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

Retrospective analysis of clinical data from 114 horses with eosinophilic keratoconjunctivitis (EKC) was conducted to describe disease characteristics, treatment approaches, and outcomes in a German equine hospital population.

Study Overview

• The study was a single-center retrospective case series focused on horses diagnosed with eosinophilic keratoconjunctivitis (EKC).
• Data were collected from 114 horses examined between January 2012 and December 2020 at a German equine referral hospital.
• The analysis aimed to describe demographic variables, clinical findings, treatment methods, and outcomes related to EKC.

Background on Eosinophilic Keratoconjunctivitis (EKC)

• EKC is an inflammatory eye disease that affects horses.
• The exact cause of EKC is unknown, but it is suspected to involve an immune-mediated mechanism.
• Clinical features include inflammation affecting the conjunctiva and cornea.

Demographics and Clinical Presentation

• 114 horses with EKC were evaluated, accounting for 163 affected eyes in total.
• Warmbloods represented 62.3% (71/114) of the cases, indicating this breed was most commonly affected in this population.
• Seasonality was noted with 67.5% (77/114) of cases presented between July and September, suggesting potential seasonal risk factors.
• Approximately 43.0% (49 horses) had bilateral disease involving both eyes.
• The cornea was involved in 85.3% (139/163 eyes), showing the cornea is frequently affected in EKC.
• During this period, EKC accounted for 2.0% of all equine ophthalmology cases (114 out of 5742), and the relative frequency of EKC increased over time (< 0.001 significance).

Treatment Approaches

• All horses received some form of medical treatment; specifics of the medical protocols were determined individually by the attending clinicians.
• 78.9% (90/114) of the horses also underwent surgical intervention, which was presumably to manage severe or refractory cases.

Outcomes and Recovery

• Follow-up data were available for 86.0% (98/114) of horses.
• Among those with follow-up, 79.6% (78/98) recovered completely from EKC.
• 12.2% (12/98) had persistent disease, indicating ongoing inflammation or corneal pathology.
• 8 horses (8.2%) ultimately required enucleation (removal of the eye), reflecting severe or non-responsive disease.
• The median recovery time for horses that improved was 30 days, indicating a relatively prolonged disease course.

Exploratory Findings

• The analysis found a statistical association between undergoing surgery and longer recovery times (< 0.001), which could reflect the severity of cases requiring surgery rather than treatment efficacy.
• Corneal lesion morphology was associated with adverse outcomes (p = 0.020), implying that certain patterns of corneal involvement may predict worse prognosis.
• Treatment strategies were selected on a case-by-case basis by clinicians rather than standardized protocols, limiting conclusions on efficacy.

Conclusions and Limitations

• The study describes clinical and epidemiological aspects of EKC in a referral hospital population over nearly a decade.
• Important findings include seasonal presentation patterns, breed distribution, common involvement of the cornea, and varied treatment approaches with generally favorable outcomes.
• However, the retrospective design and single center nature limit the ability to establish true population incidence, risk factors, breed predisposition, or to compare the effectiveness of different treatments.
• Therefore, while this provides valuable descriptive epidemiology and clinical insights, further prospective studies are required to clarify causation and optimize management of EKC in horses.