Clinical Characterization of Glaucoma in 63 Pet Rabbits (Oryctolagus cuniculus) in Japan.

Glaucoma is common in pet rabbits, with primary and secondary forms differing markedly in age of onset and bilaterality.

This retrospective study characterized glaucoma in 63 pet rabbits (Oryctolagus cuniculus) referred for ophthalmic examination at a Japanese exotic specialty hospital between 2007 and 2023. Of 222 rabbits examined, 63 (28.4%) were diagnosed with glaucoma. Primary glaucoma accounted for 52.4% of cases, secondary glaucoma for 42.9%, and a mixed-risk category for the remaining 4.8%. Primary glaucoma presented significantly earlier (mean age 4.4 ± 2.8 years) compared to secondary glaucoma (mean age 10.0 ± 5.3 years). Gonioscopy performed in primary glaucoma cases revealed a closed iridocorneal angle in 69.6% of evaluated rabbits, suggesting angle-closure as a predominant mechanism. Encephalitozoon cuniculi infection was the most frequently suspected underlying cause of secondary glaucoma. Bilateral involvement was common, ultimately documented in 75.8% of primary and 29.6% of secondary glaucoma cases, underscoring the importance of monitoring the fellow eye. Medical management relied on topical antiglaucoma medications, with many cases progressing to multi-drug regimens over time. Follow-up duration was substantially longer for primary glaucoma (median 707 days) compared to secondary glaucoma (median 59 days). The study highlights that glaucoma is a prevalent and clinically significant condition in pet rabbits, with distinct signalment differences between primary and secondary forms. The authors emphasize the need for further investigation into potential genetic contributors to primary glaucoma in this species.

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