Inadvertent injection of medetomidine in the cerebromedullaris cisterna of a dog during myelographic exam

A mixed breed dog was anesthetized for diagnostic my- elography to investigate acute onset neck pain. Instead of contrast medium, 444μg/kg medetomidine were in- advertently injected into the cerebromedullaris cisterna owing to a human error. Severe bradycardia, undetect- able peripheral pulse, respiratory arrest and loss of pu- pillary, palpebral and corneal reflexes were observed immediately after injection. Profound hypothermia developed and esophageal temperature, measured 20 minutes after medetomidine injection, was 33°C. Ati- pamezole at 1mg/kg im was administered, followed by a second dose of 0,5mg/kg iv 20 minutes thereafter. In the meantime, cardiorespiratory parameters and body temperature were monitored, and supportive care that included manually assisted pulmonary ventilation, ac- tive warming, and administration of 5 μg/kg/min dopa- mine was initiated. The dog’s clinical condition im- proved within one hour from the beginning of supportive care, at which time ocular reflexes and swal- lowing returned, spontaneous ventilation was deemed as adequate and the trachea could be extubated. The dog was discharged in good clinical conditions five days later. Human error and distraction led to a potentially life-threatening complication in the dog of this report and could have possibly been prevented with the use of checklists and with a clearer definition of roles and re- sponsibilities of the personnel involved prior to com- mencing the clinical procedure. Profound cardiovascu- lar, respiratory, and thermoregulatory depression caused by intracisternal injection of medetomidine responded to parenteral administration of its antagonist and sup- portive care.