Cow Eye Discharge: Causes, Pink Eye Risk & What to Do

Eye discharge in cows is a symptom, not a diagnosis. One of the most common causes is infectious bovine keratoconjunctivitis (IBK), often called pinkeye. This condition is linked with conjunctivitis, tearing, squinting, corneal opacity, and often a painful corneal ulcer. It tends to flare during warmer months when flies, sunlight, and pasture irritation are more intense.

Not every watery eye is pinkeye. Dust, wind, pollen, tall grass, seed heads, and plant awns can irritate the eye and trigger tearing. A foreign body trapped under the eyelid can also cause sudden discharge, blinking, and pain. In some cases, irritation opens the door for infection to develop afterward.

Discharge can also happen with conjunctivitis from other infectious agents, eyelid trauma, or deeper corneal injury. Clear tearing may be seen early, while thicker yellow or green discharge can suggest secondary bacterial infection or a more advanced eye problem. If the eye looks blue, white, or cloudy, that raises concern for corneal damage rather than mild surface irritation.

Because cattle often hide illness until discomfort is significant, even a "runny eye" deserves a closer look. When discharge is paired with squinting, light sensitivity, or a visible spot on the cornea, your vet should evaluate the eye rather than assuming it will clear on its own.

See your vet immediately if your cow is holding the eye shut, has marked swelling, a white or cloudy spot on the cornea, blood, a deep-looking ulcer, severe pain, or signs of poor appetite and isolation from the herd. These findings can mean a corneal ulcer or more serious eye injury, and delays can increase the risk of scarring or rupture.

Call your vet the same day or next day if discharge lasts more than a day, becomes thick or pus-like, or if more than one animal is affected. Pinkeye can spread within a herd, and early treatment may reduce pain and limit transmission. Calves and young stock are often affected more often, so quick action matters.

You may be able to monitor briefly if the discharge is mild, clear, and short-lived, and your cow is keeping the eye open, eating normally, and acting comfortable. Even then, watch closely for squinting, increased tearing, cloudiness, or a drop in milk production or feed intake.

Do not put random ointments, steroid eye products, or livestock sprays near the eye unless your vet tells you to. Some products can worsen corneal ulcers, and food-animal drug rules matter in cattle.

Your vet will start with a hands-on eye exam and herd history. They will look at whether one eye or both are affected, how painful the eye is, whether the cornea is cloudy, and whether there is evidence of trauma, flies, dust exposure, or recent pasture changes. They may also check nearby cattle if pinkeye is suspected.

A key step is looking for a corneal ulcer or foreign body. Your vet may evert the eyelids, flush the eye, and use fluorescein stain to highlight damage to the corneal surface. In cattle with ulceration, ruling out a plant awn or other foreign material is especially important.

Treatment depends on the cause and severity. Your vet may recommend an approved topical eye medication, systemic antimicrobial treatment where appropriate, pain control, and supportive measures such as an eye patch to reduce light exposure and irritation. In herd situations, your vet may also discuss fly control, shade, pasture management, and whether vaccination has a role for your operation.

If the eye is badly damaged, not healing, or at risk of rupture, advanced procedures may be needed. These can include more intensive rechecks, hospital-level support, or surgery in severe cases. The goal is to control pain, protect vision when possible, and reduce spread through the herd.

Home care should support, not replace, veterinary guidance. Move the cow to an area with shade, easier observation, and less dust if possible. Reducing sunlight can improve comfort because painful eyes are often very light-sensitive. Good fly control also matters, since flies can irritate the eye and help spread pinkeye organisms between cattle.

If your vet prescribes eye medication, give it exactly as directed and finish the full course unless your vet changes the plan. Clean away discharge from the eyelids with clean gauze or a soft cloth dampened with sterile saline if your vet says that is appropriate. Be gentle. Rubbing or scrubbing the eye can make a corneal injury worse.

Check the eye at least daily for worsening cloudiness, a larger white spot, more swelling, thicker discharge, or the cow keeping the eye shut. Also watch appetite, milk production, and herd behavior. If more cattle start tearing or squinting, contact your vet because herd-level control may be needed.

Do not use leftover eye drops, steroid-containing products, or homemade remedies unless your vet specifically approves them for this cow. In food animals, treatment choices must also fit legal drug-use rules and withdrawal guidance.