Think back to your childhood days. Were you ever entertained by a balloon sculptor? Was the shape that ended up in your hands or the child next to you by chance a sausage dog?
However internationally celebrated artist Jeff Koons has made a few balloon dogs himself, out of steel between 1994 and 2000 Blue, Yellow, Purple, Red and Orange. Notice I'm not using any images on here of any of those, but you can link through to see then.
The reason being that Koons has decided to sue a company that used the image of a balloon dog for their own bookends. Now if Koons had the intellectual copyright on the image of a balloon dog there may be a point in his case. But as I pointed out above he started making his balloon dogs in 1994, which is actually long after I started making mine (maybe I should counter sue). However, what is the true origin of the balloon dog. The 1975 book by "Jolly the Clown" Petri credits "Herman Bonnert from Pennsylvania at a magician's convention in 1939" as being the first balloontwister*. I have very little doubt that one of the first shapes he twisted looked like a little dog. So for at least 72 years there has been the image of the balloon dog in generations of peoples' minds.
If Koons had come up with a origional image for his sculpture, rather than reinventing an old one, he may have had a case. As it is he is clearly round the twist.
* Source Dewey, Ralph. Balloon History BalloonHQ Column (via Wikipedia)