Pinkeye management in livestock

What is pinkeye?

Infectious keratoconjunctivitis, or pinkeye, is a highly contagious bacterial infection causing inflammation and ulceration of the cornea that affects cattle, sheep, and goats. Cattle under two years old are highly susceptible to pinkeye.

The primary infectious agent causing pinkeye in cattle is the bacterium Moraxella bovis. In sheep and goats, pinkeye is caused by Chlamydia and Mycoplasma bacteria species.

Pinkeye can also result from physical irritation, such as from a sharp grass seed.

The infection can spread rapidly in the herd, leading to impacts on animal welfare, weight gains and milk production. Pinkeye can affect up to 80% of the herd, with potential consequences including:

• Blindness, which can lead to injuries.
• Loss of 3–5% of body weight.
• Decreased heifer fertility.
• Lower prices at sale and reduced selling opportunities.
• Increased labour to muster and treat, as well as treatment costs.

When to watch for it

There are many factors that contribute to the development of pinkeye, including:

• Other microorganisms
• Immune status of the animal
• Eye irritation from dust, tall grass, or thistles
• Flies
• Ultraviolet light

Flies are attracted to watery eyes, feeding on infected secretions and spreading the disease from animal to animal.

The disease typically begins with increased tear production, progresses to a cloudy cornea, and then to a swollen pink eye with a yellow ulcerated centre.

Clinical signs

Early signs of pinkeye include:

• Watery discharge from the eye.
• Increased sensitivity to sunlight (blinking).
• Redness of the membranes around the eye.
• Development of a white spot (ulcer) on the surface of the eye.
• Varying degrees of blindness in one or both eyes.
• Excessive tear production.
• Eyes appearing progressively more cloudy, inflamed and ulcerated.

Images show wet stains from discharge and advanced stages of pinkeye.

How to manage

Avoid unnecessary yarding of livestock, as this can exacerbate and spread disease. However, yarding may be required for treatment. To reduce risk:

• Wet yards to reduce dust
• Minimise time spent in yards
• Consider pour-on fly repellents or insecticidal ear tags during outbreaks
• Isolate affected animals early to prevent spread

How to treat

In cattle

• Topical antibiotics in the eye.
• Injectable anti-inflammatories.
• Injectable antibiotics depending on severity.
• Eye patches to prevent further trauma and UV exposure.
• Surgery may be required in severe cases.

Consult your vet to determine the best treatment option.

In sheep and goats

• Antibiotics targeting bacterial cell wall synthesis are less effective due to Mycoplasma lacking a cell wall.
• No vaccine is currently available for sheep and goats.

How to prevent

In cattle

• Reduce environmental risk factors such as flies, thistles, and dust
• Use the pinkeye vaccine Piligard®, which covers three strains of Moraxella bovis
  • Single dose
  • Administer 3–6 weeks before pinkeye season (usually late spring)
  • Suitable for cattle as young as 2 weeks old

Other mitigation strategies include:

• Avoid confining mobs to dry, dusty yards, laneways or paddocks
• Avoid grazing paddocks with significant grass seed or thistle burden
• Identify, treat and isolate affected animals
• Implement fly control strategies (pour-on, in-feed, ear tags, environmental controls)