Morphine with or without Acepromazine in Horses: A Kinematic Evaluation.

The objective was to demonstrate walking locomotor pattern alterations after co-administration of acepromazine and morphine in horses. Six mature horses receiving four different treatments were used. Treatments consisted of a single dose of saline solution, 0.2 mg/kg bwt of morphine hydrochloride, 0.02 mg/kg bwt of acepromazine maleate, and a combination of 0.2 mg/kg bwt of morphine hydrochloride with 0.02 mg/kg bwt of acepromazine maleate. A three-dimensional accelerometric device was used to collect data. Walking tests were performed 10 min prior to injection, and then at 5, 10, 15, and 20 min after the injection, and then every 10 min for 3 h. Eight variables were calculated including stride kinematic, coordination, and energetic parameters; moreover ground-to-lip distance (GLD), as a tranquilization parameter, was also measured. A significant interaction was observed in all the variables studied but regularity, mediolateral power, the propulsive part of the power, and the GLD. An evident counteraction of the effects caused by both, opioids and phenothiazines, in the gait pattern was observed. The co-administration of acepromazine and morphine could allow a safe opiate administration while minimizing the possible central nervous system (CNS) excitation and reducing potential locomotor adverse effects.

The use of low doses of acepromazine as an aid for lameness diagnosis in horses: An accelerometric evaluation.

OBJECTIVES: The aim of the present study was to quantify by accelerometry the trotting pattern of adult horses sedated with two different doses of acepromazine, in order to assess the use of this drug in equine lameness evaluations. METHODS: Seven mature horses were used and three treatments were administered to each horse: saline solution, acepromazine (0.01 mg/kg), and acepromazine (0.02 mg/kg). The portable gait analyzer used consisted of three orthogonal accelerometers that measure accelerations along the dorsoventral, longitudinal, and lateral axes. Baseline values were obtained and after treatment, accelerometric recordings were repeated every five minutes during the first 20 minutes after the injection and then every 10 minutes thereafter for two hours. Ground-to-lip distance was also measured. RESULTS: Administration of acepromazine decreased some of the variables investigated and differences between doses were observed. Speed, stride frequency, and stride length were significantly reduced following treatments. For coordination parameters, no significant differences among values were observed. Energetic variables suffered only weak reductions whereas ground-to-lip distance values were significantly decreased up to 120 minutes after treatment. CLINICAL SIGNIFICANCE: Acepromazine produces significant alterations in the gait pattern with differences between doses, but it does not affect coordination variables in normal unexcited horses, and at a dose of 0.01 mg/kg may be the tranquilizer of choice for evaluating lameness in this setting.