Authors : R DeRossi , L Miglioli , FO Fraz?lio , TA Kassab and GLS Miguel
Abstract: To compare the effects of two alpha-2 adrenergic receptors agonist’s drugs, xylazine and romifidine intramuscularly, using 12 randomly selected Nelore calves.The animals were divided into two groups of 6 and submitted to two treatments. Treatment 1 received 0.2 mg kgG of xylazine (XYL; mean dose 1.45 mL) of body weight, and treatment 2 received 0.04 mg kgG of romifidine (ROM; mean dose 0.56 mL) of body weight. Heart and respiratory rates, arterial pressure (systolic, diastolic, and mean), rectal temperature, and ruminal movements were measured before treatments (baseline) and at 15, 30, 45, 60, 90 120 and 150 min after drug injection. Blood for glucose was collected from the jugular vein before sedation and at 30, 60, 120 and 180 min Degree of analgesia was evaluated by introducing a sterile needle subcutaneously between the ribs and interdigitally. It was evaluated latency period (time from drug administration to recumbency), analgesia period and recovery time (from first spontaneous movements to standing). Latency period was 9?3 min and 20?8 min (mean?SD) and analgesic period was 75?8 min and 90?5 min to xylazine or romifidine, respectively. Sialorrhea and reticulum-ruminal atony were similar in both treatments. Heart and respiratory rates decreased significantly (p<0.05) in both treatments. In calves, romifidine caused the previously published and widely known alpha-2 agonists effects including bradycardia, bradypnea, hyperglycaemia, sedation and analgesia. The use of 0.04 mg kgG of romifidine (5 times less than xylazine) produced a greater duration of analgesia with similar cardiorespiratory effects than xylazine and appeared to be a good alternative to xylazine in calves raised on pasture, although its cost was higher.
R DeRossi , L Miglioli , FO Fraz?lio , TA Kassab and GLS Miguel , 2005. Pharmacological Effects of Intramuscularly Administration of Xylazine or Romifidine in Calves Raised on Pasture . Journal of Animal and Veterinary Advances, 4: 889-893.