The common and highly contagious disease infectious keratoconjunctivitis (pinkeye) can affect cattle at any age causing considerable pain and distress with significant economic losses due to reduced weight gain or weight loss.
How do cattle get infected?
A major predisposing factor in the development of pinkeye is damage to the cornea. This typically arises due to dust, long grass or plant pollens. The resulting damage then allows the bacteria, Moraxella Bovis to colonise the irritated area and start to multiply producing the characteristic signs of pink eye. Flies then feed on the secretions and spread disease from one animal to another.
What do we see?
Typically, affected animals develop a photophobia so they are squinting their eyes, the eyelids are often in spasm and there is a discharge staining the face. As the disease progresses, an ulcer starts to develop on the centre of the cornea surrounded by a ring of inflammation. The cornea develops oedema which gives it a blue appearance interfering with vision. In severe cases the cornea can perforate.
The cornerstone of treatment involves the administration of antibiotics either directly to the eye or locally. Antibiotic powders have been used widely in the past but have now fallen into disfavour due to the irritation caused by placing powders in the eye. Antibiotic eye ointment is a simple and effective means of treating mild to moderate cases. Early treatment will minimise the risk of permanent scarring to the cornea and reduced weight loss associated with pain. In more severe cases, the vet may opt for an ‘eye flap’ – temporary surgical closure of the eyelids in addition to medical treatment.
Prevention and Control
Control flies by using products that are licensed for fly control in cattle
Avoid grazing calves on long pasture
Remove affected animals from the main mob
Consider vaccination of healthy animals in known hot spots
Pinkeye in Sheep
Pinkeye is also a very common ailment afflicting sheep and goats however, unlike cattle, the pathogen implicated in disease is a Chlamydia species as opposed to Moraxella. Outbreaks in NZ are generally mild and occur annually in adult sheep during summer and autumn. As with the disease in cattle, infection is spread indirectly by dust, pollen in grass and flies which have been contaminated by the secretions of infected sheep. Handling of the face and head of sheep when drenching may be an important means of spread. Treatment, if required, generally involves the use of oxytetracycline sprays or ointments.