Eosinophilic keratoconjunctivitis in seven horses.

Eosinophilic keratoconjunctivitis was diagnosed in 7 horses at The Ohio State University between 1976 and 1994. All horses had moderate-to-severe blepharospasm, chemosis, and conjunctival hyperemia; epiphora; and extensive yellow-to-white caseous mucoid discharge. Corneal ulcers associated with this disease were perilimbal and extended centrally. All ulcers were covered with a white necrotic plaque firmly attached to the underlying cornea. Other ophthalmic abnormalities were not detected. Corneal scrapings examined cytologically contained numerous eosinophils interspersed between epithelial cells, few mast cells, and neutrophils. Microbial organism were not seen. Bacterial and fungal cultures were negative for ocular pathogens. The initial diagnosis of eosinophilic keratoconjunctivitis was made on the basis of clinical and cytologic findings. In 5 horses, the condition completely resolved after topical treatment with corticosteroid (0.05% dexamethasone) and triple antibiotic ointments. However, the duration of treatment was prolonged, with a mean treatment time of 64 days (range, 45 to 106 days). All corneal ulcers remained superficial, and despite the prolonged duration of treatment, none of the horses developed secondary bacterial or fungal keratitis. One horse underwent superficial keratectomy and had the shortest resolution time (14 days).