Puppy!
I have to admit that it was really cool to see an ending where the poop went back into his anus. From what I heard, you actually do crap your pants after you die although that dog wasn't wearing pants anyway. The sad thing is that the dog would have crapped over everything regardless of what he had done. The animation was pretty good. There could have been some more action and more jokes. It still does a good job of delivering what you would expect in a cartoon about a dog not taking a crap.
It seemed like you were going for a Ren And Stimpy angle with how you were exagerrating the body movements. There was little time for personality other than that this guy doesn't like crap. The closeup of the dog's anus was a bit unnecessary. While not great, this is worth watching if only for the rewinding part at the end. It could perhaps use some better shading.