White snakeroot can endanger the lives of persons and animals other than those that have actually eaten the plant.
In cattle and sheep:
Although animals that have fed on white snakeroot may be listless and somewhat inactive at first, the first noticeable manifestations of poisoning are loss of weight and trembling following exercise. Trembling is especially marked in the muzzle and legs. As poisoning progresses, cattle lose appetite, become constipated, lose weight, and gradually become weaker until they are not able to stand. Additional signs may include a peculiar odor to the breath and urine, excessive salivation, and quickened, difficult breathing. Later, complete relaxation without tremors and coma are seen, with death following in 2-10 days.
The clinical signs that are exhibited by poisoned sheep are similar to those shown by cattle. Death may occur in a few days or may be delayed.
In cases of chronic poisoning, post-mortem examination generally reveals extensive degenerative changes in the liver and kidney.
The onset of clinical signs in white snakeroot poisoned horses is within 2 days to 3 weeks after initial ingestion (usually after at least several days of ingestion). The major effects are related to congestive heart failure. Tremors are inconsistently observed in horses with white snakeroot poisoning. Horses may stand with legs wide apart. Sweating may be evident especially between rear legs, and stumbling in the rear legs may be noted when horses are turned. Severe depression, bloody urine, and/or choking may also occur. Sometimes swelling is present in the lower neck area, near the thoracic inlet. They may exhibit a jugular pulse and a rapid heart rate. Changes in electrocardiogram include increased heart rate, ST elevation, and variable QRS complexes, and ventricular premature beats. Cardiac arrhythmias are often present.
In guinea pigs:
The refusal to eat by the animal is the first sign, followed by listlessnss and crouching with half-closed eyes. The hair becomes rough. Muscular tremors may not be noticeable, but complete lack of muscular coordination and stupor precede death. (White snakeroot poisoning, by R. Graham and V.M. Michael. Circular #436, University of Illinois College of Agriculture,1935.)
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Last updated: April 7, 2000
Please direct all comments or requests for information to M. Williams.