A one-year-old, intact male reindeer (Rangifer tarandus) presented with an acute neurologic episode. Signalment and history made Parelaphostrongylus tenuis infection a top differential. A CSF tap further implicated P. tenuis. Necropsy revealed a cerebellar abscess. Although no worm was found, this does not rule out infection. P. tenuis is of concern among ruminants raised in areas with large white-tailed deer (Odocoileus virginianus) populations, as they are the normal final host of the parasite. Clinical signs can include both signs of spinal cord disease (ataxia, recumbancy), and brain dysfunction (head tilt, altered mentation), depending on the worms’ location. Infection is difficult to diagnose and treat. Prevention with monthly avermectin products is considered standard by many veterinarians.