So why avocados? It seems that the leaves, fruit, seeds and bark of the plant contain a toxic principle known as persin.
The primary concern is with gastrointestinal irritation, such as with cat vomiting and diarrhea. Typically, these effects are seen in cats and dogs that have ingested significant quantities of fruit or branches. Avocado ingestion causes more severe symptoms and even death in birds, goats and cattle.
Now I know what not to feed my Junior.