About 80 grow in New Mexico. Fewer than 20 are poisonous to livestock. Poisonous locoweeds contain a compound called swainsonine that affects animal growth, reproduction and the nervous system, Allison says. There's no treatment for livestock poisoned by swainsonine-containing plants. Animals that eat locoweed may run in circles, stagger or drool.
Cattle have a dazed, dull look in their eyes.
They start losing weight. Livestock that eat too much locoweed can eventually starve to death or become so weak that they're easy prey for predators like coyotes, he says. They become more susceptible to respiratory diseases and heart conditions. Locoweeds are rampant on the 14,000 acres that Snyder leases in Union and Harding counties. A Guide to the Common Locoweeds and Milkvetches of New Mexico, published by NMSU's College of Agriculture and Home Economics, helped Snyder pinpoint poisonous plants in one particular pasture.