More treatment is done in pasture cattle for pinkeye than any other diagnosis.  While pinkeye rarely causes death, it causes cattle discomfort and has considerable economic consequences.  Pinkeye caused by bacterium Moraxella bovis, most often occurs during the summer, but can occur throughout the year. 

A number of factors are involved in making animals susceptible to infection.  Some of the factors that are associated with pinkeye infection are: age of the animal (usually young animals are more susceptible); face fly infestation; irritation from plants, dust and pollen; ultraviolet light; nutritional imbalances (especially deficiencies in vitamin A, copper and selenium); as well as the presence of the IBR virus and mycoplasma.

Anything that transports secretions from one animal to another can spread pinkeye.  The face fly is considered the primary problem, the face fly feeds on the secretions around the eyes, which causes irritation to the cornea, and by moving from one animal to another spreads the disease throughout the herd.  Once an animal is infected the disease last 3 weeks or more depending on timeliness of diagnosis and the treatment regimen.  Treatment is often successful because the eye has a tremendous ability to heal, and because the organism is susceptible to many available antibiotics. 

Prevention is the best approach.  Face fly control is a good start.  Using multiple methods of control which include: fly tags, insecticide pour-ons, back rubbers, dust bags and knock-down sprays usually have the best results, additionally feed additives are available that target maggots that are laid in the manure.  A moderate to heavy infestation of face flies is 10-20 flies per animal during the middle of the day.  Managing pastures through proper grazing practices and clipping to minimize seed heads will help prevent the irritation of cattle eyes which can also help in controlling pinkeye.  A good vaccination program including vaccinating against Moraxella bovis and feeding tetracycline antibiotics in a supplement or mineral mix will improve the overall condition of your cattle and can decrease the incidence of pinkeye in your herds.  Pinkeye is an important disease in cattle, but with proper prevention and treatment, its economic impact can be minimized on your operation. 

If you are interested in learning more contact the University of Missouri Extension Center in your area or myself Jim Humphrey, Andrew County Extension Center, (816)324-3147 humphreyjr@missouri.edu