Effect of caudal epidural xylazine on intraoperative distress and post-operative pain in Holstein heifers.
OBJECTIVE
To compare the effects of caudal epidural xylazine versus saline on tolerance of paravertebral nerve block and flank surgery and on post-operative pain in heifers used for a veterinary student training laboratory.


METHODS
Randomized controlled prospective study.


METHODS
Fourteen one-year-old, nongravid, healthy Holstein heifers, weighing 360 +/- 5 kg.


METHODS
Xylazine (0.05 mg kg(-1)) or 0.9% saline (5 mL) was injected using a caudal epidural technique to seven heifers undergoing a flank surgery. Nerve block of the right paravertebral fossa was performed using equal parts of lidocaine 2% and bupivacaine 0.5%. Heart and respiratory rates, rectal temperature, rumination frequency, and appetite were recorded before and at 4, 8, and 24 hours after surgery. Scores were recorded for: tolerance of local anesthesia injections (pre-operatively), sedation, ataxia and distress (intraoperatively, every 30 minutes), and pain (4, 8, and 24 hours post-operatively).


RESULTS
The animals reaction to local anesthetic injection was judged to be less in the xylazine group by both an experienced observer (p<0.001) and student surgeons (p<0.01). The xylazine group required less local anesthetic (82.9 +/- 13.8 mL) versus the saline group (108.4 +/- 19.6 mL, p=0.035). Intraoperatively, xylazine heifers were more sedated at all times (p-values from <0.001 to 0.017), were more ataxic for the first 1.5 hours (p-values from <0.001 to 0.026), and lower in distress at all times (p-values from <0.001 to 0.007). No difference in post-operative pain or physiologic variables was found, except immediately post-operatively, rectal temperature was higher in the xylazine group (39.5 +/- 0.3 degrees C) than in the saline group (38.6 +/- 0.2 degrees C, p<0.001).


CONCLUSIONS
Compared with epidural saline, caudal epidural xylazine reduced distress of anesthetic injection and surgical manipulation in heifers and an improvement in animal well-being was apparent. This effect may have been as a result of sedation. Pre-operative epidural xylazine did not appear to improve post-surgical analgesia in our study.
Chevalier
Helene M
HM
Tufts University School of Veterinary Medicine, North Grafton, MA 01536, USA.
Provost
Patricia J
PJ
Karas
Alicia Z
AZ
D015360:Analgesia, Epidural / Q000662:veterinary*; D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D007432:Intraoperative Period; D010535:Laparoscopy / Q000662:veterinary; D010149:Postoperative Pain / Q000517:prevention & control / Q000662:veterinary*; D011446:Prospective Studies; D014991:Xylazine / Q000008:administration & dosage*
D014991:Xylazine