Effects of three acepromazine doses on the incidence of morphine-induced vomiting, sedation and some physiological variables in dogs

ABSTRACT

Background: Acepromazine was found to reduce the incidence of vomiting induced by opioids such as morphine, hydromorphone and oxymorphone in dogs. Despite the effectiveness of the phenothiazine in preventing opioid-induced vomiting in this species, a single dose of acepromazine (0.05 mg/kg) was tested and the influence of dose on the antiemetic effect of the drug is unknown. The primary objective of this study was to evaluate the effect of three acepromazine doses on the incidence of vomiting induced by morphine in dogs. A secondary aim was to assess the degree of sedation and effects on physiological variables following administration of the combinations tested.Materials, Methods & Results: All dogs received 0.5 mg/kg morphine (IM). Fifteen min before morphine, dogs in the Control, ACPLD, ACPMD and ACPHD groups were administered (IM) physiological saline or acepromazine at doses of 0.025, 0.05 and 0.1 mg/kg, respectively. In Phase 1, purpose-bred dogs (n = 8) underwent each of the four treatments in a randomized, crossover design; the incidence of vomiting, sedation, pulse rate (PR), systolic, mean and diastolic blood pressures (SAP, MAP and DAP) were investigated for 60 min. Sedation was assessed by a numeric descriptive scale (NDS, range 0-3) and a simple numerical scale (SNS, range 1-10). In Phase 2, client-owned dogs (n = 50) received a single treatment and only the incidence of vomiting was assessed. There was no significant difference between groups on the incidence of vomiting recorded in Phase 1, Phase 2 and the average of Phases 1 and 2. A significant decrease in PR was observed in most groups but no significant difference was detected between groups. Blood pressure decreased in all groups; during most of the evaluation period, SAP, MAP and DAP were significantly higher in the Control than in other treatments. Dogs in this study presented mild to intense sedation.[...]