no facts here, just opinion. i think all animals are our spirit animals and each has its own energy to bring to the one it visits. they bring messages, protection - both physical and spiritual (cats are spiritual protectors - dogs more physical). even critters like spiders - if one visits you in a dream, it's showing you how to get yourself out of some kind of mess:) (untangling the web you wove:). i used to dream so deeply every night, all night, i couldn't wait to go to sleep to see what i was gonna dream!! felt like i traveled many universes as such, and most of the time there were animals, dif ones most of the time. so i don't think we're limited to one spirit animal. in reverse, if there is a need in your life, you can call on the energy of a particular animal to share it's gifts with you, and they do so if you pay attention