Western Australia exports about 80% of its livestock and livestock products. These markets are underpinned by producers reporting unusual disease signs, abnormal behaviour or unexpected deaths in stock to their private vet, the local Department of Primary Industries and Regional Development (DPIRD) vet or the Emergency Animal Disease hotline on 1800 675 888. When producers report these disease signs, DPIRD can rule out any exotic or trade-sensitive diseases, which supports WA's continuing access to livestock markets.
Causes of pink eye
Pink eye occurs in cattle when:
- the cornea (outer surface of the eye) becomes damaged (e.g. by sunlight, abrasions, trauma, dust or dry conditions) and
- the bacteria in the Moraxella genus, most commonly Moraxella bovis, is present.
Pink eye most commonly occurs during dry conditions, especially in summer and autumn, when there are high numbers of flies present. The biggest spreaders of the bacteria are flies. The disease lasts from year to year when infected cattle become carriers of the bacteria.
Pink eye in sheep is caused by different organisms and does not spread to cattle, nor does pink eye spread from cattle to sheep.
The signs of pink eye include:
- increased blinking, streaming and watery eyes
- ulcers on the surface of the eyes
- cloudy opaque or white spots in the eye (from accumulation of pus and white blood cells)
- sensitivity to direct sunlight.
The number of affected animals can range from single animals up to 80% of a mob in severe outbreaks.
Market and welfare implications
Pink eye can cause significant production losses and impact on the welfare of affected cattle. Pink eye reduces the sale value of recovered cattle due to eye losses, scarring and blindness. Cattle with clinical pink eye are not suitable for export or to send to a saleyard. Cattle that are unable to see are not fit to load and must not be transported.
There are also reportable diseases that can look similar to pink eye in cattle that would have devastating effects on Australia’s market access and cause social and economic hardship if they entered Australia and were not reported to a vet quickly.
How a vet can help
Vets can help diagnose early cases of pink eye before they reach the stage of clinical signs or the ulcers seen on the eyes of seriously affected cattle. They can also recommend, treat and help teach appropriate treatment protocols.
There are some reportable diseases of cattle that have similar signs to pink eye. A vet can take samples for laboratory testing that will help rule out any reportable diseases, which supports WA's ongoing access to livestock markets.
Some important diseases that look like pink eye in cattle
- malignant catarrhal fever (MCF) (wildebeest associated) – reportable animal disease
- eye cancer (squamous cell carcinoma)
- infectious bovine rhinotracheitis (IBR)
Treatment of pink eye
There are a range of products and treatments for pink eye. Your private vet can advise on suitable options and provide information on how to control or prevent any further disease.
It is important to treat both eyes in affected cattle, even if only one eye is affected, as the chance of cross-infection between the eyes is high.
In early or mild cases, topical eye ointments may be used. More severe cases may require veterinary intervention where the skin surrounding the eye is injected with an antibiotic sometimes mixed with an anti-inflammatory.
It is sometimes recommended that a course of antibiotics is injected intramuscularly to help treat clinical cases and to eliminate carriers of the disease.
Where rupture of the eye is a concern, covering the eye with an eye patch or having a vet temporarily surgically close the eyelid is recommended.
Appropriate withholding periods (WHPs) and export slaughter intervals (ESIs) must be observed for any treated animals.
Prevention and control
Prevention of pink eye is preferable to treating the outbreak. Control measures include:
- isolating affected cattle
- preventing overcrowding and unnecessary yarding during high-risk months
- controlling flies, which may include the use of registered insecticides and dung beetles
- reducing dust and controlling environmental factors where practical when cattle are yarded (e.g. use of sprinklers in yards significantly reduces dust when working cattle in yards)
Currently there is only one vaccine on the market in Australia to help prevent pink eye in cattle. It needs to be used three to six weeks before the pink eye season and annual vaccination is required to maintain immunity. Use the vaccine in conjunction with advice from your local vet. If the vaccine is used in the face of an outbreak of pink eye, results can vary.
For more information, contact your private vet or DPIRD field vet.