Pinkeye in Cattle

Warning! This article contains graphic pictures. Look away if you get queasy!

Highland cow with hair blowing in the wind

Pink Eye

I  absolutely hate it when our animals are sick. I know no one likes it, but I get all worried about them and upset until I feel like they have received the medicine they need and appear to be improving. This makes summer kind of hard for me - pinkeye is EVERYWHERE! It seems like every time we turn around one of our cows or goats has a swollen, watery eye with a white haziness somewhere in it. I thought it might be helpful to highlight my favorite medical resource for our animals and give a quick summary about pinkeye and ways you can diagnose, prevent, and treat it. 

*Disclaimer: I am not a veterinarian and strongly advise you discuss any potential diagnoses and treatment options with your veterinarian first. This article is for informational purposes only. Riebel Farms LLC and its authors will not be held liable for any use of the information provided.

I think the most reliable resource for looking up medical information related to animals is the Merck veterinary manual. It is a free resource and it has A TON of useful information written by veterinarians. Most information in this article has been pulled from that website.

What is pinkeye (infectious keratoconjunctivitis) and what are the symptoms?

It is a contagious infection in the eye which leads to symptoms like eye watering, redness, swelling, and corneal ulceration and opacity (white haziness on the eye). A bacteria called Moraxella bovis is most commonly responsible for the infection, but there are other strains of the Moraxella bacteria (and other types of bacteria and viruses) that can cause it as well. Sometimes the infection can be so severe that an ulcer can form on the eye and the tissue will jut out from the normal contour of the eye. In very severe cases rupture can occur and blindness results.

highland cow with pinkeye highland cow with pinkeye highland cow with pinkeye

Risk factors for pinkeye.

Risk factors include UV light, dust, flies (transfer the bacteria from animal to animal), mechanical irritation (like getting a scratch on the eye from a plant while grazing), trace mineral deficiencies (copper or selenium), recent exposure to a sale barn or other animals (perhaps via shipping) that the animal is not normally around that could expose it to infectious agents.

Treatment for pinkeye.

-Sometimes the infection will improve and go away on its own, but at times it needs treated. The infection can worsen quickly, and over 48-72 hours the majority of the eye can become hazy. Haziness indicates severe infection and should most likely be treated.

-Don't forget to consider other reasons for symptoms that mimic pinkeye such as a foreign body (grass seed, worms, etc.) in the eye.

-In the United States, long-acting oxytetracycline (two injections of 20 mg/kg, IM or SC, at a 48- to 72-hour interval) and tulathromycin (2.5 mg/kg, SC, given once) are approved for pinkeye treatment in cattle per the Merck vet manual.

-Another useful treatment can be covering the eye with an eye patch (secured with glue to the hair surrounding the eye). The eye patch prevents sunlight from worsening the condition, and it also prevents flies from getting in the eye and spreading the infection around your herd.

-For very severe infections your vet can perform a bulbar conjunctival injection with penicillin (an injection in the tissues inside the lower eyelid). Please don't try this one yourself.

-There are also antiseptic sprays and topical oxytetracycline that can be applied directly to the eye. This is actually the approved method for treating sheep and goats, but requires three applications per day for several days and isn't as practical as a systemic injectable treatment for some operations.

Prevention of pinkeye.

-General aseptic technique should be followed when working with infected animals (wearing gloves, washing hands, disinfecting instruments between animals, etc.).

-Adequate shade should be provided for your animals to reduce the risk factor of UV light.

-Dust bags or insecticide-impregnated ear tags ("fly tags") can be used to reduce the number of flies that land on the animal's face and eyes.

-There are also vaccines that are available to help prevent pinkeye. The data isn't 100% clear, but anecdotal evidence suggests that the vaccine is helpful in reducing the number of cases of pinkeye in a herd.


For more information click the link below to go directly to the Merck Vet Manual website and the page regarding pinkeye.

Merck veterinary manual

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