A horseman washes down his horse float. Washing down and disinfecting horse equipment is an important part of minimising the spread of equine influenza.
The 20,000 doses will mostly be deployed in buffer zones in New South Wales and Queensland, but 1500 will be going to flu-free Victoria to inoculate horses participating in the lucrative spring carnival in six weeks, which includes the Melbourne Cup.
There are now 21,000 horses in New South Wales infected with the virus on nearly 2300 properties. Another 642 properties are considered suspect.
However, while new cases have been within containment lines, officials say the distance between some fresh outbreaks clearly points to a human element.
Human error is the most likely cause of the spread of the disease to Warwick Farm racing precinct. Confirmation of the disease early last weekend forced cancellation of the first public race meeting at Sydney's Rosehill since the outbreak began.
"There is now no question that many of the new infected properties in NSW are a result of people unwittingly transferring the disease," said the state's deputy chief veterinary officer Steve Dunn.
"As with the human influenza virus, equine influenza is easily spread."
NSW Officials have placed a restricted zone around a property near Armidale after confirmation two horses at Kelly's Plains had tested positive to the disease.
Armidale horse owners could expect to see new cases of equine influenza in the district if strict biosecurity isn't employed, said Mr Dunn.
"Horse owner vigilance is the key to stopping the spread. Horse owners around Armidale need to abide by the horse standstill and the recommended hygiene practices when coming into contact with horses."
Outside of the Armidale Red Zone, the remainder of the New England is an amber zone.
"The message is the same in the red and amber zones, as if you're near an infected property," he said.
"You can't move horses or horse products without a permit from your local Rural Lands Protection Board - and must report any horses showing flu-like symptoms to your local veterinarian," he said. "Don't allow your horse, or people who handle your horse, to contact other horses at this time."
Mr Dunn said the infected horses at Armidale had attended a campdrafting event held at Narrabri in August, and was already in quarantine based on its link to that event.
Meanwhile, in Queensland, the virus appears to spreading in Hendra, with three further stables understood to be affected. The discovery of the virus at Doomben has seen its racetrack, along with adjoining Eagle Farm, shut indefinitely. Both courses are just 7km from Brisbane's heart.
Racing is unlikely at either course until February next year.
There are reports that signs of the virus are emerging in horses at Deagon and Albion Park.
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