User blog comment:ANGELICBLOSSOMS/Any Ideas?/@comment-25156300-20190409030227

My first thoughts were a Lynx or a Bear (i.e. Sun Bear).

Other possibilities could be an otter, badger, or raccoon.

One thing to keep in mind is how they will do hand seals for techniques (if they have them). It would make more sense to have an animal that can at least rear back onto its hind legs to have its front feet available for weaving signs. So things like sheep or horses wouldn't fit as well. If the creature wouldn't have any techniques, or if the summoner does them, then it wouldn't matter (snakes, hawks, and slugs are used in canon and don't use hand signs).