Diagnosis and treatment of glaucoma in client-owned rabbits (Oryctolagus cuniculus): 16 eyes from 11 rabbits (2008–2019)

Background Although rabbits are commonly used as laboratory models for human glaucoma, management of this disease in pet rabbits has received little attention in the current literature. Spontaneous congenital glaucoma was initially described in New Zealand Whites as an autosomal recessive trait manifesting early in life. Glaucoma may also develop secondary to cataracts, uveitis, or other ocular pathologies. Findings associated with glaucoma in rabbits include elevated intraocular pressure (IOP), corneal edema, loss of vision, optic nerve head cupping, and progressive buphthalmia. Topical medications, intravitreal gentamicin injections, and various surgical techniques have been used to manage glaucoma in rabbits. This case series details the presentation, diagnosis, treatment, and clinical progression of glaucoma in rabbits at Cummings Veterinary Medical Center at Tufts University and VCA South Shore (Weymouth) Animal Hospital from 2008-2019. Methods The records of Cummings Veterinary Medical Center at Tufts University and VCA South Shore (Weymouth) Animal Hospital were retrospectively reviewed to identify records of rabbits diagnosed with glaucoma by a board-certified veterinary ophthalmologist or ophthalmology resident between 2008-2019. Results Glaucoma was diagnosed in 16 eyes from 11 rabbits. Median IOP at diagnosis was 39 mmHg (26-55 mmHg) with various clinical signs at presentation including vision loss (11 rabbits, 16 eyes), buphthalmia (8 rabbits, 11 eyes), corneal edema (4 rabbits, 5 eyes), and optic nerve head cupping (5 rabbits, 6 eyes). Other ocular examination findings included cataracts (5 rabbits, 8 eyes) and uveitis (4 rabbits, 8 eyes). Two rabbits were seropositive for Encephalitozoon cuniculi. All eyes were initially treated with topical medications, with 10 eyes from 7 rabbits refractory to initial medical management. Two rabbits (3 eyes) showed progressive reduction in IOPs with long-term continuing topical therapy. Two rabbits (2 eyes) underwent unilateral enucleation and 3 rabbits (5 eyes) received intravitreal gentamicin injections. Conclusions Etiology of glaucoma in rabbits is likely more varied than previously thought, as many of the cases described were not consistent with primary congenital glaucoma. Topical treatments were effective in many rabbits. In those refractory to medical management, enucleation or intravitreal gentamicin injection were successful in decreasing IOP as second-line therapy when performed.