What toxic compound is found in avocado leaves?

The toxic compound found in avocado leaves is persin. It is an oil-soluble fatty-acid derivative produced by the avocado plant and is especially concentrated in leaves, bark, and other parts that can be dangerous to animals.

Persin toxicity varies by species. Birds are particularly sensitive, while horses can develop colic, respiratory problems, fluid accumulation around the heart, and potentially fatal illness after consuming sufficient avocado material. Guatemalan avocado varieties are especially associated with toxic leaves affecting goats, sheep, and horses.

This fact is often confused with the safety of avocado flesh for people. Ripe pulp contains much lower concentrations and is generally considered safe for humans, although avocado can still trigger allergic reactions, including in people with latex-fruit syndrome. The pit and skin should not be treated as ordinary food for pets or livestock.

Persin is not cyanide, solanine, or oxalic acid. Its name is tied to the scientific name of the avocado, Persea americana, and the compound's animal-toxicity profile is the main reason avocado leaves matter in veterinary toxicology.