Retrospective Analysis of the Clinical Findings of 114 Horses with Eosinophilic Keratoconjunctivitis

Eosinophilic keratoconjunctivitis (EKC) is an inflammatory eye disease of horses with an unknown cause and suspected immune-mediated pathogenesis. This single-center retrospective case series included 114 horses (163 affected eyes) examined at a German equine referral hospital from January 2012 to December 2020. Of these horses, 71 (62.3%) were Warmbloods, 77 (67.5%) were presented from July to September, and 49 (43.0%) had bilateral disease. The cornea was involved in 139 of 163 eyes (85.3%). During the study period, 114 EKC cases occurred among 5742 ophthalmology cases (2.0%), with an increasing overall trend in hospital-based relative frequency (p < 0.001). All horses received medical treatment, and 90 (78.9%) also underwent surgery. Follow-up was available for 98 of 114 horses (86.0%): 78 (79.6%) recovered, 12 (12.2%) had persistent disease, and 8 (8.2%) underwent enucleation. Among recovered horses, median recovery time was 30 days. Exploratory analyses associated surgery with longer recovery (p < 0.001) and corneal lesion morphology with adverse outcome (p = 0.020), but treatment was clinician-selected. These findings describe EKC in one referral-hospital population but do not establish population incidence, seasonal risk, breed predisposition, or comparative treatment efficacy.