Death Camas
Horses that consume 8 to 10 lbs (4 kg) of death camas (Zigadenus spp.) salivate and develop colic and incoordination and die within several days. There are approximately 15 species of death camas, which range from moist mountain valleys to drier sandy hills and plains. They appear in early spring, often growing amongst wild onion. They are herbaceous hairless perennials with grass-like, linear, V-shaped, parallel-veined leaves arising basally from an onion-like bulb 6 to 8 inches (15 to 20 cm) below the soil surface. However, death camas' leaves are not hollow like those of onions, nor do they smell like onions when crushed. The bulb is covered with a membranous black outer coat. The inflorescence, a terminal raceme or panicle, has small, perfect, greenish white to yellow or pink flowers. The six-numbered perianth segments are separated, each with a gland at its base.
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Several toxic alkaloids, including zigacine and zigadenine, are found in all parts of the plant, but especially the bulb. Sheep are most frequently poisoned by death camas, but cattle, horses, and pigs may be affected. Poisoning is most likely to occur in early spring when few other plants are available and the succulent shoots are especially enticing.
Sheep show signs of poisoning after eating as little as 1/2 lb (250 g) of the green plants. Convulsions, coma, and death occur if sheep eat 2 to 3 lbs of green plant per 100 lbs body weight (2 to 3 kg/100 kg). Poisoning may occur in horses after they have eaten about 8 to 10 lbs (4 kg) of the plants. Salivation, colic, muscular weakness, and a staggering gait are reported in horses, with death occurring after several days.
In most cases of death camas poisoning, little can be done to reverse the poisoning. Activated charcoal or kaolin/ pectin suspension may be given by stomach tube to decrease further toxin absorption. Supportive therapy and analgesics may be beneficial in managing the signs of colic.
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