Sedated dental procedures increase endogenous plasma ACTH concentration in horses in the fall

Objective To measure the effect of sedation with detomidine and butorphanol and a routine dental procedure on endogenous plasma ACTH concentrations of healthy older horses and to determine how long this effect, if any, persists to improve testing recommendations for pituitary pars intermedia dysfunction (PPID). It was hypothesized that a sedated dental procedure would not significantly affect endogenous plasma ACTH concentrations as compared to baseline in healthy adult horses. Methods This prospective crossover study included 12 healthy mares of various breeds, aged 8 to 20 years, from the university herd with no clinical signs or history of PPID. Horses were sampled during both the spring (February 2025) and fall (September/October 2025) undergoing either a sedated oral examination or dental equilibration in alternating fall and spring periods. Blood samples were collected to quantify plasma ACTH concentrations from 0 minutes to 72 hours following sedation. Results There was a significant effect of season but not procedure on plasma ACTH concentration. In the fall, sedation was significantly associated with increased plasma ACTH concentrations; however, the effect was no longer significant after 15 minutes. There was no significant effect of sedation and dentistry detected on plasma ACTH concentration in the spring. Conclusions Season and timing of sample collection following sedation influenced plasma ACTH concentration. Clinical Relevance PPID sampling can be performed 15 minutes after sedation in the fall. It is unknown whether results would differ in horses with PPID.