Flies are a major pest for many reasons and in Kentucky’s beef herds they can be the source that spreads a serious eye infection among the herd.

Pinkeye is a bacterial infection of the eye that, if left untreated, can result in complete blindness, said John T. Johns, a beef cattle specialist with the University of Kentucky Cooperative Extension Service.

The biggest problem it causes for beef producers is decreased weaning weight. Research conducted by UK has shown that calves that have had pinkeye in just one eye weaned 30 pounds lighter than those without pinkeye. If the disease occurred in both eyes, it decreases weaning weight by 70 pounds.

“This is a significant factor in terms of taking dollars out of the pockets of our beef producers,” Johns said.

If blindness results, not only will the producer sustain a loss in weaning weight but also will receive a discount in price at sell time.

Treatment should be done to animals that develop pinkeye but prevention is the key, Johns said. Face fly control is very important. While flies do not cause pinkeye, they are the vector that spreads the bacteria from animal to animal. Preventing eye irritation from seed heads in overgrown pastures is also an important factor.

Providing good vitamin and mineral nutrition in both cows and calves is very important to allow them to mount an immune response and to fight off the disease, he said. Vaccines are also available and can be used, although there are several strains of the bacteria that cause pinkeye and not all the vaccines contain all the strains of the bacteria.

“Pinkeye can be a difficult disease to prevent but it is well worthwhile,” Johns said. “It is very costly to the producer not to try to prevent pinkeye in his beef cows.”