Are Amazon Parrots Aggressive? How To Deal With One?

Our pet amazon parrot Emerald and dog have been been living together for years in harmony until recently. My parrot now started to attack and chase our dog who is well trained and tolerant of our pet bird. However, we are concerned of him snapping at the bird one day if the abuse continues.

Emerald climbs down off her cage to try to bite him and to chase him out of the room. She also does this to other family members or visitors. She never did that before. She seems to be jealous. She will even come after me if I stop her from attacking others.