Effects of acepromazine maleate, isoxsuprine hydrochloride and prazosin hydrochloride on laminar microcirculatory blood flow in healthy horses.

摘要

Laser Doppler flowmetry was used to measure the effects of acepromazine maleate, isoxsuprine hydrochloride, and prazosin hydrochloride on laminar microcirculatory blood flow. Five adult horses (450 - 500 kg), free of evidence of laminitis or other inflammatory conditions of the lower limb were used. Holes were drilled on the dorsum of each front hoof to the depth of the junction of the sensitive and insensitive laminae. Temperature, pulse rate and respiratory rate were obtained before beginning themeasurements. Pulse rate was measured at 15-minute intervals throughout the measurement period. A laser Doppler probe was placed in each hole. Baseline Doppler flow measurements were obtained. Following baseline determinations either acepromazine maleate (0.066 mg/kg), isoxsuprine hydrochloride (0.6 mg/kg) or prazosin hydrochloride (0.025 mg/kg) were injected intravenously. Drugs were randomly assigned and repeated 3 times in each horse. Laminar microcirculatory blood flow was then measured continuously for 180 minutes. These data were analysed using univariate (mixed model) repeated measures analysis. None of the drugs had any significant effect on laminar microcirculatory blood flow. Acepromazine maleate, isoxsuprine hydrochloride and prazosin hydrochloride have no laminar microcirculatory blood flow effect in standing, healthy horses at dosages used. Efficacy in the use of these 3 drugs for the treatment of laminitis is questionable. However, this study was performed in healthy horses and the results may not be applicable in horses with laminitis.