Vet Pathol 28:74-78 (1991) BRIEF COMMUNICATIONS and CASE REPORTS Glaucoma in Horses

In contrast to its frequent occurrence in dogs and cats, several owners, trainers, and veterinarians (Table 2). Uni-glaucoma in horses seems to be rare. This low prevalence is lateral corneal cloudiness was the initial and major complaint difficult to explain in light of the frequency of ocular trauma, in six of the eight adult horses. Enlargement of the globe corneal perforation, or severe uveitis in horses-conditions followed the observation ofcorneal opacity, but the rapidity that predispose the eye to glaucoma in other species.w- " It of onset or rate of enlargement is unknown for most of the has been suggested that the resistance of the equine eye to horses. In one horse, the enlargement was reported to have the development of glaucoma may be related to the presence occurred gradually over a 2.5-year period, and, in another, of alternative routes of aqueous outflow in the event of ob- it occurred over a 2-month period, beginning 18 months after struction of the conventional trabecular meshwork.v-! ' AI- the observed onset ofcorneal edema. One foal was presented ternatively, the lack of instrumentation necessary to assess with congenital microphthalmia that had progressed to meg-intraocular pressure in horses may be at least partly respon- aloglobus. One adult horse had a primary complaint ofblind-sible for the infrequent diagnosis of glaucoma. ness and nonhealing corneal ulcer, and one had been treated We were able to find only three published reports of con- for clinically diagnosed equine recurrent uveitis for 3 months firmed glaucoma in horses; none of the studies contains de- before enlargement ofthe globe prompted reexamination and tailed histologic description. 1,4,6 Textbooks and review arti- a diagnosis of glaucoma