Causes The infectious organism most commonly isolated from the eyes of cattle affected with pinkeye is Moraxella bovis . Veterinarians have also found that Mycoplasma bovoculi and IBR virus are capable of causing an eye infection resembling pinkeye. Environmental and nutritional factors contribute a great deal to the development of pinkeye. The ultraviolet component of sunlight is necessary to initiate the disease. Irritation from weed and grass seed that get into the eyes during grazing contribute to the infection, or may initiate or simulate pinkeye.
Dust is also a factor.
Vitamin A deficiency and inadequate protein intake may be factors that possibly contribute to lessened resistance to eye infections. The face fly has been associated with an increased incidence of pinkeye in recent years. Research at the University of Nebraska's North Platte Station has demonstrated that face fly feeding produces mechanical injury to the conjunctiva and spreads IBR virus and Moraxella bovis from animal to animal as the fly feeds on eye and nose secretions of cattle. The infection can also be spread by direct contact when the eye secretions of an infected animal are rubbed into the eye of an uninfected animal. Control Pinkeye is caused by a combination of factors.