Identifying Plant Poisoning in Livestock

Poisonous plant intoxication is a common and often deadly problem costing the western livestock industry in the United States more than $340 million every year. Despite the costs and high frequency of occurrence, arriving at a positive diagnosis of plant poisoning in livestock is challenging. The purpose of this paper is to provide a framework to help range pro fessionals make an accurate, or definitive, diagnosis. We provide suggestions for investigating and sampling field cases of suspected plant poisoning, and for integrating important information. An essential part of making an accurate diagnosis is obtaining and understanding the animals, location, plant communities involved, and management strategies being used (Table 1). Compiling animal information such as type and condition of animals, age, sex, nutritional status, and vaccination history as well as identifying clinical signs, lesions, number of affected animals, and progression of disease are the first steps in identifying a cause. These find ings are critical because they will be used to direct the inves tigation. This background information should be included with all samples collected and when submitting samples to your veterinarian or diagnostician. This information is essential to all involved in helping make an accurate diagnosis. Once this information is gathered, a list of potential causes called a "differential diagnosis" should be developed. This list will be used to develop an investigative plan that will focus on confirming the right diagnosis and excluding all other possibilities. Making a complete and thorough list will require engaging appropriate experts (Table 2). The local veterinarian is a key player in this process. Many infectious, degenerative, and immunologic diseases produce clinical signs, biochemical changes, and lesions identical to those caused by toxins and poisonous plants. Local veteri narians will be familiar with disease conditions that occur in the area. He or she will also know other local or state