FieldDxBlightClinical signs, differential diagnosis, treatment and prevention in cattle, goats and sheep.
Overview
A very common, highly contagious eye infection of cattle, spread by flies and direct contact. Moraxella bovis, with Moraxella bovoculi also frequently found though its exact role is unclear.
Clinical signs
- Early photophobia, blepharospasm and epiphora.
- Mucopurulent ocular discharge.
- Conjunctivitis.
- Central corneal ulceration in cattle.
- Corneal opacity and oedema, hazy white to blue.
- Reduced appetite.
- One or both eyes affected.
Predisposing factors
- Ultraviolet solar radiation.
- Face flies acting as vectors.
- Dust and mechanical irritation.
- Plant awns, particularly foxtail grasses.
Look-alikes to rule out
Treatment
- Systemic oxytetracycline or tulathromycin, both FDA-approved for IBK in cattle.
- Topical oxytetracycline with polymyxin B ointment.
- Dilute hypochlorous acid spray.
- Eye patches, for protection and antimicrobial benefit.
- 1% atropine ointment where there is uveitis.
- NSAIDs such as flunixin meglumine.
Drugs mentioned: Flunixin Meglumine Oxytetracycline Tulathromycin Atropine Flunixin
Prevention
1. Control face flies with topical or parenteral treatments, dust bags and insecticide ear tags. 2. Mow pastures carrying mature seed awns. 3. Keep a trace mineral supplementation programme running. 4. Isolate affected animals. 5. Disinfect equipment and handling materials. 6. Vaccine efficacy is disputed and reports are mixed. 7.
Source
MSD Veterinary Manual — Infectious Keratoconjunctivitis in Cattle and Small Ruminants (accessed 2026-07-31)
Condensed and attributed, never reproduced whole. Open the full entry in the app.