Effect of topical ophthalmic instillation of rocuronium bromide on the intraocular pressure of kestrels (Falco tinnunculus) and little owls (Athene noctuae)

OBJECTIVE: To assess the effect of rocuronium bromide-induced mydriasis on the intraocular pressure (IOP) of kestrels (Falco tinnunculus) and little owls (Athene noctuae). ANIMALS: 13 adult kestrels and 13 adult little owls. PROCEDURES: All birds were ophthalmologically normal. During the first of 2 treatment periods, a 1% rocuronium bromide solution was topically instilled in both eyes of all birds at a dose of 0.12 mg (12 μL) for kestrels and 0.20 mg (20 μL) for little owls. No ophthalmic treatments were administered during the second (control) treatment period, which was conducted 1 week after the first. During both treatment periods, rebound tonometry was used to measure IOP before rocuronium bromide instillation or at the beginning of the control period (baseline) and at predetermined times after baseline or until the pupillary light reflex returned to normal. All IOP measurements were obtained between 8 am and 5 pm. RESULTS: The mean IOP did not differ significantly from baseline for either species during the control treatment period. During the rocuronium bromide treatment period, complete mydriasis was achieved in all birds. The mean IOP was significantly decreased from baseline and from the corresponding mean IOP for the control period beginning 60 and 30 minutes after drug instillation for kestrels and owls, respectively, and reached its nadir at 60 minutes after drug instillation for both species. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that topical instillation of rocuronium bromide in the eyes successfully induced mydriasis and decreased the IOP of common kestrels and little owls.