If you're talking about your animal guide then you don't summon them, and you don't get to pick which one you want. Generally the best way to find your animal guide is through guided meditation where, if it wishes, your animal guide will make itself known to you. An animal guide generally represents lessons you need to learn and that it will help you with. It will often be something you least expect. For instance, mine is a great grey whale.
Animal guides are spirit entities that do not exist on the physical plane. You might be able to see your guide in your mind's eye, but neither you nor anyone else will be able to see them as physically present.
On the other hand, if you're talking about a "wolf companion" as in the Elfquest comics and role-playing game, that is nothing but fantasy and isn't going to happen.