Proceedings: Influence of etorphine, acepromazine and diprenorphine on cardiovascular function in ponies.

The research focuses on the effects of a neuroleptanalgesic drug combination of etorphine and acepromazine on the cardiovascular function of ponies. It investigates how the administration of these drugs and their antagonist, diprenorphine, influenced cardiovascular metrics such as heart rate, cardiac output and stroke volume in twelve Welsh Mountain ponies.

Article Explanation

• The study subjected twelve Welsh Mountain ponies, with body weights ranging from 185 to 336 kg, to an intravenous (i.v.) injection of a neuroleptanalgesic drug combination comprising etorphine and acepromazine. This drug combination is also known as Large Animal Immobilon, and was administered at a recommended dose rate of 24 μg/kg for etorphine and 100 μg/kg for acepromazine.
• Cardiovascular measurements were taken prior to the injection and at specific intervals up to 30 minutes after injection in order to monitor the effects of the drug combination on the ponies’ cardiovascular functions.
• The authors primarily focused on observing changes in key cardiovascular parameters, including heart rate, stroke volume (the amount of blood pumped by the left ventricle of the heart in one contraction) and cardiac output (the amount of blood the heart pumps through the circulatory system in a minute).
• Results showed that the administration of the neuroleptanalgesic drug combination led to pronounced increases in the ponies’ heart rates. There was also a moderate increase in cardiac output and a significant reduction in stroke volume throughout the period of neuroleptanalgesia, which is a state of calm or rest induced by a combination of an analgesic and a neuroleptic drug.
• Following this, the ponies were then administered with an intravenous injection of the etorphine antagonist drug, diprenorphine, known as Revivon, at a dose of 30 μg/kg. At this point, further measurements were borrowed to observe the impact of the antagonist on the effects of the neuroleptanalgesic drugs.

The research suggests these observations could be important in understanding the cardiovascular effects of anesthesia and other neuroleptanalgesic drug combinations in large animals, potentially shaping best practice for their use in the future.