Pinkeye causes economic losses according to NDSU
Published Jan. 11, 2020
Pinkeye or infectious bovine keratoconjunctivitis (IBK) is common in the cattle industry and across the world.
According to North Dakota State University Extension (NDSU), “The economic impact of IBK in the cattle industry results from a loss in production due to increased medical treatment costs and injury from extra handling, reduced weight gain, decreased milk production and devaluation of sale animals due to eye disfigurement.”
According to Gerald Stokka, NDSU Extension veterinarian and livestock stewardship specialist, the bacteria Moraxella bovis is one of the primary agents cultured in cases of pinkeye. However, other bacterial agents such as Moraxella ovis and Moraxella bovoculi and mycoplasma species, among others, also have been isolated from cases of pinkeye.
Stokka notes there are numerous physical factors such as age and breed, UV light exposure, wind and pollen and pasture conditions that can also influence the occurrence of pinkeye.
Stokka continues, “The presence of other infectious organisms in the tissues surrounding the eye, as well as concurrent upper respiratory infections, can cause the pinkeye problem to be much more severe.”
Epidemiology
Stokka notes pinkeye is an infectious eye disease that is found in nearly all breeds of cattle throughout the world.
He notes some evidence indicates breed-related differences in susceptibility. Bos indicus breeds, such as Zebu and Brahman, seem to be more resistant than Bos taurus breeds such as Hereford and Angus.
He explains cattle with little or no pigmentation around the eye may also have a higher susceptibility of the disease.
“Summer and early fall are the peak seasons for pinkeye, although it has been reported in all seasons,” says Stokka. “This is the time when implicated bacteria can be recovered from cattle eyes at the highest rates. It also is the time when environmental factors that influence the development of pinkeye are at their peak.”
He continues, “M. bovis has different strains of and several different types within each strain. Each type of M. bovis has slightly different physical properties, yet all are capable of causing disease.”
“Immunity to one type does not mean the animal is immune to the other types of the organism,” says Stokka. “M. bovis has the ability to switch from one type to another and, in doing so, is able to evade the immune response that the animal may have to infection.”
He notes calves are much more susceptible to pink eye than older cows or bulls and animals that have been infected once are not likely to develop this disease again for more than a year.
“Environmental factors such as UV light, wind, dust, tall pasture grasses and weeds will lead to a higher rate of disease within a herd,” Stokka explains.
“Face flies are a very important factor in the spread of the disease within a herd. Flies pick up and spread the organism on their legs while feeding on the area around the eyes,” says Stokka. “The interaction of risk factors such as higher daily environmental temperatures and fly pressure tend to make cattle congregate into tighter spaces, allowing for easier transmission of offending organisms.”
He notes the presence of other organisms in the conjunctiva, the pink inside lining of the eyelid and covering on the eyeball, may increase the severity of the disease.
Clinical signs
Stokka explains clinical appearance of pinkeye can be varied. The rate of progression depends on the animal and it can infect one or both eyes.
“The earliest indication of a problem is an increase in tearing and squinting. Animals will have excessive wetness around their eye and down the side of their face, and be reluctant to open their eye,” Stokka explains. “If both eyes are involved, the animal may be hesitant to move.”
Stokka notes upon closer examination, producers may find the inside lining of the eye and the whire portion of the eye may appear to be puffy and read. As the disease progresses the clear surface of the eye may take on a cloudy or white appearance.
“An ulcer may develop in the cornea.,” he explains. “This is when the eye is most painful.”
“Healing occurs when blood vessels move into the normally clear cornea and the healthy corneal cells slide across the ulcer,” says Stokka. “If the ulcer is severe and deep enough, the eye can rupture.”
He notes, most infected eyes will heal in three to six weeks. Eyes that have been severely affected will have a white scar on the surface.
“These scars may fade through time,” he says. “Eyes that have ruptured may become blind and extremely disfigured.”
Treatment
“Good management practices may increase the rate of healing and decrease the spread of infection,” Stokka stresses. “Separating affected cattle and providing them a shaded area with accessible food and water lowers the animals’ stress and allows them to heal more efficiently.”
He notes antibiotic therapy, fly control and environmental management are the best methods of treatment.
“Moving cattle to a new pasture may decrease fly pressure and create more space between cattle.”
He continues, “Most bacterial pathogens implicated in pinkeye are susceptible to antibiotic therapy. Long-acting antibiotics with label claims for pinkeye include oxytetracycline and tulathromycin.
“No label claims are available for the treatment or prevention of pinkeye with the use of medicated feed antibiotics,” he says.
For dairy operations, show cattle or those used to being handled, eye drops or ointments are one method of treatment for animals that are in a confined space.
“Covering the eye with a cloth patch glued over the face may help make the animal more comfortable by decreasing the sunlight irritation,” he says. “More importantly, it helps decrease the spread of the disease by preventing flies from getting to the infected eye secretions.”
Skotta along with colleagues James Gaspers, Brett Webb and Neil Dyer published the publication titled, Pinkeye through NDSU Extension.
Callie Hanson is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.
