EVALUATION OF THE EFFICACY OF A NEW TRANSDERMIC FENTANYL SOLUTION ON THE PERIOPERATIVE PAIN MANAGEMENT FOR ORTHOPAEDIC SURGERY IN DOG: PRELIMINARY STUDY

The aim of the study was to evaluate the analgesic effectiveness of a transdermic fentanyl solution for the intra‐operative and postoperative pain control during orthopaedic surgery in dog Fifteen dogs of various breeds and ages were enrolled in the study. Dogs admitted in the study were considered healthy on the basis of blood screening and clinical exam. Before the administration of 2.6 mg/kg of fentanyl transdermic solution, clinical parameters as heart rate (HR), respiratory rate (RR), blood pressure and temperature were recorded as well as pain and sedation scores. After fentanyl administration dogs were monitored each hour for 4 hours before the induction of anaesthesia and all the parameters recorded. Induction of the anaesthesia was performed with propofol and the maintenance with isoflurane in oxygen. During the procedure HR, RR, blood pressure, end‐tidal CO2 (EtCO2), end‐tidal isoflurane (EtIso) and temperature were recorded every five minutes. If an increase of the cardiovascular parameters more than 20% was recorded, fentanyl bolus at 2 mcg/kg was administered. At the end of the procedure time to reach palpebral reflex, extubation, head movements, sternal recumbency and standing were recorded. Pain check, with a Glasgow short form scale, was done every 2 hours for the first 8 hours after exubation and than every 4 hours for 48 hours. If pain score was more than 5 or 6 methadone 0.1 mg/kg IV was administered In 2 cases a high sedation score was recorded before induction of anaesthesia. Propofol required for induction was 4‐7 mg/kg. During surgery 2 dogs required rescue analgesia. Nine dogs required mechanical ventilation. HR and blood pressure were stable in 14 dogs. One dog required dopamine infusion for the maintenance of mean arterial pressure over 60 mm Hg. Mean time to extubation, head movement, sternal recumbency and standing were 17±12 min, 25±17 min, 46±28 min and 85±24 min, respectively. Two dogs required rescue analgesia in the postoperative period. A mild hypothermia was registered in the immediate postperative period in the majority of dogs. Urinary retention was seen in five dogs This study revealed that the fentanyl transdermic solution, given 4 hours before the induction of anaesthesia, provided good analgesia both for the intraoperative and the postperative period. No adverse affects were recorded and an excellent cardiovascular stability was registered in all dogs in the intraoperative period. No evident sparing effect was recorded for the induction dosage of propofol while a sparing effect on isoflurane was identified for the maintenance of anaesthesia. Urinary output should be checked after the administration of fentanyl transdermic solution because of possible urinary retention. Fentanyl transdermic solution at the dosage of 2.6 mg/kg was effective as sole agent for the perioperative pain management for orthopaedic surgery in dogs.