Bilateral mydriasis in common buzzards (Buteo buteo) and little owls (Athene noctua) induced by concurrent topical administration of rocuronium bromide.

Objective: To evaluate the achievement of a bilateral mydriasis in raptors induced by a concurrent topical application of rocuronium bromide and to assess any side effects that might result from its use. Animals studied  Ten healthy adult common buzzards (Buteo buteo) and 10 healthy adult little owls (Athene noctua).

Procedures: Common buzzards (Group 1) received a single dose of 0.40 mg of rocuronium bromide in each eye (total dose 0.80 mg/bird), whereas the little owls (Group 2) received a single dose of 0.20 mg in each eye (total dose 0.40 mg/bird). The drug was topically instilled in all the birds of both groups. The pupil diameter was measured with a pupillary gauge and the assessment of the pupillary light reflexes was performed using a standard light source.

Results: Maximal pupillary diameter was 8.10 ± 0.56 mm in the right eye and 8.05 ± 0.59 mm in the left eye for Group 1 and 10.0 ± 0.75 mm in both eyes for Group 2. No statistical differences were evidenced between the achieved pupillary diameters of both eyes in each group. The maximal pupillary diameter was achieved at T110 min and T40 min for Groups 1 and 2, respectively. The drug did not cause noticeable adverse effects in the examined birds.

Conclusions: A single concurrent topical administration of rocuronium bromide to the eyes of the examined birds induced a complete bilateral mydriasis in both eyes without causing any adverse effect.