A single case of accidental fatal poisoning by Dieffenbachia picta, (dumb cane) (Araceae) in a 9-y-old female Poodle is described. Clinical signs included severe, locally extensive erosive/ulcerative glossitis accompanied by marked dyspnea of acute onset. The animal did not respond to emergency procedures to relieve severe respiratory distress; fatal asphyxiation ensued from edema of the glottis a few hours after the first clinical signs were observed. According to the owner, the dog had access to a tall, potted dumb cane plant and chewed the thick stem of the plant intensely. The owner did not authorize a necropsy of the animal. The diagnosis of Dieffenbachia picta poisoning was based on the history of accidental consumption of dumb cane and clinical signs. A comparison of this single case with other reports of dumb cane poisoning suggests that dogs poisoned by Dieffenbachia species usually recover uneventfully with conservative management and that death from asphyxiation is a rare but possible consequence of this intoxication. Severe edematous swelling of the glottis with occlusion of the larynx airway passage can occur in those cases in which large amounts of sap are quickly squeezed from the plant during intense chewing. Death would occur if owners do not seek veterinary care immediately and if emergency procedures are not instituted on time.