Equine Recurrent Uveitis: Welfare and Long-term Management
Disease Overview
Equine recurrent uveitis (ERU, 'moon blindness', periodic ophthalmia) is a progressive, immune-mediated inflammatory condition of the uveal tract (iris, ciliary body, choroid) causing repeated episodes of intraocular inflammation. It affects 2-25% of horses worldwide, with higher prevalence in Appaloosas (genetic predisposition), warmbloods, and horses in endemic Leptospira areas. It is the leading cause of equine blindness. Each uveitic episode causes cumulative intraocular damage.
Welfare Impact of ERU
ERU causes significant welfare harm through: acute pain during flares (photophobia, blepharospasm, epiphora, miosis — horses rub their eyes, show signs of pain); visual impairment progressing to blindness from cataracts, posterior synechiae, glaucoma, retinal detachment, and phthisis bulbi (end-stage shrunken eye); stress and anxiety in blinded horses navigating their environment; and chronic low-grade discomfort from structural intraocular changes between flares.
Acute Flare Treatment
Acute uveitic flares require prompt treatment to reduce intraocular damage: topical corticosteroids (prednisolone acetate, dexamethasone) reduce inflammation; topical atropine dilates the pupil, prevents posterior synechiae, and relieves ciliary spasm pain; systemic NSAIDs (flunixin meglumine, phenylbutazone) provide additional anti-inflammatory and analgesic effect; and dark stable environment reduces photophobic discomfort. Treatment must be intensive in acute phases (every 1-4 hours topically) and continued for several weeks.
Surgical Management: Cyclosporine Implant
Suprachoroidal cyclosporine implants are the most effective long-term treatment for ERU, particularly in horses with frequent, severe recurrences. Surgically implanted beneath the sclera, they deliver low-dose cyclosporine locally to the uveal tract over 2+ years, suppressing the immune-mediated inflammatory cycle. Clinical trials show significant reduction in flare frequency and severity, slowing progression to blindness. Vitrectomy (removal of vitreous) is another surgical option, removing the immune complex repository that drives ERU.
Blind Horse Welfare Management
Blind horses can have good quality of life with appropriate management: stable environment (consistent layout, avoiding sudden changes); companion animals (goats, other horses) providing auditory and olfactory cues; tactile cues on fencing; introduction to new environments slowly; daily handling maintaining trust and predictability; turnout in familiar, secure paddocks; and removal of hazards. Owner education about recognising subtle pain signs and managing a blind horse safely is essential for long-term welfare.