ASSESSMENT OF OPHTHALMIC DIAGNOSTIC PARAMETERS, CONJUNCTIVAL FLORA, AND PHARMACOLOGIC DILATION OF A LARGE POPULATION OF JUVENILE AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS).

Abstract

American alligators (Alligator mississippiensis) are an important apex predator of semiaquatic habitats of the southern United States. Commercial alligator farming has grown in the last several decades, leading to a need to understand the health conditions that affect this species to ensure appropriate management and welfare. The aims of this study were 1) to establish and describe normative data including results of common ophthalmic diagnostic tests and conjunctival flora, 2) document ocular pathology in this population, and 3) assess the effect of topical rocuronium bromide and 10% phenylephrine for facilitating pharmacologic mydriasis. A total of 165 juvenile American alligators were evaluated in this study. Assessment included palpebral fissure length (PFL), intraocular pressure (IOP), strip meniscometry (SM), central corneal thickness (CCT), anterior segment examination, and bacterial and fungal culture sampling of the conjunctiva. Topical rocuronium bromide (RB) and 10% phenylephrine (PE) were applied to the right eye (OD) of eight individuals, and pupil diameter (PD) of both eyes measured at regular time intervals. Mean (±standard deviation [SD]) PFL was 10.55 ± 1.47 mm, IOP was 8.16 ± 1.48 mmHg, CCT was 150.06 ± 8.25 µm, and SM was 3.42 ± 2.07 mm/5 s. Culture results stress the importance of proper handling protocols in crocodilians given the high number of opportunistic pathogens isolated from the conjunctiva, as well as the first report of isolation of Lactococcus garvieae in this species. Acquired ophthalmic lesions, likely traumatic, were recorded and no congenital anomalies were observed. Topical administration of RB and PE resulted in a significant increase in nonilluminated pupil diameter (PD) starting at 20 min, and maximum dilation was achieved at 90 min. Fundic examination was achievable, and no adverse systemic effects were noted. This study contributes to a growing body of knowledge regarding ocular health of American alligators.