Abstract

Rays, most commonly cownose rays (Rhinoptera bonasus) and Atlantic stingrays (Hypanus sabina), are popular elasmobranchs in North American aquariums due to their docile nature and adaptability to various habitats.^1,2 Reports of ophthalmic diseases in captive rays are limited.³ The purpose of this case series is to describe ulcerative keratopathy of varying levels of severity in captive cownose rays.

Eleven cownose rays and one Atlantic stingray housed in two different habitats were examined. Of the cownose rays, there were five juvenile and six adult rays. Juvenile rays were housed in a 2,500-gallon touch-tank (n=5 cownose rays, n=1 Atlantic stingray). Adult cownose rays were housed in a 75,000-gallon ray pool (n=6). The six adult rays (unknown ages; male=4, female=2) were noted to have severe corneal opacification prior to examination. All rays in the touch tank (age: 1–6 months; male=4, female=2) were clinically normal but were examined to determine if juvenile rays in a different environment had corneal disease. Slit lamp biomicroscopy and fluorescein staining were performed in all rays (n=12) by a veterinary ophthalmologist.

Bilateral corneal lesions in the adult cownose rays were severe (n=6). Lesions included epithelial erosions (n=4), edema (n=5), diffuse fibrosis (n=3), bullae (n=4), pigmentation (n=2), vascularization (n=3), granulation tissue (n=1), intrastromal hemorrhage (n=2), crystalline deposits (n=1), lackluster appearance (n=2), and corneal perforation (n=1). Intraocular findings included rubeosis iridis (n=2), dyscoria (n=3), hyphema (n=1), and anterior and posterior synechiae (n=4). Periocular skin lesions included hyperemia (n=1), depigmentation (n=1), and ulceration (n=1). Fluorescein stain uptake was positive (n=4). Fungal and aerobic corneal cultures (n=4) were negative. A corneal biopsy (n=1) revealed necrotizing and granulocytic keratitis.

Corneal lesions in all juvenile cownose rays were mild (1/5 bilateral). Lesions included epithelial erosions (n=5), edema (n=5), bullae (n=3), pigmentation (n=1), vascularization (n=2), crystalline deposits (n=3), and lackluster appearance (n=3). Intraocular findings included miosis (n=2), rubeosis iridis (n=4), dyscoria (n=1), and anterior and posterior synechiae (n=1). Periocular skin lesions included hyperemia (n=2), depigmentation (n=1), and ulcerations (n=2). Fluorescein stain uptake was positive (n=5). The Atlantic stingray did not have any ocular lesions.

There were limitations in this study including the retrospective nature, the inability to examine all of the rays in the adult pool, and the inability to examine the affected rays at another time point.

This is the first report of corneal disease in captive rays. All cownose rays examined had corneal lesions, regardless of the degree of clinical disease noted. Those with more severe lesions had evidence of anterior uveitis, suspected to be secondary to corneal disease. The etiology of these lesions was not determined. No ocular lesions were observed in the Atlantic stingray which may suggest a species-specific etiology. Parasitic, bacterial, traumatic, nutritional, or environmental etiologies were considered. Future research should be aimed at determination of etiology and further classification of this keratopathy. The presence of these lesions suggests that regular ophthalmic examinations may be indicated in captive cownose rays.

Acknowledgements

The authors would like to acknowledge the staff of Ocean Adventures and the Institute for Marine Mammals Studies (Gulfport, MS) for their time and assistance in this case series.

*Presenting author
⁺Student presenter

Literature Cited

1.  Bigelow HB, Schroeder WC. 1953. Fishes of the Western North Atlantic. Part 2. Sears Foundation for Marine Research, Yale University, New Haven. 588.

2.  Elasmobranch husbandry manual: captive care of sharks, rays and their relatives. 2004. Columbus, OH: Ohio Biological Survey, Inc. 100–101.

3.  Garner MM. 2013. A retrospective study of disease in elasmobranchs. Vet Pathol 50(3):377–389.