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Background Gliomas in dogs remain poorly understood. Objectives To characterize the clinicopathologic findings, diagnostic imaging features and survival of a large sample of dogs with glioma using the Comparative Brain Tumor Consortium diagnostic classification. Animals Ninety‐one dogs with histopathological diagnosis of glioma. Methods Multicentric retrospective case series. Signalment, clinicopathologic findings, diagnostic imaging characteristics, treatment, and outcome were used. Tumors were reclassified according to the new canine glioma diagnostic scheme. Results No associations were found between clinicopathologic findings or survival and tumor type or grade. However, definitive treatments provided significantly (P = .03) improved median survival time (84 days; 95% confidence interval [CI], 45‐190) compared to palliative treatment (26 days; 95% CI, 11‐54). On magnetic resonance imaging (MRI), oligodendrogliomas were associated with smooth margins and T1‐weighted hypointensity compared to astrocytomas (odds ratio [OR], 42.5; 95% CI, 2.42‐744.97; P = .04; OR, 45.5; 95% CI, 5.78‐333.33; P < .001, respectively) and undefined gliomas (OR, 84; 95% CI, 3.43‐999.99; P = .02; OR, 32.3; 95% CI, 2.51‐500.00; P = .008, respectively) and were more commonly in contact with the ventricles than astrocytomas (OR, 7.47; 95% CI, 1.03‐53.95; P = .049). Tumor spread to neighboring brain structures was associated with high‐grade glioma (OR, 6.02; 95% CI, 1.06‐34.48; P = .04). Conclusions and Clinical Importance Dogs with gliomas have poor outcomes, but risk factors identified in survival analysis inform prognosis and the newly identified MRI characteristics could refine diagnosis of tumor type and grade.

Because of dogs' prolonged evolution with humans, many of the canine cognitive skills are thought to represent a selection of traits that make dogs particularly sensitive to human cues. But how does the dog mind actually work? To develop a methodology to answer this question, we trained two dogs to remain motionless for the duration required to collect quality fMRI images by using positive reinforcement without sedation or physical restraints. The task was designed to determine which brain circuits differentially respond to human hand signals denoting the presence or absence of a food reward. Head motion within trials was less than 1 mm. Consistent with prior reinforcement learning literature, we observed caudate activation in both dogs in response to the hand signal denoting reward versus no-reward.

Background Diagnosis of Chiari‐like malformation‐associated pain (CM‐P) or clinically relevant syringomyelia (SM) is challenging. We sought to determine common signs. Animals One hundred thirty client‐owned Cavalier King Charles spaniels with neuroaxis magnetic resonance imaging (MRI) and diagnosis of CM‐P/SM. Dogs with comorbidities causing similar signs were excluded with exception of otitis media with effusion (OME). Methods Retrospective study of medical records relating signalment, signs, and MRI findings. Dogs were grouped by SM maximum transverse diameter (1 = no SM; 2 = 0.5‐1.99 mm; 3 = 2‐3.9 mm: 4 = ≥4 mm). Differences between all groups—groups 1 versus 2‐4 and groups 1‐3 versus 4—were investigated. Continuous variables were analyzed using 2‐sample t‐tests and analysis of variance. Associations between categorical variables were analyzed using Fisher's exact or chi‐square tests. Results Common signs were vocalization (65.4%), spinal pain (54.6%), reduced activity (37.7%), reduced stairs/jumping ability (35.4%), touch aversion (30.0%), altered emotional state (28.5%), and sleep disturbance (22%). Head scratching/rubbing (28.5%) was inversely associated with syrinx size (P = .005), less common in group 4 (P = .003), and not associated with OME (P = .977). Phantom scratching, scoliosis, weakness, and postural deficits were only seen in group 4 (SM ≥4 mm; P = .004). Conclusions and Clinical Importance Signs of pain are common in CM/SM but are not SM‐dependent, suggesting (not proving) CM‐P causality. Wide (≥4 mm) SM is associated with signs of myelopathy and, if the dorsal horn is involved, phantom scratching (ipsilateral) and torticollis (shoulder deviated ipsilateral; head tilt contralateral).

Background Magnetic resonance imaging (MRI) has been widely used in human medicine for evaluating lower urinary tract diseases; however, its application in veterinary medicine remains limited. Hypothesis/Objectives To compare MRI with computed tomography (CT) in visualizing urethral and bladder wall layers and to assess the feasibility and diagnostic utility of MRI for evaluating lower urinary tract anatomy and pathology in dogs. It was hypothesized that the T2‐weighted (T2W) sequence would provide the most distinct visualization of urethral layers, while the contrast‐enhanced T1‐weighted (post‐T1W) sequence would best delineate bladder wall layers. Animals Five healthy dogs and six dogs with suspected uroepithelial tumors. Methods Magnetic resonance imaging sequences (T2W, pre‐T1W, and post‐T1W) and contrast‐enhanced CT (post‐CT) were performed. Images were evaluated for urethral and bladder wall layer distinction, urethral conspicuity, image quality, and characteristics of lower urinary tract tumors. Results T2W sequence clearly delineated urethral wall layers and differentiated the urethral mucosal layer from the lumen using urine as a natural contrast. Post‐T1W sequence enhanced bladder wall layer visualization, improving anatomical boundary conspicuity and aiding in tumor invasion detection. In contrast, post‐CT allowed rapid imaging with minimal motion artifacts but provided limited soft‐tissue detail. Conclusion and Clinical Importance Magnetic resonance imaging demonstrated superior efficacy in evaluating anatomic structures and lesions of the lower urinary tract, particularly in assessing tissue invasion. Combining T2W and post‐T1W sequences optimized diagnostic accuracy, making MRI a valuable tool for assessing lower urinary tract pathology in dogs.

Background In small breed dogs, enlarged ventricles of the brain are a common finding on magnetic resonance imaging (MRI). In humans, enlarged lateral ventricles are usually the consequence of mesencephalic aqueduct stenosis. Cerebrospinal fluid (CSF) velocity measurements indicating obstruction are lacking in dogs. Objectives Measure CSF velocity in small breed dogs with ventricular enlargement. Animals Velocity of CSF in 17 small breed dogs with enlarged ventricles and 8 small breed dogs with normal‐sized ventricles was measured by phase‐contrast MRI at the mesencephalic aqueduct, foramen magnum (FM) and second cervical vertebra (C2). Methods Peak systolic (PSV) and diastolic (PDV) velocity, peak velocity (PV), difference between peak systolic and diastolic velocity (DPV), average velocity (AV) and maximum average velocity (MAV) were measured. Results Dogs with enlarged ventricles had lower PDV, PV, AV, and MAV at the dorsal subarachnoid space of the FM compared with dogs without enlargement (p < 0.05). At the ventral subarachnoid space of FM, moderate decreases in PDV, PV, DPV, AV, and MAV were found with increasing severity of ventricular enlargement. Conclusion Ventricular enlargement may be associated with or result in altered CSF flow dynamics, particularly decreased velocity at the craniocervical junction. This relationship may, in turn, reflect underlying structural changes, such as skull shape or craniocervical abnormalities. Therefore, enlarged ventricles in small breed dogs should be considered pathological findings.

Background Information regarding repeat magnetic resonance imaging (MRI) findings in dogs with meningoencephalitis of unknown origin (MUO) is sparse and it is unknown whether brain atrophy occurs. Objectives To determine whether brain atrophy occurs in MUO and evaluate if there is an association between atrophy and survival or relapse. Animals Twenty‐three dogs diagnosed with MUO that underwent MRI of the brain on two occasions at least six months apart. Methods Retrospective study. Interthalamic adhesion thickness to brain height ratio (ITr), lateral ventricle to brain height ratio (LVr), interthalamic adhesion thickness/brain height to lateral ventricle/brain height (ITr/LVr), bicaudate ratio (BCR) and total parenchymal brain volume (TPBV) were measured on both MRI studies and compared. Results Thirteen dogs relapsed and four died during the study period. Median time between MRIs was 12 months, and only one imaging study (1/23) was considered normal on the second scan. All MRI variables measured significantly changed between imaging studies, but only higher TPBV was associated with increased survival (OR = 1.59, CI = 1.006–2.51, p = 0.047); no variables were found to be associated with relapse. New lesions were identified in six dogs (four of which also showed contrast enhancing lesions), with 5/6 of these dogs subsequently relapsing. Conclusions and Clinical Importance Brain atrophy likely occurs in dogs with MUO and is associated with worse outcomes. Clinical relapse might be likely in dogs with new or contrast‐enhancing lesions on repeat MRI, so more aggressive treatment should be considered in these dogs.

A 5‐year‐old male golden retriever was presented after a subacute onset of left‐sided Horner syndrome (HS). The dog had anisocoria with left‐sided miosis, ptosis of the upper eyelid, and third eyelid protrusion in the left eye. Because of the absence of additional neurological abnormalities, clinical signs were suggestive of left isolated HS, and the lesion was localized at the level of either the preganglionic or postganglionic neuron of the sympathetic chain. Magnetic resonance imaging (MRI) of the head and total body computed tomography (CT) identified marked narrowing and irregularity of the left internal carotid artery (ICA) in addition to loss of normal vessel flow‐void and T1‐weighted hyperintensity in the lumen of the left ICA. Except for these abnormalities, MRI and CT results were normal. These findings were suggestive of left internal carotid artery dissection (ICAD), suggesting that ICAD should be considered as a possible differential diagnosis of HS in dogs.

Gliomatosis cerebri (GC) represents an antemortem diagnostic challenge in the absence of histopathology. Proton magnetic resonance spectroscopy (1H‐MRS) features of the disease in humans include elevated myo‐inositol (mI)‐to‐creatine and decreased N‐acetyl‐aspartate (NAA)‐to‐creatine ratios. Brain 1H‐MRS findings at 3 Tesla (3 T) field strength in dogs with GC have not yet been described. A 12‐year‐old West Highland White Terrier was presented with a progressive history of multifocal encephalopathy. A 3 T MRI revealed a diffuse, bilateral, ill‐defined, intra‐axial white matter lesion that was T2W and FLAIR hyperintense, T1W iso‐ to hypointense, showed no contrast enhancement, and was associated with moderate mass effect. 1H‐MRS with voxel positioning at the left parietal area showed highly elevated mI and decreased NAA levels compared to healthy control dogs measured using the same protocol in the thalamus. GC was confirmed by stereotactic brain biopsy. Comparable 1H‐MRS changes to those reported in humans were identified in a dog with GC.

Background Limited recent data exists regarding discospondylitis in dogs. Hypothesis/Objectives (i) Describe the signalment, clinical and imaging findings, etiologic agents, treatment, and outcome of dogs with discospondylitis, (ii) determine diagnostic agreement between radiographs, CT, and MRI with regard to the presence of discospondylitis and its location, and (iii) determine risk factors for relapse and progressive neurological deterioration. Animals Three hundred eighty‐six dogs. Methods Multi‐institutional retrospective study. Data extracted from medical records were: signalment, clinical and examination findings, diagnostic results, treatments, complications, and outcome. Potential risk factors were recorded. Breed distribution was compared to a control group. Agreement between imaging modalities was assessed via Cohen's kappa statistic. Other analyses were performed on categorical data, using cross tabulations with chi‐squared and Fisher's exact tests. Results Male dogs were overrepresented (236/386 dogs). L7‐S1 (97/386 dogs) was the most common site. Staphylococcus species (23/38 positive blood cultures) were prevalent. There was a fair agreement (κ = 0.22) between radiographs and CT, but a poor agreement (κ = 0.05) between radiographs and MRI with regard to evidence of discospondylitis. There was good agreement between imaging modalities regarding location of disease. Trauma was associated with an increased risk of relapse (P = .01, OR: 9.0, 95% CI: 2.2‐37.0). Prior steroid therapy was associated with an increased risk of progressive neurological dysfunction (P = .04, OR: 4.7, 95% CI: 1.2‐18.6). Conclusions and Clinical Importance Radiograph and MRI results could be discrepant in dogs with discospondylitis. Prior trauma and corticosteroids could be associated with relapse and progressive neurological dysfunction, respectively.

Magnetic resonance imaging (MRI) has changed veterinary diagnosis but its long-sequence time can be problematic, especially because animals need to be sedated during the exam. Unfortunately, shorter scan times implies a fall in overall image quality and diagnosis reliability. Therefore, we developed a Generative Adversarial Net-based denoising algorithm called HawkAI. In this study, a Standard-Of-Care (SOC) MRI-sequence and then a faster sequence were acquired and HawkAI was applied to the latter. Radiologists were then asked to qualitatively evaluate the two proposed images based on different factors using a Likert scale (from 1 being strong preference for HawkAI to 5 being strong preference for SOC). The aim was to prove that they had at least no preference between the two sequences in terms of Signal-to-Noise Ratio (SNR) and diagnosis. They slightly preferred HawkAI in terms of SNR (confidence interval (CI) being [1.924–2.176]), had no preference in terms of Artifacts Presence, Diagnosis Pertinence and Lesion Conspicuity (respective CIs of [2.933–3.113], [2.808–3.132] and [2.941–3.119]), and a very slight preference for SOC in terms of Spatial Resolution and Image Contrast (respective CIs of [3.153–3.453] and [3.072–3.348]). This shows the possibility to acquire images twice as fast without any major drawback compared to a longer acquisition.