FIRST: Blow the balloon up almost completely, leaving approximately 3" to 4" uninflated. Tie the nozzle, and twist as follows:
Twist three bubbles (about 2-3" each) for head (l) and ears (2 & 3), bring together and twist the ears onto the head bubble;
Twist off three more medium-sized bubbles (about 3-4" each) for the neck (4) and legs (5 & 6), bring together and twist the legs onto the neck;
Twist a long bubble (about 7") for the body (7) and two more bubbles for the back legs (8 & 9) (same length as the front legs), twist the legs onto the body, leaving a tail (10). Decorate eyes and mouth and nose with a Sharpie or other low alcohol marker.
Note: the actual length of any of the bubbles for the dog, or any other of the following animals is not written in stone. Each balloon does not always blow up to exactly the same length, so twist your bubbles proportionate to the overall length so that you don't end up running out of balloon or have too much left over! Once you've mastered the balloon dog, you can try out more advanced balloon animals.