The aim of the present study was to assess the clinical and histopathological findings in a canine model of ischemic stroke. Cerebral ischemic stroke was induced by middle cerebral artery occlusion in four healthy beagle dogs using silicone plugs. They showed neurological signs of forebrain dysfunction such as reduced responsiveness, head turning, circling, postural reaction deficits, perceptual deficits, and hemianopsia. These signs gradually regressed within 4 weeks without therapy. On magnetic resonance imaging, T2 hyperintensity and T1 hypointensity were found in the cerebral cortex and basal ganglia. These lesions were well-defined and sharply demarcated from adjacent brain parenchyma with a homogenous appearance. No abnormalities of the cerebrospinal fluid were observed. At necropsy, atrophic and necrotic lesions were observed in the cerebral cortex. The cerebral cortex, basal ganglia, and thalamus were partially unstained with triphenyl-tetrazolium chloride. Histopathologically, typical features of infarction were identified in cortical and thalamic lesions. This study demonstrates that our canine model resembles the conditions of real stroke patients.

White blood cells (WBCs) and storage period are the main factors of transfusion reactions. In the present study, cytokine/chemokine concentrations after leukoreduction (LR) and irradiation (IR) in stored canine whole blood were measured. Red blood cell storage lesion caused by IR and LR were also compared. Blood samples from 10 healthy Beagles were divided into four groups (no treatment, LR-, IR-, and LR + IR-treated). Leukocytes were removed by filtration in the LR group and gamma radiation (25 Gy) was applied in the IR group. Immunologic factors (WBCs, interleukin-6 [IL-6], C-X-C motif chemokine ligand 8 [CXCL-8], and tumor necrosis factor-alpha) and storage lesion factors (blood pH, potassium, and hemolysis) were evaluated on storage days 0, 7, 14, 21, and 28. Compared to the treated groups, IL-6 and CXCL-8 concentrations during storage were significantly higher in the control (no treatment) group. LR did not show changes in cytokine/chemokine concentrations, and storage lesion presence was relatively mild. IR significantly increased CXCL-8 after 14 days of storage, but IR of leukoreduced blood did not increase CXCL-8 during 28 days of storage. Storage lesions such as hemolysis, increased potassium, and low pH were observed 7 days after IR and storage of blood, regardless of LR. IR of leukoreduced blood is beneficial to avoid immune reactions; however, storage lesions should be considered upon storage.

ABSTRACT. The purpose of this study was to assess the normal distribution of 18 F-fluoro-2-deoxy-D-glucose (FDG) uptake of canine brain structures using a high-resolution research tomography-positron emission tomography (HRRT-PET) and 7 T-magnetic resonance imaging (MRI) fusion system. FDG-PET and T2-weighted MRI of the brain were performed on 4 healthy laboratory beagle dogs. On MRI, regions of interests (ROIs) were manually drawn over 51 intracranial structures, including nine gross structures and 42 detailed structures. Relative standard uptake value ratio (rSUV=SUV of ROI/SUV of whole brain) was calculated for each ROI. The HRRT-PET and 7 T-MRI fusion imaging system demonstrated significant differences in glucose metabolism among various intracranial structures. Among gross structures, the midbrain and the pons and medulla oblongata had the highest uptake (rSUV: 1.12 ± 0.03) and lowest uptake (rSUV: 0.90 ± 0.06) of FDG, respectively. When rSUVs were calculated on detailed regions, the caudal colliculus and the longitudinal fibers of pons had the highest (rSUV: 1.62 ± 0.05) and the lowest (rSUV: 0.63 ± 0.03) glucose metabolism, respectively. Because the high resolution of PET-MRI fusion images provided clearly identifiable metabolic activities of canine brain, the HRRT-PET and 7 T-MRI fusion imaging might be a good tool for evaluation of intracranial diseases in canines. KEY WORDS: 7 T-MRI, canine brain, FDG, HRRT-PET.

The purpose of this study was to identify time-related changes in clinical, MRI, histopathologic, and immunohistochemical findings associated with ischemic stroke in dogs. Additionally, the association of cerebrospinal fluid (CSF) and tissue levels of interleukin (IL)-6 with clinical prognosis was assessed. Ischemic stroke was induced by permanent middle cerebral artery occlusion (MCAO) in nine healthy experimental dogs. The dogs were divided into three groups according to survival time and duration of the experimental period: group A (survived only 1 day), group B (1-week experimental period), and group C (2-week experimental period). Neurologic status was evaluated daily. Magnetic resonance imaging (MRI) was performed according to a predetermined schedule. Concentration of IL-6 in CSF was measured serially after ischemic stroke. Postmortem examination was performed for all experimental dogs. During histopathological examination, variable degrees of cavitation and necrosis due to neuronal cytopathic effects, such as pyknotic nuclei and cytoplasmic shrinkage, were observed on the affected side of the cerebral cortex in all dogs. Immunohistochemistry specific for IL-6 showed increased expression in the ischemic lesions. CSF IL-6 concentrations and ischemic lesion volumes 1 day after ischemic stroke were significantly higher in group A compared to groups B and C.