With many dogs, you really have to watch your fingers when trying to give them a treat.
Our guys do quite well being gentle taking treats; perhaps partially because they get a lot of practice. Only when she's very excited, Cookie gets grabby, trying to quickly take the treat and get back to whatever she's been focused on. It becomes particularly obvious when I try to use the "Look a that" game to teach her to ignore a squirrel, for example.
Level of arousal is certainly one criteria to keep in mind when trying to get your dog take treats gently.
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