Comparative Med
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A study using an ovine model of transdermal intrathecal catheterization was planned to investigate the neurotoxicity of magnesium sulfate. Nonpregnant Merino cross ewes (n = 8; age, 5 y; weight, 55.0 ± 6.5 kg) were anesthetized for placement of a lumbar intrathecal catheter. The study protocol defined a 5-d recovery period after introduction of the catheter before the administration of test substances (2 mL of 0.9% saline or 50 or 150 mg MgSO4) followed by euthanasia 1 wk later. ⋯ Postmortem CT imaging of 3 sheep confirmed the location of the catheter within the spinal cord. Procedural refinement for the placement of intrathecal catheters in sheep by avoiding an invasive surgical procedure was unsuccessful. We therefore recommend a complete or partial surgical approach for the insertion of an intrathecal catheter in sheep or fluoroscopy or ultrasonography intraoperatively to confirm correct placement of the catheter.