Basil used to chase his leg when he got excited – breeders have the tails docked on schipperkes when they are very very young puppies because its a breed standard; schipperkes have curly-q spitz tails naturally. I think this practice originated with the canal boats to keep the tails from getting caught in lines; you can read one story here and another:

One final note on Schipperkes I found on The Breeds Of Dogs website: Schipperke legend tells of a shoemaker who, in 1609, became irritated at the persistent thieving of his neighbour’s dog and, after finally catching him at it, cut off his tail. The much-improved appearance of the mutilated thief supposedly was copied, starting the trend for docking. (www.thebreedsofdogs.com) – Shelly’s Pet Corner

I finally got a short, not so great, video of Iggy chasing his leg: