Seizures and syncope can be difficult for veterinarians to distinguish because this distinction often relies on an owner’s description of events at home, and owners often describe the two conditions in a similar fashion. This patient, a 9-year-old female spayed West Highland White Terrier, was presented with a recent history of episodic loss of consciousness that had characteristics of both seizures and syncope. She also had abnormal neurologic signs and a previous history of Sick Sinus Syndrome and pacemaker implantation. Because of her history of cardiac disease, her pacemaker was interrogated, an echocardiogram was performed, and thoracic radiographs were taken, with none of these diagnostics showing any abnormalities that would suggest a cause for loss of consciousness. Her pacemaker precluded magnetic resonance imaging (MRI), but given the neurologic deficits and episodes it was decided that she should have a computed tomography (CT) scan to rule out intracranial lesions. The CT scan revealed a contrast enhancing forebrain mass, which was determined to be the cause of her neurologic signs. The episodes of loss of consciousness were suspected to be seizures, also caused by this mass.