The quickly retreating long days of summer are the main culprit for pinkeye infections in cattle due to greater fly pressure around the face and pasture access potentially causing physical trauma to the eye. Yet other potentially causative agents and injuries that can occur year-round make it prudent to always have an eye out for infectious bovine keratoconjunctivitis (IBK).
“Pinkeye” is sometimes used as an overarching term for any disease of the eye, but IBK refers to a watery eye and an ulcer on the cornea, said Dustin Loy on an episode of the American Association of Bovine Practitioners podcast, “Have You Herd?” The professor and microbiologist at the Nebraska Veterinary Diagnostic Center explained that in classic IBK, the primary causative agent is the bacteria Moraxella bovis.
Other causative organisms include Mycoplasma bovoculi, which is often seen in calves, particularly ones also dealing with respiratory problems. “We think about Mycoplasma with respiratory disease, but there are Mycoplasmas that are host-adapted to the eye,” said the veterinarian. This bacteria is often present in calves; the question is what occurs to stimulate it to cause disease. These aren’t binary pathogens that turn off and on as they travel between animals, Loy said. Instead, he described that, “If it gets the right environmental signals, it might start making more toxins.”
In addition to pathogenic factors, John Angelos of the University of California, Davis noted that out-of-season pinkeye may result from copper and selenium deficiencies. This is mostly observed with beef cattle, but some research has been done on this topic with dairy calves. A deficiency in vitamin A may also be a concern. Perhaps most important for dairy producers is the risk of physical trauma to the eye by dusty bedding material.
“This is a disease you need to think of as multifactorial,” advised the professor.
Farms can attempt to limit pinkeye with vaccination. This may or may not be effective, the pair discussed. In general, making the decision to invest in a pinkeye vaccine depends on how widespread the problem is, what the cost is, and what other factors may be at play. Loy recommended evaluating other potential causes first.
“I don’t think vaccination is going to be the silver bullet,” Angelos agreed. However, you may see results if it is implemented appropriately. That means giving the vaccine enough time to elicit an immune response (generally four weeks before you expect to see cases) and utilizing a booster dose where possible, he said.
When pinkeye infections do occur, it can be hard to stop them from quickly escalating. “Timely treatment is underrated in these cases,” said Loy. Work with your veterinarian to determine an appropriate and legal treatment for individual cases or a herd-level problem. He noted that pinkeye injuries can take time to heal, so determine what stage of the disease an animal is in before treating them. Antibiotics will only be effective with active infections.
As an overall prevention strategy, Loy urged that records are a farmer’s friend. Keep track of when and how many pinkeye cases occur. This information will allow you to judge if things are better or worse this year and help you know when and how to prepare for next year.
