Effect of sedation with detomidine on intraocular pressure with and without topical anesthesia in clinically normal horses

Objective-To determine the effect of sedation with detomidine on intraocular pressure (IOP) in standing horses and whether topical ocular application of anesthetic alters this effect. Design-Clinical trial. Animals-15 clinically normal horses. Procedures-Horses were assigned to group 1 (n = 7) or 2 (8). Intraocular pressure measurements were obtained at baseline (before sedation) and 10 minutes after IV administration of detomidine (0.02 mg/kg [0.009 mg/lb]). Group 1 horses had an additional IOP measurement at 20 minutes after sedation. For group 2 horses, topical ocular anesthetic was administered 10 minutes prior to baseline IOP measurements. Results-Mean +/- SD baseline IOP for horses without topical anesthesia (group 1 horses; IOP, 24.30 +/- 3.09 mm Hg) was significantly lower, compared with that of horses with topical anesthesia (group 2 horses; IOP 30.40 +/- 3.25 mm Hg). Compared with baseline values, IOP at 10 minutes after sedation decreased significantly in all horses (by 3.61 +/- 1.48 mm Hg and 5.78 +/- 4.32 mm Hg in groups 1 and 2, respectively). In group 1 horses, IOP at 10 (20.69 +/- 3.45 mm Hg) and 20 (19.96 +/- 2.13 mm Hg) minutes after sedation was significantly decreased, compared with baseline values; however, the difference between IOP at 10 versus 20 minutes was not significant. The difference in IOP between group 1 and 2 horses at 10 minutes after sedation was not significant. Conclusions and Clinical Relevance-IV administration of detomidine caused a decrease in IOP in clinically normal horses and may be a safe sedative when performing ocular procedures. (J Am Vet Med Assoc 2012;240:308-311)