The relevance of many mycotoxins to small animal health is difficult to assess, because available information has not been collated and reviewed. Only aflatoxins, penitrem A, and roquefortine have been confirmed in natural mycotoxicoses in pets. Effects of tricothecene mycotoxins, patulin, and penicillic acid on dogs and cats have only been studied experimentally and have not been confirmed in natural outbreaks. Although they make up only a small portion of the cases presented to veterinarians, mycotoxicoses often require special effort. Establishing an accurate diagnosis is crucial to minimize exposure and provide adequate treatment. In most cases, clinical examination, clinical pathologic testing, and analytical chemistry analysis of suspect feed are necessary to reach a diagnosis.