MY DOG JUST ATE ONIONS?

There was this wrap with lettuce and stuff in it, including onions which are toxic to dogs, and my dog jumped up and took it. I found her eating it with nothing else lef but a little lettuce, the bread part, and 2 onions. (There were more) Shes a small dog. A toy poodle and a runt. What should i do ? Pplease help :(