Clinical features and outcomes of horses presenting with equine immune
mediated keratitis (IMMK) to two veterinary hospitals in the United
Kingdom and Finland: 96 cases (2009-2021).
Abstract
Background: Limited literature exists regarding equine Immune
Mediated Keratitis (IMMK) in Europe. North America-based publications
describe minimal blepharospasm, rare corneal ulceration and no uveitis;
clinical impression suggests that these signs are common in Europe.
Objectives. Assess the prevalence of blepharospasm, corneal
ulceration and uveitis and their impact on outcome in horses diagnosed
with IMMK in European countries. Study design: Retrospective case
series of 95 horses with IMMK in the UK and Finland. Methods.
Clinical records of horses with IMMK were retrospectively evaluated. The
UK and Finland populations were comparable; therefore, descriptive
statistics were performed on combined data on subtypes of IMMK and
clinical features. Odds ratios (OR) and confidence intervals (CI) were
calculated for impact of blepharospasm, ulceration or presence of
uveitis on the outcome of enucleation and treatment duration.
Results. IMMK subtype was classified as 10/95 (10.5%)
epithelial, 50/95 (52.6%) anterior stromal, 15/95 (15.8%) mid-stromal,
4/95 (4.2%) endothelial cases and 16/19 (16.8%) unrecorded.
Blepharospasm was documented in 35/95 (36.8%), corneal ulceration in
28/95 (29.5%), and signs of uveitis in 24/95 (25.4%) of horses.
Increased odds of enucleation were associated with the presence of
blepharospasm (OR 5.9, 95% CI 1.7-20.8), corneal ulceration (OR 3.3,
95% CI 1.0-10.5) and signs of uveitis (OR 8.6, 95% CI 2.5-29.6). The
presence of blepharospasm, corneal ulceration or uveitis did not
significantly alter the odds of ongoing medication. Main
limitations: Data were collected over a wide timeframe and the
diagnosis was mainly made without histopathology. A broad definition of
uveitis was used and there was a bias towards complicated cases being
retained for follow up. Conclusions. The clinical features of
IMMK were similar between two geographically distinct European countries
but different to findings described in the USA. Blepharospasm, corneal
ulceration and signs of uveitis can occur with IMMK and increase the
odds of enucleation.
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