Veterinarians from the University of Melbourne are investigating whether kangaroos that appear to be “drunken” and “staggering” in central Victoria have suffered neurological damage because of a common pasture crop.
Wildlife rescuers have reported a spike in the number of eastern grey kangaroos that appear to have Phalaris “staggers”, a condition commonly seen in ruminants such as sheep and cattle that have been grazing on the new shoots of Phalaris grasses, particularly Phalaris aquatica.
“A kangaroo with full blown toxicity is just horrible,” Manfred Zabinskas from Five Freedoms Animal Rescue told Guardian Australia. “Their head flies around like they have got a broken neck; they summersault; they crash into fences and trees … they look like they are drunk.”
Phalaris, also known as canary grass, is a tall perennial grass with large seed heads that was introduced to southeastern Australia as a pasture crop and has historically been popular among farmers because it is drought tolerant, able to cope with salinity, and has an extensive root system that can be used to stabilise gullies and water courses.
But some farmers have moved away from the species because it causes phalaris toxicity, or staggers, a condition that can cause abrupt heart failure or a slower neurological decline in ruminants, particularly sheep.
In domestic animals, the condition can be managed by introducing copper into their diet and moving them away from phalaris on to a different food source.
But in wild animals such as kangaroos, the condition is believed to be irreversible.
“The kindest thing to do is to euthanise them,” Zabinskas said.
There is very little research into phalaris toxicity in kangaroos. A study published in the Australian Veterinary Journal in 2014 examined the brain and spinal column of seven kangaroos that had died after showing symptoms of the condition and found evidence of a “greenish discolouration” of the grey matter, consistent with signs of phalaris toxicity in ruminants.
One of the co-authors of the study was Pam Whiteley from the Melbourne University school of veterinary biosciences. She said it was too early to say whether kangaroos spotted staggering around by wildlife carers in recent weeks suffered from phalaris toxicity, but that the university would be conducting autopsies to try to confirm the diagnosis.
Zabinskas said there had been a marked increase in the number of kangaroos with apparent phalaris toxicity this year, possibly because of a greater than usual abundance of the crop.
Phalaris is found along roadways, in paddocks, in public reserves, and on the fringe of Melbourne around Craigieburn and Epping.
“You see some areas that are hectare after hectare of 100% phalaris growth,” Zabinskas said.
Karen Macartney, from the Wildlife Rescue and Information Network, said she was called to euthanise a kangaroo on Thursday, which had been attacked by a dog because it was unable to run away.
“They get to the stage where they are just helpless and they are open to any dog or fox or carnivore that comes along and has a bite,” she said.
Wildlife carers are trying to raise the profile of the issue with the department of environment, land, water and planning in Victoria and have asked anyone who sees a kangaroo exhibiting signs of phalaris toxicity to report it to the department first, before calling a volunteer wildlife agency.