Sedative Effects of Dexmedetomidine and Ketamine or Dexmedetomidine and Midazolam on Tear Production, Ocular Perfusion Pressure and Pupil Diameter in Rabbits.

BACKGROUND

Administration of sedatives may be necessary for anxious and uncooperative animals. However, different sedative combinations may have confounding effects on ocular parameters. These effects can be crucial in ophthalmology.

OBJECTIVES

This study aims to investigate the effects of sedation with dexmedetomidine and ketamine, or dexmedetomidine and midazolam, on tear production (TP), ocular perfusion pressure (OPP) and pupil diameter (PD) in fourteen male New Zealand rabbits.

METHODS

The animals were randomly divided into two equal groups. In the DK group, a combination of dexmedetomidine (0.025 mg/kg) and ketamine (30 mg/kg), and in the DM group, a combination of dexmedetomidine (0.1 mg/kg) and midazolam (2 mg/kg) was administered. TP, OPP and PD were measured 15 min before administration of the sedatives, as well as 5, 15 and 20 min after.

RESULTS

Both sedative protocols induced a significant decrease in TP and OPP (p < 0.05), but no significant change was observed in the PD (p > 0.05). While the mean TP did not significantly differ between the two groups, the DK group showed considerably lower mean OPP and higher mean PD compared to the DM group.

CONCLUSIONS

According to our results, using artificial tears following both prescribed sedative protocols seems necessary. However, we recommend that dexmedetomidine-ketamine not be administered in rabbits at risk for glaucoma, as this protocol can significantly reduce OPP. Otherwise, the mentioned protocol can be a good choice in situations where fundoscopy is required, as it does not lead to miosis in healthy rabbits.