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.

Accelerometric Evaluation of the Locomotor Pattern After Administration of Morphine in Conscious Healthy Horses.

The objective of the present study was to compare, using accelerometry, the gait changes produced after administration of a dose of 0.2 mg/kg of morphine at the walk in healthy horses. Six mature horses were used, and all animals received two different treatments with, at least, two weeks interval in between. Treatments administered consisted of a single dose of 10 ml of saline solution or a total of 0.2 mg/kg of morphine diluted in 10 ml of saline solution. A three-dimensional accelerometric device was used to collect data continuously while horses were walking. The walking test was performed 10 min prior to injection, and then at 5, 10, 15 and 20 min after injection and then every 10 min for 3 h. Eight variables were calculated including stride kinematic, coordination and energetic parameters. Additionally, the force of acceleration and three components of the power were calculated. Significant interaction was only observed for stride length, propulsion power and the propulsive part of the total power with a reduction in values after morphine administration. Compared to baseline values, stride length values were significantly reduced for 80 min and again 110 min after injection of the opioid and at 5, 15, 20, 30 and 40 min in the case of propulsion power values. For the propulsion component of power, these differences were observed for 20 min when compared to baseline values. The administration of 0.2 mg/kg of morphine to conscious healthy horses produces limited effects on the gait pattern of horses and the effects on locomotor activity are minimal at this dose, not being an important concern for the administration of analgesia in a clinical setting.

A kinematic comparison of the locomotor pattern of horses sedated with detomidine alone and in combination with low doses of butorphanol.

BACKGROUND: Chemical restraint is often used to perform diagnostic and minor surgical procedures; α2 -adrenoceptor agonists are the most commonly used drugs; however, the combination with an opiate can induce a profound sedation. There is a lack of kinematic studies examining the effects of the combination of these drugs on locomotor patterns. OBJECTIVES: The objective of the study was to evaluate the duration of the effects of sedation with detomidine and detomidine combined with a low dose of butorphanol on the movement patterns of horses. STUDY DESIGN: The study was a controlled, randomised, blinded and crossover experiment. METHODS: Each of six horses was injected intravenously with saline (0.9%) solution (10 mL), detomidine diluted in saline solution (0.01 mg/kg bwt) or a combination of detomidine (0.01 mg/kg bwt) and butorphanol (0.02 mg/kg bwt) diluted in saline solution, in a random order. A single accelerometer positioned at the sacrum was used for gait assessment 15 min before (baseline) and 5, 15, 30, 45, 60, 75, 90, 105 and 120 min after each injection. Eight variables were measured, including speed, stride frequency, stride length, regularity, dorsoventral power, propulsive power, mediolateral power and total power; force of acceleration and the three components of power were calculated. The degree of sedation was measured by the ground-to-lip distance. RESULTS: There were significant differences among groups, with shorter effects after the injection of the combination of drugs, for most parameters. MAIN LIMITATIONS: A small number of horses were involved in the study. CONCLUSIONS: The combination of detomidine and butorphanol produces a shorter effect on almost all accelerometric parameters, probably due to the excitement produced by the opioid drug causing a quicker return to normal values. Accelerometry offers a method of objectively monitoring gait abnormalities in walking sedated horses.

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.