Pinkeye, a highly contagious disease in cattle, can spread rapidly if not promptly addressed. This bacterial infection, which primarily affects the eyes, can lead to irritation, excessive tearing, and in severe cases, blindness. Given its mode of transmission through direct contact and flies, an outbreak can swiftly engulf an entire herd. Therefore, early detection and immediate action are crucial, as managing it becomes significantly more challenging once it takes hold.
While pinkeye can strike at any time, it often follows a seasonal pattern. Cases typically surge in the spring, peak during the hot summer months, and gradually subside by fall. This pattern is a result of the bacteria’s preference for warm, moist conditions and the environmental factors that contribute to pinkeye, such as dust, tall grasses, and an increase in face flies, which are more prevalent in the warmer months. Cattle with lighter-colored eyes, like Herefords and Charolais, are particularly at risk due to their sensitivity to sunlight, making pinkeye a significant concern during bright, sunny days. Understanding this seasonal pattern can help cattle owners prepare and take preventive measures in advance.
Once pinkeye sets in, treatment can be time-consuming and labor-intensive, requiring careful monitoring and medical intervention. Even mild cases can quickly escalate, so isolating infected cattle is crucial to prevent further spread. Quarantining affected animals not only protects the rest of the herd but also gives the infected cattle a better chance at healing without reinfection. The earlier you catch and treat pinkeye, the better the outcome—not just for the individual cow but for your entire operation.
What Causes Pinkeye in Cattle?
The primary cause of pinkeye is a bacteria called Moraxella Bovis. If an eye is damaged, this little guy will get into the cow’s eye, causing all kinds of problems.
Common Triggers:
- Face flies – They feed on eye secretions and carry the bacteria from cow to cow.
- Dust & tall grasses – These can scratch the eye, creating the perfect opening for infection.
- Sunlight sensitivity – Cattle with light-colored eyes, like Herefords and Charolais, are more vulnerable.
- Poor nutrition – Vitamin A, Copper, and Selenium deficiency can worsen pinkeye.
Factors like face flies, dust, and tall grasses can cause eye irritations, creating an entry point for the bacteria. Face flies, in particular, feed on eye secretions and carry the bacteria from one cow to another. This mode of transmission underscores the importance of controlling flies in your pasture to prevent the spread of pinkeye.
Some studies have also found that certain cattle breeds are more likely to get pinkeye than others. Herefords and Charolais are a couple of the breeds that are more likely to get it. This reason is due to the lack of pigmentation around their eyes and their increased sensitivity to sunlight.
Improper nutrition can also contribute to the outcome of this disease, and Vitamin A, Copper, and Selenium deficiency can make it more severe.
How to Spot Pinkeye: Three Stages of Symptoms
When it comes to pinkeye in cattle, the symptoms usually unfold in three distinct stages that give you clues about the disease’s progression. In the first stage, you might notice signs like excessive tearing, increased blinking, and a slight cloudiness in the eye. These early symptoms are subtle, so keeping a close eye on your herd for any changes is essential.
As pinkeye advances to the second stage, the initial irritation tends to worsen. The cloudy appearance of the eye may become more pronounced, and you might start seeing a spreading ulcer across the cornea, with new blood vessels appearing as the eye turns a noticeable shade of pink. In the final stage, the infection can become severe—ulcers may cover most of the cornea, inflammation spreads, and a pus-like substance can form, potentially leading to vision loss or even permanent damage if not treated promptly.
Stage 1 – Early Signs:
- During this stage, cattle will have excessive tearing
- Will also have an increased sensitivity to sunlight
- Due to the irritation and sensitivity, the cattle will tend to blink more than usual
- The cornea will develop a slightly cloudy grey appearance due to inflammation
- It can progress to a small ulcer, which will appear as a small white spot
Stage 2 – Getting Worse:
- Signs from Stage 1 will continue, but the ulcer will spread across the cornea
- The eye will become more cloudy in color
- Some of the dark colors of the iris can still be seen
- Blood vessels on the outside portion will begin to grow to make it appear pink (this is what gives the disease its name)
Stage 3 – Severe Infection:
- The ulcer covers most of the cornea
- Inflammation spreads to the inner part of the eye
- The inside of the eye will fill with a pus-like substance called fibrin, making the eye appear yellow
How to Prevent Pinkeye in Cattle
There have been many myths regarding pinkeye prevention because of the random nature of outbreaks and the many factors contributing to the disease. This has led to many different methods being used; some have been successful, while others have not so much.
Proper management that reduces the risk factors of cattle getting pinkeye is the best step to keep this disease at bay. When the disease doesn’t show up as much, the concentration of the bacteria will be reduced, thus lowering the chance of an outbreak.
Fly control in your operation is an excellent first step in controlling this disease. The problem with this is that face flies only live on the animal for a short time, making it difficult to do this. Taking care of the larval and egg stages, as well as the adult stages, is your most effective strategy. I go over the steps that you can take in controlling fly populations in a previous article, “How do you control flies on cattle?”
Another strategy is to keep your pastures grazed at the correct height. This strategy will prevent the grasses from reaching seed-head development, which will reduce the chance of eye irritation in your cattle. If you cannot keep the pasture grazed to the correct height, then mowing will work instead.
How to Treat Pinkeye in Cattle
Treating cattle with pinkeye early is essential to stop it from spreading throughout your herd. Catching the disease in its initial stages means you can use simpler, less intensive treatments before the infection worsens. Early intervention not only reduces the risk of severe complications but also helps minimize the overall labor and expense associated with treatment.
The treatment needed depends mainly on the stage at which the symptoms appear. In the early stages, a single dose of a long-acting antibiotic might be enough to control the infection. As the disease progresses, more aggressive measures, like additional medication and even protective patches, might be required to prevent further damage. Closely watching your cattle can help you identify the right time to step in and take action.
Stage 1
Treating the infected cattle with long-acting oxytetracycline, such as Bio-mycin 200 or LA200, will be very effective at this stage. The recommended dose is 4.5cc per 100 lbs of body weight subcutaneously or under the fold of the skin. A second dose given within 48 to 72 hours may increase the percentage that will respond to treatment.
It is also recommended that you put a patch over the infected eye. This patch will prevent other irritants from getting in there, making the problem worse. It will also help with the cow’s increased sensitivity to sunlight.
Commercially available patches will work well for covering the eye. If you do not want to do that, 5″ x 6″ blue jean patches cut to size with glue on three sides, leaving the bottom open, will also work. To ensure that the patch stays on, use cattle backtag cement to glue it in place. Just make sure not to get any glue in the eye.
Stage 2
Treatment for stage 2 pinkeye often continues with the same tetracycline dosage used in stage 1, which helps to control the infection. In addition to this, a bulbar injection can be very effective—this means administering a shot into the white part of the eye to target the affected tissues directly. This injection helps to ensure that the medication reaches the specific areas where the infection is causing damage, promoting faster healing and reducing discomfort.
Many producers have found success using either penicillin or dexamethasone in these bulbar injections. Penicillin adds another layer of antibiotic protection, while dexamethasone helps reduce eye inflammation. Both options work well to alleviate symptoms and support recovery, so your choice might depend on your herd’s overall health and your veterinarian’s recommendations. Monitoring your cattle closely after treatment will help you gauge the effectiveness and make any necessary adjustments.
Stage 3
At this stage, an oxytetracycline injection and bulbar conjunctival injection will be necessary. You will also need to place an eyepatch. Finally, the third eyelid of the cow will need to be sutured over the eye and closed.
Suturing the third eyelid over the eye will prevent debris or other irritants from getting in. It will also make the eye more comfortable, reduce excessive tearing, and possibly shed bacteria.
Another advantage of suturing the eyelid shut is that it supports a fragile cornea, helping to prevent corneal rupture.
Disclaimer: Any suturing should be done by a veterinarian or someone who has been adequately trained to do that so as not to run the risk of damaging the cow’s eye.
Michigan State has a publication that goes into more detail about cattle pinkeye if you would like to read more about it.
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