ABSTRACT
Toxic Principle and Mechanism of Action Many Prunus species contain cyanogenic glycosides, the primary glycosides being amygdalin (Laetrile) and prunasin.1 Prunasin is especially high in the new growth and in wilted or frosted leaves, while amygdalin is highest in the seeds. The ripe pulp of the berries surrounding the seeds is not toxic. At least 2000 plant species, many from the 27 genera represented in the Rosaceae contain cyanogenic glycosides, but relatively few have been associated with poisoning in livestock, and fewer still have affected household pets. The major sources of cyanogenic glycosides responsible for poisoning of ruminants are sorghums such as Johnson and Sudan grasses (Sorghum species), and a number of the Prunus genus. Ruminants are particularly sensitive to plant-induced cyanide poisoning because the cyanogenic glycosides are rapidly hydrolysed in the rumen by plant and bacterial enzyme action to produce the highly toxic hydrogen cyanide (HCN, or prussic acid).2 Simple stomached animals such as horses, pigs, and dogs are rarely poisoned by plant cyanogenic glycosides because their digestive systems lack the ability to rapidly hydrolyse the glycosides to HCN. Dogs are very rarely affected by cyanide poisoning from plant origin. There are a few occasions where dogs have eaten quantities of choke cherry leaves and berries and heavenly-bamboo (Nandina domestica) and developed cyanide poisoning.3,4
amygdalin,6 dogs that eat quantities of fallen apricots have the potential for poisoning, especially if the pits are cracked open to expose the seeds to the animals digestive system.
