Tramadol Administered Intravenously Either as a Bolus or a Slow Injection in Pain Management of Romifidine-Sedated Calves Undergoing Umbilical Hernia Repair

SIMPLE SUMMARY: Due to the anatomical and physiological characteristics of cattle, many surgical and diagnostic procedures are often performed in cattle using standing sedation and local blocks combined with mild physical restraint. However, some procedures (e.g., abdominal surgery) are not suitable candidates for standing surgeries and are performed more easily and more safely with general anesthesia. The severity and clinical relevance of ruminants pain is probably often underestimated. The aim of the present study is to evaluate the effect of tramadol administered intravenously either as a bolus or a slow injection in romifidine-sedated calves undergoing umbilical hernia repair. Intramuscular administration of romifidine followed by tramadol either as an IV bolus or an IV slow injection provided suitable myorelaxation, deep sedation and adequate analgesia to perform umbilical hernia repair. ABSTRACT: Umbilical hernias in calves occur with relative frequency. Most abdominal surgeries can be performed in cattle using standing sedation and local blocks. Romifidine is widely used in calves, alone or in combination with opioids. Tramadol administered as an intravenous slow injection provided better analgesia than an IV bolus in cows. The aim of the present study was to compare the response to surgical stimulus, and sedative effects of tramadol administered intravenously either as a bolus or a slow injection in romifidinesedated calves. Twenty Frisian calves undergoing umbilical hernia repair received romifidine (0.08 mg/kg IM; time 0) followed by tramadol (1 mg/kg IV) 5 min later either as a bolus (n = 10, B group) or a slow injection over 10 min (n = 10, SI group). Surgical area was infiltrated with lidocaine (4 mg/kg). Heart rate (HR), respiratory rate (RR), systolic, dyastolic and mean arterial pressure (SAP, DAP, MAP), sedation scores and response to surgical stimulus were recorded for up to 55 min. After the calves recovered a standing position, postoperative pain scores were assessed for up to 50 min. Sedation scores were significantly higher in the SI group than in the B group at 55 min (p < 0.05). HR, RR, SAP and response to surgical stimulus were significantly higher in the B group than in the SI group (p < 0.05). No significant differences were recorded in postoperative pain scores between groups (p > 0.05). Romifidine IM followed by intravenous tramadol, as a bolus or slow injection and local infiltration with lidocaine provided adequate sedation and analgesia in calves undergoing umbilical hernia repair.