What is Prussic Acid Poisoning?
Prussic acid does not occur freely in normal, healthy plants. Instead, certain sugar compounds called cyanogenic glycosides contain the cyanide ion (CN-) and only form prussic acid when degraded by certain enzymes. Living plant tissues can contain both cyanogenic glycoside (called dhurrin in Sorghum species) and enzymes (beta-glycosidase or emulsin) in separate cells. When plant tissues are damaged, such as by freezing, chopping, or chewing, enzymes can come in contact with the cyanogenic glycoside and produce prussic acid. Bacterial action in the rumen of cattle and sheep can also release prussic acid from glycosides. Prussic acid production is apparently more likely to occur in ruminants because both chewing and rumen bacteria release cyanide. Hydrochloric acid in the stomachs of horses and swine destroys plant enzymes that release the toxin. Sheep are slightly more resistant to cyanide than are cattle, and Hereford cattle have been reported to be less susceptible than other breeds.
