There are reports of horses dying in the Northern Territory after eating a poisonous plant.
Last year's bumper wet season is being blamed for the spread of the Indigofera plant in arid outback areas.
It was this plant which passed on the toxin Indospicine to a consignment of feral horses used in the pet food which caused dozens of dog deaths in Victoria earlier in the year.
The toxin is found in native plants of the Indigofera (Indigo) species across Australia, but the species that produces high levels of the toxin is found in northern Australia.
The toxin has been previously shown to build up in the tissue of some grazing animals when they continue to eat these plants and dogs are especially sensitive.
Horses and camels have been known to succumb to the poison as well.
ABC News is reporting a number of work horses on a station in central Australia have now died.
The cause of the deaths has not been confirmed but experts say the symptoms and presence of the Indigo plant points to the toxin again.
Until the deaths of the dogs in Gippsland earlier in the year, Indospicine toxicity had not previously been reported in Victoria.
More than 20 dogs are known to have died and dozens more became severely ill after eating pet mince in June.
An investigation found a consignment of feral horses from the NT to the culprit.
It has led to fresh calls for the Federal government to introduce laws to govern the pet food industry.
In Victoria, horses can be legally used in a knackery for use as pet food in accordance with the Australian Standard for the Hygienic Production of Pet Meat.
There are no indications of any risk to human health nor of human food safety issues associated with these cases to date.
In the NT, Indospicine is also known as Birdsville disease.
Indigofera is a low, spreading plant with a thick taproot that enables it to withstand drought conditions and respond rapidly to rainfall.
Horses and cattle are generally resistant to the effects of indospicine.
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