Sugar free gum contains a chemical called xylitol which can be rather toxic to most non-human animals. In animals, it can cause liver damage and very low blood sugars. There have been some reports of this causing issues in rabbits as well, so it would be recommended for most animals that ingest sugar free products to get blood work done to check the blood sugar and liver function. At this point, if she has not shown signs of low blood sugar (abnormal mentation, lethargy), she will probably be ok. I'm willing to guess that the amount she ate is not enough to cause too many issues, but a trip to the vet might still be a good idea. You could always call first and see what their protocol is and whether or not they recommend coming in to get her checked out. They can also help you figure out if she ate a toxic dose. (Of course, check to see if the gum was sugar free first. If it does not contain xylitol, she should be fine and will pass the gum on her own.)
