While pinkeye is seldom thought of as a costly problem because it rarely cause death, it does cause eye irritation, pain and occasionally blindness along with reduced feed intake.
“With losses in average daily gain due to a case of pinkeye [in dairy heifers] estimated at 20 to 40 pounds, animal performance suffers greatly from just a single case,” says Morgan Adkins, a graduate student with the University of Georgia’s College of Veterinary Medicine (UGCVM).
“Perhaps one of the most frustrating parts of this disease is not knowing if or when a herd will be affected,” adds Brad Heins, a veterinarian with UGCVM. “Even if a herd has been free of it for years, flies may come from a neighboring pasture carrying new strains of the organisms and cause an outbreak of disease.”
Initial signs of pinkeye include excessive tearing, sensitivity to light, and redness on the white portions of the eye. Treatment options include long acting antibiotics, eye patches and even surgery. If antibiotics are used, treatment records need to be maintained so that appropriate withdrawal times can be observed.
Prevention is a better option. Fly tags are commonly used, but it’s important to rotate tags annually so that resistance doesn’t occur. There are three types of tags available: Organophosphates, which should never be used on lactating cattle; Pyrethrin or Synergized Pyrethrin, and Abamectin.
“Additionally, new combination tags have become common in the market which contain two or more classes of chemical targeting flies,” says Heins. “These tags, while usually effective, do speed the rate of fly tag resistance due to dual chemical exposure.”
Pour-on insecticides or back rubbers can also be used to reduce external parasites. And insect growth regulators might help in decreasing the number fly generations that occur over the summer.