Magnetic resonance imaging characteristics of atlanto-axial subluxation in 42 dogs: Analysis of joint cavity size, subluxation distance, and craniocervical junction anomalies.

Background: Atlanto-axial (AA) subluxation can be a complex syndrome in dogs. Accurate identification and assessment of this condition are key to providing treatment and resolution. Aim: The purpose of this retrospective study was to describe the magnetic resonance imaging (MRI) characteristics of AA subluxation and associated neurologic deficits. Methods: A multicenter review of dogs with a diagnosis of AA subluxation was conducted, evaluating signalment, neurologic grade, duration of signs, and MRI characteristics. MRI characteristics included degree of spinal cord compression and joint subluxation, integrity of odontoid ligaments, presence of a dens, spinal cord signal intensity, and presence of syringohydromyelia, hydrocephalus, and Chiari-like malformation. A control population with normal AA joints was also evaluated. MR images of 42 dogs with AA subluxation were compared to 26 age and breed-matched control dogs. Results: Affected dogs had a median age of 27 months and a median weight of 2.7 kg, and the most commonly affected breed was the Yorkshire terrier (47.5%). Spinal cord signal hyperintensity, increased AA joint size, and cross-sectional cord compression at the level of the dens and mid-body C2 were associated with AA subluxation. No associations were found between cord compression, the appearance of the dens, or cord signal intensity and neurologic grade. Affected dogs did not have a higher incidence of Chiari-like malformation, syringohydromyelia, or hydrocephalus than control dogs, and their neurologic grade was not associated with MRI findings. Lack of dens and/or odontoid ligaments was associated with larger subluxations. Conclusion: Dogs with clinical signs of AA subluxation were significantly more likely to have intramedullary hyperintensity at the level of compression ( p = 0.0004), an increased AA joint cavity size ( p = 0.0005), and increased spinal cord compression at the level of dens and mid-body C2 (p ≤ 0.05). The authors suggest an AA joint cavity size >1.4 mm and a subluxation distance >2.5 mm as cutoffs for MRI diagnosis of AA subluxation in dogs. No differences were noted between dogs with AA subluxation and control dogs regarding syringohydromyelia, hydrocephalus, and Chiari-like malformation.

T1ρ, T2 mapping, and EPIC-µCT Imaging in a Canine Model of Knee Osteochondral Injury.

The dog is the most commonly used large animal model for the study of osteoarthritis. Optimizing methods for assessing cartilage health would prove useful in reducing the number of dogs needed for a valid study of osteoarthritis and cartilage repair. Twelve beagles had critical-sized osteochondral defects created in the medial femoral condyle of both knees. Eight dogs had T1ρ and T2 magnetic resonance imaging (MRI) performed approximately 6 months after defect creation. Following MRI evaluations, all 12 dogs were humanely euthanatized and cartilage samples were obtained from the medial and lateral femoral condyles, medial and lateral tibial plateaus, trochlear groove, and patella for proteoglycan and collagen quantification. Equilibrium partitioning of an ionic contrast (EPIC)-µCT was then performed followed by the histologic assessment of the knees. Correlations between T1ρ, T2, EPIC-µCT and proteoglycan, collagen, and histology scores were assessed using a multivariate analysis accounting for correlations from samples within the same knee and in the same dog. Pearson's correlation coefficients were calculated to assess the strength of significant relationships. Correlations between µCT values and biochemical or histologic assessment were weak to moderately strong (0.09-0.41; p < 0.0001-0.66). There was a weak correlation between the T2 values and cartilage proteoglycan (-0.32; p = 0.04). The correlation between T1ρ values and cartilage proteoglycan were moderately strong (-0.38; p < 0.05) while the strongest correlation was between the T1ρ values and histological assessment of cartilage with a correlation coefficient of 0.58 (p < 0.0001). These data suggest that T1ρ shows promise for possible utility in the translational study of cartilage health and warrants further development in this species. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:368-377, 2020.

Magnetic resonance imaging diagnosis and arthroscopic treatment of medial meniscal injury in a dog with a palpably stable stifle.

A dog with lameness, stifle effusion, and osteophytes, but in which the stifle retained stability for 10 months after the onset of lameness, was evaluated with 3T magnetic resonance imaging (MRI). Imaging revealed a tear in the caudal meniscotibial ligament of the medial meniscus. Arthroscopy findings correlated well with MRI and a partial meniscectomy was subsequently carried out, without any surgery to stabilize the stifle, and lameness resolved.

Diagnostic par imagerie à résonance magnétique et traitement arthroscopique d'une blessure du ménisque médial chez un chien ayant un grasset stable à la palpation. Un chien présentant de la boiterie, de l'effusion du grasset et des ostéophytes, mais pour lequel le grasset a conservé de la stabilité pendant 10 mois après l'apparition de la boiterie, a été évalué à l'aide de l'imagerie à résonance magnétique (IRM) 3T. L'IRM a révélé une déchirure dans le ligament méniscotibial caudal du ménisque médial. Les résultats de l'arthroscopie présentaient une bonne corrélation avec l'IRM et une méniscectomie partielle a ensuite été réalisée sans chirurgie pour stabiliser le grasset et la boiterie a été résolue.(Traduit par Isabelle Vallières).

Induced Pluripotent Stem Cell-Derived Neural Stem Cell Therapy Enhances Recovery in an Ischemic Stroke Pig Model.

Induced pluripotent stem cell-derived neural stem cells (iNSCs) have significant potential as an autologous, multifunctional cell therapy for stroke, which is the primary cause of long term disability in the United States and the second leading cause of death worldwide. Here we show that iNSC transplantation improves recovery through neuroprotective, regenerative, and cell replacement mechanisms in a novel ischemic pig stroke model. Longitudinal multiparametric magnetic resonance imaging (MRI) following iNSC therapy demonstrated reduced changes in white matter integrity, cerebral blood perfusion, and brain metabolism in the infarcted tissue. The observed tissue level recovery strongly correlated with decreased immune response, enhanced neuronal protection, and increased neurogenesis. iNSCs differentiated into neurons and oligodendrocytes with indication of long term integration. The robust recovery response to iNSC therapy in a translational pig stroke model with increased predictive potential strongly supports that iNSCs may be the critically needed therapeutic for human stroke patients.

Comparison of ultrasonography and magnetic resonance imaging to arthroscopy for diagnosing medial meniscal lesions in dogs with cranial cruciate ligament deficiency.

OBJECTIVE To compare the accuracy of ultrasonography and MRI for diagnosing medial meniscal lesions in dogs with cranial cruciate ligament (CCL) deficiency. DESIGN Diagnostic test evaluation. ANIMALS 26 dogs (31 stifle joints) with CCL deficiency. PROCEDURES A single surgeon physically examined each dog and performed ultrasonography and arthroscopy of affected stifle joints to identify medial meniscal lesions. Video recordings of the arthroscopic procedure were saved and subsequently reviewed by the same surgeon and by a second surgeon working independently and blinded to results of all examinations. A radiologist blinded to results of all examinations evaluated MRI scans of the affected joints. Correct classification rate (CCR), sensitivity, and specificity of ultrasonography and MRI were calculated twice, with each of the 2 surgeons' arthroscopic assessments used as the reference standard. RESULTS Compared with arthroscopic examination by the unblinded surgeon, ultrasonography had a CCR of 90%, sensitivity of 95% (95% confidence interval [CI], 73% to 100%), and specificity of 82% (95% CI, 48% to 97%). For MRI, these values were 84%, 75% (51% to 90%), and 100% (68% to 100%), respectively. Compared with arthroscopic assessment by the blinded surgeon, ultrasonography had a CCR of 84%, sensitivity of 86% (95% CI, 64% to 96%), and specificity of 78% (95% CI, 40% to 96%). For MRI, these values were 77%, 68% (45% to 82%), and 100% (63% to 100%), respectively. CONCLUSIONS AND CLINICAL RELEVANCE These data suggested imperfect performance but clinical usefulness of both ultrasonography and MRI for diagnosing medial meniscal lesions in dogs.

The effect of platelet-rich plasma on osseous healing in dogs undergoing high tibial osteotomy.

OBJECTIVES: The purpose of this study was to investigate whether platelet-rich plasma (PRP) enhances osseous healing in conjunction with a high tibial osteotomy in dogs. STUDY DESIGN: Randomized controlled trial. METHODS: Sixty-four client-owned pet dogs with naturally occurring rupture of the anterior cruciate ligament and that were to be treated with a high tibial osteotomy (tibial plateau leveling osteotomy) were randomized into the treatment or control group. Dogs in the treatment group received autologous platelet-rich plasma activated with calcium chloride and bovine thrombin to produce a well-formed PRP gel that was placed into the osteotomy at the time of surgery. Dogs in the control group received saline lavage of the osteotomy. All dogs had the osteotomy stabilized with identical titanium alloy implants and all aspects of the surgical procedure and post-operative care were identical among dogs of the two groups. Bone healing was assessed at exactly 28, 49, and 70 days after surgery with radiography and ultrasonography and with MRI at day 28. The effect of PRP on bone healing was assessed using a repeated measures analysis of covariance with radiographic and ultrasonographic data and using a t-test with the MRI data. RESULTS: Sixty dogs completed the study. There were no significant differences in age, weight, or gender distribution between the treatment and control groups. Twenty-seven dogs were treated with PRP and 33 were in the control group. The average platelet concentration of the PRP was 1.37x106 platelets/µL (±489x103) with a leukocyte concentration of 5.45x103/µL (±3.5x103). All dogs demonstrated progressive healing over time and achieved clinically successful outcomes. Time since surgery and patient age were significant predictors of radiographic healing and time since surgery was a significant predictor of ultrasonographic assessment of healing. There was no significant effect of PRP treatment as assessed radiographically, ultrasonographically, or with MRI. CONCLUSION: The PRP used in this study did not hasten osseous union in dogs treated with a high tibial osteotomy.

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.

Utility of MRI for Characterizing Articular Cartilage Pathology in Dogs with Medial Coronoid Process Disease.

OBJECTIVE: To determine whether assessment of morphological MRI sequences or delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) would have strong correlations with arthroscopic assessment of cartilage pathology in dogs with naturally occurring medial compartment pathology of the elbow. METHODS: Dogs tentatively diagnosed with medial coronoid disease had evaluation of their affected elbows using radiography, morphological MRI sequences, and dGEMRIC MRI evaluation prior to arthroscopy. Elbow radiographs were graded 0-6 for severity of changes. Cartilage of the medial coronoid process (MCP) and humeral trochlea (HT) were scored on a 0-3 scale using anatomical MRI sequences. The T1 relaxation times for the MCP and trochlea were quantified using dGEMRIC. Cartilage pathology was graded arthroscopically using a modified Outerbridge score (MOS) by a surgeon blinded to MRI assessment. Correlations between radiography and MOS, and between MRI and MOS, were quantified. RESULTS: Twenty-six elbows in 14 dogs were evaluated. There were statistically significant (p < 0.05) moderate correlations between radiographic scores and MOS for the MCP (r = 0.71) and HT (0.57). There was a statistically significant moderate correlation between morphological MRI scoring and MOS for the HT (r = 0.54; p < 0.05), but not for the MCP (p > 0.05). There was a weak, but significant correlation, between the dGEMRIC value and MOS of the MCP (r = 0.41; p < 0.05), but no correlation between the dGEMRIC values and MOS for the HT (p > 0.05). CLINICAL RELEVANCE: Statistically significant correlations to MOS were identified for both radiography and MRI but neither diagnostic modality provided sufficiently strong correlations to serve as a substitute for arthroscopic evaluation of the articular cartilage.

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.

MRI-Based Assessment of Intralesional Delivery of Bone Marrow-Derived Mesenchymal Stem Cells in a Model of Equine Tendonitis.

Ultrasound-guided intralesional injection of mesenchymal stem cells (MSCs) is held as the benchmark for cell delivery in tendonitis. The primary objective of this study was to investigate the immediate cell distribution following intralesional injection of MSCs. Unilateral superficial digital flexor tendon (SDFT) lesions were created in the forelimb of six horses and injected with 10 × 106 MSCs labeled with superparamagnetic iron oxide nanoparticles (SPIOs) under ultrasound guidance. Assays were performed to confirm that there were no significant changes in cell viability, proliferation, migration, or trilineage differentiation due to the presence of SPIOs. Limbs were imaged on a 1.5-tesla clinical MRI scanner postmortem before and after injection to determine the extent of tendonitis and detect SPIO MSCs. Clusters of labeled cells were visible as signal voids in 6/6 subjects. Coalescing regions of signal void were diffusely present in the peritendinous tissues. Although previous reports have determined that local injury retains cells within a small radius of the site of injection, our study shows greater than expected delocalization and relatively few cells retained within collagenous tendon compared to surrounding fascia. Further work is needed if this is a reality in vivo and to determine if directed intralesional delivery of MSCs is as critical as presently thought.

Evaluation of a New Surgical Treatment for Equine Hind Limb Proximal Suspensory Desmitis.

OBJECTIVE: To evaluate the effects of a new microfracture and ligament splitting procedure on ligament healing and to examine the usefulness of magnetic resonance (MR) imaging for monitoring ligament healing over time using a collagenase model of hind limb proximal suspensory desmitis. STUDY DESIGN: Experimental in vivo study. ANIMALS: Healthy adult horses (n=6). METHODS: Horses were free of lameness with normal hind limb proximal suspensory ligaments (PSL). The origin of both hind limb PSL was injected with collagenase and underwent MR imaging 2 weeks later, followed by the microfracture and ligament splitting procedure on 1 limb, with the opposite limb serving as the sham-operated control. Serial lameness and MR examinations were performed. Horses were euthanatized 210 days after surgery, the PSL harvested, and histology, biochemistry, and gene expression performed on both PSL. RESULTS: Collagenase lesions viewed on MR images appeared similar to those seen clinically. Serial MR images demonstrated resolution of abnormal signal intensity and tissue formation in the microfracture sites within the third metatarsal bone. Treated limbs had histologic evidence of connective tissue appearing to originate from the small perforations and blending into the ligament but no statistical differences were identified. Gene expression for cartilage oligomeric matrix protein and decorin were significantly increased in treated compared to control limbs. CONCLUSION: The microfracture and ligament splitting procedure did incite a tissue response but further clinical investigation is necessary to determine if this tissue remodeling at the bone-ligament interface translates to improved clinical outcome. MR imaging may be useful to follow healing in horses with hind limb proximal suspensory desmitis.

MANDIBULAR SQUAMOUS CELL CARCINOMA IN A BOBCAT (LYNX RUFUS).

A 23-yr-old female spayed bobcat (Lynx rufus) presented with a 1-wk history of hypersalivation. On examination, the right mandible was markedly thickened, the right mandibular dental arcade was missing, and the oral mucosa over the right mandible was ulcerated and thickened. Skull radiographs and fine needle aspirate cytology were supportive of squamous cell carcinoma. The bobcat was euthanized as a result of its poor prognosis. Necropsy confirmed a diagnosis of oral squamous cell carcinoma of the mandible. To the authors' knowledge, this is the first report of oral squamous cell carcinoma in a bobcat.

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.

IMAGING DIAGNOSIS--RADIOGRAPHIC, ULTRASONOGRAPHIC, COMPUTED TOMOGRAPHIC, AND FLUOROSCOPIC APPEARANCE OF A DISTAL PELVIC LIMB ARTERIOVENOUS MALFORMATION IN A YOUNG GERMAN SHEPHERD DOG.

A German shepherd puppy presented for evaluation of a suspected arteriovenous fistula on the distal aspect of the right pelvic limb. Radiographs demonstrated expansion and resorption of the tarsal and metatarsal bones, and ultrasound detected a vascular abnormality. Using computed tomographic angiography, a complex arteriovenous malformation (AVM) involving the distal tibia, tarsus, and the metatarsus and an osteochondritis dissecans (OCD) lesion of the talus were identified. Based on these findings, therapeutic limb amputation was performed. Fluoroscopic angiography, vascular casting, and dissection were then used to further characterize features of this previously unreported AVM with concurrent bony lesions and OCD.

A SURVEY OF RADIOLOGISTS AND REFERRING VETERINARIANS REGARDING IMAGING REPORTS.

An imaging report is a vital communication tool between a radiologist and clinician. In a field where in-person communication may not be readily available, it is imperative that the report clearly relays pertinent clinical information in a timely manner. The purpose of this observational study was to describe and compare opinions and expectations of small animal general practitioners, veterinary specialists, and veterinary radiologists regarding the imaging report. Online surveys were distributed, and data were collected from 202 veterinary clinicians and 123 veterinary radiologists. The majority (89%) of clinicians were satisfied with their imaging reports and stated that they read the radiology report as soon as it was available (92%). Just less than half (48%) of clinicians indicated it was standard of care that a board-certified veterinary radiologist read all imaging studies. Radiologists and clinicians agreed that a clinical history (98% and 94%, respectively) and clinical question (82% and 68%, respectively) were needed to generate a good radiology report. Fifty-five percent to 70% of clinicians prefer red bulleted reports, which included incidental findings (96%); while radiologists slightly favored prose reporting (37-46%). Clinicians found it helpful when additional imaging (86%), medical (71%), and surgical recommendations (73%) were made. About one-third of specialists who had been in practice for >11 years thought they were better able to interpret imaging for their own specialty than the radiologist. Clinicians voiced discontentment with reports that were not completed in a timely manner or did not give a prioritized differential list. Further studies are warranted to provide a more in-depth evaluation of veterinary radiology reporting structure and style.

FOCUSED ASSESSMENT WITH SONOGRAPHY AS AN AID FOR THE DIAGNOSIS OF GASTROINTESTINAL PERFORATION IN A BOBCAT ( FELIS RUFUS ).

A 10-yr-old female spayed bobcat (Felis rufus) presented with a 3-day history of lethargy, anorexia, and two episodes of vomiting. An emergency field visit was scheduled to perform abdominal radiography and ultrasonography. The bobcat was assessed to be approximately 5-10% dehydrated, on the basis of decreased skin turgor and tacky mucous membranes. Free peritoneal gas, reduced abdominal serosal detail, and an abnormal-appearing right-sided intestinal segment were identified in the abdominal radiographs. However, the emergency field clinicians were not knowledgeable of these abnormalities, because the radiographs could not be processed in the field. During an initial complete abdominal ultrasound evaluation, a nondependent hyperechoic interface with reverberation artifact suggestive of intestinal or free gas and focal intestinal changes indicative of marked enteritis or peritonitis were identified. Free peritoneal fluid was not present on initial examination. In a focused abdominal sonography for trauma (FAST) scan, made after subcutaneous fluid administration, a small volume of anechoic free fluid was present in the peritoneal space. With ultrasound guidance, the fluid was aspirated and appeared grossly turbid. This fluid was subsequently confirmed as septic suppurative effusion, secondary to a foreign body-associated intestinal perforation. The use of a FAST scan is well described in human medicine, and to a limited degree in veterinary literature. This case represents a novel application of FAST scanning in an emergency field setting in a nontraumatized patient. This case report illustrates the utility of the FAST scan in yielding critical clinical information after fluid resuscitation in a zoological setting.

Use of a Nitinol Wire Stent for Management of Severe Tracheal Stenosis in an Eclectus Parrot (Eclectus roratus).

A 25-year-old, female eclectus parrot (Eclectus roratus) presented for dyspnea 3 weeks after anesthesia and surgery for egg yolk coelomitis. Radiography, computed tomography, and tracheoscopy revealed multiple tracheal strictures spanning a length of 2.6 cm in the mid to distal trachea. Histopathologic examination revealed mild fibrosis, inflammation, and hyperplasia consistent with acquired tracheal strictures. Tracheal resection was not considered possible because of the length of the affected trachea. The strictures were resected endoscopically, and repeated balloon dilation under fluoroscopic guidance over the course of 10 months resulted in immediate but unsustained improvement. Computed tomography was used to measure the stenotic area. A 4 × 36-mm, custom-made, nitinol wire stent was inserted into the trachea under fluoroscopic guidance. After stent placement, intermittent episodes of mild to moderate dyspnea continued, and these responded to nebulization with a combination of saline, acetylcysteine, and dexamethasone. Multiple attempts to wean the patient off nebulization therapy and to switch to a corticosteroid-free combination were unsuccessful. The parrot eventually developed complications, was euthanatized, and necropsy was performed. Histologically, the tracheal mucosa had widespread erosion to ulceration, with accumulation of intraluminal exudate and bacteria, severe degeneration of skeletal muscle and tracheal rings, prominent fibrosis, and mild to moderate, submucosal inflammation. Clinicopathologic findings in this case suggested tracheomalacia, which has not been previously described in birds. Custom-made tracheal stents can be used for severe tracheal stenosis in birds when tracheal resection and anastomosis is not possible. Complications of tracheal stent placement in birds may include tracheitis and tracheomalacia. To our knowledge, this is the first report of tracheal stent placement in an avian species.

Functional metastatic parathyroid adenocarcinoma in a dog.

A 12-year-old dachshund dog was presented for persistent hypercalcemia and hyperparathyroidism despite bilateral parathyroidectomy. Magnetic resonance imaging of the head, neck, and cranial mediastinum identified an increased number of cranial mediastinal lymph nodes with heterogeneous signal intensity. Hypercalcemia and hyperparathyroidism resolved after surgery to remove multiple cranial mediastinal lymph nodes, one of which contained presumed metastatic parathyroid tissue.

Adénocarcinome parathyroïdien métastatique fonctionnel chez un chien. Un chien Dachsund âgé de 12 ans a été présenté pour de l'hypercalcémie et de l'hyperparathyroïdie persistantes malgré une parathyroïdectomie bilatérale. Une imagerie par résonance magnétique de la tête, du cou et du médiastin crânien a identifié un nombre accru de ganglions lymphatiques médiastinaux avec une intensité hétérogène du signal. L'hypercalcémie et l'hyperparathyroïdie se sont résorbées après la chirurgie pour enlever les nombreux ganglions lymphatiques médiastinaux crâniens, dont l'un contenait du tissu parathyroïdien métastatique présumé.(Traduit par Isabelle Vallières).

Development and characterization of a Yucatan miniature biomedical pig permanent middle cerebral artery occlusion stroke model.

BACKGROUND: Efforts to develop stroke treatments have met with limited success despite an intense need to produce novel treatments. The failed translation of many of these therapies in clinical trials has lead to a close examination of the therapeutic development process. One of the major factors believed to be limiting effective screening of these treatments is the absence of an animal model more predictive of human responses to treatments. The pig may potentially fill this gap with a gyrencephalic brain that is larger in size with a more similar gray-white matter composition to humans than traditional stroke animal models. In this study we develop and characterize a novel pig middle cerebral artery occlusion (MCAO) ischemic stroke model. METHODS: Eleven male pigs underwent MCAO surgery with the first 4 landrace pigs utilized to optimize stroke procedure and 7 additional Yucatan stroked pigs studied over a 90 day period. MRI analysis was done at 24 hrs and 90 days and included T2w, T2w FLAIR, T1w FLAIR and DWI sequences and associated ADC maps. Pigs were sacrificed at 90 days and underwent gross and microscopic histological evaluation. Significance in quantitative changes was determined by two-way analysis of variance and post-hoc Tukey's Pair-Wise comparisons. RESULTS: MRI analysis of animals that underwent MCAO surgery at 24 hrs had hyperintense regions in T2w and DWI images with corresponding ADC maps having hypointense regions indicating cytotoxic edema consistent with an ischemic stroke. At 90 days, region of interest analysis of T1 FLAIR and ADC maps had an average lesion size of 59.17 cc, a loss of 8% brain matter. Histological examination of pig brains showed atrophy and loss of tissue, consistent with MRI, as well as glial scar formation and macrophage infiltration. CONCLUSIONS: The MCAO procedure led to significant and consistent strokes with high survivability. These results suggest that the pig model is potentially a robust system for the study of stroke pathophysiology and potential diagnostics and therapeutics.

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.