Cerebral computerized tomography-scan demonstrating ischemic stroke in a filly following intravenous antibiotic administration

Abstract Performing a brain computerized-tomography scan (CT-scan) on a foal requires specific equipment and anesthesia for large animals. However, the information obtained may demonstrate lesions responsible for the neurological deficits. Especially, CT-scan findings may help to understand a mechanism of cerebral ischemia. Indeed, categories of cerebral ischemia are divided in three types: territorial infarctions (downstream of the territory of an artery), watershed infarctions (slow-flow at the junction of two arterial territories) and lacunar infarctions (small-vessel occlusions) [1-3]. Hypersensitivity reactions and type I anaphylactic IgE antibody reactions are severe potential adverse effects of sulfonamide administration, which occur in about three percent of cases [4]. In horses, anaphylaxis is often clinically expressed as hypotension and collapse [5, 6]. Cardiovascular collapse may lead to multi-organ slow-flow leading to infarction with multi-organ failure and death. We report the case of a filly that suffered a presumed watershed cerebral infarction after antibiotic injection, indicated on a brain CT-scan. This was attributed to a cerebral slow-flow during cardiovascular collapse, at the posterior junction of the right cerebral arteries. No abnormalities were initially identified on the CT-scan, however, a review of the imaging by a radiologist specialized in cerebrovascular diseases detected a limited right occipital cortico-sub-cortical lesion in the visual cortex, interpreted as an ischemic scar in the watershed area related to hemodynamic infarction. This case highlights that detection of brain lesions by CT-scan might require specialized knowledge and careful reading for interpretation particularly in the case of limited lesions.