Training with treats is very effective during the 'learning' phase of training. While some dogs need only our approval or a pat on the side as a reward for good behavior, others need a little more incentive to respond consistently to our commands.
Treats are an excellent way to reinforce desired behavior if they are used correctly.
To keep pets from becoming dependent on treats for behavior that is expected of them, we recommend limiting treat-giving to the learning phase of training. When she lies down, reward her with the treat. As you advance into the testing phase, replace the treat with verbal praise and patting. You can occasionally give a treat during this phase but don't let her see it until you have a proper response to your verbal command. This is the most difficult command to teach and you may need every tool in your toolbox to get your dog to respond consistently.