When Controlling Pinkeye, Prevention is the Name of the Game
Infectious bovine keratoconjunctivitis, AKA pinkeye. It’s common. It’s highly infectious. It can cause discomfort—even blindness. And, it’s probably impossible to totally eradicate. But, with the proper management techniques, you can help reduce its incidence—and your herd’s risk.
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Controlling pinkeye in your herd can be a constant challenge. This bacterial disease causes infection and ulceration of the cornea and inflammation of the eye and skin surfaces lining the eye (conjunctiva). If not properly treated, this infection can cause painful ulcers in the cornea and even result in permanent corneal scars and eyeball rupture leading to blindness.
To make matters worse, the condition seems to come back yearly, to varying degrees, when conditions are right for it.
It’s a disease that John Angelos, DVM, Ph.D., Associate Professor at the University of California, Davis, knows well. He has spent the better part of 10 years researching causes and potential treatments for this costly disease. He’s even helped to identify a second species of bacteria associated with some cases of pinkeye.
“The bacterium Moraxella bovis has been known to cause pinkeye for many years,” Angelos told Bovine Health Watch recently. “So far this new species Moraxella bovoculi that we first reported in 2007 to be in some pinkeye cases from as far back as 2002, has not been proven to directly cause pinkeye.”
He and fellow researchers at UC Davis identified and named the new Moraxella species while culturing eyes for an antibiotic efficacy trial in 2002. In addition to his research activities, Angelos works on the Livestock Medicine and Surgery Service at the Veterinary Medical Teaching Hospital, UC Davis and teaches food animal medicine and surgery to veterinary students.
Research has shown that Moraxella bovis attaches to the cornea with hair-like protein extensions called pili. It is believed that toxins produced by this organism then damage the cornea, leading to development of a corneal ulcer. Angelos said one of the first signs of pinkeye is tearing and squinting. Depending on the severity of the case, the associated pain from this eye disease can result in loss of gain and lost value in beef cattle. In dairy situations calves may also fail to gain; in addition, other losses might come from a producer’s inability to sell milk if a dairy cow is treated with antibiotics.
How and why do cows get it?
The Moraxella bacteria are spread in one of several ways, but by far the most common vector is a fly that feeds around the eyes and carries infected eye fluids from one animal to another. The disease can also be spread by humans, particularly when they are treating animals and fail to use gloves or disinfectants to prevent cross contamination between animals.
“Moraxella bovis can be isolated from the eyes and noses of normal healthy cattle,” Angelos said. “We think the Moraxella bacteria may reside in carrier animals in a herd. Then, when environmental factors that promote disease increase, the condition resurges. These risk factors are probably important in allowing the bug to cause infections that finally result in corneal ulceration and clinical disease.”
Risk factors for pinkeye include exposure to ultraviolet light (sunlight), dry conditions, dust, light skin around the eyes, and compromised immunity. All these things may increase the chances that a cow will develop pinkeye when exposed to the bacteria.
How is it treated?
Once cattle get pinkeye, Angelos said there are many ways to treat them and most involve antibiotic use. The protocols range from systemic antibiotic administration to topical applications in the eye or under the conjunctiva. Feeding antibiotics has also been shown to help reduce severity of pinkeye outbreaks in herds.
Only two drugs currently have official label claims for treating cattle pinkeye, he said. These include tulathromycin and the 200 mg/ml and 300 mg/ml formulations of oxytetracycline, such as Agrimycin® 200. Other antibiotics are known to be effective, but use of these drugs for pinkeye treatment is considered “off-label,” according to Angelos, who stressed that all treatment programs should be orchestrated by the herd’s veterinarian who can assess the situation and recommend the best treatment protocol.
Can you prevent—or at least minimize its incidence?
Since many of pinkeye’s risk factors are difficult—if not impossible—to control, prevention can be challenging. However, dairy producers can take several simple steps to reduce the risk.
Flies are important culprits to address, according to Angelos. Insecticide-impregnated ear tags can make cattle less attractive targets for flies. Some of these products can be used safely in lactating dairy cows.
Trace mineral supplementation can help promote healthy immune systems and potentially make herds less susceptible to pinkeye infections. Trace minerals such as copper and zinc are particularly important, though the mineral needs of each herd will vary, depending on the mineral content of the soil and forage in each geographic area.
When working cattle, sound sanitation practices can also help reduce the chances of pinkeye being spread by cattle handlers, Angelos pointed out. Wearing disposable gloves—ideally a fresh pair for every animal examined or at least disinfecting gloves between animals—is essential, as is the use of an effective disinfectant on instruments that come in contact with infected eyes or eye fluids. Clothing can become soaked with infected eye fluids, so wearing a plastic apron and disinfecting it between animals is also important. In addition, changing clothes before working healthy cattle or at least working with pinkeye affected animals at the end of the day may help reduce chances for inadvertently spreading the disease to healthy animals.
Vaccination is the main crux of prevention, Angelos contends, although producers can still experience variable results with today’s vaccines.
“Some producers find vaccinations more helpful than others,” he said. “The differences in perceived benefit from vaccination are probably related to Moraxella strain differences from herd to herd. Some herds may harbor a strain that is different from what is present in commercial vaccines, all of which are currently derived from the better known Moraxella bovis organism,” he explained. “Producers should consider using vaccines in conjunction with other control methods when developing a pinkeye prevention program,” Angelos said.
Where do producers fall short?
One area that often needs improvement is sanitary practices, according to Angelos. Sometimes workers treat animals without wearing gloves and/or disinfecting between animals, thereby helping spread Moraxella from animal to animal.
Another common mistake that producers make is waiting until pinkeye starts in the herd before vaccinating.
“They often wait until they see cases. We recommend vaccinating before fly season starts. It takes about a month to mount a good immune response, so we suggest starting a vaccination program about six weeks before you expect to see pinkeye in the herd. Don’t wait until you have a problem before you start to prevent it. That’s way too late.”
Pinkeye facts
√ Pinkeye is most common during summer months
√ Younger cattle seem to be more susceptible
√ Can be a painful disease
√ Can make cattle eat less
√ Affected cattle squint or hold eyes shut
√ Usually affects only one eye
√ Ulcer begins near the central part of the cornea
√ Ulcer may expand to occupy most of the cornea
√ It may erode the entire thickness of the cornea
√ It can cause edema, and “blue eye”
√ It can rupture the eye, causing permanent blindness
√ Recovery period varies; usually from 1-5 weeks
√ Pinkeye results in high annual economic losses
Pinkeye Risk Factors
√ Dry dusty environment
√ Sunlight
√ Flies
√ Lighter skin around the eyes
√ Trace mineral deficiencies that can compromise animal immunity
Progression of Clinical Signs
√ Excessive tearing
√ Frequent blinking or squinting
√ Decreased appetite due to pain
√ Corneal ulceration and cloudiness
√ Potential blindness or eye rupture
How to Reduce Chances for a Severe Pinkeye Outbreak
√ Vaccinate before there’s a problem
√ Minimize the presence of flies
√ Use disinfectants and disposable gloves when working pinkeye affected cattle
√ Promote optimal health and immunity
√ Provide mineral supplementation
√ Reduce dust
I-site Delivers Results for Neyer Farms—Without the Frustration
Bryan Neyer owns and orchestrates the management of five farms that milk 1,000 cows and raise about 3,500 heifers annually. So, any health product he selects has to be dependable and easy to use. That’s why he’s relied on I-SITE XP for pinkeye protection for the past two years.
After years of frustration with thick, gummy pinkeye vaccines, Bryan Neyer was ready for a change.
“I was looking for a pinkeye vaccine I could use on the young cow, but I also wanted something that was syringeable,” explained Neyer, who operates Neyer Farms, a family operation with five locations across two counties near Mount Pleasant, Mich. His brother works with him on the farm, as do his three boys, ages 13, 15 and 17. His mother and father are retired, but still live on the farm as does his wife, Yvonne.
With five different locations and operators, it’s essential that Neyer select products that are effective and easy to use. And, previous pinkeye vaccines didn’t fit that description.
“I had always had problems with pinkeye vaccines before and hated using them,” he commented. “They were thick and milky, and they gummed up the syringes. After two or three doses you couldn’t get the vaccine out, and you’d have to pull the syringe apart.”
So, when his drug supplier suggested I-SITE, Bryan was ready to try it. Two years later, he hasn’t looked back. He says I-SITE not only goes through the syringes easily, it also has protected his herd more than adequately from the pain and economic losses of pinkeye.
“Pinkeye can go like rampage when you get it started in a group. You can have two out of five easily if you are unvaccinated. We had a really good year last year; I didn’t treat much of anybody for pinkeye. I attribute that a lot to the vaccine.”
Of course other factors—including how bad the flies are—influence the incidence of pinkeye. Bryan says he uses rub strips, and insecticide sprays at one of his barns that attract a lot of flies.
He also recommends vaccinating early. “If you wait too long, it doesn’t work nearly as well,” he said. “If the flies are already out there, it’s much harder to get control of them at that point.”
In his part of the country, where the summer season is shorter, he uses I-SITE just once a year. But he uses it religiously—for economic and ethical reasons.
“Because we move cattle from farm to farm a lot, and because part of our business is selling cattle, we are true believers in vaccinating. We do it not only for the health of our cows, but all the herds we sell cattle into. This year we probably sold almost 900 cows. Most go right into the dairy herd to make money, so it’s important to vaccinate them to be clean and looking good. We never have complaints about our cows getting sick or getting their cattle sick.”
Fighting Those Pesky Flies: An Integrated Pest Management Program Can Help
It’s clear that flies contribute to a host of problems for dairy producers. One of those problems is pinkeye, or infectious bovine keratoconjunctivitis (IBK), which is caused by the Moraxella bovis and M. bovoculi bacteria. Pinkeye consistently ranks as one of the costliest diseases in California cattle according to John Maas, DVM, M.S., extension veterinarian at the University of California, Davis.
Pinkeye is especially problematic for calves less than a year of age, Maas emphasized, so it’s important to do everything possible to reduce their risk of exposure. There are a number of products and techniques that, while not approved for use with lactating cows, are safe and effective with calves and heifers—and cows on pasture before calving for the first time.
We can’t rid the world of face flies completely, but Dr. Maas says an integrated pest management program for dairy calves can keep them at bay and reduce economic losses from such conditions as pinkeye. Here are a few of the tips he shared with Bovine Health Watch.
√ Know your options. One of the most commonly used fly deterrents for calves is ear tags impregnated with insect repellent. But, there are also sprays and pour-on compounds, as well as fly baits. Fly baits, in fact, are safe, even around lactating cows, and can minimize flies near barns and corrals. Consider your situation and talk with your veterinarian to determine the best approach for your operation.
√ Plan ahead. Purchase insecticides and ear tags early, so that you are prepared for the upcoming season.
√ Alternate drugs. Regardless of the approach you take, it’s a good idea to switch the class of drug you use every year or two to address drug resistance. For instance, if you used a pyrethroid ear tag last year, try an organophosphate ear tag this year. Several new classes of ear tag insecticides have also been developed in the past few years.
√ Wait for the flies. To further prevent drug resistance, wait until the fly population is relatively high in the spring/summer before applying ear tags. Remove the tags in the autumn.
√ Don’t forget the larvae. Because fly larvae develop in cow manure, another control measure is killing the larvae there. Insect growth regulators (IGRs) are safe and less susceptible to resistance than other approaches. IGRs, such as methoprene, do not kill the larvae, but prevent it from maturing by mimicking a juvenile fly hormone. They can be purchased as feed-through products—which are safe for calves and heifers. Insecticides that actually kill the fly larvae are also available.
√ Consult your veterinarian. Always work with your veterinarian in selecting the best tactics and products for your situation. With the addition of many new products on the market, with a variety of active ingredients, this is particularly important.
√ Follow instructions. Always follow the manufacturer’s instructions, age recommendations, warnings and precautions for ear tags and all other fly control products. These products contain substances that can be toxic to you, your family and your pets, so always use gloves when handling them, and keep them away from food and food preparation areas.
√ Keep records. It’s important—and can save time in the long run—to record products, treatment dates and lot numbers.