Recent heavy rain on the North Coast has led to new cases of Yersiniosis or flood mud scours, with a handful of cases in the Richmond Valley and in the lower Hunter, following rain in July. The weekend's latest falls will only compound the problem and producers are advised to be on the lookout for the disease.
Two of the three Lismore area cases reported to LLS this winter were neighbours. Cattle were reported to be in excellent condition and alive the day before they were found, said North Coast Local Land Services District Veterinarian Phil Kemsley.
The fatal bacterial disease is a North Coast phenomenon, with British and European breeds dying quickly, while Brahman and Brahman cross take longer, and can show signs of poor condition before they die from toxic shock.
There remain many unanswered questions about the disease, said Dr Kemsley, but the main story is about the bacteria Yersinia, which multiplies in decaying plant material in cool, wet soil.
"This can occur in swampy areas, dam edges and in depressions in pasture; often known as melon holes," he said. "Outbreaks can also happen after floods in winter when flood mud sticks to pasture."
The bacteria can also be found around hay feeders where hooves have bogged the feed around its edges.
"The bacteria Yersinia likes low temperatures and low oxygen levels typical in poorly drained paddocks and grows in dry grass material contaminated with mud."
LLS vet based at Taree, Lyndell Stone said the cases in the Hunter were sporadic and tended to involve more than one animal in a mob.
"It is important cattle have access to hay in the cold weather as the breakdown of roughage in the gut gives them heat," she said."But we have seen disease outbreaks around self feeders so it is important to look at where these are placed and if there's too much mud then move them."
It doesn't take a flood to spark the disease with last winter's drought triggering a dozen cases on the Northern Rivers, as cattle explored the wettest parts of paddocks in a bid to get a green feed.
"Yersinia is unpredictable," said Dr Kemsley. "Last year during drought was the worst in 30 years. The disease has been well documented for decades but we are still learning.
He explained that Yersiniosis often presents as an outbreak with several cattle in the herd affected, making it critical to identify the disease early.
Adults are usually affected, sometimes weaners but never in calves.
Yersinia lives in the gut and is typically found there in low numbers. the trigger that causes the population to over run is not well understood. Signs of Yersinia can vary from fever to severe diarrhea resulting in dramatic weight loss.
"In some cases, affected cattle can be found dead despite having good body condition. Others have diarrhea for several days, which results in dramatic weight loss." Dr Kemsley said.
Cattle can be treated with an antibiotic if caught early. Moving mobs to higher country is the obvious solution but not always possible.
As the disease presents as a toxic shock, cattle show fever in the early stages but with septicemia in the blood stream they can hemorrhage quickly. Towards the end they get very cold.
It is a disease of the winter, with cases presenting from June to September with a rare case showing up in early November.
Dr Kemsley advises producers call their vet for advice. A diagnosis can be done on an old carcass as well as a fresh one, with samples taken from the gut and even dags on the tail.
It is crucial to have suspicious cases investigated by a veterinarian as the infection responds well to treatment with an antibiotic. If cattle loose body condition from the disease, the period of convalescence can be long, with animals needing supplementary feed to regain the weight.
"Human Yersinia infection from cattle is rare. As long as people wash their hands after handling cattle affected by the disease, it is not a threat to human health." Dr Kemsley said.
"It is a matter of being informed, but not alarmed."
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