COOPERATIVE EXTENSION SERVICE • UNIVERSITY OF KENTUCKY COLLEGE OF AGRICULTURE, LEXINGTON, KY, 40546

ID-135 Infectious Bovine Keratoconjunctivitis (Pinkeye) in Cattle Michelle Arnold, Veterinary Diagnostic Laboratory, and Jeff Lehmkuhler, Animal and Food Sciences

Introduction nfectious Bovine Keratoconjunctivitis conjunctiva retina (IBK), also known as pinkeye, is a costly cornea choroid diseaseI for the beef producer. Tremen- dous losses stem from poor weight gain iris sclera and loss of appetite in affected animals suffering from visual impairment and pupil lens ocular pain. The largest economic loss anterior optic nerve is incurred through decreased growth chamber suspensory as affected calves are on average 35-40 ligament pounds lighter at weaning compared conjunctiva to healthy calves. Lower performance in post-weaning cattle also has also been documented with reduced average Figure 1. Parts of the eye. daily gain, 365th day weight, and final weight. Additionally, the drug cost for treatment, decreased market value due to corneal scarring, the loss of value of effects of the disease. Prevention is based Contributing Factors show and breeding stock, and reduced on maximizing herd immune status, milk production from dairy animals also minimizing the presence of pathogens, Many different combinations of these make this disease a significant economic and maintaining an irritant-free environ- factors working together can occur consideration. ment as much as possible. within one herd at one time. The first reports of pinkeye appeared in 1889. More than a century later, despite UV Light or Sunlight all that is known about how the disease Cause Ultraviolet light or sunlight causes develops, control programs often are damage to corneal epithelial cells, allow- Pinkeye is caused by the bacteria Mo- only partially successful. In particular, ing the bacteria to penetrate the cornea raxella bovis. It sticks to the surface of the pinkeye vaccines are often ineffective in and multiply. Lack of pigment around eyeball (cornea) with hairlike projections preventing outbreaks during the sum- the eye allows increased UV radiation to called pili. Once attached, it releases a mer. It is important to understand that sensitize the eye, resulting in inflamma- toxin that kills the cells on the surface of many factors are involved in the develop- tion and infection. ment of pinkeye, including environment, the cornea, leading to the characteristic season of the year, concurrent diseases, corneal ulcers seen with this disease. Face Flies The organism is located in the eyes and the strain of bacteria involved, and the These pests contribute to pinkeye animal’s genetic makeup and immune nasal cavities of infected cattle. Cattle are the only known reservoir of Moraxella in two ways. First, they irritate the eye system. Once pinkeye begins, it is highly when feeding on secretions. Then they contagious and can spread rapidly within bovis, and infected carrier animals may harbor this organism year-round without efficiently transmit the organism from the herd. Control of contributing factors infected to non-infected animals. These and prompt, effective treatment in the showing any signs of eye problems. Once pinkeye begins in a herd, it is highly insects may harbor the bacteria on their face of an outbreak are necessary to re- wings and legs for up to three days after duce the spread and limit the damaging contagious and can spread rapidly by direct contact through nasal and ocular feeding on infected material. discharges and by vectors such as flies.

Agriculture and Natural Resources • Family and Consumer Sciences • 4-H Youth Development • Community and Economic Development EXTENSION Excessive Eye Irritation Clinical Signs Long-acting antibiotics, such as long- acting tetracycline or the prescription Irritation may be due to dust, trauma Pinkeye is a disease principally of the antibiotic tulathromycin, are labeled for or injury, wind, tall grass with seed heads, cornea. It occurs initially in one eye but treatment of pinkeye. Your veterinarian thick-stemmed hay, or high ammonia lev- may cross-infect the other eye. Onset of may prescribe the antibiotics florfenicol els. Grazing close to thorns, barbed wire, clinical signs may begin one day to two or ceftiofur to be used in an off-label and tufts of dry grass can scratch the weeks post-infection. manner for treatment as well. Injectable cornea. Pollen and seed heads, especially Pinkeye is characterized early by antibiotics are generally the best option in unclipped pastures, may injure the eye. tearing, overflow of tears onto the face, because of their long duration of activity When animals eat in to the middle of blinking, and squinting/seeking shade. and effectiveness in eliminating bacteria. round bales, the hay surrounding their These signs progress to corneal edema Topical sprays only remain in the eye a heads may contain stems, seed heads, (the eye becomes cloudy or opaque) and few minutes before tears wash them away, and dust which may cause eye irritation. central corneal ulceration (a circular pit so application is generally required three Any irritation to the eye allows Moraxella develops in the center of the eye), usually to four times daily to be effective. It is dif- bovis to invade and cause pinkeye. within 24-48 hours. ficult for any spray or ointment to remain Other Microorganisms Conjunctivitis (swelling and red- in the eye long enough to eliminate the ness of the tissues) of varying severity is bacteria unless treatments are repeated Certain viral diseases (infectious bo- sometimes seen. Cattle have decreased multiple times daily. vine rhinotracheitis or IBR and bovine appetite due to excessive pain. Some When severe ulceration exists, the viral diarrhea or BVD) and bacteria cases resolve spontaneously, however, eyeball may need extra protection with (Mycoplasma sp., Chlamydophila sp.) severe damage to the cornea can arise if either a patch or the eyelids may need to may be contributors to pinkeye in certain left untreated. In milder cases, corneal be sutured (stitched) together. Patches cases. They either can create the right damage might completely resolve within protect the eye from light, flies and other environment for infection or add to the two to four weeks. More severe corneal irritants but they remove the ability to severity of the disease. A newly isolated damage may lead to deep ulceration and monitor the affected eye. Suturing the strain of bacteria known as Moraxella corneal rupture, possibly with the loss of eyelids together will physically support bovoculi may play an important role in eye contents or a cone-shaped bulging the stability of the globe and offers pro- pinkeye but research has not confirmed of the eye. In contrast to other species, tection from irritants as well. Consult this. Other problems, such as physical cattle may retain all or partial vision after your veterinarian for assistance on how trauma or trauma due to squamous cell corneal rupture. Once the severe stromal and when to apply these extra protective carcinoma, may also predispose the eye defects have healed, a dense corneal scar measures. to secondary bacterial infection. may result that can last years. Stress Treatment Prevention Pinkeye is a complicated, multifac- Weaning, commingling, transport, Preventing spread by treating affected eted disease. It is said that “an ounce of poor nutrition, parasites, and weather are animals is the single most important fac- prevention is worth a pound of cure,” just a few examples of stressors for cattle. tor in controlling a disease outbreak. and nowhere is it more appropriate than Stress tends to decrease the animal’s im- Early detection of animals with the with pinkeye. The best plan is to reduce mune response to disease. first clinical signs (tearing, squinting, or remove as many risk factors as pos- Breed and blinking) and then prompt, effec- sible in order to keep the eyes healthy tive treatment are essential to reducing and better equipped to fend off disease. All breeds of cattle can be affected spread and limiting damage to the eye. If Prevention is based on maximizing herd by pinkeye, but some breed differences possible, isolation of the affected animal immune status, minimizing the presence have been reported. More cases have away from the herd also will help limit of pathogens, and maintaining as irritant- been reported in Hereford cattle. Lower the spread. In cases where a producer is free environment as possible. incidences have been reported in Brah- unable to treat new cases quickly, giving man-type cattle and in cattle with greater an injectable antibiotic to all susceptible Maximize Herd Immune Status pigmentation at the ocular margins. animals along with topical fly repellent An overall good level of nutrition, ad- Older cattle appear less susceptible to may be the best course of action to reduce equate vitamin and trace mineral intake, Moraxella ocular infections compared to the spread of pinkeye in the herd. a comprehensive vaccination program cattle two years old or younger. A higher Early and effective treatment with the including the respiratory viral diseases prevalence has been reported in male correct antibiotic reduces the duration IBR and BVD, parasite control, and basic cattle. of the carrier state, when spread usu- biosecurity practices are all exceptionally ally occurs to unaffected herd mates.

2 important in improving the cow’s or calf’s Minimize the Concentration of preferably when the eye is just begin- ability to fight off any disease process M. Bovis (and M. Bovoculi) ning to tear excessively and before any (not just pinkeye). There is no scientific medications are used. A recent clinical evidence to support feeding excessive Immediate detection and isolation trial of these “homemade vaccines” (au- levels of any vitamin or mineral, includ- of affected animals followed by effective togenous M. bovis vaccines) concluded ing Vitamin A, will prevent diseases of treatment with long-acting antibiotics these are often ineffective in controlling the eye. Biosecurity measures such as will shorten the period of corneal ulcer- naturally occurring pinkeye. Failure quarantine of new arrivals to the farm ation and speed healing time. Perhaps of the vaccine to present the “correct” (including show animals) for three weeks most importantly, treatment will reduce M. bovis antigen may make the vaccine before commingling with the herd are the duration of the carrier state when ineffective or induce a non-protective important in case any of these animals recurrence and transmission most of- response. Although there are reports of is incubating a disease. ten occur. Active cases of pinkeye with autogenous vaccine success, they cannot excessive tearing attract flies that spread be considered consistently effective. Maintain an Irritant-Free Environment the bacteria so topical application of a fly repellent to the face will help reduce Prevent eye irritation with good face Summary vector spread. Vaccination may help pre- fly control, mow tall grass, provide shade vent disease and eliminate carriers but Pinkeye is one of the most common and clean water, and reduce sources of vaccines are not consistently effective. diseases of cattle and is of major eco- stress (such as overcrowding/overgraz- Does vaccination work? Many differ- nomic importance in Kentucky. The keys ing) if possible. Control face flies with ent commercial vaccines against Morax- to prevention and control of an outbreak ear tags impregnated with insecticide ella bovis such as Piliguard, Vision 20/20, are maximizing the herd’s immune sta- and topically administered insecticides Alpha 7/MB-1, I-Site XP, Maxi/Guard, tus, minimizing the concentration of the by way of back and face rubbers or dust Pinkeye Shield, Ocuguard and SolidBac Moraxella bacteria, and maintaining as bags they must walk under to get to water are marketed for pinkeye prevention; due irritant-free an environment as possible. or mineral (see UK Extension Publication to strain differences, these may or may Treatment decisions are influenced by ENT-11, Insect Control on Beef Cattle). not be useful. Of 123 clinical trials, only numerous factors such as effectiveness of Removal of fly breeding grounds and the 48 trials reported significant protection the drug selected, cost, labor availability, use of certain feed additives will decrease from commercial vaccines. Therefore, it withholding times, facilities, and avail- the number of flies. Provide shade to pro- is unlikely that vaccination is the solution ability of veterinary support. Vaccines tect from UV rays. Clean drinking water to all pinkeye problems although it may are not consistently effective in disease (instead of stagnant pond water) is critical reduce the overall incidence of disease prevention and cannot be completely because intake is greater with clean water and severity of clinical signs. When com- relied upon to prevent pinkeye. The best and this helps provide plenty of fluid in mercial vaccines are not effective, some strategy of treatment, prevention and the eye, especially in dry, dusty, and/or companies offer “autogenous bacterins” control of pinkeye for a particular herd windy conditions. The precorneal tear which are vaccines made from bacteria is dependent on a thorough analysis of film is essential in eye defense mecha- cultured from pinkeye cases from one the current situation on that individual nisms as tears wash away pathogens and particular farm. All cultures must be farm and is best accomplished with the tear proteins are an important part of taken early in the course of disease; help of the local veterinarian. protective mechanisms.

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