Good start but you need to working on your fluidity. Your neck and head are disproportionate to the body and it jerks around as you did not take the time to animate it. Your legs 'pop' (your missing frames and they don't show a fluid motion.) A big thing to watch out for is the motion of the flank and back as well as the underbelly. Yours enlarges, pops and wiggles and overall just doesn't look right. It should follow a fluid waving motion as the shoulders dip down and the hind quarters rise and vise-versa as it cycles. Your tail, though it is not in full view, is all over the place. It should follow the same path of action as the back with a fluid waving motion or it could remain mostly static bobbing up and down slightly depending on what you're going for.
hope that helps.