The spread of a rare plant have reportedly caused hundreds of sheep in Australia to exhibit bizarre behavior and die.
Farmers in New South Wales report that 800 sheep were poisoned after grazing on the Darling Pea plant, a purple pea-shaped flower with toxins poisonous to livestock.
The plant spread across the region after a massive bushfire -- which burned more than 130,000 acres of the Warrumbungle National Park and farms at Coonabarabran last January -- cleared a broad area of weeds and other plants and made room for the plant to grow, the Australian Broadcasting Corporation (ABC) reports.
Once ingested, the plant’s toxins take hold of an animal’s brain and attack an "enzyme involved in metabolism," Greg McCann, a regional veterinarian, told ABC.
"They lose the ability to judge where their feet are. They become wonky, fall over, appear to be blind, walking into things," he said.
The Sydney Morning Herald reports the poison gradually affects the sheep's central nervous systems.
"They lose weight to start with and then get staggery, the progression gets worse, they get uncoordinated and depressed, they don't know where their feet are and they become recumbent and die that way,” local vet Bob McKinnon told the outlet. He said the animals' behavior was "similar to that of a drunk."
“They just go to a post and bang their head on it till they crack their heads open,” Louise Knight, who runs a farm in central New South Wales with her husband, told The Sydney Morning Herald after losing 800 sheep. “It’s like dealing with a thousand heroin addicts.”
The plant, a member of the Swainsona species, is native to Australia. The first signs of its toxic effects on animals show up within weeks.
According to the Northern Territory Government, "[d]epending on the animal species and the amount eaten, clinical signs of ‘Swainsona’ poisoning may become evident within two to six weeks and progress to a chronic or fatal stage after eight weeks."
However, the poisonous effects of the plant may be reversed if the animal weans itself off ingesting the plant for several months, the report notes.