Nonulcerative bullous keratitis associated with Pseudomonas alcaligenes infection in a Thoroughbred mare

Abstract

SummaryA 5‐year‐old Thoroughbred mare presented with an intermittently mildly painful right eye with a nonulcerative corneal opacity of several weeks' duration that had improved with topical steroids but recurred when steroids were withdrawn. Ophthalmic examination demonstrated a focal region of moderate corneal oedema and midstromal corneal infiltrate centrally but no other significant ocular abnormalities, and suggested a diagnosis of immune‐mediated keratitis. Empirical courses of both topical and systemic anti‐inflammatory drugs, both nonsteroidal and steroidal, led to initial improvement but bullous keratopathy developed when corneal oedema became profound. Due to the rapidly progressive nature of the bullous keratopathy combined with poor response to medical therapy, a keratectomy and conjunctival graft were performed under general anaesthesia. Intraoperative corneal culture of the keratectomy site grew Pseudomonas alcaligenes, a common soil and water contaminant. Histopathology of the keratectomy specimen revealed neutrophilic inflammation. Keratectomy and conjunctival graft led to resolution of ocular pain and inflammation, with an acceptable cosmetic and visual outcome. This report describes an unusual case of a nonulcerative Pseudomonas keratitis that responded well to surgical therapy, and underscores the complicated nature of nonulcerative keratitis in horses.