I have never seen a dog chase its tail in real life.
I always assumed that it was one of those things used in cartoons and comics that doesn't actually happen.
This morning i was enlightened and delighted.
BTW, the title of this post comes from my all-time favorite Garfield comic strip.
(i think somewhere i still have the original that i clipped out of the paper when it was first published in the early/mid-80s)