On two cattle farms several animals showed constipation or diarrhea, d
ullness, hemolytic anemia and red urine after ingestion of Mercurialis
annua. In this case report the clinical symptoms and the results of b
lood examinations on those two farms are described. Treatment consiste
d in the removal of Mercurialis annua from the feed of the animals and
a symptomatic treatment of the most severely affected animals.