Credit: Larry Allain, National Wetlands Research Center USGS.
The plant is not very palatable, but will be eaten by animals with no other forage; poisonings typically occur from ingestion of green plant material or material in hay. The toxic components can cause liver failure, referred to as "walking disease" or "sleepy staggers". Signs include weight loss, weakness, sleepiness, yawning, incoordination, yellowish discoloration to mucous membranes (icterus), neurologic problems secondary to liver failure (aimless walking, chewing motions, head pressing). Animals may appear to be normal at first, then become suddenly affected; the syndrome progresses rapidly over a few days to a week.
Toxic to Horses