Influence of atipamezole on effects of midsacral subarachnoidally administered detomidine in mares
Skarda, R.T.; Muir, W.W.
American Journal of Veterinary Research 59(4): 468-477
1998
ISSN/ISBN: 0002-9645 PMID: 9563633 Document Number: 493404
The effects of atipamezole on detomidine midsacral subarachnoidally-induced analgesia, cardiovascular and respiratory activity, head ptosis and position of pelvic limbs were examined in 10 healthy mares. Using a randomized, blinded, crossover study design, mares were administered midsacral subarachnoidally detomidine at 0.03 mg/kg of body weight, diluted in 3 ml of cerebrospinal fluid, followed by atipamezole (0.1 mg/kg) or sterile saline solution (control), i.v. 61 min later and saline solution (3 ml, midsacral subarachnoidally) on a separate occasion, at least 2 weeks later. Subarachnoidally administered detomidine induced perineal analgesia (mean+or-SD onset, 9.0+or-4.6 min; duration, 130+or-26 min), marked head ptosis, moderate changes in pelvic limb position, cardiovascular and respiratory depression, sweating in analgesic zones and diuresis. Intravenously administered atipamezole significantly reduced mean scores of detomidine-induced perineal analgesia, head ptosis, pelvic limb position, sweating and diuresis; partially antagonized detomidine-induced bradycardia and did not effect detomidine-induced bradypnoea. Most effects of midsacral subarachnoidally administered detomidine, except bradycardia and bradypnoea, were reversed by atipamezole (0.1 mg/kg, i.v.), indicating that most of the actions of detomidine were mediated via activation of alpha 2-adrenergic receptors.