The purpose of this study was to compare acute cerebral perfusion measured by computed tomography, stroke lesion volume measured by magnetic resonance imaging, and motor function in Sprague-Dawley rats supplied by Charles River (Charles River, Quebec, Canada) and Harlan (Harlan, Michigan, USA). During the acute stages of ischemia (<3 hours), Sprague-Dawley rats supplied by Harlan had a greater reduction in blood flow (67%) than rats supplied by Charles River (37%). MRI at days 1 and 6 after

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... emia showed larger lesions in the Charles River animals compared to Harlan animals (P<0.05) at both time points. Lesion volume decreased in both Charles River and Harlan rats at day 6 compared to day 1 (P<0.05) and corresponded to lesion size on histology. The Harlan animals had significant functional deficits (P<0.05) one day after surgery in postural hang reflex, forelimb placement, and tactile fraction first tests, whereas rats supplied by Charles River had no significant functional impairment as a result of surgery. The current study provides evidence that differences in response to ischemia between rats of the same strain supplied by different vendors should be an important consideration when animals are selected for the study of cerebral ischemia.