F635
Pinkeye

Causes: This disease is caused by the bacteria Moraxella bovis (M. bovis). Many genetic and environmental influences can increase the chances of developing the disease. Some of these influences are listed below:

1. Exposure to excessive sunlight (ultraviolet light).
2. Animals with light hair on the head and lighter pigment of the eyelids and surrounding structures. (For example, white faced cattle.)
3. Horn flies, face flies, house flies, and stable flies.
4. Certain plants (long stemmed, coarse feed or hay), weeds (cheat grass), and feeding conditions (overhead feeders and large round bales).
5. Excessive wind, pollen, and dust.
6. Other bacterial or viral infections (IBR, Mycoplasma, BRSV, etc.).

Clinical Signs: The infection begins by causing swelling and redness to eyelid lining (conjunctiva) and surrounding tissues. The eye is very sensitive to light and may experience excessive tearing. These animals can have an increased temperature and often go off feed due to the pain associated with the infection. With time (2-6 days), the center of the eye becomes cloudy and an ulcer may develop. If the infection is severe, the entire eye can become involved, sometimes resulting in rupture of the eye, and/or blindness. One or both eyes can be involved and recovery usually occurs within 3-5 weeks.

Disease Transmission: Pinkeye is spread from animal to animal by direct contact with infectious material containing M. bovis. This infectious material can be spread by flies, animal-to-animal contact, buckets, hands, and equipment. Studies show that M. bovis is found in the eye and nasal secretions of infected animals and that some animals can harbor the infection for up to a year in the nasal cavities.

Prevention: Disease prevention for pinkeye focuses on five major areas:

1. Provide fly control - Fly tags, sprays, and dust bags.
2. Provide adequate protection from sunlight - Allow access to shade and protection from the sun. Select for animals that have more pigment around the face and eyes.
3. Maintain an environment free of irritation - This means keeping weeds, pollen, and dust to a minimum.
4. Vaccination programs - Many products are available that are labeled to prevent pinkeye infections. Responses to these vaccines vary from herd to herd and location to location; therefore, it is highly recommended that a local veterinarian be consulted regarding the use of these vaccines.
5. Maintain optimal immune status for the herd - All animals in the herd should receive adequate nutrition, be part of a thorough vaccination program, and be managed in a way to prevent excessive stress due to environmental extremes, handling, and other diseases.