Don't worry too much if you planted it in the spring and it was growing well you should get new shoots from what is left of the base. A Brown Turkey that was shipped to me this spring was snapped off just above ground level by UPS during shipping, I tried rooting the top piece with no luck but what was left of the bottom sent out new shoots. You can always try your luck with the top part or parts of it, just check this list, there are several methods that others have used with success.
Go to the hardware store and get some heavy wire fencing with half inch square holes in it and put it around the trees. You could get some feral cats to roam around, the ones in our neighborhood seem to keep anything they can catch and eat in check.
Woody.

Try rooting some cuttings. The existing tree will probably send up shoots from the base. If you are OK with a bush, keep 3-4. If you want a tree, pick one and train it as a new trunk.

Take a black plastic container 1-2gallon size. Cut one side so you can wrap around the main trunk, centering the trunk in the middle of the bottom of the container (you may have to trim out a small opening from the bottom of the container to allow room for the diameter of the trunk).
Then tape the cut side of your container. Fill the container full of potting soil and gently pack, water, fill, pack, etc. Leave about an inch space at the top of the container for watering. Never let this pot dry out. Every couple of days, you should water the pot. In four to five weeks, you'll have a potted fig tree with roots.
At that time, cut the main trunk below the pot and separate.
Leave the remaining plant in the ground. In the Spring, you'll get shoots growing from the roots left in the ground. For added frost protection, place an 8-10inch mound of mulch over this area. Good luck. You should have two trees to work with in the spring. A potted one and the bush that will grow from the remaining roots in the ground.

Well, I'm not sure if my method will help you if your tree is completely dead from the chewed part upward. If your tree looks survivable except for some bark that is chewed at the bottom, then my advice still rates.