Transdermal fentanyl and its use in ovine surgery

•Pre-emptive analgesia improves post-operative drug levels.•The use of fentanyl patches in sheep is beneficial in a surgical environment.•Careful application of patches is required for effective activity.•2 µg/kg/hr provides effective blood fentanyl concentrations over 1 ng/ml.

Fentanyl delivered via a transdermal patch has the potential to decrease the need for post-operative handling of sheep undergoing surgical procedures. Two studies were performed to test: (1) the ideal timing for the application of pre-emptive analgesic patches and (2) the efficacy of a 2 µg/kg/h dose, as extrapolated from other species.The first study had sheep divided into two groups. Group 1 had a fentanyl patch applied for 24 h prior to a patch change and group 2 had a fentanyl patch applied 72 h prior to a change.The second study applied the results obtained in the first and tested the efficacy of 2 µg/kg/h as an effective dose in an orthopaedic surgical environment.Results indicated that the ideal time for pre-emptive fentanyl patch administration is 24-36 h prior to surgery and that 2 µg/kg/h is an effective minimum therapeutic dose rate for the use of fentanyl as an analgesic in an orthopaedic surgical environment.