Our boy Jackson learned sit, lay, shake and is currently learning to roll over and he's only 4 months old. We've slowly been weening him off treats. Like Rae said, just give him praise instead of a treat every once in a while, then move it to praise half the time, then praise most of the time. Eventually your dog will learn to not expect a treat, but praise instead. This is what was told to me by a dog trainer at the local pet store. We've been slowly doing this and it's definitely showing improvements.

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- Dave