Sheep producers are being urged to be "on guard" for the incidence of footrot as continual wet weather dampens the southern states.
And there is a growing fear producers are declaring consignments sold on online livestock trading platforms "are free of benign footrot or scald", despite no assessment of the animals' feet.
Leading veterinarians and sheep health experts are warning farmers to be vigilant when buying sheep.
Elders senior livestock production advisor Rob Inglis said animal health experts are on high alert for increased notifications of the highly contagious foot disease.
"The wet weather and long grass is lending itself to the perfect storm for the foot infection," Mr Inglis said.
"Sheep numbers are building and there are a lot of sheep being traded.
"And a lot of sheep are traded online......vets aren't getting to see them, not like the days in the saleyards where there was an LLS vet poking around inspecting sheep.
"That just isn't happening as much now because there are so many sheep being traded out of saleyards."
Benign footrot has significant production impacts, especially under current wet conditions, where dense wet pastures could cause flare ups, causing lameness, pain and leading to declines in condition scores.
Central Tablelands Local Land Services Regional Veterinarian Bruce Watt said so far this season they haven't had any more notifications of footrot than usual, but the wet conditions is likely to amplify the transmission of the infection.
"We had a peak a couple of years ago, but we are getting on top of it now," Mr Watt said.
"At the moment it is not out of hand."
However, Mr Watt said sheep sold outside of saleyards through online platforms are always a consideration.
"In Victoria they don't regulate footrot so it is certainly more of a consideration there than it is in NSW," he said.
"I am not seeing a dramatic spike in the instance, but those sort of warnings are always relevant."
According to Nutrien Ag Solutions Bendigo livestock manager and A-Plus assessor Nick Byrne if you are not declaring footrot you are full of danger.
"You are not doing the right thing by yourself and you're not doing the right thing by the industry for the sake of a few bob on a pen of sheep," Mr Byrne said.
"I'd be disappointed if it was going on.
"It is different if you unknowingly know your sheep are carrying it......that could happen if they come from a property where they haven't been walking around in long grass and it's benign.
"But as an assessor I can only speak for myself and you wouldn't do it in a million years."
He said the infection is more prevalent in wetter years.
"The last two years, and it is shaping up to be the same again, there has been a lot of areas that are wet, or experiencing very good seasons, and sheep have been walking around in wet grass through the winter and spring," Mr Byrne said.
"We have had issues down here in the last three years on a particular place or two, where they have never had a problem before.
"A lot of it is scald, and the amount of zinc sulphate that we have sold through the shop in the last few years is ridiculous compared to five years ago."
He said as an agent and an assessor he has sold and bought a lot of sheep on AuctionsPlus and never had a problem.
AuctionsPlus uses the nationally accepted Sheep Health Declaration as its foundation of duty of disclosure for footrot in assessments.
Signs of foot rot include lame sheep, inflammation between the digits and under-running of the sole and heel of the foot.
In some severe cases sheep will lie down or walk on their knees.
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