Perineal analgesic actions of epidural clonidine in cattle.
OBJECTIVE
To determine the analgesic, sedative, motor, cardiac and respiratory effects of epidural clonidine in cattle.


METHODS
Prospective randomized study.


METHODS
Six healthy male cattle weighing between 236 and 365 kg.


METHODS
To investigate the effect of epidural clonidine, the animals received 2 and 3 micro g kg(-1) of clonidine diluted to 8 mL with 0.9% saline. Two treatments were utilized as controls. The animals from the first control treatment received 2% lidocaine (0.4 mg kg(-1)) and those from the second received an equal volume of 0.9% saline. Each animal received each treatment in random order. Evaluations of analgesia, sedation, muscle relaxation, heart rate, respiratory rate and rectal temperature were obtained at 0 (basal), 2, 5, 10, 15 and 30 minutes after epidural injection, and then at 30-minute intervals until loss of analgesia occurred. All the animals received a standard noxious stimulus consisting of needle insertion into the skin and deep muscle; a 4-point scale was used to score the response. A second scale was used to score sedation and a third for muscle relaxation.


RESULTS
Both doses of clonidine were effective in producing analgesia of the tail, perineum, and upper hindlimb. Complete analgesia was present before (mean +/- SE = 9 +/- 4 vs. 19 +/- 9 minutes) and lasted longer (311 +/- 33 vs. 192 +/- 27 minutes) for the 3 microg kg(-1) versus the 2 microg kg(-1) dose, respectively. A dose-dependent sedative effect of clonidine was also observed, with a peak effect between 60 and 180 minutes. No effects on heart or respiratory rates were observed with either dose of clonidine.


CONCLUSIONS
Epidural administration of 2 and 3 micro g kg(-1) of clonidine in cattle in this study provided bilateral perineal analgesia/anesthesia with a dose-dependent onset and duration of action.


CONCLUSIONS
Further studies are required to determine whether the analgesia is sufficient for surgery.
D015360:Analgesia, Epidural / Q000662:veterinary*; D000700:Analgesics / Q000008:administration & dosage* / Q000627:therapeutic use; D000818:Animals; D002417:Cattle / Q000502:physiology*; D003000:Clonidine / Q000008:administration & dosage* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006614:Hindlimb; D007268:Injections, Epidural / Q000662:veterinary; D008297:Male; D010146:Pain / Q000517:prevention & control / Q000662:veterinary*; D010147:Pain Measurement / Q000187:drug effects / Q000662:veterinary; D010502:Perineum; D011446:Prospective Studies; D012119:Respiration / Q000187:drug effects; D013623:Tail; D013997:Time Factors; D016896:Treatment Outcome
D000700:Analgesics; D003000:Clonidine