GRAZIERS impacted by the unprecedented north west flood are being urged to remain vigilant, with cattle that managed to survive the deluge continuing to be struck down.
Diseases such as three day sickness and botulism remain a threat in the region as producers struggle to recover from February's devastation.
GI Brahman stud owner and Muttaburra veterinarian Libby Harriman said ongoing health concerns remained for cattle that survived the initial catastrophe.
"Post flooding we had a lot of critically ill animals in that initial period, there was a reasonable outbreak of three day sickness but that seems to have run its course now," Dr Harriman said.
"But there's still ongoing health issues and we are getting quite a lot of random mortalities, particularly in the weaner group and even some older cattle."
Dr Harriman said a scheme available in northern Australia provided grants to allow vets to investigate unexpected mortalities.
Under the Northern Australia Biosecurity Surveillance Significant Disease Investigation Network, $2000 per case is available for vets to research unusual deaths or illness.
"As part of that network, any unexpected mortalities of cattle or unusual sickness symptoms is funded to do diagnostics to identify the cause.
"That's really important as even if people think it's three day sickness, we need to know that it's not some random virus blown in on the monsoon trough."
Dr Harriman said she had undertaken quite a few investigations and most northern vets had signed up to the scheme.
She said botulism remained a concern given the long period of time spores could remain in the soil.
"We've done a few investigations around botulism, it's one of those diseases that is more or less impossible to diagnose because only a tiny amount of toxin in the system can kill them, so it's about ruling out other causes.
"Botulism doesn't go away and the spores are generally found in the soil and multiply in rotting carcases, so even though people have done their due diligence and buried as many as possible, you can't bury every carcase, or dead kangaroo."
Dr Harriman said internal parasites like worms were also causing issues, with the prevalence increasing as the grass grew.
Virbac Australia veterinarian and technical services manager Matt Ball said botulism thrived in decaying animal and plant matter and the lethal toxin was likely to be present for years to come.
"The number of animal carcases made conditions ideal for the proliferation of the disease," Dr Ball said.
"With many cattle in recovery mode, survivors will be driven to chew bones to obtain vital nutrients."
Both vets recommended producers vaccinate any cattle with unknown vaccination status, and those that have not been vaccinated in the past two years.
Dr Ball said even after vaccination, only 70-80 per cent of cattle may be protected, with a range of issues affecting success including cattle missed in mustering or compromised immunity on vaccination day.
Dr Ball said with the higher risk, a booster should pick up the 20 per cent of animals that may still be vulnerable.