Morphine with or without Acepromazine in Horses: A Kinematic Evaluation

Area of Science:

• Veterinary pharmacology
• Equine locomotion analysis
• Animal behavior and physiology

Background:

• Opioid administration, like morphine, can cause central nervous system excitation and adverse locomotor effects in horses.
• Acepromazine, a phenothiazine tranquilizer, can also influence equine gait and behavior.
• Understanding the combined effects of these drugs is crucial for safe clinical application.

Purpose of the Study:

• To investigate the impact of co-administering acepromazine and morphine on the walking locomotor patterns of horses.
• To determine if acepromazine can mitigate the adverse locomotor effects associated with morphine administration.
• To evaluate the safety and efficacy of this drug combination in equine practice.

Main Methods:

• Six mature horses received four treatments: saline, morphine, acepromazine, or a combination of morphine and acepromazine.
• A 3D accelerometric device was used to collect gait data during walking tests.
• Measurements included kinematic, coordination, and energetic gait variables, along with ground-to-lip distance (GLD).

Main Results:

• Significant interactions were observed in most gait variables, indicating drug-specific effects.
• The co-administration of acepromazine and morphine demonstrated a counteraction of the individual drug effects on the gait pattern.
• Regularity, mediolateral power, propulsive power, and GLD showed no significant interaction.

Conclusions:

• The combination of acepromazine and morphine appears to counteract the adverse locomotor effects of each drug individually.
• This combination may offer a safer approach to opioid administration in horses, reducing CNS excitation and potential gait disturbances.
• Further research is warranted to fully elucidate the benefits and safety profile of this combined treatment in horses.