Conjunctivitis in Sheep: Red Eyes, Discharge & Common Causes
- Conjunctivitis in sheep is inflammation of the tissues around the eye. It often causes red eyes, tearing, squinting, and discharge.
- Many cases are part of infectious keratoconjunctivitis, often called pinkeye. Common contributors include Mycoplasma conjunctivae, Chlamydophila pecorum, Moraxella ovis, dust, flies, UV light, and plant irritation.
- See your vet promptly if the eye looks cloudy, the sheep keeps the eye shut, vision seems reduced, or several flockmates are affected. Eye disease can worsen fast and spread through a group.
- Early treatment can reduce pain, limit spread, and lower the risk of corneal ulcers, scarring, or permanent vision loss.
What Is Conjunctivitis in Sheep?
Conjunctivitis means inflammation of the conjunctiva, the thin pink tissue lining the eyelids and covering part of the eye. In sheep, pet parents and producers often call it pinkeye, especially when the eye is red, watery, painful, or producing discharge.
In many sheep, conjunctivitis is part of a broader eye problem called infectious keratoconjunctivitis. That term means the conjunctiva is inflamed and the cornea, the clear front surface of the eye, may also be irritated or damaged. Sheep may show only mild redness at first, but some cases progress to cloudiness, ulcers, or reduced vision.
This matters because eye pain can quickly affect grazing, weight gain, and overall welfare. Sheep with sore eyes may avoid bright light, stop eating normally, or separate from the flock. Early attention gives your vet more options and may help prevent spread to other animals.
Symptoms of Conjunctivitis in Sheep
- Red or bloodshot eye tissues
- Watery tearing or wet wool below the eye
- Squinting or keeping the eye partly closed
- Sensitivity to sunlight
- Mucus, pus, or crusting around the eyelids
- Cloudy, blue, or white cornea
- Corneal ulcer or visible eye surface defect
- Reduced appetite, poor grazing, or isolation from flock
Mild conjunctivitis may start with tearing, redness, and a little squinting. More serious cases can progress over days to marked pain, thick discharge, corneal haze, ulcers, or blindness in the affected eye. See your vet immediately if the eye looks cloudy, swollen, injured, or very painful, if the sheep will not open the eye, or if multiple sheep develop signs at the same time.
What Causes Conjunctivitis in Sheep?
Conjunctivitis in sheep can have infectious and noninfectious causes, and more than one factor is often involved. Merck notes that infectious keratoconjunctivitis in small ruminants is associated with organisms including Chlamydophila pecorum, Mycoplasma conjunctivae, Moraxella ovis, Listeria monocytogenes, Acholeplasma oculi, Colesiota conjunctivae, and Thelazia species. Not every red eye is caused by the same organism, which is one reason your vet may recommend testing.
Environmental irritation also plays a big role. Dusty bedding, wind, ultraviolet light, flies, and sharp plant material such as grass awns can irritate the eye and make infection more likely. Commingling at shows, sales, transport, or with newly introduced sheep can increase exposure. Juvenile animals are often affected more often than adults.
Some flock-level factors can make outbreaks harder to control. Close contact, poor ventilation, heavy fly pressure, and delayed treatment all increase the chance that more sheep will become affected. Trace mineral issues, especially low copper or selenium, are also listed by Merck as risk factors that may contribute in some groups.
How Is Conjunctivitis in Sheep Diagnosed?
Your vet usually starts with a hands-on eye exam and a general physical exam. In many sheep, a presumptive diagnosis is made from the pattern of redness, tearing, squinting, discharge, and any corneal cloudiness. Your vet will also look for clues that point toward trauma, a foreign body, parasites, or a more serious eye disease.
If the cornea may be involved, your vet may use fluorescein stain to check for an ulcer and may examine the eye closely for plant material or other debris. This step matters because treatment choices can change if there is a corneal ulcer or deeper injury.
When cases are severe, recurrent, spreading through the flock, or not responding as expected, diagnostic sampling can help. Merck states that microbial culture, cytology, and molecular testing may identify organisms associated with infectious keratoconjunctivitis. Cornell's Small Ruminant/Camelid Pinkeye Diagnostic Plan lists aerobic bacterial culture, Chlamydia PCR, and Mycoplasma culture from conjunctival swabs as available testing options.
Treatment Options for Conjunctivitis in Sheep
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm or clinic exam focused on the eye
- Basic eye stain if ulcer is suspected
- Isolation from affected flockmates when practical
- Shade, cleaner bedding, dust reduction, and fly control
- Vet-directed first-line medication plan using practical flock-minded options
Recommended Standard Treatment
- Full veterinary eye exam
- Fluorescein stain and closer corneal assessment
- Targeted prescription treatment based on exam findings
- Pain-control discussion and supportive care plan
- Short-term recheck to confirm healing and reduce flock spread
- Management review for flies, dust, UV exposure, and commingling risks
Advanced / Critical Care
- Detailed ophthalmic exam for severe or nonhealing cases
- Conjunctival swabs for bacterial culture, Chlamydia PCR, and/or Mycoplasma testing
- Treatment escalation for corneal ulceration, marked opacity, or vision threat
- Repeat rechecks and flock outbreak planning
- Referral-level care or surgical discussion if perforation, globe rupture, or permanent damage is a concern
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Conjunctivitis in Sheep
Bring these questions to your vet appointment to get the most out of your visit.
- You can ask your vet whether this looks like simple conjunctivitis or infectious keratoconjunctivitis with corneal involvement.
- You can ask your vet if the eye should be stained to check for a corneal ulcer or scratch.
- You can ask your vet what the most likely cause is in your flock, such as Mycoplasma, Chlamydia, Moraxella, flies, dust, or plant irritation.
- You can ask your vet whether this sheep should be separated from the flock and for how long.
- You can ask your vet what conservative, standard, and advanced treatment options make sense for this case and your budget.
- You can ask your vet whether any medications have meat or milk withdrawal times that affect your management plan.
- You can ask your vet if other sheep should be checked now, even if they only have mild tearing.
- You can ask your vet when a recheck is needed and what warning signs mean the eye is getting worse.
How to Prevent Conjunctivitis in Sheep
Prevention focuses on lowering both eye irritation and infectious spread. Keep bedding and handling areas as low-dust as possible, improve ventilation, and reduce exposure to sharp seed heads or awns that can scratch the eye. Fly control also matters, especially during warmer months and around manure-heavy areas.
Because outbreaks can follow commingling, be cautious with newly purchased sheep and animals returning from fairs, shows, or sales. Watch closely for tearing, squinting, or red eyes during quarantine. Early identification and treatment are important not only for comfort, but also to decrease transmission within the flock.
Work with your vet on flock-level prevention if pinkeye keeps returning. That may include reviewing mineral status, pasture conditions, stocking density, and whether diagnostic testing would help identify the main organism involved. Vaccines are discussed more often in cattle than sheep, and prevention in small ruminants still relies heavily on risk-factor control rather than one single tool.