As temperatures warm, flies begin to emerge. These flies bring all sorts of potential problems to the cow herd, including pinkeye. A highly contagious infectious disease, pinkeye affects cattle throughout the state of Florida. Pinkeye can cause substantial losses to the cattle industry through decreased weight gain, lowered milk production and treatment costs. Pinkeye is the most common condition affecting breeding age beef heifers, and the second most common disease of nursing calves greater than three weeks old.
The disease, also known as infectious bovine keratoconjunctivitis (IBK), is caused by the bacteria Moraxella bovis. However, viruses (e.g., bovine herpesvirus) and other bacteria that cause similar symptoms (e.g., Branhamella ovis, Moraxella bovoculi, and Mycoplasma bovoculi) have been identified. Pinkeye is caused by a combination of factors. Anything causing eye irritation is a predisposing factor for pinkeye, these include excessive sunlight, dust, pollen, face flies, weed and grass seeds, etc. These factors allow for invasion of M. bovis.
Prevention should begin with procedures to reduce initial eye irritation. Management practices that reduce the risk factors associated with pinkeye are the most effective tools in decreasing the incidence of disease.
Face flies are important vectors involved in the spread of pinkeye, as the irritated eye produces excessive tearing that attracts them. Face flies then pick up the disease causing bacteria and transfer it to other animals. Unlike horn flies, face flies spend very little time on the animal. So, one face fly can spread pinkeye to several animals in the same day. Therefore, it is critical to address control measures at the first sign of disease, if not before. A single fly-control program will not work on every operation, so it often takes multiple methods of control to achieve good results. There are several options for fly control, including fly tags, pour-ons, sprays, dust bags, back rubbers, fly traps and feed additives.
Tall grasses and coarse seed heads can irritate the eyes of cattle, causing them to tear and thus attracting face flies. A pasture management plan, including appropriate grazing and mowing, should be part of an overall pinkeye-prevention program.
Proper nutrition—low vitamin A, copper, and selenium can predispose and exacerbate pinkeye, so appropriate mineral supplementation is important.
When possible, provide enough shade so animals can limit their exposure to ultraviolet light without being overcrowded.
Currently available vaccines can be helpful. Typically vaccinations help reduce the incidence, shorten the duration and reduce the severity of cases but cannot guarantee total prevention of an outbreak. Consult your herd-health veterinarian about the timing of vaccination and which vaccine to use in your area. Many of these vaccines require a booster dose for greater efficacy.
Pinkeye can be successfully treated, but treatment must begin early to reduce the chance of permanent damage to the eye. Multiple products are approved to treat pinkeye in cattle. Also, there are other infections that look like pinkeye. Thus, it is important that you consult with your veterinarian to assist you in the diagnosis, treatment and control of pinkeye.
The best way to deal with pinkeye is to get ahead of it and stay ahead of it. Do this by using a broad-based approach that includes fly control, vaccination and pasture management. Pinkeye is an important disease of cattle, but with proper prevention and treatment programs, its significant economic impact can be minimized.