Pinkeye Treatment for Cattle

Livestock Update, June 1998

Dr. Dee Whittier, Extension Veterinarian,
Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech

Pinkeye is a bacterial eye disease that is very common in Virginia Cattle. It occurs most often during the summer but may occur any time of the year. Considerable economic loss occurs because of weight gain losses in calves and because of lost value of cattle who are left with eye scars or who are blind. Recent research data on pinkeye treatment should be considered by producers as they deal with cases of pinkeye in their herds this summer.

A study dealing with a natural outbreak of pinkeye in a herd of recently weaned Hereford calves was reported recently in the Journal of the American Veterinary Medical Association (Eastman et al. JAVMA Feb. 1998. 212[4]:560-563). 119 calves were divided into three groups when the outbreak began, separated from each other, and then treated in different ways. The three treatment groups were:

• Oxytetracycline : All calves in the group (with or without pinkeye) were given long acting tetracycline injections at the beginning of the trail. Calves with pinkeye were given a second dose of long-acting tetracycline 72 hours later. All calves in the group were fed alfalfa pellets containing oxytetracycline at a dose of 2 grams per head per day for 10 days. (Note: This level of antibiotic must be fed in a feed rather than in a mineral mix, water or other.)

• Subconjunctival penicillin : All calves with active pinkeye were given an injection of procaine penicillin G in the bulbar conjunctiva at the beginning of the trial and again 48 to 72 hours later. (Note the location of the injection! The bulbar conjunctiva is the thin membrane that covers the white part of the eye ball itself. When the injection is given a bulge is seen over the ball. Injections into the eyelid are not thought to have any value in treating pinkeye.)

• Control: No treatment given throughout the trial.

Calves were then observed about three times a week for the next 7 weeks. The number of calves with active pinkeye at each examination were recorded. The graph below summarizes the findings of the study. The combination of injecting and feeding an antibiotic cured most cases quickly and kept the number of new cases to a minimum. Eye injections cured many cases but new cases followed the treatment of cases.

The following are principles of pinkeye treatment that are supported by research evidence from this study and others.

• Oxytetracycline is effective in treating and preventing pinkeye when injected and fed at high levels.

• Treatment can be effective in bringing about earlier cures and preventing further eye damage.

• Early treatment is key to success.

• When an outbreak occurs, injecting long-acting tetracycline will stop the spread of the disease. One way to define an outbreak is when 5 to 10 percent of a group is affected.

• To prevent new cases from occurring long term antibiotics are needed (in this case feeding oxytetracycline at the rate of 2 grams per head per day for 10 days.

• Because face flies both carry the bacteria that causes pinkeye from one animal to another and irritate the eye, their control is crucial once pinkeye cases begin. Spraying cattle with a knockdown spray will prevent new cases of pinkeye.

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