Cyanide toxicosis in goats after ingestion of California Holly (Heteromeles arbutifolia)

California Animal Health and Food Safety Laboratory System-Toxicology Laboratory, University of California, Davis, CA 95616, USA. Cyanogenic glycosides are found in many native and naturalized plants throughout North America. The glycosides themselves are not toxic, but they yield hydrogen cyanide (hydrocyanic or prussic acid) when they are hydrolyzed by beta-glycosidases, either as a result of injury to the plant cells or by microbial action in the rumen. Hydrogen cyanide is readily absorbed from the gastrointestinal tract. Cyanide ion binds with iron in cytochrome oxidase, interfering with cellular respiration. The clinical effects are peracute, often resulting in death less than 1 hour after ingestion. This study describes a case that resulted in significant morbidity and mortality in a herd of goats after exposure to California holly (Heteromeles arbutifolia).