Conjunctivitis in Horses Vet Guide 2025 – Dr Duncan Houston 🐴👁️

By Dr Duncan Houston, BVSc – expert guidance on identifying, diagnosing, and treating conjunctivitis (“pink eye”) in horses.

Introduction

Conjunctivitis—aka “pink eye”—is inflammation of the conjunctiva, the pink tissue lining eyelids and covering the eyeball. While often mild, it can signal infection, allergy, trauma or deeper issues. Early detection and treatment are vital to prevent discomfort, spread, and complications. This 2025 guide will walk you through types, symptoms, diagnostics, treatment, prevention, and follow-up care. 👁️🌱

📌 What Is Conjunctivitis?

Conjunctivitis is identified by redness, swelling (chemosis), discharge and discomfort such as squinting or rubbing :contentReference[oaicite:3]{index=3}. In horses, it may affect one or both eyes and vary in severity—from mild irritation to vision-threatening conditions.

🔍 Common Causes

• Infectious: bacterial or viral (e.g., equine herpesvirus) :contentReference[oaicite:4]{index=4}
• Allergic or irritant: dust, pollen, bedding, chemical sprays :contentReference[oaicite:5]{index=5}
• Trauma: foreign bodies, blunt injury affecting only one eye :contentReference[oaicite:6]{index=6}
• Parasitic: Onchocerca, Habronema, Thelazia—blood-sucking or larvae :contentReference[oaicite:7]{index=7}
• Tumors: conjunctival neoplasms or papillary growths :contentReference[oaicite:8]{index=8}

🩺 Recognizing the Signs

• Red, swollen eye tissue & eyelid
• Excessive tearing or discharge—clear to purulent
• Frequent blinking, squinting, head shaking or face rubbing :contentReference[oaicite:9]{index=9}
• Chemosis—puffed-up eyelids from fluid build-up :contentReference[oaicite:10]{index=10}
• Possible secondary signs like appetite loss or discomfort under bright light

📋 Diagnostic Approach

• History & environmental check—exposure to dust, insects, new bedding
• Physical exam: check eyelid, tear ducts, vision response, presence of debris or parasites
• Ophthalmic tests: fluorescein stain for corneal ulcers; Schirmer tear test for dry eye
• Conjunctival swab or cytology for suspected infectious, eosinophilic or parasitic causes :contentReference[oaicite:11]{index=11}
• Biopsy for masses or chronic lesions :contentReference[oaicite:12]{index=12}
• Differential diagnoses: corneal ulceration, uveitis, glaucoma—urgent referral if severe pain or vision loss

💊 Treatment Strategies

Infectious Cases

• Topical antibiotic ointment/drops (chloramphenicol, neomycin-polymyxin) :contentReference[oaicite:13]{index=13}
• Oral antibiotics for deep infection

Allergic/Irritant Types

• Flush eye with saline solution—homemade warm salt water helps remove debris :contentReference[oaicite:14]{index=14}
• Topical anti-inflammatories or topical corticosteroids if no ulcer present
• Fly masks, avoid dusty turnout, use low-dust bedding

Parasitic/Immune-Mediated Forms

• Ivermectin or systemic anthelmintic for Onchocerca or Habronema :contentReference[oaicite:15]{index=15}
• Topical steroids for eosinophilic or nodular types, under vet supervision

Trauma or Foreign Bodies

• Remove offending object, flush with sterile saline
• Topical antibiotics and NSAIDs; consider referral if deeper tissue injured

Tumors or Growths

• Surgical excision or biopsy of masses; chemical cauterization or cryotherapy as needed :contentReference[oaicite:16]{index=16}

📆 Treatment Timeline & Monitoring

• Most mild cases improve within 2–5 days after treatment :contentReference[oaicite:17]{index=17}
• Continue topical therapy for 7–10 days or per vet’s direction
• Follow up within 1–2 days; reassess if no improvement, signs worsen, or vision affected

🛡️ Prevention & Management

• Fly control: masks, traps, sprays in insect season
• Clean, dust-free stalls and paddocks
• Don’t share buckets or grooming tools without disinfecting :contentReference[oaicite:18]{index=18}
• Regular deworming helps prevent parasitic eye issues
• Minimize allergen exposure: low-dust hay, frequent stall cleaning

📊 Summary Table

📈 When to Seek Vet Help

• Vision impairment, corneal ulcer, severe swelling or pain
• No improvement after 48 hours of treatment
• Signs of deeper eye disease—cloudy cornea, unusual pupil, intense light sensitivity
• Recurring conjunctivitis—could indicate chronic or systemic issues

📲 Ask A Vet Support & Conclusion

Conjunctivitis in horses ranges from mild, easily treatable issues to signs of more serious eye disease. By understanding the types, applying the right care, and monitoring progress, most horses recover fully with no lasting effects.

Need a tailored eye care plan, outbreak prevention tools, or in-app vet advice? Ask A Vet provides expert guidance, reminders, and consultations whenever you need. Download the Ask A Vet App today to keep your horse’s vision bright and healthy! 🌟👁️