The best way to keep pinkeye out of your cattle herd continues to be through vigilance and sound management.
Known to the scientific community as infectious bovine keratoconjunctivitis or IBK, pinkeye is caused by infection with the bacterium Moraxella bovis. The organism can be carried by flies, and animals spread it via secretions. For it to develop, pinkeye requires irritation, whether through face flies buzzing around the eyes or from the weeds, dust and UV sunlight in the animal’s daily surroundings. The organism is constantly mutating, with at least 20 known strains; that’s reduced the effectiveness of vaccination.
The infection runs four to eight weeks; the initial symptoms are excessive weeping of the affected eye or closure due to pain. The eye then clouds over, and a blue spot forms on the cornea; this can lead to a scar or even a rupture, interfering with vision or blinding the animal. Dr. Clint Krehbiel, professor of beef cattle nutrition and health in the Department of Animal Science at Oklahoma State University said, “You’d have to catch it very quick and get an antibiotic in the animal to prevent long-term damage,  so producers that are paying close attention probably get by okay. But for those who let things slide too far, it can definitely be problematic.”
“The jury’s out on how effective pinkeye vaccines are,” University of Missouri Extension Veterinarian Dr. Craig Payne told Ozarks Farm & Neighbor. “Not to say that they can’t be, but some of the studies that you’ll come across will show benefits and some will not.” He said there are other things going on that will contribute to that variance; among those are the presence of other diseases or stresses that could weaken the animal’s immune system.
Similarly, Payne said there are conflicting data on the value of vaccinating animals in a herd that’s already been exposed. “Once you give the vaccine,” he said, “there’s going to be a period of time for the animal to process that vaccine and develop the immune response, whereas if the animal is already infected, we know that they are already in the process of generating antibodies to fight off that bacterial infection.”
Most commonly, antibiotic treatment only takes place when the animal is displaying clinical signs of pinkeye. Payne said he’ll occasionally hear of producers with a significant number of cattle breaking with the disease who proceed to treat the whole population, but that raises the issue of timing. “If that vector is not present in the eye for the antibiotic to get to and kill off,” he said, “that antibiotic’s only going to hang around for a couple of days. So, it’s still possible that the animal comes down with pinkeye.”
White-faced breeds like Hereford are more susceptible, because the lack of pigment in the eyelid exposes the eyes to UV light.
The key, he said, is to practice good management. “If, for example, you’re in a pasture with a lot of brush and a lot of coarse weeds or roughage, there’s always eye injury that can set-up a precursor for an infection,” he said. “The producers know where their bottom-line comes from and hopefully do pay close attention.”


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