Hymenoxon, a sesquiterpene lactone also found in bitterweeds/sneezeweeds is the principle toxin.
Sheep must eat from 50-150% of their body weight of green plant before being fatally poisoned.
A perennial or annual in some areas, with many branches, growing to 12-18 inches in height. The leaves are alternate, being stemmed at the base, and stemless higher on the plant. The leaves and stems are covered with hairs giving a whitish wooly appearence. The showy yellow flowers are produced one to a stem, there often being multiple flowers on the plant. Each 1-2 inch diameter flower has 25-50 ray florets, the rays reflexing with age of the flowers.
Loss of appetite, vomiting rumen cotents, that may appear as green staining around the lips and nose.
Reluctance to move, muscle tremors, and incoordination, followed by prostration.
Affected sheep recover slowly if they are given a nutritious diet, and prevented from eating more of the plant. The prognosis is poor for animals with inhalation pneumonia.
Rapid, pounding heart rate.
Coughing may indicate the presence of an inhalation pneumonia resulting from the regurgitation of rumen contents