Droperidol-fentanyl as an aid to blood collection in rabbits.

Administration of a droperidol-fentanyl combination to laboratory rabbits at a dose of 2.5 mg/kg and 0.05 mg/kg body weight, respectively, produced vasodilatation which greatly facilitated blood withdrawal from the central auricular artery. The method eliminated the need for vacuum devices or topical irritants and posed little risk or discomfort to the animal.