Whether you’re experiencing above average rainfall or feeling a smidge like someone left the oven broiler on, the odds of flies being a frustration in your area this summer are good. Though face flies are certainly pesky to cattle, annoyance can transition to a real problem when flies spread illness through the herd. Looking for guidelines relating to identifying, treating and preventing pinkeye? We’ve got you covered.

Our team sat down with Brad White, veterinarian and director of the Beef Cattle Institute at Kansas State University, to understand how pinkeye develops and methods to keep cattle comfortable while they’re on the mend.

“We think about pinkeye in cattle because this is something that comes up every summer. As we talk through some of the issues associated with pinkeye, it’s important to understand some of the causes,” White says, stressing the benefits of knowing what leads to pinkeye and how it might present in the field. “One early sign will be squinting. Squinting or aversion to sunlight, maybe a lot of watering of that eye, but we don’t always see it that early.”

Pinkeye — or infectious bovine keratoconjunctivitis (IBK) — is essentially inflammation of the cornea, White explains.

“The cornea is the surface of your eye, which is very sensitive. If you’ve ever had a scratched cornea, it is a very, very painful thing,” White says. “Most of us don’t keep track of how many times a day we blink unless you have a corneal ulcer, but then you start keeping track because it’s very painful.”

When cattle are out on pasture, the chances of encountering some sort of debris or receiving a minor injury to the eye are always present. Later in the summer months, areas of the country that are dry can experience mature, stemy grasses. As cattle lower their heads to graze, they can scratch their eye on those stems.

“The surface of the eye is actually a pretty darn good barrier to bacteria unless it’s disrupted. And once it’s disrupted, that bacteria can set up shop, allowing that corneal ulcer to expand.”
— Brad White

Once the eye gets irritated, cattle can be exposed to bacteria associated with pinkeye. According to White, the most common bacterial cause of pinkeye is Moraxella bovis, followed by M. bovoculi.

“The surface of the eye is actually a pretty darn good barrier to bacteria unless it’s disrupted. And once it’s disrupted, that bacteria can set up shop, allowing that corneal ulcer to expand,” White stresses. “The other thing that I would throw in there that plays a role: sunlight and UV rays. Those can be challenging to that eye, especially if it’s damaged.”

Those bacteria can also be moved from animal to animal by flies. It’s important to distinguish which flies we’re talking about, as not all flies are created equal. Face flies in cattle look like a common housefly and typically land on the face (as one would probably expect from the name). The threshold for economic damage to livestock by flies can vary depending on who is asked, but we can all agree that any flies present can cause frustration to animals.

The heart of prevention

So, what is the No. 1 tip White has for producers to head off pinkeye? Get on top of your comprehensive fly-control program.

“When we think about fly control, there’s a lot of tools and techniques. I would encourage you to work with your veterinarian, talk to the extension folks and come up with a strategy,” White recommends. “The reason that I think a strategy is important is sometimes, and I find myself falling into this rut once in a while, that I am reactive.”

Perhaps flies have slipped your mind. One day a producer goes out to check cattle and realizes they have an issue. What happens at that point is that the producer treats their cattle, but doesn’t have a plan in place for further efforts. Without a plan and the correct equipment, producers may be spending money but not getting anywhere with overall control of flies.

The other issue with treating cattle for flies without a plan comes from a drug-resistance angle.

“Flies, like any other parasite, can build resistance to some of the chemicals that we use. One way that we can encourage resistance is by not applying the right dose or by not dosing the right animals at the right time,” White says. “A great example is fly tags. They can be an excellent tool for controlling flies when applied in a timely fashion, but they don’t last forever.”

Treating the breakthroughs

Despite all our best efforts, breakthrough of pinkeye can happen. There are options available to producers to treat symptoms.

“There are antibiotics that we can use, but you’re going to have to have a veterinarian-client-patient relationship (VCPR) to use those antimicrobials to treat this disease,” notes White, who classifies cattle into two treatment groups. “I broadly define pinkeye into two stages: Eye watery, really blinking and keeping that eye closed a lot, or, the presence of a big white opacity or whiteness to the outside of the eye.”

Catching pinkeye at an early stage gives producers a chance to lessen long-term issues. If we can treat those animals and manage the disease via medications, eye patches or isolating those individuals, we may be able to head off the infection before it develops further.

Once the disease progresses to later stages, you will see the big white eye typically associated with pinkeye. For cattle that are going to be feeder animals, this may be less of a concern. Though we certainly want to preserve their vision, producers will have some animals that end up with a white spot or a scar on that eye. Earlier treatment is therefore better.

The information above is summarized from the July 12, 2023, episode of Angus at Work. To access the full episode, including further information on prevention and treatment of pinkeye, click here.

Editor’s note:  [Lead photo by David F from Getty Images.]

Angus Beef Bulletin EXTRA, Vol. 16, No. 8-A