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Pinkeye in Livestock

Pinkeye (infectious bovine keratoconjunctivitis) is a common infectious disease affecting the eyes of livestock, typically cattle, goats, and sheep.  It has been estimated that U.S. producers lose $150 million per year due to pinkeye because of reduced weight gain, milk production, and treatment costs.


Pinkeye is most often caused by the bacteria Moraxella bovis also known as M. bovis.  Other causes of pinkeye are the virus IBR (infectious bovine rhinotracheitis), Mycoplasma bacteria, Chalmydia bacteria, and Neisseria bacteria.  Factors that increase the incidence of pinkeye are excessive UV light, flies, dust, tall plants, seed heads, hay, and some viruses.  These factors serve as a means of transmitting the bacteria from an object to an animal or from animal to animal, and may irritate the eye drawing flies or the bacteria itself.  Flies are the most harmful when it comes to pinkeye.  The fly will feed on the eye and nose secretions of an infected animal and then transmit the bacteria to an uninfected animal.  Research has shown that face flies can remain infected with M. bovis for up to three days following feeding on infected material.  

Signs and Symptoms:

The first, most common signs of pinkeye are excessive watering of the eye and squinting due to pain.  As the disease progresses the cornea becomes cloudy or white.  An ulcer will most likely develop in the center of the eye if left untreated.  In extreme cases the cornea ruptures and the eye fluid will leak out.  Temporary blindness usually occurs if the eye clouds over and a white scar may remain on the eye after healing, causing sight problems.

Young animals are the most susceptible to pinkeye because older animals tend to build up a resistance to the disease.  However, animals can become infected more than once so it is still important to take preventative measures in cattle of all ages.  


There are several ways to treat pinkeye.  Studies have shown that M. bovis is very sensitive to injectible medicines containing oxytetracyclines, ceftofur, penicillin, and sulfonamides.  Feed additives containing oxytetracylines also have been shown to reduce treatment time and severity of the disease.  It is suggested to contact your veterinarian before using any of these products to determine which one is the best treatment to use on your animals.


To aid in the control of pinkeye you should have a good fly control program using spray insecticides, dust bags or back rubs, insecticide-impregnated ear tags, larvacides, or fly traps.   Feed additives that target the maggots in the manure may also aid in fly control if fed early in the year.  Grass, weed and brush control by grazing, mowing, or spraying reduces pollen dust and mechanical irritation that increase the incidence of pinkeye.  Spreading hay out and not feeding hay containing mature seed heads can also reduce eye irritants.  Breeds of animals with little pigmentation around the eyes are more susceptible to pinkeye that animals with darker eyelids.  Vaccinating against pinkeye along with IBR and BVD viral diseases can also reduce incidences of pinkeye in herds.  Maintaining animal health and condition through proper nutrition, offering minerals year-round and a good vaccination program will decrease the incidence of disease.

For more information about pinkeye contact your local University of Missouri Extension in Madison County at 783-3303 or your local veterinarian.  The University of Missouri Extension is an equal opportunity/ADA institution.

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