Comparative study among acepromazine, chlorpromazine and methotrimeprazine in different doses, through bispectral index, term and pressure algimetry, in dogs

Abstract

The study’s objective was to realize comparisons among different acepromazine, chlorpromazine and methotrimeprazine doses, evaluate parametric changes, test analgesia using press and term algimetry, and evaluate bispectral condition. 90 mongrel dogs were used, male and female, adult, weighting 10 to 15 Kg as a rule, distributed in 9 groups with 10 animals each. At first, second and third groups acepromazine was used at 0,1; 0,05 e 0,025 mg/Kg, respectively. At forth, fifth and sixth groups, chlorpromazine was used at 1,0; 0,5 and 0,25 mg/Kg, respectively. At seventh, eighth and ninth groups, methotrimeprazine at 1,0; 0,5 and 0,25 mg/Kg was used, respectively. All drugs were administered intravenously. Objects of study: heart rate (HR), non invasive blood pressure (SAP, MAP, DAP), respiratory rate (f), capnography (ETCO₂), pulse oxymetry (SatO₂), mouth and rectal temperature, bispectral index (BIS), electromyography (EMG%), press and term algimetry.  Somatic analgesia was evaluated by animal’s response to nociceptives stimulus. We concluded that chlorpromazine had more hypotension.   Dogs showed higher hypnosis level at chlorpromazine group, with evident myorelaxation. All groups showed analgesia to thermic and mechanic stimulus. Acepromazine group showed high duration to both pain stimuli. Bispectral index was shorten at chlorpromazine group at 1,0 mg/kg doses, showing higher hypnosis index, and acepromazine was the less depressing considering the bispectral index.