Gadoxetate disodium (Gd-EOB-DTPA) contrast-enhanced magnetic resonance imaging for differentiation between benign and malignant splenic lesions in dogs.

Malignant splenic lesions in dogs are common, with hemangiosarcoma diagnosed most frequently, and there have been no consistent clinicopathologic, gross, or imaging characteristics identified that differentiate malignant from benign splenic lesions. Histopathology is required for definitive diagnosis, and given the poor long-term prognosis of malignant splenic lesions, a noninvasive tool to aid in diagnosis would be valuable. This prospective cohort study utilized gadoxetate disodium, a liver-specific contrast agent (Gd-EOB-DPTA; Eovist), to identify the general lesion and pre- and postcontrast signal characteristics of benign and malignant splenic and hepatic lesions in dogs with naturally occurring disease. Twenty-five dogs were enrolled, Eovist-enhanced MRI was performed, and dogs were taken to surgery for splenectomy and other organ biopsy. All histopathology and MRI studies were evaluated by a single pathologist and a single radiologist, respectively. The associations between the tumor type and numerous variables defined on MRI were evaluated using Fisher's exact tests, and the significance was identified at a P-value of .05. Malignant splenic masses were identified in 11/25 (44%) dogs, and 5/11 malignancies represented hemangiosarcoma. The presence of abdominal effusion (P = .017) and the presence of hepatic nodules on MRI (P = .009) were associated with splenic malignancy. There were no benign T2 hyperintense and no malignant T2 hypointense lesions (P = .021). Utilization of the T2 W MRI sequence may aid in the identification of malignant splenic lesions, particularly when accompanied by abdominal effusion and hepatic lesions.

Magnetic resonance imaging subtraction vs. pre- and post-contrast 3D gradient recalled echo fat suppressed imaging for evaluation of the canine and feline brain.

Subtraction magnetic resonance imaging (MRI) has been reported to increase accuracy in the diagnosis of meningeal and inflammatory brain diseases in small animals. 3D T1W gradient recalled echo (GRE) techniques have been proposed as a suitable alternative to conventional spin echo sequences in imaging the canine brain. The aim of this study was to compare subtraction images and paired pre- and post-contrast 3D T1W GRE fat suppressed (FS) images in canine and feline MRI studies using clinical diagnosis as the gold standard. Paired pre- and post-contrast T1W 3D FS GRE images and individual subtraction images of 100 small animal patients were randomized and independently evaluated by 2 blinded observers. Diagnosis categories were "normal," "inflammatory," "neoplastic," and "other." Clinical diagnosis was made in the same categories and served as the gold standard. Image interpretation results were compared to the clinical diagnosis. Interobserver agreement was determined. Clinically, 41 studies were categorized as "normal," 18 as "inflammatory," 28 as "neoplastic," and 13 as "other." The agreement of the pre- and post-contrast GRE images with the gold standard was significantly higher than that of the subtraction images (k = 0.7491 vs. k = 0.5924; p = 0.0075). The largest sources of error were misinterpretation of "other" as "normal" and "normal" as "inflammatory." There was no significant difference between the two observers (p = 0.8820). Based on this study, subtraction images do not provide an advantage to paired pre- and post-contrast FS GRE images when evaluating the canine and feline brain.

Computed tomographic characteristics of confirmed and presumed noncutaneous pythiosis in 25 dogs.

Pythium insidiosum is an aquatic oomycete that causes granulomatous infection in dogs, most commonly cutaneous and gastrointestinal. Ultrasonographic characteristics of gastrointestinal pythiosis have been described; occasionally, CT is utilized in the clinical setting, and CT features of pythiosis have not been published. The purpose of this retrospective, multicenter, descriptive study is to describe CT characteristics of noncutaneous canine pythiosis. The following CT parameters were recorded: lesion anatomic location, number, shape, margination, size, attenuation pre- and postcontrast, enhancement pattern, lymph nodes affected, other lesions identified, and presence of peritoneal effusion or steatitis. Descriptive statistics demonstrating the frequency of lesion appearances were performed. Twenty-five dogs with noncutaneous pythiosis lesions that underwent CT were included; 19 had primarily gastrointestinal infections, four primarily arterial infections, one intrathoracic and intra-abdominal infection, and one primary pulmonary infection. In dogs with primary gastrointestinal infection, lesions were most common at the ileocolic junction and were most frequently focal, well-defined, moderate to marked circumferential wall thickening that was homogeneous and smoothly marginated precontrast, with moderate heterogeneous contrast enhancement. Most dogs had involvement of multiple gastrointestinal regions. Of four dogs with primary arterial involvement, three had large aneurysmal dilatations of the cranial mesenteric artery with severe mural thickening. All dogs had regional lymphadenopathy, which was variable but generally mild. Nine dogs had peritoneal effusion; six dogs had steatitis. CT features of pythiosis can overlap with neoplasia, but pythiosis should be considered as a differential, especially in young dogs. Findings supported using CT as an adjunct imaging test for increasing clinical suspicion of noncutaneous pythiosis.

CT features of feline cystic bronchiectasis forming mass lesions.

Case series summary: Cystic bronchiectasis was diagnosed in three cats with known histories of chronic coughing using CT and histopathology. CT of the lungs revealed large space-occupying lesions that compressed and displaced unaffected pulmonary parenchyma and vessels. The masses were soft tissue attenuating in two cases and gas-cavitated with areas of dependent fluid in one case. All three cats were found to have mineral attenuating material in lesions and in other dilatated airways. Generalized bronchial wall thickening was also present and indicative of chronic lower airway disease. These findings were supported by histopathology showing inflammatory changes and dilatated airways in the collected tissues. In the two cases in which post-contrast CT series were acquired, the lesions had rim-enhancement. Relevance and novel information: Cystic bronchiectasis is a rare presentation of bronchiectasis in cats and may mimic a pulmonary mass lesion, which could be mistaken for neoplasia or abscessation. The lack of central enhancement or presence of gas cavitation on CT, concurrent presence of diffuse bronchial wall thickening, other areas of bronchiectasis and the presence of broncholithiasis may alert the clinician to the possibility of cystic bronchiectasis related to chronic lower airway disease.

Radiographic lung congestion scores in dogs with acute congestive heart failure caused by myxomatous mitral valve disease.

BACKGROUND: In humans, lung congestion scores are predictive of recurrence of acute congestive heart failure (CHF) and are superior to cardiac biomarkers in predicting survival. OBJECTIVES: The primary aim of this retrospective study was to determine if a modified lung congestion score (LCS) in dogs diagnosed with acute CHF because of myxomatous mitral valve disease was associated with time until recurrence or death. ANIMALS: Complete medical records were available for a total of 94 dogs between 2010 and 2019, but only 35 dogs fulfilled the criteria for inclusion. METHODS: This retrospective study used descriptive statistics to describe the cumulative and corrected LCS. Correlations were used to examine the association of the corrected LCS and time until recurrence or death, selected echocardiographic variables, and timing of furosemide administration. RESULTS: The mean LCS was 8.4 (SD 3.3) and corrected LCS was 0.48 (SD 0.19). The pattern was predominantly symmetric (40% of dogs) and focal (caudal) but more commonly right-sided when asymmetric (40% vs 20%). The median number of days after initial diagnosis of acute CHF to readmission and death was 150 days (range 4-572), and 266 days (range 5-965), respectively. No significant association between the dog's corrected LCS and number of days until readmission (r = .173, P = .42) nor survival (r = .109, P = .56) was found. There was a negative significant correlation (r = -.71, P < .001) between the time interval of furosemide administration and corrected LCS.

Case report: Treatment of congenital lobar emphysema with lung lobectomy in a puppy.

An 11-week-old, sexually intact female Catahoula Leopard dog was evaluated for a multiple-week history of exercise intolerance and intermittent periods of respiratory distress. Thoracic radiographs revealed a markedly hyperinflated right lung field, with compression of the surrounding lung lobes. Thoracic computed tomography further localized the hyperinflation to the right middle lung lobe, with suspicion of congenital lobar emphysema. A right intercostal thoracotomy with right middle lung lobectomy was performed successfully. Histopathology results confirmed bronchial cartilage hypoplasia with marked emphysema and pleural fibrosis. The puppy recovered from surgery uneventfully and was discharged from the hospital without any postoperative complications. At 18 months postoperatively, the dog was clinically normal with no return of respiratory distress. This case report describes successful surgical treatment of a large breed puppy with the uncommonly reported condition of congenital lobar emphysema.

The "Claw Sign" may aid in axial localization in cases of peripherally located canine glioma on MRI.

The "claw sign" is a radiographic sign studied in human imaging to determine if a mass arises from a solid structure or organ versus a close adjacent location, resulting in distortion of the outline of an organ. We investigated its utility in characterizing MRI axial localization of peripherally located intracranial glioma versus meningioma, due to their overlap in MRI appearance. This retrospective, secondary analysis, cross-sectional study aimed to report the sensitivity, specificity, and inter- and intraobserver variabilities using kappa statistics, hypothesizing that the claw sign will have strong inter- and intraobserver agreement (κ > 0.8). Dogs with a histologically confirmed diagnosis of peripherally located glioma or meningioma and available 3T MRI data were retrieved from medical record archives from 2009 to 2021. A total of 27 cases, 11 glioma and 16 meningioma, were included. The postcontrast T1-weighted images were provided to five blinded image evaluators in two separate randomized sessions separated by a 6-week wash out period. Prior to the first evaluation, evaluators were provided with a training video and set of training cases for the "claw sign," which were excluded from the study. Evaluators were asked to rate cases as "positive," "negative," or "indeterminate" for the "claw sign." The sensitivity and specificity for the "claw sign" for the first session were 85.5% and 80%, respectively. The interobserver agreement for identifying the "claw sign" was moderate (κ = 0.48), and the intraobserver agreement across the two sessions was substantial (κ = 0.72). These findings indicate the claw sign is supportive but not pathognomonic for intra-axial localization in cases of canine glioma on MRI.

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

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

Cranial and vertebral osteosarcoma commonly has T2 signal heterogeneity, contrast enhancement, and osteolysis on MRI: A case series of 35 dogs.

Magnetic resonance imaging (MRI) is commonly used to evaluate the central nervous system (CNS) in dogs; however, published studies describing the MRI appearance of cranial and vertebral osteosarcoma are scarce. In this multicenter, retrospective, case series study, MRI studies of 35 dogs with cranial or vertebral osteosarcoma were prospectively scored by consensus of two veterinary radiologists. Recorded characteristics were location, signal intensity (compared to gray matter), homogeneity, contrast enhancement, margin delineation, local invasion, osteolysis, osteosclerosis, zone of transition, periosteal proliferation, pathological fracture, meningeal/CNS involvement, and presence of metastatic disease. Locations included the parietal bone (n = 1), occipital bone (n = 2), or cervical (n = 5), thoracic (n = 17), lumbar (n = 7), or sacral vertebrae (n = 3). Common features included signal heterogeneity in T2-weighted (T2W) images (n = 35), contrast enhancement (in all 34 dogs with postcontrast MRI), osteolysis (n = 34), compression of the CNS or cauda equina (n = 33), an associated soft tissue mass (n = 33), a long zone of transition (n = 30), osteosclerosis (n = 28), signal isointensity to normal-appearing gray matter in T1-weighted images (T1W, n = 26), and T2W hyperintensity of adjacent brain or spinal cord (n = 23). Other findings included periosteal proliferation (n = 18), meningeal contrast enhancement (n = 17), T1W and T2W hypointense foci in the soft tissue mass (n = 14), invasion into adjacent bones (n = 10), pathological vertebral fractures (n = 7), regional lymphadenopathy (n = 6), skip metastases (n = 2), lung nodule (n = 1), diaphragmatic nodule (n = 1), and brain invasion (n = 1). Contrast enhancement was typically strong and heterogeneous. Magnetic resonance imaging features of cranial and vertebral osteosarcoma were analogous to those previously reported for other imaging modalities. Osteosarcoma should be a differential diagnosis for compressive, contrast-enhancing, osteolytic lesions of the cranium or vertebrae.

Magnetic Resonance Imaging in 50 Captive Non-domestic Felids - Technique and Imaging Diagnoses.

Magnetic resonance imaging (MRI) is the recognized gold standard for diagnostic imaging of the central nervous system in human and veterinary patients. Information on the use of this modality and possible imaging abnormalities in captive non-domestic felids is currently limited to individual case reports or small case series. This retrospective study provides information on technique and imaging findings in a cohort of cases undergoing MRI at an academic Veterinary Medical Center. The University of Tennessee College of Veterinary Medicine MRI database was searched for non-domestic felids undergoing MRI of the brain or spine from 2008 to 2021. Medical record data were recorded, and MRI studies were reviewed. Fifty animals met the inclusion criteria. The most common brain diseases were Chiari-like malformation (n = 8) and inflammatory conditions (n = 8). Other abnormalities included pituitary lesions (n = 5), brain atrophy (n = 2), and one each of metabolic and traumatic conditions. Fourteen animals had a normal brain MRI study. The most common spinal abnormality was intervertebral disc disease (n = 7). Other disorders included vertebral dysplasia (n = 2), presumptive ischemic myelopathy (n = 1), subdural ossification causing spinal cord compression (n = 1), and multiple myeloma (n = 1). Spinal cord swelling of undetermined cause was suspected in two animals, and seven patients had a normal MRI study of the spine. MRI is a valuable tool in the diagnostic workup of non-domestic felids with presumptive neurologic disease.

Imaging features of retroperitoneal extra-adrenal paragangliomas in 10 dogs.

Retroperitoneal paragangliomas are rare tumors of the neuroendocrine system. Only a few canine case reports are available with rare descriptions of their imaging features. The objectives of this multi-center, retrospective case series study were to describe the diagnostic imaging features of confirmed retroperitoneal paragangliomas and specify their location. Medical records and imaging studies of 10 affected dogs with cytological or histopathologic results concordant with retroperitoneal paragangliomas were evaluated. Dogs had a median age of 9 years. Four of them had clinical signs and laboratory reports compatible with excessive production of catecholamines. Six ultrasound, four CT, four radiographic, and one MRI studies were included. The paragangliomas did not have a specific location along the aorta. They were of various sizes (median 33 mm, range: 9-85 mm of length). Masses had heterogeneous parenchyma in six of 10 dogs, regardless of the imaging modality. Strong contrast enhancement was found in all CT studies. Encircling of at least one vessel was detected in six of 10 masses, clear invasion of a vessel was identified in one of 10 masses. In five of 10 cases, the masses were initially misconstrued as lymph nodes by the on-site radiologist. Retroperitoneal paragangliomas appear along the abdominal aorta, often presenting heterogeneous parenchyma, possibly affecting the local vasculature, and displaying strong contrast enhancement on CT. Clinical signs can be secondary to mass effects or excessive catecholamine production. Underdiagnosis and misdiagnosis of this tumor are suspected as they can be silent, of small size, or confused with other structures.

High-field MRI using standard pulse sequences has moderate to substantial interobserver agreement and good accuracy for differentiation between intracranial extra-axial histiocytic sarcoma and meningioma in dogs.

Intracranial extra-axial histiocytic sarcoma shares common MRI features with meningioma. As histiocytic sarcoma carries a generally worse prognosis than meningioma, the ability to differentiate between these two neoplasms is of clinical value. The aim of this retrospective diagnostic accuracy and observer agreement study was to evaluate the accuracy and reliability of high-field MRI to differentiate between these two tumors, using standard pulse sequences and published MRI features. A total of 51 dogs were included (26 meningiomas and 25 histiocytic sarcomas). Magnetic resonance imaging examinations were independently assessed by three experienced board-certified radiologists, evaluating 18 imaging features. They were asked to assign each case to one of three categories (meningioma, histiocytic sarcoma, and undetermined). Agreement for the MRI diagnosis across all three reviewers was moderate (κ 0.54) while paired interobserver agreement ranged from moderate to substantial (κ 0.58-0.74) with percent agreement ranging between 86.1% and 87.7%. Overall, the probability of correctly diagnosing meningioma in a dog with this tumor ranged between 79.2% and 94.4%, and the probability of correctly diagnosing histiocytic sarcoma in a dog with this tumor ranged between 76.0% and 92.3%. The overall probability to diagnose the correct tumor, irrespective of type, ranged between 79.2% and 89.7%. Histiocytic sarcomas tended to have more extensive edema and more often had combined perilesional and distant meningeal enhancement affecting both pachy- and leptomeninges, while for meningiomas, meningeal enhancement tended to more commonly be perilesional and pachymeningeal. Imaging features that seemed more useful to make a correct diagnosis included "location/type of meningeal enhancement," "osseous changes in the adjacent neurocranium," "cystic changes," and "herniation severity."

Influence of a novel scaffold composed of polyurethane, hydroxyapatite, and decellularized bone particles on the healing of fourth metacarpal defects in mares.

OBJECTIVE: To determine the effect of a novel scaffold, designed for use in bone regeneration, on healing of splint bone segmental defects in mares. STUDY DESIGN: In vivo experimental study. SAMPLE POPULATION: Five adult mares (4-10 years old; mean weight, 437.7 kg ± 29 kg). METHODS: Bilateral 2-cm full-thickness defects were created in the fourth metacarpal bones (MCIV) of each horse. Each defect was randomly assigned to either a novel scaffold treatment (n = 5) or an untreated control (n = 5). The scaffold was composed of polyurethane, hydroxyapatite, and decellularized bone particles. Bone healing was assessed for a period of 60 days by thermography, ultrasonography, radiography, and computed tomography (CT). Biopsies of each defect were performed 60 days after surgery for histological evaluation. RESULTS: On the basis of radiographic analysis, scaffold-treated defects had greater filling (67.42% ± 26.7%) compared with untreated defects (35.88% ± 32.7%; P = .006). After 60 days, CT revealed that the density of the defects treated with the scaffolds (807.80 ± 129.6 Hounsfield units [HU]) was greater than density of the untreated defects (464.80 ± 81.3 HU; P = .004). Evaluation of histology slides provided evidence of bone formation within an average of 9.43% ± 3.7% of the cross-sectional area of scaffolds in contrast to unfilled defects in which connective tissue was predominant throughout the biopsy specimens. CONCLUSION: The novel scaffold was biocompatible and supported bone formation within the MCIV segmental defects. CLINICAL SIGNIFICANCE: This novel scaffold offers an effective option for filling bone voids in horses when support of bone healing is indicated.

Pharmacokinetic characterization of fluorocoxib D, a cyclooxygenase-2-targeted optical imaging agent for detection of cancer.

SIGNIFICANCE: Fluorocoxib D, N-[(rhodamin-X-yl)but-4-yl]-2-[1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indol-3-yl]acetamide, is a water-soluble optical imaging agent to detect cyclooxygenase-2 (COX-2)-expressing cancer cells. AIM: We evaluated the pharmacokinetic and safety properties of fluorocoxib D and its ability to detect cancer cells in vitro and in vivo. APPROACH: Pharmacokinetic parameters of fluorocoxib D were assessed from plasma collected at designated time points after intravenous administration of 1 mg / kg fluorocoxib D in six research dogs using a high-performance liquid chromatography analysis. Safety of fluorocoxib D was assessed for 3 days after its administration using physical assessment, complete blood count, serum chemistry profile, and complete urinalysis in six research dogs. The ability of fluorocoxib D to detect COX-2-expressing cancer cells was performed using human 5637 cells in vitro and during rhinoscopy evaluation of specific fluorocoxib D uptake by canine cancer cells in vivo. RESULTS: No evidence of toxicity and no clinically relevant adverse events were noted in dogs. Peak concentration of fluorocoxib D (114.8 ± 50.5 ng / ml) was detected in plasma collected at 0.5 h after its administration. Pretreatment of celecoxib blocked specific uptake of fluorocoxib D in COX-2-expressing human 5637 cancer cells. Fluorocoxib D uptake was detected in histology-confirmed COX-2-expressing head and neck cancer during rhinoscopy in a client-owned dog in vivo. Specific tumor-to-normal tissue ratio of detected fluorocoxib D signal was in an average of 3.7 ± 0.9 using Image J analysis. CONCLUSIONS: Our results suggest that fluorocoxib D is a safe optical imaging agent used for detection of COX-2-expressing cancers and their margins during image-guided minimally invasive biopsy and surgical procedures.

Retrobulbar and Tongue Base Pyogranulomatous Myositis Resulting in Strabismus in a Dog: Case Report.

A seven-year-old female spayed Australian Shepherd was presented for a 3-day history of left eye ventromedial strabismus, episcleral injection, protrusion of the third eyelid, miosis, and enophthalmia. Magnetic Resonance Imaging (MRI) identified lesions in the left medial pterygoid muscle and left tongue base. Cytology and histopathology revealed pyogranulomatous inflammation with rod-shaped bacteria and pyogranulomatous myositis, respectively. One month of oral antibiotics resolved both lesions. Repeat MRI showed a mild decrease in size of the left medial pterygoid muscle consistent with fibrosis. Clinically, residual, positional ventral strabismus remained upon dorsal neck extension, but all other ophthalmic abnormalities resolved. To the authors' knowledge, this is the first report of pyogranulomatous myositis causing this constellation of clinical signs and of repeat imaging depicting resolution of these lesions with therapy.

Magnetic Resonance Imaging Findings in 13 Neurologic Pot-Bellied Pigs.

This study reports the magnetic resonance imaging (MRI) findings in 13 pot-bellied pigs presented to our institution with neurological deficits. Nine pigs had abnormal MRI findings (7 with spinal cord localization and 2 with brain localization), with three of them having histopathological confirmation of the diagnoses. MRI diagnoses included a myopathy suspected to be secondary to Erysipelothrix rhusiopathiae, a round cell neoplasia involving the vertebral canal, myelomalacia, a cervical cyst like extradural lesion, pelvic fracture with secondary cauda equina involvement, two cases of fibrocartilaginous embolism or acute non-compressive nucleus pulposus extrusion, multifocal brain infarcts, and a cystic fourth ventricle dilation resulting in obstructive hydrocephalus and syringomyelia. Four pigs had normal MRI studies, with one of them ultimately diagnosed with idiopathic vestibular disease. This retrospective study illustrates the wide variety of diagnoses achieved with MRI of the head or vertebral column in pigs, several of them having never been described in this species. Some of the conditions identified had a good outcome. This justifies using MRI as an ante-mortem diagnostic tool as it can provide relevant information about the prognosis which can significantly influence treatment recommendations. Our findings suggest that MRI should be considered as a valuable imaging modality, when feasible, in pigs with neurological deficits.

Magnetic Resonance Imaging Features of Extradural Spinal Neoplasia in 60 Dogs and Seven Cats.

This retrospective study describes the MRI features of extradural spinal neoplasia in 60 dogs and seven cats to identify potential distinguishing features between tumor classes and individual tumor types within each class. In dogs, mesenchymal tumors were most common (48%), with undifferentiated sarcomas being the predominant tumor type. Round cell neoplasms were second most common (35%), with lymphoma and multiple myeloma/plasma cell tumor comprising the majority of cases. Only two benign tumors were identified. In cats, lymphoma was most common (5/7), with one case of mesenchymal neoplasia and one case of metastatic carcinoma. Despite some overlap, certain imaging features were able to help prioritize differential diagnoses. The combined features that predicted round cell neoplasia (84%) included the preservation of vertebral shape, homogeneous contrast enhancement, and lesion centering on bone. The combined features that predicted mesenchymal neoplasia (73%) included altered vertebral shape, heterogeneous contrast enhancement, and lesion centering on paraspinal soft tissues. Round cell neoplasms were more likely to have cortical sparing, preservation of overall shape, lesion centering on bone, small soft tissue tumor size, and homogeneous contrast enhancement. Both epithelial and mesenchymal neoplasms were more likely to have cortical lysis, a cavitary component to the soft tissue mass and medium to large soft tissue mass size. The findings of this study can aid in prioritizing differential diagnoses in cases of extradural spinal neoplasia in cats and dogs, which can impact case management, but tissue sampling remains the gold standard for definitive diagnosis.

Investigation of parameters predicting the need for diagnostic imaging beyond computed tomography in the evaluation of dogs with thoracolumbar myelopathy: Retrospective evaluation of 555 dogs.

Thoracolumbar myelopathy encompasses a number of disease processes such as intervertebral disc disease, discospondylitis, trauma, congenital malformations, neoplasia, and intramedullary spinal cord disease. Compressive disc herniations are most common in dogs and require imaging procedures such as myelography, computed tomography (CT), and/or magnetic resonance imaging (MRI) to determine the need and location for decompressive surgery. The purposes of this retrospective, cross-sectional study were to evaluate all dogs undergoing thoracolumbar CT imaging as the initial diagnostic step between 2010 and 2015 and determine whether any of the imaging characteristics could be used to predict the need for additional imaging in the form of myelography, CT myelography, and/or MRI. A total of 555 dogs were identified in this time frame which underwent CT imaging for myelopathy of the thoracolumbar region. Various parameters including age, gender, sexual status, breed, chronicity, site of lesion, time of study, and contrast administration were evaluated. Findings indicated that 7.6% of dogs needed additional imaging after CT. Dachshunds were less likely to need additional imaging (P = 0.0111) as were patients scanned during normal business hours (P = 0.0075). Increasing age of the patient increased the likelihood of additional imaging (P = 0.0107). Dogs which did not have additional imaging performed were 21.89 times more likely to require surgery than those which did have additional imaging (P < 0.0001). Findings supported the use of CT as a first-line imaging modality for dogs presenting with thoracolumbar myelopathy.