I agree with both Fallen and 239 on this one.
The third is actually a chakra that uses very acute energy at large bursts. When you work with it, it reacts with energy around it and allows one to percieve what's around them in a different way. Entities like your spirit animal, give off certain forms of energy that your third eye easily reacts with. However, your third eye needs to be in good condition, opened, and clean for you to successfully percieve anything. Remember to keep your mind open and relaxed when trying to communicate with your spirit animal.