Just 24 hours after Betsy Bueno of Santa Rosa, Calif., began feeding her horses a new batch of hay, one colicked and began to show neurologic signs. Within days, two of her 12 horses required euthanasia and seven were showing similar clinical signs. "I thought they had gotten some poisonous hemlock outside," Bueno said. But her veterinarian asked to look at her hay. In the jumble of green material comprising a bale, it can be difficult for a ...