Safety and interim survival data after intracranial administration of M032, a genetically engineered oncolytic HSV-1 expressing IL-12, in pet dogs with sporadic gliomas.

OBJECTIVE: The diagnosis of glioma remains disheartening in the clinical realm. While a multitude of studies and trials have shown promise, improvements in overall survival have been disappointing. Modeling these tumors in the laboratory setting has become increasingly challenging, given their complex in situ behavior and interactions for therapeutic evasion. Dogs, particularly brachycephalic breeds, are known to spontaneously develop gliomas that resemble human gliomas both clinically and pathophysiologically, making canines with sporadic tumors promising candidates for study. Typically, survival among these dogs is approximately 2 months with palliation alone. METHODS: The authors have completed the first stage of a unique phase I dose-escalating canine clinical trial in which the safety and tolerability of M032, a nonneurovirulent oncolytic herpes simplex virus-1 vector genetically engineered to express interleukin-12, are being studied in pet dogs with gliomas undergoing maximum safe tumor resection and inoculation of the cavity with the viral infusate. RESULTS: Twenty-five canine patients were enrolled between January 2018 and August 2020. One patient was electively withdrawn from the trial by its owner, and 3 did not receive the virus. For the 21 dogs that remained, 13 had high-grade gliomas, 5 had low-grade gliomas, and 3 were undetermined. According to histopathological analysis, 62% of the tumors were oligodendrogliomas. At the time of this report, the median overall survival from the date of treatment was 151 days (± 78 days). No significant adverse events attributable to M032 or dose-limiting toxicities have been observed to date. CONCLUSIONS: In this largest study of oncolytic viral therapy for canine brain tumors to date, treatment with M032 did not cause harm and the combination of surgery and oncolytic viral therapy may have contributed to prolonged survival in pet dogs with spontaneous gliomas. Forthcoming in-depth radiographic, immunohistochemical, and genetic analyses will afford a more advanced understanding of how this treatment impacts these tumors and the immune system. Our goal is to utilize these findings bitranslationally to inform human studies and refine therapies that will improve outcomes in both humans and pet dogs with gliomas.

A Bibliometric Analysis of 4 Major Foot and Ankle Surgery Journals.

Research publication is a central to the scientific process and comprehensive bibliometric analysis is a leading way to better understand trends within research. Currently, there are limited bibliometric analyses of literature pertaining to foot and ankle surgery. This study aims to quantify the volume of research and investigate what may affect publication and citation. Journals associated with the 3 major orthopedic foot and ankle societies (Foot & Ankle International[FAI], Foot and Ankle Surgery, and The Foot) and one podiatric college (Journal of Foot and Ankle Surgery®) were evaluated from January 2009 to December 2018 using Scopus (Elsevier, Amsterdam, the Netherlands). Descriptive statistics were used to summarize article characteristics and regression modeling was used to determine factors associated with a country's current and future productivity and an article's citation rate. A total of 4994 articles were published over the 10-year period, with the largest contributor of publications being the United States of America (USA), who produced 2096 (41.8%) publications. Regression analysis found no association between a country's productivity and gross domestic product or population. There was no significant relationship between a country's baseline publication rate and future publication rate. The variables significantly associated with an increased citation count were; the number of years since publication, the number of authors, publication in FAI and if the article was a review. To our knowledge this is the largest bibliometric analysis of foot and ankle publications. The majority of research is being produced by the USA, but there are numerous complex factors associated with citation and publication rates. Further research is required to fully assess these factors and characterize the state of foot and ankle surgery research.

Overview of randomised controlled trials in hallux valgus surgery (2,184 patients).

BACKGROUND: The aim of this study is to provide an overview of randomised controlled trials (RCTs) in hallux valgus correction surgery summarising the available high-quality evidence. METHODS: Following PRISMA guidelines, we searched the Cochrane Central Register of Controlled Trials, Ovid MEDLINE (1946 to 1 February 2020) and Embase (1980 to 1 February 2020). We excluded non-randomised trials, systematic reviews and case-series. We also excluded trials of MTPJ arthrodesis. Trials that met our inclusion criteria were assessed by two authors using a binary outcome measure of whether they reported statistically significant findings. These were then classified according to intervention groups. RESULTS: 32 RCTs met the inclusion criteria and were included. The total number of patients in those trials was 2,184. Only 4 RCTs (12.5%) reported significant differences between the intervention and the control groups. The remaining trials evaluated scarf or chevron osteotomies in 18 RCTs, and 10 RCTs compared other osteotomies or technical aspects of hallux valgus surgery using functional and radiological outcome measures with none reporting significant differences. CONCLUSION: Evidence from RCTs of hallux valgus surgery suggest that scarf and chevron osteotomies are the most popular techniques and lead to similar clinical outcomes.

Treatment of hallux valgus by Scarf osteotomy - rates and reasons for recurrence and rates of avascular necrosis: A systematic review.

BACKGROUND: We reviewed the rates of and reasons for hallux valgus (HV) recurrence and the rates of avascular necrosis following Scarf osteotomy. METHODS: We searched the Cochrane Library, PubMed, and Embase databases for studies reporting operative management of HV using Scarf osteotomy. The primary endpoints were reasons for and rates of HV recurrence. The secondary endpoint was the rate of avascular necrosis. RESULTS: We included 15 studies with 946 operations for HV. Seven studies reported no recurrence, six reported recurrence rates of 3.6-11.3%, one reported a recurrence rate of 30%, and one reported a recurrence rate of 78%. Thirteen studies (678 feet) reported other complications from Scarf osteotomy without avascular necrosis. CONCLUSIONS: Although HV recurrence is not uncommon following Scarf osteotomy, patient-related factors, surgical competence, and longer follow-up are more likely to be associated with recurrence. Avascular necrosis is an infrequent complication in HV patients treated using Scarf osteotomy.

Overview of Randomized Controlled Trials in Total Knee Arthroplasty (47,675 Patients): What Have We Learnt?

BACKGROUND: The aim of this study is to provide an overview of randomized controlled trials (RCTs) in primary total knee arthroplasty summarizing the available high-quality evidence. METHODS: Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2019, Issue 3), Ovid MEDLINE, and Embase. We excluded nonrandomized trials, trials on unicompartmental knee arthroplasty or revision surgery, systematic reviews, and meta-analyses. Trials that met our inclusion criteria were assessed using a binary outcome measure of whether they reported statistically significant findings. These were then classified according to the intervention groups (surgical approach, tourniquet use, design, etc.). RESULTS: Four hundred and three RCTs met the inclusion criteria and were included. The total number of patients in those 403 RCTs was 47,675. Only 33 RCTs (8.2%) reported significant differences between the intervention and the control groups. The trials were grouped into surgical approach 34, tourniquet 31, minimally invasive surgery 13, patient specific instrumentation 30, knee design 37, fixation 27, mobile bearing 47, navigation 50, polyethylene 19, technique 27, patella resurfacing 26, drain 19, closure 16, and others 27 RCTs. CONCLUSION: For the vast majority of patients, a standard conventional total knee arthroplasty with a surgical approach familiar to the surgeon using standard well-established components, with or without tourniquet, without surgical drain leads to satisfactory long-term clinical outcomes.

Overview of randomised controlled trials in orthopaedic research: search for significant findings.

BACKGROUND: The majority of recent orthopaedics randomised controlled trials (RCTs) have been non-inferiority trials with no significant clinical or statistical differences between treatment groups. The aim of this study was to evaluate randomised trials for significant findings in the orthopaedic literature based on the main elective procedures undertaken across different subspecialties. METHODS: We evaluated the following procedures: anterior cervical discectomy and fusion (ACDF), subacromial decompression (SAD), carpal tunnel decompression (CTD), total hip replacement (THR), anterior cruciate ligament reconstruction (ACLR), total knee replacement (TKR) and hallux valgus correction (HVC). Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2018, Issue 1), Ovid MEDLINE (1946 to 12 January 2018) and Embase (1980 to 12 January 2018). Trials that met our inclusion criteria were assessed using a binary outcome measure of whether they reported statistically significant findings. RESULTS: We included 1078 RCTs across seven most commonly performed elective procedures. Of those, only 16% (172/1078) reported significant findings [ACDF 26/77 (33.8%); SAD 2/22 (9%); CTD 11/72 (15.3%); THR 52/281 (18.5%); ACLR 21/239 (8.8%); TKR 55/357 (15.4%); HVC 5/30 (16.7%)]. The number of RCTs per year of publication has increased dramatically particularly since early 2000s-with over 100 RCTs of those seven procedures published in 2017 alone. CONCLUSIONS: This is the first study to undertake a comprehensive review of orthopaedic RCTs in elective practice. The number of RCTs in orthopaedic research is steadily increasing. However, only 16% of trials reports significant differences between interventions. CLINICAL RELEVANCE: For trials comparing different surgical techniques, this evidence provides treating surgeons with the flexibility to utilise available resources and infrastructure to deliver patients care without compromising clinical outcomes. Further, for trials comparing different treatment modalities, this study helps to inform the shared decision-making process when counselling patients on the effectiveness of surgical interventions.

Convection-enhanced delivery of cetuximab conjugated iron-oxide nanoparticles for treatment of spontaneous canine intracranial gliomas.

Cetuximab conjugated iron-oxide nanoparticles (cetuximab-IONPs) have shown both in-vitro and in-vivo anti-tumor efficacy against gliomas. The purpose of this pilot study was to evaluate the safety and potential efficacy of cetuximab-IONPs for treatment of spontaneously occurring intracranial gliomas in canines after convection-enhanced delivery (CED). The use of CED allowed for direct infusion of the cetuximab-IONPs both intratumorally and peritumorally avoiding the blood brain barrier (BBB) and limiting systemic effects. A total of eight dogs participated in the study and only two developed mild post-operative complications, which resolved with medical therapy. All canines underwent a single CED treatment of the cetuximab-IONPs over 3 days and did not receive any further adjuvant treatments. Volumetric analysis showed a median reduction in tumor size of 54.9% by MRI at 1-month (4-6 weeks) follow-up. Five dogs were euthanized due to recurrence of neurological signs other than seizures, two due to recurrent seizures, and one dog died in his sleep. Median survival time after surgery was 248 days (mean 367 days).

Cranioplasty Using Titanium Mesh After Skull Tumor Resection in Five Dogs.

OBJECTIVE: To describe the clinical details, surgery, postoperative imaging, and short to mid-term outcome after cranioplasty with titanium mesh in dogs with large skull tumors. STUDY DESIGN: Case series. ANIMALS: Client-owned dogs with skull tumors (n=5). METHODS: All tumors were removed via craniectomy and a sheet of titanium mesh was contoured to reconstruct the calvarial defect and sutured to surrounding musculature. RESULTS: Four dogs had multilobular tumors of bone and 1 dog had a soft tissue sarcoma invading the cranial vault. Neurologic examination was unchanged or improved postoperative, a good cosmetic appearance was achieved, and no complications were noted at 2 weeks postoperative. Late postoperative computed tomography (CT) in 2 dogs and magnetic resonance (MR) imaging in 1 dog confirmed the presence of the titanium mesh without migration. There was no interference of the mesh with image interpretation and definitive radiation therapy was pursued in 1 dog without complication. Late follow-up reported 2 dogs euthanatized; at 44 weeks postoperative due to tumor re-growth; at 12 weeks postoperative for hemoabdomen, respectively. One dog drowned at 40 weeks postoperative, 1 dog was lost to follow-up, and 1 dog is alive at 83 weeks postoperative free of clinical signs. CONCLUSIONS: Titanium mesh is suitable for cranioplasty based on its strength, biocompatibility, and excellent handling characteristics. It does not interfere with acquisition or interpretation of CT or MR images, thereby allowing postoperative imaging for ongoing assessment.

Evaluation of magnetic resonance imaging for the differentiation of inflammatory, neoplastic, and vascular intradural spinal cord diseases in the dog.

Magnetic resonance imaging (MRI) is a common test for dogs with suspected intradural spinal cord lesions, however studies on diagnostic performance for this test are lacking. Objectives of this multi-institutional, retrospective, case-control study were to estimate sensitivity and specificity of MRI for (1) distinguishing between histopathologically confirmed intradural spinal cord disease versus degenerative myelopathy in dogs, (2) categorizing intradural spinal cord diseases as neoplastic, inflammatory, or vascular; and (3) determining tumor type within the etiologic category of neoplasia. Additional aims were to (1) determine whether knowledge of clinical data affects sensitivity and specificity of MRI diagnoses; and (2) report interrater agreement for MRI classification of intradural spinal lesions. Cases were recruited from participating hospital databases over a 7-year period. Three reviewers independently evaluated each MRI study prior to and after provision of clinical information. A total of 87 cases were sampled (17 degenerative myelopathy, 53 neoplasia, nine inflammatory, and eight vascular). Magnetic resonance imaging had excellent (>97.6%) sensitivity for diagnosis of intradural spinal cord lesions but specificity varied before and after provision of clinical data (68.6% vs. 82.4%, P = 0.023). Magnetic resonance imaging had good sensitivity (86.8%) and moderate specificity (64.7-72.5%) for diagnosing neoplasia. Sensitivity was lower for classifying inflammatory lesions but improved with provision of clinical data (48.1% vs. 81.5%, P = 0.015). Magnetic resonance imaging was insensitive for diagnosing vascular lesions (25.0%). Interrater agreement was very good for correctly diagnosing dogs with intradural lesions (ĸ = 0.882-0.833), and good (ĸ = 0.726-0.671) for diagnosing dogs with neoplasia.

Post-operative Salmonella surgical site infection in a dog.

Following decompressive surgery for degenerative lumbosacral stenosis, a 6-year-old German shepherd dog developed a subcutaneous infection at the surgical site and discospondylitis at the lumbosacral intervertebral disc. Salmonella enterica subsp. enterica, serotype Dublin was recovered from the surgical site. Salmonella of a different serovar was isolated from a sample of the raw meat-based diet that the owner fed the dog.

Infection postopératoire du site chirurgical parSalmonellachez un chien. Après une chirurgie de décompression pour une sténose lombo-sacrée dégénérative, un chien Berger allemand âgé de 6 ans a développé une infection sous-cutanée au site chirurgical et une discospondylite au disque intervertébral lombo-sacré. Salmonella enterica sous-esp. enterica de sérotype Dublin a été isolée du site chirurgical. Une salmonelle d'un sérovar différent a été isolée d'un échantillon de l'alimentation à base de viande crue donnée par le propriétaire au chien.(Traduit par Isabelle Vallières).

Atypical Chronic Ankle Instability in a Pediatric Population Secondary to Distal Fibula Avulsion Fracture Nonunion.

Chronic ankle instability is a disabling condition, often occurring as a result of traumatic ankle injury. A paucity of published data is available documenting chronic ankle instability in the pediatric population. Much of the data has been confined to the adult population. We present 2 cases of chronic ankle instability, 1 in a 12-year-old and 1 in a 9-year-old patient. Unlike the typical adult etiology, the cause of instability was a dysfunctional lateral ligamentous complex as a consequence of bony avulsion of the tip of the fibula. Both patients had sustained a twisting injury to the ankle. The fractures failed to unite. The nonunion resulted in dysfunction of the anterior talofibular ligament with consequent chronic ankle instability. At the initial clinical assessment, magnetic resonance imaging was requested for both patients. In patient 1 (12 years old), the fracture was fixed with 2 headless screws and was immobilized in a plaster cast for 6 weeks. In patient 2 (9 years old), because of the small size of the avulsed fragment, fixation was not possible. A modified Gould-Broström procedure was undertaken, facilitating repair of the avulsed fragment using anchor sutures.

IMAGING DIAGNOSIS-VERTEBRAL POLYOSTOTIC LYMPHOMA IN A GERIATRIC DOG.

A 9-year-old spayed female Scottish terrier presented with an 8-day history of progressive paraparesis. Neurological examination suggested a painful T3-L3 myelopathy. Multifocal uniform contrast-enhancing masses involving the vertebral bodies, pedicles, laminae, and spinous processes of two vertebrae and compressing the spinal cord were present on MRI. Fluoroscopic-guided fine needle aspiration of one of the vertebral lesions revealed a predominantly lymphoblastic population of cells compatible with a diagnosis of lymphoma. To the authors' knowledge, this represents the first published case of canine lymphoma with vertebral involvement, characterized with MRI.

Segmentation of the canine corpus callosum using diffusion-tensor imaging tractography.

OBJECTIVE: We set out to determine functional white matter (WM) connections passing through the canine corpus callosum; these WM connections would be useful for subsequent studies of canine brains that serve as models for human WM pathway disease. Based on prior studies, we anticipated that the anterior corpus callosum would send projections to the anterior cerebral cortex whereas progressively posterior segments would send projections to more posterior cortex. MATERIALS AND METHODS: A postmortem canine brain was imaged using a 7-T MRI system producing 100-µm-isotropic-resolution diffusion-tensor imaging analyzed by tractography. Using regions of interest (ROIs) within cortical locations, which were confirmed by a Nissl stain that identified distinct cortical architecture, we successfully identified six important WM pathways. We also compared fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial diffusivity, and axial diffusivity in tracts passing through the genu and splenium. RESULTS: Callosal fibers were organized on the basis of cortical destination (e.g., fibers from the genu project to the frontal cortex). Histologic results identified the motor cortex on the basis of cytoarchitectonic criteria that allowed placement of ROIs to discriminate between frontal and parietal lobes. We also identified cytoarchitecture typical of the orbital frontal, anterior frontal, and occipital regions and placed ROIs accordingly. FA, ADC, radial diffusivity, and axial diffusivity values were all higher in posterior corpus callosum fiber tracts. CONCLUSION: Using six cortical ROIs, we identified six major WM tracts that reflect major functional divisions of the cerebral hemispheres, and we derived quantitative values that can be used for study of canine models of human WM pathologic states.

Extramedullary spinal cysts in dogs.

OBJECTIVE: To (1) synthesize the terminology used to classify extramedullary spinal cysts in dogs to clarify some of the commonly reported misconceptions, and (2) propose a classification scheme to limit confusion with terminology. STUDY DESIGN: Literature review. METHODS: An online bibliographic search was performed in January 2013 for articles relating to extramedullary spinal cysts in dogs using PubMed (http://www.pubmed.gov/) and Google Scholar (http://scholar.google.com/) databases. Only peer-reviewed clinical literature describing cystic lesions pertaining to the spinal cord and associated structures was included. RESULTS: From 1962 to 2013, 42 articles were identified; 25 (95 dogs) reported meningeal cysts, 10 (24 dogs) described 60 extradural cysts, 3 reports (18 dogs) described discal cysts or acute compressive hydrated nucleus pulposus extrusions (HNPE). Spinal cysts were categorized by location based on cross-sectional imaging as meningeal or extradural non-meningeal. Sub-classification was then performed based on surgical findings and pathology. Meningeal cysts included arachnoid diverticulae and Tarlov (perineural) cysts. Extradural non-meningeal cysts included intraspinal cysts of the vertebral joints, ligaments and discs. Discal cysts also fit this category and have been reported extensively in humans but appear rare in dogs. CONCLUSIONS: Extramedullary spinal cysts should be first classified according to location with a sub-classification according to pathologic and surgical findings. Previous canine cases of discal cysts appear to represent a different disease entity and the term acute compressive HNPE is therefore preferred.

Evaluation of standard magnetic resonance characteristics used to differentiate neoplastic, inflammatory, and vascular brain lesions in dogs.

Magnetic resonance (MR) imaging characteristics are commonly used to help predict intracranial disease categories in dogs, however, few large studies have objectively evaluated these characteristics. The purpose of this retrospective study was to evaluate MR characteristics that have been used to differentiate neoplastic, inflammatory, and vascular intracranial diseases in a large, multi-institutional population of dogs. Medical records from three veterinary teaching hospitals were searched over a 6-year period for dogs that had diagnostic quality brain MR scans and histologically confirmed intracranial disease. Three examiners who were unaware of histologic diagnosis independently evaluated 19 MR lesion characteristics totaling 57 possible responses. A total of 75 dogs with histologically confirmed intracranial disease were included in analyses: 51 with neoplasia, 18 with inflammatory disease, and six with cerebrovascular disease. Only strong contrast enhancement was more common in neoplasia than other disease categories. A multivariable statistical model suggested that extra-axial origin, T2-FLAIR mixed intensity, and defined lesion margins were also predictive of neoplasia. Meningeal enhancement, irregular lesion shape, and multifocal location distinguished inflammatory diseases from the other disease categories. No MR characteristics distinguished vascular lesions and these appeared most similar to neoplasia. These results differed from a previous report describing seven MR characteristics that were predictive of neoplasia in dogs and cats. Findings from the current study indicated that the high performance of MR for diagnosing canine intracranial diseases might be due to evaluator recognition of combinations of MR characteristics vs. relying on any one MR characteristic alone.

ACVIM Consensus Statement on the management of status epilepticus and cluster seizures in dogs and cats.

BACKGROUND: Seizure emergencies (ie, status epilepticus [SE] and cluster seizures [CS]), are common challenging disorders with complex pathophysiology, rapidly progressive drug-resistant and self-sustaining character, and high morbidity and mortality. Current treatment approaches are characterized by considerable variations, but official guidelines are lacking. OBJECTIVES: To establish evidence-based guidelines and an agreement among board-certified specialists for the appropriate management of SE and CS in dogs and cats. ANIMALS: None. MATERIALS AND METHODS: A panel of 5 specialists was formed to assess and summarize evidence in the peer-reviewed literature with the aim to establish consensus clinical recommendations. Evidence from veterinary pharmacokinetic studies, basic research, and human medicine also was used to support the panel's recommendations, especially for the interventions where veterinary clinical evidence was lacking. RESULTS: The majority of the evidence was on the first-line management (ie, benzodiazepines and their various administration routes) in both species. Overall, there was less evidence available on the management of emergency seizure disorders in cats in contrast to dogs. Most recommendations made by the panel were supported by a combination of a moderate level of veterinary clinical evidence and pharmacokinetic data as well as studies in humans and basic research studies. CONCLUSIONS AND CLINICAL RELEVANCE: Successful management of seizure emergencies should include an early, rapid, and stage-based treatment approach consisting of interventions with moderate to preferably high ACVIM recommendations; management of complications and underlying causes related to seizure emergencies should accompany antiseizure medications.

GM2 gangliosidosis associated with a HEXA missense mutation in Japanese Chin dogs: a potential model for Tay Sachs disease.

GM2 gangliosidosis is a fatal lysosomal storage disease caused by a deficiency of ß-hexosaminidase (EC 3.2.1.52). There are two major isoforms of the enzyme: hexosaminidase A composed of an α and a ß subunit (encoded by HEXA and HEXB genes, respectively); and, hexosaminidase B composed of two ß subunits. Hexosaminidase A requires an activator protein encoded by GM2A to catabolize GM2 ganglioside, but even in the absence of the activator protein, it can hydrolyze the synthetic substrates commonly used to assess enzyme activity. GM2 gangliosidosis has been reported in Japanese Chin dogs, and we identified the disease in two related Japanese Chin dogs based on clinical signs, histopathology and elevated brain GM2 gangliosides. As in previous reports, we found normal or elevated hexosaminidase activity when measured with the synthetic substrates. This suggested that the canine disease is analogous to human AB variant of G(M2) gangliosidosis, which results from mutations in GM2A. However, only common neutral single nucleotide polymorphisms were found upon sequence analysis of the canine ortholog of GM2A from the affected Japanese Chins. When the same DNA samples were used to sequence HEXA, we identified a homozygous HEXA:c967G>A transition which predicts a p.E323K substitution. The glutamyl moiety at 323 is known to make an essential contribution to the active site of hexosaminidase A, and none of the 128 normal Japanese Chins and 92 normal dogs of other breeds that we tested was homozygous for HEXA:c967A. Thus it appears that the HEXA:c967G>A transition is responsible for the GM2 gangliosidosis in Japanese Chins.

Insertion of the dorsal oblique muscle in the dog: an anatomic basis for ventral strabismus associated with oculomotor nerve dysfunction.

OBJECTIVE: To describe the insertion of the dorsal oblique (DO) muscle in relationship to the equator of the globe in dogs. PROCEDURE: The study was conducted on 10 fresh cadaver eyes from five dogs, which were euthanized for disease processes unrelated to ocular disease. A manual vernier caliper was used to determine the calculated measurements. RESULTS: The median anterior-to-posterior diameter of the globe was 21 mm. The median length from the vertex of the anterior pole to the anterior point of insertion of the DO tendon was 11.5 mm. The median length from the posterior pole to the posterior point of insertion of the DO tendon was 10 mm. The width of tendon of insertion of the DO tendon was 3.25 mm. CONCLUSIONS: In disorders involving the oculomotor nerve or the oculomotor nerve nucleus in the mesencephalon, the resultant strabismus is directed ventrolaterally. Based on the insertion of the superior oblique muscle in humans, we hypothesized that the DO muscle would likely explain the ventral deviation in disorders of the oculomotor nerve or its nucleus. In this study, the point of the insertion of the DO muscle tendon was posterior to the equator. Based on this anatomic location, unopposed function of the DO muscle would be expected to result in ventral deviation of the globe.

Clinicopathologic and MRI characteristics of presumptive hypertensive encephalopathy in two cats and two dogs.

Two dogs and two cats were evaluated for the acute-onset of abnormal mentation, recumbency, and blindness. All cases had systemic hypertension, ranging from 180 mm Hg to 260 mm Hg. MRI of the brain disclosed noncontrast-enhancing, ill-defined, T2-weighted (T2W) hyperintensities in the white matter of the cerebrum in the areas of the frontal, parietal, temporal, and occipital lobes. Lesions were also observed in the caudate nuclei and thalamus (n = 1 in each). Intracranial hemorrhage was observed in one animal. Diffusion-weighted imaging (DWI) was consistent with vasogenic edema in two animals. Retinal lesions were observed in three animals. Hypertension was secondary to renal disease in three animals. A primary underlying disorder was not identified in one animal. Normalization of blood pressure was achieved with amlodipine either alone or in combination with enalapril. In one cat, hypertension spontaneously resolved. In three cases, neurologic improvement occurred within 24-48 hr of normalization of blood pressure. The presumptive diagnosis of hypertensive encephalopathy was supported by the MRI findings and neurologic dysfunction coincident with systemic hypertension in which the neurologic dysfunction improved with treatment of hypertension. The prognosis appears good for the resolution of neurologic deficits with normalization of blood pressure in animals with hypertensive encephalopathy.