Why are acorns poisonous?
Acorns contain a substance called gallotannin. In the rumen, gallotannin is metabolized to gallic acid and tannic acid. Tannic acid causes ulceration of the mouth, esophagus, and gastrointestinal tract. Tannic acid is especially toxic to the renal tubules, and renal failure tends to be the hallmark of this disease. In the fall, this substance concentrates in acorns and increases the risk of animal poisoning when acorns are ingested.
