YEW, JAPANESE YEW
- Distinguishing features
- Yews are evergreen trees and shurbs that have flat, needle-like leaves , about 1 inch long. They grow in opposite pairs along twigs. A distinguishing feature of the yew is the red fleshy berry that forms a cup around a black seed.
- These plants are landscape shrubs with small, narrow, strap-like evergreen leaves that are two-ranked along the stem. The leaves taper bluntly to a point. The fleshy fruit (known as an aril) turns red when ripe.
- Animals gain access when trimmed hedges or shrubs are carelessly cast into pastures or when animals escape into landscaped areas.
- Toxic principle
- Taxine alkaloids (A and B) are believed to inhibit depolarization in the heart. The whole plant, except for the red aril (fruit), is toxic.
- This plant is highly toxic to herbivores. As little as 6-8 ounces of fresh yew may kill an adult cow or horse.
- Acute onset and sudden death are common. Often animals are found dead with no premonitory signs.
- Clinical signs
- trembling, muscle weakness, dyspnea, and collapse are cardinal clinical signs. Arrhythmia, bradycardia, and diastolic heart block appear to be the cause of death.
- Laboratory diagnosis
- some laboratories can detect yew alkaloids in appropriate samples such as rumen contents.
- Diagnosis often depends on finding evidence of yew leaves in the rumen or stomach contents.
- assisted respiratory and vascular support may be helpful
- detoxification measures, including activated charcoal and catharsis, should be promptly taken
- atropine may be helpful to combat the cardio-depressant effect of taxine, but must be given early in the course of the disease.
Read more in the Poisonous Plants of Pennsylvania Publication