A 7-w-old Samoyed-cross pup was presented with central nervous system signs approximately 18 h following administration of the second of 2 doses of loperamide. Circling, vocalization, head pressing and unreactive pupils were present. There was no history of trauma. Improvement was seen shortly following administration of activated charcoal and 0.2 ml naloxone. Naloxone treatment was repeated at 2-h intervals over 12-h. Approximately 20 h following the initial clinical evaluation, the puppy was released to the owner for home care and observation.