Why?

Why do dogs chase their tails? Seriously! Last night I watched as Kayla, the pug that I'm dog-sitting, enthusiastically went after her tail. It was really as if she didn't register the fact that her tail is part of her body...like it was independently bugging her. What an interesting and quite entertaining phenomenon...perhaps that is exactly why dogs were "programmed" to chase their own tails...for our entertainment! (P.S...the picture above is not actually a picture of Kayla, just a close facsimile!) :)