title: The effects of xylazine, detomidine, acepromazine and butorphanol on equine solid phase gastric emptying rate.
abstract: The aim of this study was to measure the effects of specific commonly used sedative protocols on equine solid phase gastric emptying rate, using the 13C-octanoic acid breath test (13C-OABT). The gastric emptying of a standard 13C-labelled test meal was measured once weekly in 8 mature horses over two 4 week treatment periods. Each horse acted as its own control. In treatment Period 1, saline (2 ml i.v.), xylazine (0.5 mg/kg i.v.), detomidine (0.01 mg/kg i.v.) or detomidine/butorphanol combination (0.01/0.02 mg/kg i.v.) was administered in randomised order after ingestion of the test meal. During treatment Period 2, test meal consumption was followed by saline, xylazine (1.0 mg/kg i.v.), or detomidine (0.03 mg/kg i.v.) administration, or preceded by acepromazine (0.05 mg/kg i.m.) in randomised order. The 13C:12C ratio of sequential expiratory breath samples was determined by isotope ratio mass spectrometry, and used to measure the gastric half-emptying time, t 1/2, and duration of the lag phase, t lag, for each of the 64 tests. In treatment Period 1, detomidine/butorphanol prolonged both t 1/2 and t lag with respect to xylazine 0.5 mg/kg and the saline control (P < 0.05). In Period 2, detomidine 0.03 mg/kg delayed each parameter with respect to saline, acepromazine and xylazine 1.0 mg/kg (P < 0.001). Xylazine 1.0 mg/kg also lengthened t lag relative to the saline control (P = 0.0004), but did not cause a significant change in t 1/2. Comparison of treatment periods showed that the inhibitory effect of detomidine on gastric emptying rate was dose related (P<0.05). These findings may have clinical significance for case selection when these agents are used for purposes of sedation and/or analgesia.
mesh_terms: D000075:Acepromazine / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D001944:Breath Tests; D002077:Butorphanol / Q000494:pharmacology; D002210:Caprylates / Q000493:pharmacokinetics; D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes; D004305:Dose-Response Relationship, Drug; D005746:Gastric Emptying / Q000187:drug effects* / Q000502:physiology; D018589:Gastroparesis / Q000662:veterinary; D006736:Horses; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology; D016014:Linear Models; D014991:Xylazine / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D000700:Analgesics; D002210:Caprylates; D002247:Carbon Isotopes; D006993:Hypnotics and Sedatives; D007093:Imidazoles; D002245:Carbon Dioxide; D014991:Xylazine; D000075:Acepromazine; C041255:detomidine; D002077:Butorphanol