We trained our dogs to take treats gently by wrapping our hand around the goodie, keeping fingers tucked so they wouldn't get nipped. If they were too aggressive while trying for the treat, we'd go "OWW" loudly (pulling away), and follow up with the word "easy"! Spencer takes treats so gently now, he always drops them, but even the little kids can feed him meat without getting hurt. Same with big girl Greta. Lots of praise when they learned to go easy helps reinforce the training. Good luck, and hope this works...others I'm sure have other methods.