by Karl H. Kazaks
RAPHINE, VA – Pinkeye is one of the most common cattle diseases in Virginia. It’s also difficult to control, being a multifactorial disease.
Recently, the Rockbridge Cattlemen’s Association invited Virginia Tech’s Dr. John Currin to discuss pinkeye and how to manage it. The event, which took place at the McCormick Farm, attracted over 40 people from the regional ag community.
Pinkeye is a bacterial infection of the cornea. Cattle cornea are protected by a system of defenses, including tears, pigments, eyelids and the immune system. There are many factors which can lead to a breakdown of that protection system and increase the risk of pinkeye, including but not limited to sunlight, flies, dust, weeds and tall grass. Pinkeye is also more common in white-faced breeds.
The specific bacteria which cause pinkeye are Moraxella bovis, Moraxella bovoculi and Mycoplasma species.
Pinkeye occurs eight times as often in calves as in cows, so the economic impact of pinkeye is most readily measurable by identifying how it affects calves. Currin referenced a 2014 study which found that calves that suffer from pinkeye on average will weigh 20 pounds less at weaning weight than calves that don’t. Yearling weight may also be less in calves that suffer from pinkeye.
Treatment of pinkeye has been a challenge for the veterinarian community for decades, Currin said. Without treatment, roughly one-third of cases will self-heal, one-third of cases will heal but leave a significant scar and one-third of cases will lead to blindness or scarring. It’s clear that early treatment is more effective than later treatment.
Treatment can involve an eye injection, a subcutaneous injection or an eye patch. “If you use an eye patch, use lots of glue” to prevent the patch from being rubbed off, Currin said.
LA-200® is labelled to treat pinkeye, as is Draxxin®. However, there is evidence resistance is developing to Draxxin. It may be best to retain Draxxin for respiratory diseases and use a different treatment for pinkeye. There is no antibiotic labelled for pinkeye which can be mixed with feed or mineral.
If injecting into the eye, Currin advised, don’t stick the needle in the eyelid – insert the needle right under the membrane. Consult your vet to learn the proper technique.
Because pinkeye is a multifactorial disease, control requires a multifaceted approach. For example, you may choose to provide shade to eliminate sun stress, bush-hog to eliminate weeds and tall grass or take measures to control the fly population.
Face files feed off of the secretion of the eyes and noses of cattle and can damage the cornea when feeding. They can also transmit pinkeye. Thus, investing in some kind of fly treatment could play a role in reducing pinkeye in your herd. The strategies you use will depend on the specifics of your farm layout and operation.
There are vaccines for M. bovis but they require boosters, and the efficacy of the vaccine is compromised when cattlemen don’t utilize the booster. Studies vary in their conclusions on whether vaccines are positively effective in controlling pinkeye. More research is needed, and possibly new vaccines.
However, the random nature of pinkeye makes the disease hard to study. There may be a genetic component to the susceptibility of cattle to pinkeye.
For more information on pinkeye, check with your veterinarian or local Extension agent.