Your baby is simply developing her prey drive by chasing and nipping at things just as she did her littermates - she doesn't know better. To her, it's entirely natural and indeed it is instinctive for young pups to nip, bite and play aggressively in order to develop their prey drive.
Here is a similar training method to one I use but I usually just say "yes" to mark an approved behavior in place of the clicker as young toy puppies sometimes fear a clicker or its sound when young but use one if you dog is okay with it. This trainer teaches a fun-loving, normal, nipping puppy how to gain some control and avoid this totally normal puppy behavior from becoming part of his routine behavior as he grows older, though most grow out of it whatever you do or don't do as they age unless they are highly prey-driven or dominant.
ClickerSolutions Training Articles -- Biting Pant Legs & Ankles
Chasing your moving feet and biting ankles and pantslegs is a 100% natural dog behavior! But it's not much fun for you. Let's apply the four steps of problem-solving to find a solution:
1. Identify the specific problem. Here, biting ankles and pants legs.
2. Define what you want the puppy to do instead. The answer to this question is *never* "Stop doing the problem behavior." You could suppress the behavior, and the dog could choose to do something even worse! Save yourself a ton of frustration -- and your dog a ton of confusion -- and choose a preferred behavior. In this instance, I'd say, "Walk nicely next to me."
3. Manage the situation so the undesired behavior becomes unreinforcing or impossible. Why is the puppy doing it? Because it's natural to chase and bite moving things.
So step one, if the puppy pounces, STOP MOVING. As soon as the puppy pauses, click and treat -- reinforce the pause in activity. Start walking... stop the moment his teeth touch your ankles, legs or clothes. Never again take a step while the puppy is biting you.
If you don't have time to do that, then MANAGE the situation and put the puppy somewhere where he can't bite you! Or take a different route! Don't get frustrated by your lack of planning and blame the pup.
If you find that the puppy does it only at certain times -- when he's overstimulated or tired, for example, or when you first get home or when you put the leash on -- manage the situation. Identify the triggers and plan for them.
4. Train the preferred behavior. Teach your pup it's fun and reinforcing to walk by your side. Reinforce heavily for any steps at your side -- this is a great foundation for loose-leash walking.
In this method, the dog has learned walking with mom is fun -- more fun than biting ankles and pants legs.
It is never, ever necessary to yell at, growl at, shake, muzzle grab, or otherwise physically punish this behavior. (Gee, I bet those behaviors make the pup anxious to walk at your side during loose leash walking. NOT!) ) Be proactive, not reactive. What has the pup learned if you use physical corrections?
That type of correction says, "I am bigger and stronger and you must do what I want." Is that what you want your pup to learn? If your pup is ever going to get large, or if he's ever going to be around children, physically-challenged people, or the elderly, I don't think you do. Teach what you want -- don't react and punish. If you have to react, YOU screwed up and let it happen. Don't punish the puppy for your poor planning.
Melissa Alexander 2002