As the flies have started to descend, it’s time to think about pink eye again.
Pink eye, or infectious bovine keratoconjunctivitis (IBK), is a common eye problem in Australia’s cattle herd.
You’ll recognise cattle with IBK because they will have a watery or sometimes pus-filled discharge running down their face from the affected eye.
They’ll also probably be squinting because light coming into that eye causes pain and the eyeball itself will either have a blue appearance, due to the swelling of the cornea, and/or an ulcer (seen as a ‘divot’ out of the middle).
In severe cases the eyeball changes to a red or pink colour and starts to form a cone shape. These cases can result in rupture of the eyeball.
Just remember that IBK only affects the eyes, so if the cow has other problems — like a discharge from the nose or is off her feed — then there could be something else going on.
IBK is also a disease of herds, so we expect more than one animal to be showing signs.
Having IBK can affect the eyesight of cattle but also significantly affects their welfare. Cattle will seek shade to alleviate the pain of light entering the affected eye, and ruptured eyeballs require a vet visit to surgically remove them.
The total annual cost of IBK for southern Australia has been estimated to be $8.9 million, in terms of treatment, prevention, and production outlays (Cost of Endemic Disease Report 2022, MLA).
Traditionally, the main cause of IBK was considered to be the bacteria Moraxella bovis spread by dust, flies, woody herbage and close contact.
However, in recent years the way IBK occurs is now thought to be more complex.
Not only does Moraxella bovis have multiple strains, but other bacteria have also been identified as being involved in IBK outbreaks. These include Moraxella bovoculi, Mycoplasma bovis, Mycoplasma bovoculi and bovine herpes virus 1.
There is also increasing evidence around various risk factors playing a significant role, rather than just spreading of the causative agent.
Bos taurus breeds are more susceptible than Bos indicus breeds, while cattle under the age of two years are at greatest risk as well as those with properties with high dust and fly levels.
It’s a complex problem and there are many different treatment options, control options and prevention options available.
These range from eye patches, eye ointments and sprays as well as methods to control environmental dust and flies. Vaccines can also be part of the solution.
However, given we know that the cause is likely to be multifactorial, a vaccine won’t necessarily be the silver bullet we’d like it to be.
So, if you’re having a ponder about pink eye this summer, have a chat to your vet about some strategies to suit your farm and production system.
Dr Rosie Waite works for Scottsdale Veterinary Service in north-east Tasmania and enjoys the opportunity to talk cows and drive around the rolling hills. Rosie has spent time working along the northern coast of Tasmania at Smithton and Ulverstone, and has completed her Master’s in Dairy Science where her focus was the use of young dairy bulls.
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