Dealing With Pinkeye in Cattle
Pinkeye or infectious bovine kerato-conjunctivitis was first diagnosed in 1889, and remains an economically important disease in cattle today. There are three different types of pinkeye. The first is a vitamin A deficiency which we only see in winter when feeding poor quality hay. The second type is viral. It is associated with IBR, and a good herd health program, with the proper vaccines given at the proper time, will prevent this type of pinkeye from occurring. The third type is bacterial and is spread by face flies. The best defense here is to control the flies and then keep the seed heads clipped off the pasture grasses. We clip to keep the stems, pollen, and dust from irritating the cattle’s eyes and making them water. Watery eyes attract face flies and make it more likely that if an infection gets started, it could race through the entire herd.
Ear tags, dusters, back rubs, face flips and feed throughs can be used alone or in combination to keep the fly population as low as possible. If your best efforts fail and pinkeye results, treat affected animals early and consider vaccinating the herd for pinkeye. An effective vaccine is more expensive than fly control, but much less expensive than a pinkeye outbreak.
Pinkeye is caused by the bacterium, Moraxella bovis, and the source being the eyes of carrier cattle. The carriers do not necessarily exhibit symptoms but serve as the source of bacteria for the rest of the herd. Face flies are the most prominent vectors in the spread of pinkeye. The greater amount of face flies, the higher the risk of pinkeye. Calves are more likely to be infected than adults. Calves born to heifers have more problems than those born to mature cows. Weather conditions may affect the amount of ultraviolet light the animal’s eyes are exposed to. Summer and fall are the height of infection, due to increased light intensity and fly populations. Wind, dust and pollen irritate eyes, making pinkeye more likely. Vaccinating cattle with IBR virus or any modified live vaccine during fly season may result in increased susceptibility to pinkeye.
Excessive tearing of the eyes and squinting to sunlight is the first sign, and when treatment should start to be most effective. Within 24 to 48 hrs. an ulcer will appear, and if left untreated, severe scarring, and ultimately blindness can result.
Long acting tetracyclines are the only labeled treatments for pinkeye. One injection of this product will generally result in fast healing, however, 2 injections are better, as they reduce bacterial load in the eye, limiting the spread of bacteria. Glue on eye patches are also useful, as they protect the infected eyes from sunlight, dust and fly travel, and will fall off on their in about 10 days.