The effect of cervical epidural injection of morphine and the combination of morphine and detomidine on recovery from anesthesia in adult horses.

Abstract: To evaluate the effect of cervical epidural injection of morphine alone and morphine in combination with detomidine on recovery from anesthesia in horses. Methods: Blinded, randomized, crossover, Latin square design. Methods: A group of six healthy adult horses aged 9 ± 3 years and weighing 471 ± 76 kg (mean ± standard deviation). Methods: Horses were administered each of three treatments during a 1 hour general anesthetic with a 4 day washout period. Treatments were: 1) cervical epidural injection of saline 0.011 mL kg (S); 2) morphine 0.1 mg kg (M); and 3) morphine 0.1 mg kg with detomidine 0.01 mg kg (MD). Data evaluating the quality of rope-assisted anesthetic recovery included accelerometry-based recovery score, time to first movement, time to sternal recumbency, time to standing and number of attempts to stand. Data were analyzed using a generalized linear mixed model. Significance was set at p < 0.05. Results: Recovery scores were 24.4 ± 10.0, 23.9 ± 6.7 and 19.9 ± 7.7 for treatments S, M and MD, respectively (p = 0.463). Times for first movement, sternal recumbency and standing were 33 ± 16, 22 ± 18 and 45 ± 10 minutes; 48 ± 26, 57 ± 29 and 69 ± 25 minutes; and 55 ± 20, 61 ± 28 and 70 ± 23 minutes for treatments S, M and MD, respectively. Conclusions: Cervical epidural injection of morphine alone and morphine with detomidine did not negatively affect recovery compared with saline. Conclusions: The use of cervical epidural injection of morphine alone or morphine in combination with detomidine does not negatively affect the recovery quality of horses from general anesthesia.