Comparison of three-dimensional printed patient-specific guides versus freehand approach for radial osteotomies in normal dogs: Ex vivo model.

OBJECTIVE: To compare the accuracy of three-dimensional (3D) printed patient-specific guide (PSG) with a freehand (FH) approach for radial osteotomies in ex vivo normal dogs. STUDY DESIGN: Experimental study. ANIMALS: Twenty four ex vivo thoracic limb pairs from normal beagle dogs. METHODS: Computed tomography (CT) images were collected preoperatively and postoperatively. Three osteotomies tested (n = 8/group) were: (1) uniplanar 30° frontal plane wedge ostectomy, (2) oblique plane (30° frontal, 15° sagittal) wedge ostectomy, and (3) single oblique plane osteotomy (SOO, 30° frontal, 15° sagittal, and 30° external). Limb pairs were randomized to a 3D PSG or FH approach. The resultant osteotomies were compared with virtual target osteotomies by surface shape-matching postoperative to the preoperative radii. RESULTS: The mean ± standard deviation osteotomy angle deviation for all 3D PSG osteotomies (2.8 ± 2.8°, range 0.11-14.1°) was less than for the FH osteotomies (6.4 ± 6.0°, range 0.03-29.7°). No differences were found for osteotomy location in any group. In total, 84% of 3D PSG osteotomies were within 5° deviance from the target compared to 50% of freehand osteotomies. CONCLUSION: Three-dimensional PSG improved FH accuracy of osteotomy angle in select planes and the most complex osteotomy orientation in a normal ex vivo radial model. CLINICAL SIGNIFICANCE: Three-dimensional PSGs provided more consistent accuracy, which was most notable in complex radial osteotomies. Future work is needed to investigate guided osteotomies in dogs with antebrachial bone deformities.

Accuracy of pin placement in the canine thoracolumbar spine using a free-hand probing technique versus 3D-printed patient-specific drill guides: An ex-vivo study.

OBJECTIVE: To compare pin placement accuracy, intraoperative technique deviations, and duration of pin placement for pins placed by free-hand probing (FHP) or 3D-printed drill guide (3DPG) technique. SAMPLE POPULATION: Four greyhound cadavers. METHODS: Computed tomography (CT) examinations from T6-sacrum were obtained for determination of optimal pin placement and 3DPG creation. Two 3.2/2.4-mm positive profile pins were inserted per vertebra, one left and one right from T7-L7 (FHP [n = 56]; 3DPG [n = 56]) by one surgeon and removed for repeat CT. Duration of pin placement and intraoperative deviations (unanticipated deviations from planned technique) were recorded. Pin tracts were graded by two blinded observers using modified Zdichavsky classification. Descriptive statistics were used. RESULTS: A total of 54/56 pins placed with 3DPGs were assigned grade I (optimal placement) compared with 49/56 pins using the FHP technique. A total of 2/56 pins placed with 3DPGs and 3/56 pins using the FHP technique were assigned grade IIa (partial medial violation). A total of 4/56 pins placed using the FHP technique were assigned grade IIIa (partial lateral violation). No pins were assigned grade IIb (full medial violation). Intraoperative technique deviations occurred with 6/56 pins placed using the FHP technique and no pins with 3DPGs. Overall, pins were placed faster (mean ± SD 2.6 [1.3] vs. 4.5 [1.8] min) with 3DPGs. CONCLUSIONS: Both techniques were accurate for placement of spinal fixation pins. The 3DPG technique may decrease intraoperative deviations and duration of pin placement. CLINICAL RELEVANCE: Both techniques allow accurate pin placement in the canine thoracolumbar spine. The FHP technique requires specific training and has learning curve, whereas 3DPG technique requires specific software and 3D printers.

MRI ischemic and hemorrhagic lesions in arterial and venous territories characterize central nervous system intravascular lymphoma in dogs.

Intravascular lymphoma (IVL) is characterized by the proliferation of large malignant lymphocytes within the lumen of blood vessels. This retrospective, multi-center, case series study aimed to describe the MRI features of confirmed central nervous system IVL in dogs and compare them with histopathological findings. Medical record databases from seven veterinary centers were searched for cases of histologically confirmed IVL. Dogs were included if an MRI was performed. The MRI studies and histopathology samples were reviewed to compare the MRI changes with the histopathological findings. Twelve dogs met the inclusion criteria (12 brains and three spinal cords). Imaging of the brains revealed multifocal T2-weighted/FLAIR hyperintense and T1-weighted iso-hypointense lesions, with variable contrast enhancement; areas of abnormal diffusion both in arterial and venous territories in diffusion-weighted imaging; and meningeal enhancement. On gradient echo images (GRE), the changes comprised tubular susceptibility artifacts, consistent with the "susceptibility vessel sign", and additional variably sized/shaped intraparenchymal susceptibility artifacts. Spinal cord lesions presented as fusiform T2-weighted hyperintensities with scattered susceptibility artifacts on GRE and variable parenchymal and meningeal contrast enhancement. On histopathology, subarachnoid hemorrhages and neuroparenchymal areas of edema and necrosis, with or without hemorrhage, indicating ischemic and hemorrhagic infarctions, were found. These lesions were concurrent with severely dilated meningeal and parenchymal arteries and veins plugged by neoplastic lymphocytes and fibrin. Due to the unique angiocentric distribution of IVL, ischemic and hemorrhagic infarcts of variable chronicity affecting both the arterial and venous territories associated with thrombi formation can be detected on MRI.

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.

Accuracy of three-dimensionally printed animal-specific drill guides for implant placement in canine thoracic vertebrae: A cadaveric study.

OBJECTIVE: To assess the accuracy of three-dimensionally (3-D) printed drill guides in constraining the trajectory of drill tracts for implants in canine thoracic vertebrae. STUDY DESIGN: Experimental ex vivo study. SAMPLE POPULATION: Five canine thoracic vertebral column specimens. METHODS: Guides to constrain drill trajectories were designed on the basis of computed tomographic (CT) imaging of six thoracic vertebrae (T8-T13) and were 3-D printed. The guides were used to create drill tracts in these vertebrae by both an experienced and a novice surgeon, and CT imaging was repeated. The entry point and angulation of actual and planned drill tracts were compared for both surgeons. Unintended cortical violations were also assessed by using a modified Zdichavsky classification. RESULTS: Fifty-eight drill tracts were created in 30 vertebrae. Mean entry point deviation was 1.4 mm (range, 0.4-3.4), and mean angular deviation was 5.1° (range, 1.5°-10.8°). There were no differences between surgeons in entry point deviation (P = .07) or angular deviation (P = .22). There were no unintended cortical bone violations, and all drill tracts were classified as modified Zdichavsky grade I. CONCLUSION: The 3-D printed guides used in the current study yielded drill tracts with small linear and angular errors from intended paths and 100% accuracy for placement within vertebral pedicles and bodies. This technique was conveniently used by both an experienced and a novice surgeon. CLINICAL SIGNIFICANCE: This technique might be immediately applicable to clinical cases requiring thoracic vertebral stabilization and may allow safe and accurate implant placement for surgeons with varying experience levels.

The Evolution of Educational Technology in Veterinary Anatomy Education.

"All learning is in the learner, not the teacher." Plato was right. The adage has passed the test of time and is still true in an era where technology accompanies us in not only professional but also recreational life every day, everywhere. On the other hand, the learner has evolved and so have the sources being used to satisfy curiosity and learning. It therefore appears intuitive to embrace these technological advances to bring knowledge to our pupils with the aim to facilitate learning and improve performance. It must be clear that these technologies are not intended to replace but rather consolidate knowledge partly acquired during more conventional teaching of anatomy. Veterinary medicine is no outlier. Educating students to the complexity of anatomy in multiple species requires that three-dimensional concepts be taught and understood accurately if appropriate treatment is to be set in place thereafter. Veterinary anatomy education has up to recently walked diligently in the footsteps of John Hunter's medical teaching using specimens, textbooks, and drawings. The discipline has yet to embrace fully the benefits of advancement being made in technology for the benefit of its learners. Three-dimensional representation of anatomy is undeniably a logical and correct way to teach whether it is through the demonstration of cadaveric specimen or alternate reality using smartphones, tablets, headsets or other digital media. Here we review some key aspects of the evolution of educational technology in veterinary anatomy.

Minimally invasive microsurgical decompression of an intervertebral disc protrusion in a dog.

OBJECTIVE: To report the successful treatment of intervertebral disc protrusion with minimally invasive microsurgery in a large breed dog. STUDY DESIGN: Retrospective case report. ANIMAL: A 4-year-old, neutered male, German shepherd dog presented with chronic progressive ambulatory paraparesis and thoracolumbar pain; lumbar intervertebral disc protrusion and severe spinal cord compression at L2-L3 were diagnosed. METHODS: A minimally invasive approach was used to access the target surgical area by using a muscle splitting technique and retractors. Intraoperative fluoroscopy confirmed correct placement. Magnification and illumination through a surgical microscope were used (microsurgery) to perform the spinal cord decompression by means of a foraminotomy and lateral corpectomy. RESULTS: Technically, the combination of fluoroscopy and muscle splitting approach offered adequate minimally invasive access. Microsurgery allowed for precise and efficient spinal cord decompression. Clinically, no immediate postoperative neurological deterioration was observed. Opioid usage was limited to 24 hours postoperatively. Focal muscle swelling was observed postoperatively for 2 days, and hospital stay was 3 days. At 7 weeks postoperatively, neurological examination results were normal, and postoperative MRI confirmed spinal cord decompression. No complications were reported. CONCLUSION: The procedure was associated with a small incision, limited muscle trauma, early improvement of the neurological status, a short hospital stay, and limited postoperative pain. CLINICAL SIGNIFICANCE: This case provides evidence that minimally invasive microsurgery is an effective treatment for intervertebral disc protrusion in large breed dogs and may offer benefits regarding postoperative pain and functional recovery.

Minimally invasive spine surgery in dogs: Evaluation of the safety and feasibility of a thoracolumbar approach to the spinal cord.

OBJECTIVE: To describe the safety and feasibility of a minimally invasive spine surgery technique to access the thoracolumbar vertebral canal in dogs. STUDY DESIGN: Prospective study. ANIMALS: Six healthy research dogs. METHODS: Dogs were placed under anesthesia for MRI to evaluate vertebral column and spinal cord integrity. Minimally invasive surgery was performed at multiple sites. Access to the vertebral canal was achieved by means of foraminotomy, discectomy, and lateral minicorpectomy by using minimally invasive access and a surgical microscope. Sequential neurological examinations, pressure algometry pain quantification, and creatine kinase levels were evaluated before and after surgery for 7 days. Magnetic resonance imaging, computed tomography, and histopathology were performed on day 6 postoperatively after animals were humanely killed to evaluate the impact of surgery on spinal cord, muscles, and bone. RESULTS: The vertebral canal was successfully accessed, and the ventral aspect of the spinal cord was identified at all sites. No neurological deterioration was observed. Postoperative pain was not different compared with baseline except in one dog on the day after surgery. CONCLUSION: Minimally invasive spine surgery was a safe and feasible technique to access the thoracolumbar vertebral canal and the ventral aspect of the spinal cord in dogs. Findings supported postoperative pain benefits. CLINICAL SIGNIFICANCE: Minimally invasive spine surgery is a valid surgical technique to access the thoracolumbar vertebral canal at single or multiple sites in dogs.

Spinal subarachnoid diverticula in dogs: A review.

Spinal subarachnoid diverticula are fluid dilations of the subarachnoid space that can cause a compressive myelopathy in dogs. These diverticula are usually associated with high motion areas in the cervical and caudal thoracic spine. The definitive etiopathogenesis has not been determined but likely involves congenital or acquired causes. Pugs, French bulldogs, and Rottweilers are overrepresented breeds. Clinical signs typically include ataxia, paresis, and upper motor neuron urinary and/or fecal incontinence; pain is a less common feature. Diagnosis is based on advanced imaging, with magnetic resonance imaging now being favored given the additional detail of the spinal cord parenchyma that can be obtained. Outcomes are better with surgical intervention than with medical therapies, though there is a lack of long-term data. No superior surgical technique has been identified, and questions remain on the significance of addressing leptomeningeal adhesions at the time of surgery. Clinical signs can recur, though not always due to recurrence of diverticulum formation, and pugs may be less likely to have a successful long-term outcome.

Diverticule subarachnoïdien spinal chez des chiens : une revue. Les diverticules subarachnoïdiens spinaux sont des dilatations liquides de l'espace subarachnoïdien qui peuvent causer une myélopathie compressive chez les chiens. Ces diverticules sont généralement associés à des régions à motion élevée de la colonne vertébrale cervicale et caudale. L'étiopathogénie définitive n'a pas été déterminée mais implique fort probablement des causes congénitales ou acquises. Les carlins, bulldogs français et rottweiler sont des races sur-représentées. Les signes cliniques inclus typiquement de l'ataxie, de la parésie et un neurone moteur supérieur d'incontinence urinaire et/ou fécale; la douleur est une caractéristique moins fréquente. Le diagnostic est basé sur des analyses avancées d'imagerie, avec l'imagerie par résonnance magnétique maintenant favorisée étant donné les détails additionnels du parenchyme de la colonne vertébrale qui peuvent être obtenus. Les résultats sont meilleurs avec l'intervention chirurgicale qu'avec les thérapies médicales, bien qu'il y ait un manque de données à long terme. Aucune technique chirurgicale supérieure n'a été identifiée, et des questions persistent sur l'importance de s'attarder aux adhésions leptoméningées au moment de la chirurgie. Les signes cliniques peuvent réapparaitre, quoique pas toujours à cause de la récurrence de la formation des diverticules, et les carlins pourraient être moins enclin à avoir une issue favorable à long terme.(Traduit par Dr Serge Messier).

IMAGING DIAGNOSIS-MAGNETIC RESONANCE IMAGING AND HISTOPATHOLOGICAL FEATURES OF A SKULL BASE CHORDOMA IN A CAT.

An 8-year-old domestic short-haired cat was presented with anorexia, lethargy, ataxia and one episode of consciousness loss. A midline vertically orientated, biconcave, extra-axial mass originating from the basioccipital bone was detected on magnetic resonance images of the head. The mass was T1W iso- to hypointense when compared with normal grey matter, T2W hyperintense with small areas of isointensity and heterogeneously enhanced with contrast. Multiple signal voids were observed on T2* images. Histopathological evaluation confirmed a chordoma. To the authors' knowledge this is the first report of the imaging characteristics of a chordoma affecting the skull base in a cat.

Vertebral venous system abnormalities identified with magnetic resonance imaging in sighthounds.

In humans, abnormalities of the vertebral venous system are considered rare but significant causes of radiculopathy and myelopathy. Published information on abnormalities of the canine vertebral venous system is currently lacking. Aims of this retrospective descriptive study were to characterize magnetic resonance imaging (MRI) abnormalities of the vertebral venous system in a population of sighthounds, report prevalence of vertebral venous system abnormalities within that population and explore possible clinical significance. Our hospital database was searched over the period of 2002-2013 for sighthounds with MRI studies of the vertebral column. Medical records and MRI studies for included dogs were retrieved and findings were recorded by a single observer. A total of 92 sighthounds were sampled. Eleven cases (prevalence 12%) showed abnormal enlargement of the internal vertebral venous plexus (10/11 unilaterally, 1/11 bilaterally), external vertebral venous plexus (7/11 cases unilaterally), and/or intervertebral veins (8/11 unilaterally, 2/11 bilaterally, and 1/11 unilaterally and bilaterally at different sites). The majority of the abnormalities were right sided and the most common location for abnormalities was C6/7. Of the 11 cases, nine did not have a definitive diagnosis. Seven of those nine cases had an abnormality in a neuroanatomical localization that could wholly or partly explain the clinical signs. Findings indicated that, while the prevalence of vertebral venous system abnormalities was low in this sample of sighthounds, the majority of dogs with these abnormalities had clinical signs that matched the location of the abnormalities. Further prospective research is needed to investigate potential underlying aetiologies for vertebral venous system abnormalities in dogs and clarify their clinical significance.

Idiopathic head tremor in English bulldogs.

Idiopathic head tremor (IHT) syndrome is a recognized but poorly characterized movement disorder in English bulldogs (EBs). The data analyzed were collected via a detailed online questionnaire and video recordings. Thirty-eight percent of the population demonstrated IHT. The first presentation was early in life. There was no sex or neutered status predisposition. The condition disappeared with time in 50% of the cases. The direction of the head movement was vertical or horizontal. The number of episodes per day and the duration of the episodes were greatly variable. The majority of episodes occurred at rest. Most of the episodes were unpredictable. And there was no alteration of the mental status for most dogs during the episodes. Stress has been reported as a suspected trigger factor. IHT in EBs can be considered an idiopathic paroxysmal movement disorder.

A proposed radiographic classification scheme for congenital thoracic vertebral malformations in brachycephalic "screw-tailed" dog breeds.

Congenital vertebral malformations are common in brachycephalic "screw-tailed" dog breeds such as French bulldogs, English bulldogs, Boston terriers, and pugs. The aim of this retrospective study was to determine whether a radiographic classification scheme developed for use in humans would be feasible for use in these dog breeds. Inclusion criteria were hospital admission between September 2009 and April 2013, neurologic examination findings available, diagnostic quality lateral and ventro-dorsal digital radiographs of the thoracic vertebral column, and at least one congenital vertebral malformation. Radiographs were retrieved and interpreted by two observers who were unaware of neurologic status. Vertebral malformations were classified based on a classification scheme modified from a previous human study and a consensus of both observers. Twenty-eight dogs met inclusion criteria (12 with neurologic deficits, 16 with no neurologic deficits). Congenital vertebral malformations affected 85/362 (23.5%) of thoracic vertebrae. Vertebral body formation defects were the most common (butterfly vertebrae 6.6%, ventral wedge-shaped vertebrae 5.5%, dorsal hemivertebrae 0.8%, and dorso-lateral hemivertebrae 0.5%). No lateral hemivertebrae or lateral wedge-shaped vertebrae were identified. The T7 vertebra was the most commonly affected (11/28 dogs), followed by T8 (8/28 dogs) and T12 (8/28 dogs). The number and type of vertebral malformations differed between groups (P = 0.01). Based on MRI, dorsal, and dorso-lateral hemivertebrae were the cause of spinal cord compression in 5/12 (41.6%) of dogs with neurologic deficits. Findings indicated that a modified human radiographic classification system of vertebral malformations is feasible for use in future studies of brachycephalic "screw-tailed" dogs.

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.

Feasibility and accuracy of intraosseous endoscopy for inspection of thoracolumbar and lumbar pedicle drill tracts in a canine large-breed cadaveric model.

OBJECTIVE: To evaluate the feasibility of endoscopic inspection of thoracolumbar and lumbar pedicle tracts in a canine large-breed model and its accuracy for the detection of breached versus nonbreached tracts. ANIMALS: 2 greyhound cadavers. METHODS: CT scans of 2 greyhound cadavers from the sixth thoracic vertebra to the sacrum were obtained. Fifty-six pedicles were randomized to have drill tracts with different modified Zdichavsky grades (nonbreached, partial/full medial breach, or partial/full lateral breach) using 3-D-printed guides. Endoscopy was performed on a single occasion from October 9 to 10, 2023, using a 1.9-mm 0-degree needle arthroscope in a randomized blinded fashion. The grading of drill tracts was performed on postoperative CT. Specificity, sensitivity, positive and negative predictive values, and time to assign endoscopic grade were investigated. RESULTS: Postoperative CT confirmed 43 nonbreached tracts, 7 medial breaches (partial/full), and 5 lateral breaches (partial/full). One tract was excluded because of guide misplacement. Intraosseous endoscopy was successfully performed in the remaining 55 drill tracts. Sensitivity to detect medial and lateral breaches was 71.4% and 60.0%. Negative predictive value was 93.1%. Specificity was 94.2%. Positive predictive value for detection of medial and lateral breaches was 83.3% and 54.5%. Median (range) time to assign an endoscopic grade was 118 (30 to 486) seconds. CLINICAL RELEVANCE: Intraosseous endoscopy of pedicle drill tracts may be a useful adjunct technique during pedicle screw/pin placement in dogs.

A transmandibular lateral transsphenoidal navigated surgical approach to access a pituitary macroadenoma in a warmblood mare.

A 16-year-old warmblood mare was referred with a progressive history of behavioral changes and left-sided blindness. Following neuroanatomical localization to the forebrain, magnetic resonance imaging of the head revealed a well-delineated, 4.5 cm in diameter, round pituitary mass causing marked compression of the midbrain and optic chiasm. Euthanasia was recommended but declined by the owners. Veterinary specialists and a human neurosurgeon collaboratively prepared for surgical case management. A novel navigated transmandibular lateral transsphenoidal approach was developed to access the region of the sella turcica and practiced on cadaver specimens. The horse was anesthetized and placed in sternal recumbency with the head above the heart line. Using a cone beam computed tomography (CBCT)-coupled navigation system, a navigated pin traversing the vertical ramus of the mandible and the lateral pterygoid muscle was placed in a direct trajectory to the predetermined osteotomy site of the basisphenoid bone. A safe corridor to the osteotomy site was established using sequential tubular dilators bypassing the guttural pouch, internal and external carotid arteries. Despite the use of microsurgical techniques, visualization of critical structures was limited by the long and narrow working channel. Whilst partial resection of the mass was achieved, iatrogenic trauma to the normal brain parenchyma was identified by intraoperative imaging. With consent of the owner the mare was euthanized under the same general anesthesia. Post-mortem magnetic resonance imaging and gross anatomical examination confirmed partial removal of a pituitary adenoma, but also iatrogenic damage to the surrounding brain parenchyma, including the thalamus.

Craniectomies for Dogs With Skull Multilobular Osteochondrosarcoma Using the Misonix Bone Scalpel: Cadaveric Evaluation and Retrospective Case Series.

To evaluate the Misonix bone scalpel (MBS) for craniotomies in dogs and describe clinical findings and surgical experience in 3 dogs with large multilobular osteochondrosarcoma (MLO) of the skull. Cadaver evaluation and retrospective case series. One canine cadaver; 3 client-owned dogs. Craniotomies of different sizes and at different locations were performed with MBS. Dural tear and bone discoloration were recorded. Clinical, imaging, and surgical findings of dogs diagnosed with MLO and where MBS was used for craniectomies were retrospectively included. Cadaveric evaluation identified MBS as an efficient tool for rapid craniectomies (>5minutes) albeit dural tears and some small foci of bone discoloration were observed. Craniectomies could be performed without complications in 3 dogs with MLO without dural tear or bone discoloration. .Excision was in complete in all cases. The short-term outcome was good, and the long-term outcome was fair to good. Piezoelectric bone surgery with the Misonix bone scalpel is an alternative technology to perform craniectomies in dogs. It was not associated with complications in 3 dogs diagnosed and surgically treated for MLO. Dural tears and suspected bone necrosis can occur. Great care should be taken when using CT to establish disease free surgical osteotomy.

SCN9A variant in a family of mixed breed dogs with congenital insensitivity to pain.

BACKGROUND: Congenital insensitivity to pain (CIP) and hereditary sensory and autonomic neuropathies (HSANs) are a rare group of genetic disorders causing inability to feel pain. Three different associated variants have been identified in dogs: 1 in Border Collies, 1 in mixed breed dogs, and 1 in Spaniels and Pointers. OBJECTIVES: To clinically and genetically characterize CIP in a family of mixed breed dogs. ANIMALS: Two mixed breed dogs from the same litter were independently presented: 1 for evaluation of painless fractures, and the other for chronic thermal skin injuries. METHODS: Physical, neurological, and histopathological evaluations were performed. Whole genome sequencing of 1 affected dog was used to identify homozygous protein-changing variants that were not present in 926 control genomes from diverse dog breeds. RESULTS: Physical and neurological examinations showed the absence of superficial and deep pain perception in the entire body. Histopathological evaluations of the brain, spinal cord and sensory ganglia were normal. Whole genome sequencing identified a homozygous missense variant in SCN9A, XM_038584713.1:c.2761C>T or XP_038440641.1:(p.Arg921Cys). Both affected dogs were homozygous for the mutant allele, which was not detected in 926 dogs of different breeds. CONCLUSIONS AND CLINICAL IMPORTANCE: We confirmed the diagnosis of CIP in a family of mixed breed dogs and identified a likely pathogenic variant in the SCN9A gene. The clinical signs observed in these dogs mimic those reported in humans with pathogenic SCN9A variants causing CIP. This report is the first of a spontaneous pathogenic SCN9A variant in domestic animals.

Perception of challenges in management of neurological cases in the emergency room.

OBJECTIVE: To investigate emergency clinicians' comfort level in assessing neurological emergencies and to identify opportunities to foster enhanced training of clinical neurology in the emergency room. DESIGN: Internet-based survey. SETTING: University teaching hospitals and private referral centers. SUBJECTS: One hundred and ninety-two emergency and critical care specialists and resident trainees (ECC) and 104 neurology specialists and resident trainees (NEUR) in clinical practice. INTERVENTIONS: An internet-based survey was distributed via veterinary professional organizations' listserves and message boards and responses were collected between March and April 2020. ECC completed a survey evaluating stress levels associated with neurological emergencies, confidence with neurological examinations, and neuroanatomical localization. NEUR completed a similar survey to report their perception of their ECC colleagues' confidence in the assessment of neurological cases. Chi-square and Mann-Whitney U-tests were used to compare categorical responses and confidence scores between groups. P < 0.002 was considered significant. MEASUREMENTS AND MAIN RESULTS: Fifty-two percent of ECC found neurological emergencies slightly challenging, whereas 85% of NEUR found them moderately to extremely challenging for ECC (P < 0.0001). ECC's median self-reported confidence score in performing a neurologic examination on a scale of 0-100 was 75 (interquartile range [IQR], 27), while NEUR reported a median ECC confidence of 44 (IQR, 25; P < 0.0001). Median self-reported ECC confidence in localizing intracranial, spinal, and neuromuscular disease was 67 (IQR, 40), 88 (IQR, 21), and 60 (IQR, 37), respectively, which was significantly higher than median NEUR-reported ECC confidence of 35 (IQR, 38), 51 (IQR, 31), and 18 (IQR, 20), respectively (all P < 0.0001). Following case transfer, 34% of ECC received NEUR feedback in >75% of cases. CONCLUSIONS: Noticeable discrepancies between ECC and NEUR perceptions of ECC clinical confidence were seen, while no firm evidence of neurophobia could be inferred. Improvements in interdepartmental communication and teaching of clinical neurology may be warranted.

A novel missense variant in the L2HGDH gene in a cat with L-2-hydroxyglutaric aciduria and multicystic cerebral lesions.

CASE DESCRIPTION: A 9-month-old intact male domestic shorthair cat was evaluated for increasing frequency of generalized tonic-clonic seizures. CLINICAL FINDINGS: The cat was reported to have had episodes of circling between the seizures. Upon examination, the cat had bilateral inconsistent menace response but otherwise normal physical and neurological examinations. DIAGNOSTICS: Magnetic resonance imaging (MRI) of the brain identified multifocal, small, rounded intra-axial lesions within the subcortical white matter containing fluid with similar characteristics as cerebrospinal fluid. Evaluation of urine organic acids showed increased excretion of 2-hydroxyglutaric acid. An XM_023255678.2:c.397C>T nonsense variant in the L2HGDH gene encoding L-2-hydroxyglutarate dehydrogenase was identified using whole genome sequencing. TREATMENT AND OUTCOME: Levetiracetam treatment was initiated at 20 mg/kg PO q8h, but the cat died after a seizure 10 days later. CLINICAL RELEVANCE: We report the second pathogenic gene variant in L-2-hydroxyglutaric aciduria in cats and describe for the first time multicystic cerebral lesions on MRI.