Studies to determine the optimal dose of medetomidine for the dog.

This study was designed to determine optimal doses of medetomidine which, when given intravenously or intramuscularly, produce analgesia/anesthesia or tranquility in dogs. Forty-eight mature, mongrel, healthy dogs weighing between 5 and 40 kg were randomized to one of four categories according to the dose of medetomidine given: zero, low, medium, high. Low dose was 280 micrograms/m2* given i.v. or 375 micrograms/m2 given im Medium dose was 750 micrograms/m2 given iv or 1000 micrograms/m2 given im High dose was 1220 micrograms/m2 given iv or 1625 micrograms/m2 given im Dogs were given the compound iv; then at least 2 weeks (100 half-lives) later, it was given i.m. Parameters measuring analgesic/anesthetic effects or ataractic effects were monitored during a control period, and at 1/4, 1/2, 1, 2, 3, 4, 5, and 6 h after dosing. A positive (ideal) response was determined by comparing a score based upon the parameters measured to observations of an ideal response made by the investigators. The numbers of dogs, receiving each dose that manifested ideal responses at 1/2 h and returned to normal enough to be left unattended at 3 h, were determined; and the optimal dose was based upon the lowest dose that produced the desired response and the highest dose that permitted the dogs to be left unattended by 3 h. Doses of medetomidine of 750 micrograms/m2 given i.v. and 1000 micrograms/m2 given i.m. were considered to be optimal of the 3 non-zero doses used.(ABSTRACT TRUNCATED AT 250 WORDS)