Diagnosis of a toxicosis, as with any disease, is based on history, clinical signs, lesions, laboratory examinations, and in some cases, analytical procedures. Circumstantial evidence is valuable and should be noted but does not replace a thorough clinical and postmortem examination. Histories from animal owners may stress obvious factors and omit subtle, important details. “Sudden death” is often actually “tardy observation,” or sometimes the animal is simply found dead.
Pertinent data and samples should be submitted to the diagnostic laboratory. A complete history is necessary to develop the scheme of laboratory investigation and may be valuable in case of litigation. Information should be detailed. For example, a notation of CNS signs is insufficient; most animals exhibit some type of CNS signs before death. Exact actions and signs should be described. Examples of pertinent information include the following: 1) number of animals exposed/sick/dead, age, weight, and a chronology of morbidity and mortality; 2) clinical signs and course of the disease; 3) any prior disease conditions; 4) lesions seen at necropsy, with careful examination of ingesta; 5) response to treatment (medication should be listed to avoid analytic confusion); 6) related events, eg, feed change, water source, other medications, feed additives, pesticide applications; 7) description of facilities (a drawing or digital photograph may be helpful), access to refuse, machinery, etc; and 8) recent past locations and when moved. The diagnostic laboratory should be contacted if there are questions regarding the appropriate sample, amount, or container. (Also see Collection and Submission of Laboratory Samples.)