The use of pulsed electromagnetic field (PEMF) therapy to provide post-operative analgesia in the dog

Abstract

Electromagnetic field therapy has been used in human and veterinary medicine to promote tissue healing and alleviate a variety of chronic medical conditions. The purpose of this study was to evaluate the effects of PEMF therapy (0.5 Hz delivered in a continuous cycle of 20-minutes on then 20-minutes off) on post-operative pain in dogs. Sixteen healthy dogs weighing 19.8 ± 6.2 kg (mean ± SD) and aged 15.4 ± 10.7 months were evaluated following routine ovariohysterectomy. Anesthesia consisted of atropine (0.04 mg kg−1 SQ), acepromazine (0.02 mg kg−1 SQ), fentanyl (0.01 mg kg−1 SQ), thiopental to effect (10–15 mg kg−1 IV) and maintenance with halothane. Pain score (numeric rating scale, 0–28), heart rate, respiratory rate, indirect mean arterial pressure (MAP) and body temperature were evaluated before anesthetic premedication, at extubation, 30 minutes after extubation and then hourly for 6 hours. Following extubation, dogs were randomly assigned to one of four treatment groups with four dogs per group: (1) PEMF off, 0.9% NaCl IV; (2) PEMF on, 0.9% NaCl IV; (3) PEMF off, morphine 0.25 mg kg−1 IV; (4) PEMF on, morphine 0.25 mg kg−1 IV. One observer, who was unaware of treatment, obtained behavioral observations and physiological data. Due to the small sample size, data were analyzed by Kruskal–Wallis with significance considered with p < 0.05. Pain score in group 4 [1.5, 0–5 (median, range)] was significantly less than group 1 (8, 6–13) at 30 minutes, but not different from group 2 (5.5, 4–7) or 3 (4.5, 2–9). Significant differences in MAP occurred at 300 minutes (groups 3 and 4 less than group 1) and at 360 minutes (group 4 less than groups 1 and 2). These results suggest that PEMF may augment analgesia following ovariohysterectomy in dogs and that further study of the analgesic effects of PEMF is warranted.