Reprogramming the Canine Glioma Microenvironment with Tumor Vaccination plus Oral Losartan and Propranolol Induces Objective Responses.

Purpose: Malignant gliomas have a highly immune suppressive tumor microenvironment (TME) which renders them largely unresponsive to conventional therapeutics. Therefore, the present study evaluated a therapeutic protocol designed overcome the immune barrier by combining myeloid cell targeted immunotherapy with tumor vaccination. Experimental Design: We utilized a spontaneously occurring canine glioma model to investigate an oral TME modifying immunotherapy in conjunction with cancer stem cell (CSC) vaccination. Dogs were treated daily with losartan (monocyte migration inhibitor) and propranolol (myeloid-derived suppressor cell depleting agent) plus anti-CSC vaccination on a bi-weekly then monthly schedule. Tumor volume was monitored by MRI and correlated with patient immune responses. Results: Ten dogs with histologically confirmed gliomas were enrolled into a prospective, open-label clinical trial to evaluate the immunotherapy protocol. Partial tumor regression was observed in 2 dogs, while 6 dogs experienced stable disease, for an overall clinical benefit rate of 80%. Overall survival times (median = 351 days) and progression-free intervals (median = 163 days) were comparable to prior studies evaluating surgical debulking followed by immunotherapy. Dogs with detectable anti-CSC antibody responses had an increased overall survival time relative to dogs that did not generate antibody responses (vaccine responder MST = 500 days; vaccine non-responder MST = 218 days; p = 0.02). Conclusions: These findings suggest that combining myeloid cell targeted oral immunotherapy with tumor vaccination can generate objective tumor responses, even in the absence of conventional therapy. Overall, this approach has promise as a readily implemented therapeutic strategy for use in brain cancer patients.

Use of Handheld Raman Spectroscopy for Intraoperative Differentiation of Normal Brain Tissue From Intracranial Neoplasms in Dogs.

The aim of this study was to assess feasibility and accuracy of a hand-held, intraoperative Raman spectroscopy device as a neuronavigation aid to accurately detect neoplastic tissue from adjacent normal gray and white matter. Although Raman spectra are complicated fingerprints of cell signature, the relative shift corresponding to lipid and protein content (2,845 and 2,930 cm-1, respectively), can provide a rapid assessment of whether tissue is normal white or gray matter vs. neoplasia for real-time guidance of tumor resection. Thirteen client-owned dogs were initially enrolled in the study. Two were excluded from final analysis due to incomplete data acquisition or lack of neoplastic disease. The diagnoses of the remaining 11 dogs included six meningiomas, two histiocytic sarcomas, and three gliomas. Intraoperatively, interrogated tissues included normal gray and/or white matter and tumor. A total of five Raman spectra readings were recorded from the interrogated tissues, and samples were submitted for confirmation of Raman spectra by histopathology. A resultant total of 24 samples, 13 from neoplastic tissue and 11 from normal gray or white matter, were used to calculate sensitivity and specificity of Raman spectra compared to histopathology. The handheld Raman spectroscopy device had sensitivity of 85.7% and specificity of 90% with a positive predictive value of 92.3% and negative predictive value of 81.6%. The Raman device was feasible to use intraoperatively with rapid interpretation of spectra. Raman spectroscopy may be useful for intraoperative guidance of tumor resection.

A pilot study of optical neuronavigation-guided brain biopsy in the horse using anatomic landmarks and fiducial arrays for patient registration.

BACKGROUND: Optical neuronavigation-guided intracranial surgery has become increasingly common in veterinary medicine, but its use has not yet been described in horses. OBJECTIVES: To determine the feasibility of optical neuronavigation-guided intracranial biopsy procedures in the horse, compare the use of the standard fiducial array and anatomic landmarks for patient registration, and evaluate surgeon experience. ANIMALS: Six equine cadaver heads. METHODS: Computed tomography images of each specimen were acquired, with the fiducial array rigidly secured to the frontal bone. Six targets were selected in each specimen. Patient registration was performed separately for 3 targets using the fiducial array, and for 3 targets using anatomic landmarks. In lieu of biopsy, 1 mm diameter wire seeds were placed at each target. Postoperative images were coregistered with the planning scan to calculate Euclidian distance from the tip of the seed to the target. RESULTS: No statistical difference between registration techniques was identified. The impact of surgeon experience was examined for each technique using a Mann-Whitney U test. The experienced surgeon was significantly closer to the intended target (median = 2.52 mm) than were the novice surgeons (median = 6.55 mm) using the fiducial array (P = .001). Although not statistically significant (P = .31), for the experienced surgeon the median distance to target was similar when registering with the fiducial array (2.47 mm) and anatomic landmarks (2.58 mm). CONCLUSIONS AND CLINICAL IMPORTANCE: Registration using both fiducial arrays and anatomic landmarks for brain biopsy using optical neuronavigation in horses is feasible.

Onscreen-guided resection of extra-axial and intra-axial forebrain masses through registration of a variable-suction tissue resection device with a neuronavigation system.

OBJECTIVES: To describe a novel surgical technique in which neuronavigation is used to guide a tissue resection device during excision of forebrain masses in locations difficult to visualize optically. STUDY DESIGN: Short case series. ANIMALS: Six dogs and one cat with forebrain masses (five neoplastic, two nonneoplastic) undergoing excision with a novel tissue resection device and veterinary neuronavigation system. METHODS: The animals and resection instrument were coregistered to the neuronavigation system. Surgery was guided by real-time onscreen visualization of the resection instrument position relative to the preoperative MR images. Surgical outcome was evaluated by calculating residual tumor volume according to postoperative MRI. RESULTS: The technique was technically simple and led to the collection of diagnostic tissue samples in all cases. Postoperative MRI was available in six cases, two with gross-total resection, three with near-total resection, and one with subtotal resection. CONCLUSION: Neuronavigation-guided resection of intra-axial and extra-axial brain masses with the resection device resulted in gross-total or near-total resection in five of six animals with tumors otherwise difficult to visualize. Risk of brain shift limited absolute reliance on navigation images. CLINICAL SIGNIFICANCE: Real-time neuronavigation assistance is a feasible method for guidance and successful resection of brain masses that are poorly visualized because of intra-axial or deep location, tumor appearance, or hemorrhage.

Comparative Molecular Life History of Spontaneous Canine and Human Gliomas.

Sporadic gliomas in companion dogs provide a window on the interaction between tumorigenic mechanisms and host environment. We compared the molecular profiles of canine gliomas with those of human pediatric and adult gliomas to characterize evolutionarily conserved mammalian mutational processes in gliomagenesis. Employing whole-genome, exome, transcriptome, and methylation sequencing of 83 canine gliomas, we found alterations shared between canine and human gliomas such as the receptor tyrosine kinases, TP53 and cell-cycle pathways, and IDH1 R132. Canine gliomas showed high similarity with human pediatric gliomas per robust aneuploidy, mutational rates, relative timing of mutations, and DNA-methylation patterns. Our cross-species comparative genomic analysis provides unique insights into glioma etiology and the chronology of glioma-causing somatic alterations.

Surgical decompression, with or without adjunctive therapy, for palliative treatment of primary vertebral osteosarcoma in dogs.

Vertebral osteosarcoma (OSA) is the most common primary vertebral tumor in dogs, however studies examining the survival time after surgical decompression of these tumors are limited. There is also limited information regarding the benefit of adjunctive treatments such as radiation therapy or chemotherapy in these patients. The goal of this study was to determine survival time of dogs with primary vertebral OSA after palliative decompressive surgery alone and combined with radiation therapy and/or chemotherapy. Records from 22 client-owned dogs diagnosed with primary vertebral OSA and treated with decompressive surgery were collected retrospectively from eight referral institutions. Survival time was assessed for dogs treated with surgery alone as well as dogs who received adjunctive radiation therapy and/or chemotherapy. Median survival time in the 12 dogs treated with surgery alone was 42 days (range: 3-1333 days). The three dogs treated with surgery and chemotherapy had a median survival time of 82 days (range: 56-305 days). Only one dog was treated with surgery and radiation therapy; this dog survived 101 days. Six dogs were treated with surgery, radiation therapy and chemotherapy; these dogs had a median survival time of 261 days (range: 223-653 days). Cause of death in all cases that survived the initial postoperative period was euthanasia secondary to confirmed or suspected tumor regrowth. The results of this study suggest that definitive radiation therapy, possibly combined with concurrent chemotherapy, significantly improves survival in dogs treated with palliative decompressive surgery for vertebral OSA and should be the treatment of choice in selected cases.

Determination of surgical exposure obtained with integrated endoscopic thoracolumbar hemilaminectomy in large-breed cadaveric dogs.

OBJECTIVE: To define boundaries of minimally invasive integrated endoscopic hemilaminectomy at 4 sites in the canine thoracolumbar spine. STUDY DESIGN: Experimental, randomized cadaveric study. ANIMALS: Six cadaver dogs that had been humanely euthanized for reasons unrelated to this study. METHODS: Hemilaminectomy was performed with an integrated endoscopic system at T11-12, T12-13, L1-2, and L2-3, 1 at each site, on the left or right side of each dog. Each site was randomly assigned either a 19-mm or a 23-mm cannula. The entire procedure, including soft tissue dissection, was performed through the cannula. Afterward, spines were imaged by computed tomography (CT) to measure the cranial and caudal extent of the hemilaminectomy from the center of the disc space. RESULTS: The mean ± SD cranial extent of the hemilaminectomy was 4.5 ± 1.4 mm for the 19-mm cannula and 5.6 ± 1.4 mm for the 23-mm cannulas (P = .0757). The caudal extent of the hemilaminectomy was 9.5 ± 2.2 mm for the 19-mm cannula and 10.3 ± 1.6 mm for the 23-mm cannula (P = .206). The mean length of the hemilaminectomy was 13.0 ± 1.5 mm for the 19-mm cannula and 15.0 ± 2.1 mm for the 23-mm cannula (P = .022). CONCLUSION: Integrated endoscopic systems were reliably used to access the spinal canal within the range of the above measurements relative to the disc space as identified by CT or magnetic resonance imaging. CLINICAL SIGNIFICANCE: Integrated endoscopy can be considered as an option in dogs with thoracolumbar disc extrusions or other pathology measuring within the parameters defined by this study. Access may be possible beyond the dimensions defined in this study with probing and repositioning.

In vitro effect of chlorambucil on human glioma cell lines (SF767 and U87-MG), and human microvascular endothelial cell (HMVEC) and endothelial progenitor cells (ECFCs), in the context of plasma chlorambucil concentrations in tumor-bearing dogs.

The objective of this study was to investigate a possible mechanism of action of metronomic chlorambucil on glioma by studying the in vitro cytotoxicity and anti-angiogenic effects on glioma and endothelial cells, respectively. The in vitro LD50 and IC50 of chlorambucil were determined using human SF767 and U87-MG glioma cell lines, human microvascular endothelial cells (HMVECs) and human endothelial colony forming cells (ECFCs). Results were analyzed in the context of chlorambucil concentrations measured in the plasma of tumor-bearing dogs receiving 4 mg m-2 metronomic chlorambucil. The LD50 and IC50 of chlorambucil were 270 µM and 114 µM for SF767, and 390 µM and 96 µM for U87-MG, respectively. The IC50 of chlorambucil was 0.53 µM and 145 µM for the HMVECs and ECFCs, respectively. In pharmacokinetic studies, the mean plasma Cmax of chlorambucil was 0.06 µM. Results suggest that metronomic chlorambucil in dogs does not achieve plasma concentrations high enough to cause direct cytotoxic or growth inhibitory effects on either glioma or endothelial cells.

Consensus recommendations on standardized magnetic resonance imaging protocols for multicenter canine brain tumor clinical trials.

The National Cancer Institute Comparative Brain Tumor Consortium, Patient Outcomes Working Group, propose a consensus document in support of standardized magnetic resonance imaging protocols for canine brain tumor clinical trials. The intent of this manuscript is to address the widely acknowledged need to ensure canine brain tumor imaging protocols are relevant and have sufficient equivalency to translate to human studies such that: (1) multi-institutional studies can be performed with minimal inter-institutional variation, and (2) imaging protocols are consistent with human consensus recommendations to permit reliable translation of imaging data to human clinical trials. Consensus recommendations include pre- and postcontrast three-dimensional T1-weighted images, T2-weighted turbo spin echo in all three planes, T2*-weighted gradient recalled echo, T2-weighted fluid attenuated inversion recovery, and diffusion weighted imaging/diffusion tensor imaging in transverse plane; field of view of ≤150 mm; slice thickness of ≤2 mm, matrix ≥ 256 for two-dimensional images, and 150 or 256 for three-dimensional images.

Magnetic Resonance Imaging Appearance and Mechanism of Action of Five Hemostatic Agents Used in Neurosurgery.

OBJECTIVE: To describe the magnetic resonance (MR) image appearance of 5 hemostatic agents placed in the brain, and to review their clinical application. STUDY DESIGN: Descriptive ex vivo and in vivo study. ANIMALS: Canine cadavers (n=4), client-owned dogs (n=4). METHODS: Heads from 4 canine cadavers were used, each with 5 hemostatic agents placed in specific locations in the brain. Hemostatic agents were used in their native form in 2 cadaveric brains, and in 2 others the materials were saturated with fresh whole blood prior to placement to mimic application in a field of active hemorrhage. The heads underwent MR imaging and the images were reviewed. Postoperative MRI images from 4 dogs undergoing brain tumor resection were retrospectively reviewed and compared to the images from the cadavers. All clinical cases and cadaveric specimens underwent surgical closure prior to MR imaging including placement of titanium mesh over the craniotomy defect with a dural graft of porcine small intestinal submucosa (SIS) sealed with Tisseel (fibrin sealant). RESULTS: The SIS and Tisseel used in the dural graft were consistently indistinguishable from the surrounding tissues on MR images. The MR imaging appearance of the remaining 4 hemostatic agents (Gelfoam, Avitene, Surgicel, and Floseal) placed on the surface or in the parenchyma of canine brain, varied with MR sequence weighting and blood saturation. CONCLUSION: Accurate evaluation of the degree of brain tumor resection on postoperative MR images requires careful differentiation between hemorrhage, residual tumor, and hemostatic agents implanted.

Effects of conventional and slanted ventral slot procedures on the biomechanical behavior of the C5-C6 vertebral motion unit in dogs.

OBJECTIVE To compare the effects of conventional and slanted ventral slot procedures on the biomechanical behavior of the C5-C6 vertebral motion unit (VMU) in dogs. SAMPLE 14 vertebral columns (C4 through C7) from canine cadavers. PROCEDURES Specimens were assigned to a conventional or slanted ventral slot group (n = 7/group). For each specimen, the C5-C6 VMU was tested in ventral and dorsal bending and positive and negative axial torsion before and after surgery. Range of motion (ROM), stiffness, and energy absorption were compared between the 2 groups. RESULTS Both procedures significantly increased the ROM and stiffness and significantly decreased the energy absorption of the C5-C6 VMU in ventral and dorsal bending. Both procedures also increased the ROM in positive and negative axial torsion. In negative torsion, total stiffness and stiffness over the maximum ROM tested decreased less for the slanted slot procedure than for the conventional slot procedure. There were no significant differences between procedures for any of the other biomechanical outcomes examined. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the biomechanical response of the C5-C6 VMU to the conventional and slanted ventral slot procedures was not significantly different, especially when considering postsurgical instability induced by both procedures. This was most likely due to disruption of the nucleus pulposus and dorsal annulus fibrosus of the disk with both procedures. On the basis of these findings, neither procedure appeared biomechanically superior. Comparative clinical studies are warranted to further evaluate the 2 procedures.

Creation of an NCI comparative brain tumor consortium: informing the translation of new knowledge from canine to human brain tumor patients.

On September 14-15, 2015, a meeting of clinicians and investigators in the fields of veterinary and human neuro-oncology, clinical trials, neuropathology, and drug development was convened at the National Institutes of Health campus in Bethesda, Maryland. This meeting served as the inaugural event launching a new consortium focused on improving the knowledge, development of, and access to naturally occurring canine brain cancer, specifically glioma, as a model for human disease. Within the meeting, a SWOT (strengths, weaknesses, opportunities, and threats) assessment was undertaken to critically evaluate the role that naturally occurring canine brain tumors could have in advancing this aspect of comparative oncology aimed at improving outcomes for dogs and human beings. A summary of this meeting and subsequent discussion are provided to inform the scientific and clinical community of the potential for this initiative. Canine and human comparisons represent an unprecedented opportunity to complement conventional brain tumor research paradigms, addressing a devastating disease for which innovative diagnostic and treatment strategies are clearly needed.

Increase in oxidative stress biomarkers in dogs with ascending-descending myelomalacia following spinal cord injury.

Multiple biochemical and immunohistochemical tests were performed to elucidate the role of oxidative stress during ascending-descending (A-D) myelomalacia by comparing dogs with this progressive terminal condition to dogs with chronic, focal spinal cord injuries (SCIs) and controls without SCI. Dogs with A-D myelomalacia exhibited increased biochemical markers for oxidative stress, including 8-isoprostane F2α and acrolein, as well as decreased endogenous glutathione with greatest changes occurring at the lesion center. Inflammation, as evident by the concentration of CD18+ phagocytes and hemorrhagic necrosis, was also exacerbated in the lesion of A-D myelomalacic spinal cord compared to focal SCI. The greatest differences in oxidative stress occurred at the lesion center and diminished distally in both spinal cords with A-D myelomalacia and focal SCIs. The spatial progression and time course of A-D myelomalacia are consistent with the development of secondary injury post-SCI. Ascending-descending myelomalacia is proposed as a clinical model that may further the understanding of the role of oxidative stress during secondary injury. Our results indicate that the pathology of A-D myelomalacia is also similar to subacute progressive ascending myelopathy in humans, which is characterized by recurrent neurodegeneration of spinal cord post-injury.

Vaccination for invasive canine meningioma induces in situ production of antibodies capable of antibody-dependent cell-mediated cytotoxicity.

Malignant and atypical meningiomas are resistant to standard therapies and associated with poor prognosis. Despite progress in the treatment of other tumors with therapeutic vaccines, this approach has not been tested preclinically or clinically in these tumors. Spontaneous canine meningioma is a clinically meaningful but underutilized model for preclinical testing of novel strategies for aggressive human meningioma. We treated 11 meningioma-bearing dogs with surgery and vaccine immunotherapy consisting of autologous tumor cell lysate combined with toll-like receptor ligands. Therapy was well tolerated, and only one dog had tumor growth that required intervention, with a mean follow up of 585 days. IFN-γ-elaborating T cells were detected in the peripheral blood of 2 cases, but vaccine-induced tumor-reactive antibody responses developed in all dogs. Antibody responses were polyclonal, recognizing both intracellular and cell surface antigens, and HSP60 was identified as one common antigen. Tumor-reactive antibodies bound allogeneic canine and human meningiomas, showing common antigens across breed and species. Histologic analysis revealed robust infiltration of antibody-secreting plasma cells into the brain around the tumor in posttreatment compared with pretreatment samples. Tumor-reactive antibodies were capable of inducing antibody-dependent cell-mediated cytotoxicity to autologous and allogeneic tumor cells. These data show the feasibility and immunologic efficacy of vaccine immunotherapy for a large animal model of human meningioma and warrant further development toward human trials.

Canine intervertebral disc fenestration using a vacuum-assisted tissue resection device.

OBJECTIVE: Describe the use and feasibility of a novel vacuum-assisted tissue resection device (VRD) for canine intervertebral disc fenestration, and compare the effectiveness of manual fenestration to the VRD. STUDY DESIGN: Randomized prospective study. ANIMALS: Canine cadavers (n = 15). METHODS: A cadaveric lumbar spine study was performed to compare the use of manual fenestration to a novel VRD for intervertebral disc fenestration. Both fenestration groups were compared to a control group. Effectiveness of fenestration was assessed by calculating a ratio of remaining nuclear weight postfenestration to total nuclear volume. Fenestrated discs with lower ratios were indicative of greater removal of nucleus pulposus. RESULTS: There was a statistically significant reduction in mean ratio (±SD) of remaining nuclear weight to volume with both fenestration groups compared to controls (0.39 ± 0.07; P < .001). There was an improved ratio using the VRD (0.23 ± 0.09) compared to manual fenestration (0.30 ± 0.10); this was not statistically significant (P = .069). It was technically difficult to fenestrate the disc spaces at L5-L6 and L6-L7 because of location and anatomy, resulting in a statistically significant increase in the median ratio of nuclear weight-to-volume ratios in both manual and VRD fenestration groups when compared to the more cranial L4-L5 disc spaces, 0.32 ± 0.08, and 0.35 ± 0.08 versus 0.25 ± 0.13 at L4-L5 (P = .026 and P = .004, respectively). CONCLUSIONS: The VRD is a feasible instrument for canine intervertebral disc fenestration. It is at least as effective as manual fenestration, and provides additional safety features.

Imaging diagnosis-magnetic resonance imaging features of metastatic cerebral lymphoma in a dog.

We describe histopathologically confirmed intracranial metastasis of cutaneous lymphoma. In magnetic resonance (MR) images there was a heterogeneous, contrast-enhancing, extraaxial mass in the right parietal and piriform lobes at the level of the optic chiasm. Our MR imaging findings are consistent with reports in humans in that lymphoma masses have indistinct borders that are iso- to hyperintense relative to adjacent gray matter on T2-weighted images. Our report varies from findings in humans in that the mass was extraaxial, whereas masses reported in humans are intraaxial. Contrast enhancement can be heterogeneous, as in our report, or homogeneous.

Evaluation of minimally invasive excisional brain biopsy and intracranial brachytherapy catheter placement in dogs.

OBJECTIVE: To evaluate a technique for minimally invasive excisional brain biopsy and intracranial brachytherapy catheter placement in dogs. ANIMALS: 5 healthy adult female dogs. PROCEDURES: Computed tomographic guidance was used to plan a biopsy trajectory to a selected area of brain with reference to a localizer grid. The procedure was performed through a 1-cm skin incision and 6-mm burr hole by use of a 9-gauge biopsy device. Five cylindrical samples (3 to 4 mm in diameter and 7 to 12 mm in length) were removed over 5 cycles of the vacuum-assisted tissue excision system, leaving approximately a 2-cm³ resection cavity. A balloon-tipped intracranial brachytherapy catheter was placed through the burr hole into the resection cavity, expanded with saline (0.9% NaCl) solution, and explanted 7 days later. RESULTS: 4 of 5 dogs survived the procedure. The fifth died because of iatrogenic brain damage. Neurologic deficits were unilateral and focal. Twenty-four hours after surgery, all surviving dogs were ambulatory, 2 dogs exhibited ipsiversive circling, 4 had contralateral proprioceptive deficits, 3 had contralateral menace response deficits, 2 had a reduced contralateral response to noxious nasal stimulation, and 1 had dull mentation with intermittent horizontal nystagmus and ventrolateral strabismus. Neurologic status improved throughout the study period. Histologic quality of biopsy specimens was excellent. CONCLUSIONS AND CLINICAL RELEVANCE: This technique enabled histologic diagnosis from high-quality biopsy specimens obtained through a minimally invasive technique and has potential applications for multimodal treatment of deep brain tumors in dogs.

An ADAMTSL2 founder mutation causes Musladin-Lueke Syndrome, a heritable disorder of beagle dogs, featuring stiff skin and joint contractures.

BACKGROUND: Musladin-Lueke Syndrome (MLS) is a hereditary disorder affecting Beagle dogs that manifests with extensive fibrosis of the skin and joints. In this respect, it resembles human stiff skin syndrome and the Tight skin mouse, each of which is caused by gene defects affecting fibrillin-1, a major component of tissue microfibrils. The objective of this work was to determine the genetic basis of MLS and the molecular consequence of the identified mutation. METHODOLOGY AND PRINCIPAL FINDINGS: We mapped the locus for MLS by genome-wide association to a 3.05 Mb haplotype on canine chromosome 9 (CFA9 (50.11-54.26; p(raw) <10(-7))), which was homozygous and identical-by-descent among all affected dogs, consistent with recessive inheritance of a founder mutation. Sequence analysis of a candidate gene at this locus, ADAMTSL2, which is responsible for the human TGFß dysregulation syndrome, Geleophysic Dysplasia (GD), uncovered a mutation in exon 7 (c.660C>T; p.R221C) perfectly associated with MLS (p-value=10(-12)). Murine ADAMTSL2 containing the p.R221C mutation formed anomalous disulfide-bonded dimers when transiently expressed in COS-1, HEK293F and CHO cells, and was present in the medium of these cells at lower levels than wild-type ADAMTSL2 expressed in parallel. CONCLUSIONS/SIGNIFICANCE: The genetic basis of MLS is a founder mutation in ADAMTSL2, previously shown to interact with latent TGF-ß binding protein, which binds fibrillin-1. The molecular effect of the founder mutation on ADAMTSL2 is formation of disulfide-bonded dimers. Although caused by a distinct mutation, and having a milder phenotype than human GD, MLS nevertheless offers a new animal model for study of GD, and for prospective insights on mechanisms and pathways of skin fibrosis and joint contractures.

Intracranial subarachnoid hemorrhage following lumbar myelography in two dogs.

Intracranial subarachnoid hemorrhage is a rare but serious complication of lumbar puncture in humans. Possible sequelae include increased intracranial pressure, cerebral vasospasm, or mass effect, which can result in dysfunction or brain herniation. We describe two dogs that developed intracranial subarachnoid hemorrhage following lumbar myelography. In both dogs, myelography was performed by lumbar injection of iohexol (Omnipaque). Both the dogs underwent uneventful ventral decompressive surgery for disk herniation; however, the dogs failed to recover consciousness or spontaneous respiration following anesthesia. Neurologic assessment in both dogs postoperatively suggested loss of brain stem function, and the dogs were euthanized. There was diffuse subarachnoid hemorrhage and leptomeningeal hemorrhage throughout the entire length of the spinal cord, brain stem, and ventrum of brain. No evidence of infectious or inflammatory etiology was identified. The diagnosis for cause of brain death was acute subarachnoid hemorrhage. Our findings suggest that fatal subarachnoid hemorrhage is a potential complication of lumbar myelography in dogs. The cause of subarachnoid hemorrhage is not known, but may be due to traumatic lumbar tap or idiosyncratic response to contrast medium. Subsequent brain death may be a result of mass effect and increased intracranial pressure, cerebral vasospasm, or interaction between subarachnoid hemorrhage and contrast medium.

Traumatic subarachnoid-pleural fistula in a dog.

Subarachnoid-pleural fistula is a rare occurrence in humans as a result of trauma or spinal surgery. Such fistulas commonly remain undiagnosed until sufficient cerebrospinal fluid accumulates in the pleural space to cause respiratory distress. We describe a subarachnoid-pleural fistula in a dog that occurred subsequent to blunt trauma sustained during a fall, with concurrent acute, traumatic intervertebral disc rupture. The extruded disc material penetrated the dura mater, allowing communication between the subarachnoid space and the extrapleural thoracic cavity. Radiographic, myelographic, and computed tomographic (CT) findings are reviewed. Abnormalities noted during myelography included an intradural-extramedullary lesion at T11-T12, with epidural leakage of contrast medium from the region of T12 extending cranially. In images from myelography and CT there was extravasation of contrast medium extending from the subarachnoid and epidural space into the extrapleural thoracic cavity.