Analgesic effect of butorphanol in ponies following castration.
BACKGROUND
In the UK butorphanol has a marketing authorisation for administration to horses for sedation in combination with detomidine, and at a higher dose (0.1 mg/kg bwt), for the alleviation of pain. There is only a limited number of clinical studies designed to examine the analgesic effects of butorphanol administration following surgery.


OBJECTIVE
To investigate the effect of premedication with butorphanol on post operative pain following castration under general anaesthesia in ponies.


OBJECTIVE
Ponies receiving butorphanol would experience less pain after castration than ponies that did not receive butorphanol.


METHODS
A randomised, observer blinded clinical study in which 20 ponies received butorphanol and detomidine (Group B) or detomidine alone (Group C). Anaesthesia was induced with ketamine and diazepam and open castration performed. Pain was assessed by one individual using a dynamic interactive visual analogue scale (DIVAS) 100 mm in length (0 = no pain, 100 mm the maximum possible pain for that procedure). 'Rescue' analgesia was administered when DIVAS >50 mm and was butorphanol i.v. On the second occasion DIVAS was >50 mm, flunixin was administered i.v. Data from the DIVAS were analysed using a Mann Whitney Test.


RESULTS
Only one animal did not require rescue analgesia after surgery (Group C). DIVAS were not significantly different between groups (P = 0.063).


CONCLUSIONS
Castration is sufficiently painful that administration of a single preoperative dose of butorphanol does not provide adequate post operative analgesia.
Department of Clinical Veterinary Science, University of Bristol, Langford House, Langford, Bristol BS40 5DU, UK.
E J
EJ
Love
P M
PM
Taylor
C
C
Clark
H R
HR
Whay
J
J
Murrell
D000700:Analgesics / Q000627:therapeutic use*; D000818:Animals; D002077:Butorphanol / Q000627:therapeutic use*; D006734:Horse Diseases / Q000188:drug therapy / Q000209:etiology; D006736:Horses; D008297:Male; D009919:Orchiectomy / Q000009:adverse effects*; D010149:Postoperative Pain / Q000188:drug therapy / Q000662:veterinary*
D000700:Analgesics; D002077:Butorphanol