"Toxic and noxious weeds have characteristics that make them very good at taking over pastures and other areas: they are highly aggressive, produce large numbers of seed or propagules, and are able to outcompete native, forage, or crop plants. They are also ecologically destructive by degrading habitat, waters, and have negative economic impacts.
The Washington State Noxious Weed Control Board created this booklet to assist in identifying some of the toxic plants that may affect grazing animals in Washington. This is not meant to be a comprehensive resource on all of the toxic weeds and plants that exist here; that information would fill a large volume. Rather, it is intended to help livestock owners recognize the most common ones, the symptoms they may produce, and methods for prevention and control.
While we have attempted to be as thorough as possible in descriptions and symptoms, it isn’t possible to list every detail here. This booklet is based on scientific articles and recent studies though plant toxicity is not always a precise science. Therefore, if you suspect toxicity from a listed plant, more research is always advised, and a consultation with your veterinarian is strongly recommended.
Prevention, of course, is always the best route to take if possible. Please take a look at the section on pasture management for methods and practices to help you achieve healthier pastures. There are many small (and some large) steps you can take to help keep your animals healthy."