in flexion/extension. The standard ventral slot had a significant higher increase in ROM in extension compared with the other three techniques. The slanted slot had a significant lower increase in ROM in flexion. DISCUSSION/CONCLUSION: The described ventral slot techniques have similar biomechanical effects on the canine cervical vertebral column. In contrast to the findings of a previous study, the slanted slot and inverted cone slot do not appear to provide a biomechanical benefit compared with standard ventral slot.

Magnetic Resonance Imaging Signal Alterations in Paraspinal Muscles in Dogs with Acute Thoracolumbar Intervertebral Disk Extrusion.

Muscle signal alteration detected on MRI is seen in diverse pathologic conditions. We observed signal alterations within the paraspinal muscles in dogs with acute thoracolumbar intervertebral disk extrusion. The aim of this retrospective study was to describe MRI features of paraspinal muscle signal alteration in dogs with acute thoracolumbar intervertebral disk extrusion and to investigate an association of the signal alterations with neurological grade, type and location of intervertebral disk extrusion, degree of spinal cord compression, and presence of epidural hemorrhage. Medical records of dogs undergoing MRI because of thoracolumbar intervertebral disk extrusion between August 2014 and June 2016 were reviewed. MRI was evaluated for SI changes within the paravertebral musculature, their location, extension, affected muscles, contrast enhancement, and signal void in T2* sequences. Intervertebral disk herniation was categorized as acute non-compressive nucleus pulposus extrusion (ANNPE) or compressive intervertebral disk disease. In five patients, muscle biopsies of areas with signal intensity changes were taken during surgery. In total, 103 dogs were enrolled in the study. Paraspinal muscle signal alterations were visible in 37 dogs (36%) affecting the epaxial musculature (n = 17), hypaxial musculature (n = 12), or both (n = 8). All signal alterations were hyperintense on T2-weighted images and iso- or hypointense in T1-weighted images. Signal void in T2* was not observed in any dog. Postcontrast sequences were available in 30 of the 37 dogs and showed enhancement in 45%. There was neither an association with degree of compression nor epidural hemorrhage. Intervertebral disk extrusion caudal to L1 and a higher neurological grade was associated with the presence of muscle changes. Histopathology revealed mild to moderate acute muscle fiber degeneration with edema and necrosis in three of five samples. The MRI, as well as the muscle samples, show rather unspecific changes. The underlying pathomechanism might be related to ischemia or muscle spasm, but also denervation edema may explain the signal alteration.