Clinical use of the neuromuscular blocking agents atracurium and pancuronium for equine anesthesia.

This study examined the use and effects of the neuromuscular blocking agents atracurium and pancuronium in equine anesthesia practices over a three-year period at a teaching hospital.

About The Study’s Subject Matter

• The research focused on the use of neuromuscular blocking agents, specifically atracurium and pancuronium, in equine (horse-related) anesthesia. These agents are muscle relaxants commonly used in general anesthesia for humans, but their use has been less explored in large animal anesthesia.
• Though these agents are often used for human anesthesia, their application in veterinary medicine for large animals like horses can provide important insights into more effective and controlled anesthesia practices.

Study Procedure

• Over the span of three years, 89 anesthetic procedures on 88 different equids (horse family members, including 18 different breeds ranging in age from 5 weeks to 25 years) incorporated these relaxants into their anesthesia regimen.
• The surgeries ranged from abdominal to orthopedic, ophthalmologic, thoracotomy, and soft tissues procedures. Atracurium was used more often than pancuronium because of cost-effectiveness.
• The muscle relaxants were used for various durations, up to 205 minutes, and the dosage varied from 0.12 to 0.2 mg/kg of body weight. The muscles of the face or hind limb digital extensor muscles were monitored to assess the degree of relaxation, with hind limb muscles proving more sensitive to the relaxants.

Reversal of Relaxants and Observations

• At the end of each procedure, the horses were given a relaxant antagonist called edrophonium intravenously to counteract the effects of the muscle relaxants. This was done just before moving the animals to recovery.
• The administration of edrophonium led to increased blood pressure in most equids. Heart rate changes varied, with half the equids experiencing no change or a rise in the rate, and the rest registering a decrease.
• The recovery from anesthesia was rated as excellent or good for 72 equids, fair for 11, and poor for 2, providing a measure of the effectiveness and safety of the adjunct muscle relaxants in equine anesthesia.