Contemporary use of acepromazine in the anaesthetic management of male horses and ponies: a retrospective study and opinion poll.
Authors: Driessen B, Zarucco L, Kalir B, Bertolotti L
Journal: Equine veterinary journal
Summary
# Editorial Summary: Acepromazine Use in Male Equine Anaesthesia Concerns about penile dysfunction have made practitioners cautious about using acepromazine in stallions, yet the actual incidence of this complication remained poorly documented. Driessen and colleagues reviewed perianaesthetic records from 575 male horses and ponies (42% stallions) that received acepromazine, predominantly for premedication, whilst also surveying ACVA and ECVAA diplomates on their clinical experience with this agent. Temporary penile prolapse occurred in only 2.4% of animals (14 cases, lasting 0.5–4 hours), with just one case exceeding 12 hours; permanent penile dysfunction was exceptionally rare, recalled by only one surveyed anaesthesiologist in 20 years of practice. Mean arterial pressures during anaesthesia averaged 65±9 mmHg with induction and recovery quality comparable between groups, whilst surveyed colleagues reported intraoperative hypotension infrequently despite acepromazine's known vasodilatory effects. The evidence supports reconsidering current practice restrictions: permanent penile complications occur at a rate of ≤1 in 10,000 cases, suggesting acepromazine can be used judiciously in stallions without materially greater risk than in geldings or mares, particularly when combined with other sedatives and analgesics for balanced premedication.
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Practical Takeaways
- •Acepromazine can be used safely in stallions for perianaesthetic premedication with minimal risk of permanent penile complications (≤0.01%), making it comparable to use in geldings and mares
- •Penile prolapse is a short-lived phenomenon in the vast majority of cases (<4 hours), with permanent dysfunction being exceptionally rare—guide horse owners accordingly
- •When using acepromazine as premedication combined with other sedatives and analgesics, monitor for intraoperative hypotension but expect stable recovery quality in most animals
Key Findings
- •Of 575 male horses/ponies receiving perianaesthetic acepromazine, 2.4% (14 animals) experienced penile prolapse lasting 0.5-4 hours, with only one case (0.2%) lasting >12 hours
- •Risk of permanent penile dysfunction was extremely low at ≤1 in 10,000 cases, not justifying restricted use in stallions versus geldings and mares
- •Acepromazine was predominantly used for premedication, with smooth induction in 566 animals and good/very good recovery in 70% of cases
- •Mean lowest arterial pressure averaged 65±9 mmHg; persistent intraoperative hypotension was not frequently reported by surveyed anaesthesiologists