Figure 4.

Baseline pupil size with different chemical restraint protocols; dexmedetomidine and ketamine (method CR3) (A) and dexmedetomidine and butorphanol (method CR4) (B). PLR traces from a dog under high-dose dexmedetomidine restraint (method CR2) (C) and a dog under combined injectable and inhalant restraint (method CR5) (D). Pupil responses are shown as percent of baseline pupil area. No stimulus was used in traces (A) and (B). A 100-ms flash stimulus of 11 log photons/cm²/s was given 5 seconds into (C) and (D) recordings (dashed line), resulting in a large constriction. The substantial spontaneous fluctuation in pupil size observed under injectable chemical restraint (A–C) was completely eliminated with the use of inhalant restraint (D).