Bacterial diseases, pinkeye

(infectious bovine kerato-conjunctivitis or IBK)

Pinkeye, also known as infectious bovine keratoconjunctivitis (IBK) is a common, economically important, contagious eye disease of cattle with worldwide distribution. IBK is debilitating and painful for cattle. IBK impacts on animal welfare and can cause corneal ulceration, pus filled eyeballs, eyeball rupture, blindness, weight loss, injury and death by misadventure, thirst, or starvation (Figure 1). IBK can affect herd reproduction rates and workplace health and safety.

Despite much research into IBK, questions about the cause, epidemiology, treatment and control remain. The cow’s cornea is well protected against invading microorganisms. The main cause of IBK is thought to be the bacteria Moraxella bovis. Most academic effort on pinkeye of cattle has been directed towards the understanding of Moraxella bovis. Being a bacteria, appropriate antibiotic should be ideal treatment and control by quarantine and vaccination possible. This knowledge has not translated into major advancements in the treatment and control of pinkeye.

Rather than thinking of pinkeye as caused by a single organism, it may be better to consider the disease as multifactorial, and identify and control the range of risk factors. Predisposing factors for IBK include; traumatic eye injury, UV light, wind, dust, flies, close congregation, breed, age, stressors and Moraxella bovis. Pinkeye outbreaks are more common in young British breed cattle particularly in summer when feed is drying out.

Effective eye ointments are available for pinkeye. Cloxacillin ointments are long acting and should be applied every 2 days. Aerosols and powders to be puffed in the eyes are also available but require reapplication several times a day and are probably irritant to the eye. Kerosene, turpentine and other toxic products should not be used. Home remedies may appear to work but pinkeye is considered self-limiting, even without treatment it usually heals in 2 to 3 weeks, complicating claims of effectiveness. Injectable and oral antibiotics may be dispensed by your vet, as well as injections that go under the eyelids. Pain relief and anti-inflammatories may be indicated. Flies can spread Moraxella and may cause pinkeye themselves by traumatising the eye. Fly control may be very effective in IBK outbreaks. Eye patching can also help.

Vaccines against Moraxella have been made and one is available in Australia. Cattle should be vaccinated prior to an anticipated outbreak of IBK but this will only target Moraxella.

Not every case of pinkeye is IBK, nor contagious. Targeting a single cause may be unhelpful in a multifactorial disease. The steps critical to implementing good practice with pinkeye are:

  • Get a diagnosis, is it IBK or some other eye disease?
  • Identify and treat early and aggressively with appropriate treatments.
  • Implement herd control measures- segregation, patching, fly control, vaccination, remove trauma, move paddocks, slash stalky grass.
     

Figure 1. Examples of animals with pinkeye. Images courtesy of Mac Kneipp