Dogs can eat avocado flesh in small amounts, but it is generally best to avoid feeding them avocado because it contains a fungicidal toxin called persin, which can cause health problems. The highest concentrations of persin are in the leaves, bark, pits, and skin, which should always be avoided. While dogs are more resistant to persin than some other animals, large amounts of avocado or ingestion of the pit can cause stomach upset, vomiting, diarrhea, or even more serious conditions like pancreatitis. Avocado oil or processed avocado used in some commercial dog foods is safe at regulated levels. Overall, small quantities of the flesh might be okay, but avocados are not recommended as a regular dog treat due to the risks.