Train your dog to only eat and take treats with an associated verbal cue. Begin the process at home with just the two of you and then start proofing with the help of a friend who you can instruct when it is okay to release the treat.
The verbal cue should not be something like the word "treat" or "okay" because many a stranger will use these words not knowing it is the cue.
Two ways to train the behavior, only you release the dog or anyone can knowing the proper command. The second might be better because your training will not be compromised unless you always plan to to feed your dog and never be away from the dog.
Keep in mind, when you are away from your dog and someone else will be feeding your dog, they will need to know the verbal cue if you get your dog trained well enough in the discipline.
The verbal cue should not be something like the word "treat" or "okay" because many a stranger will use these words not knowing it is the cue.
Two ways to train the behavior, only you release the dog or anyone can knowing the proper command. The second might be better because your training will not be compromised unless you always plan to to feed your dog and never be away from the dog.
Keep in mind, when you are away from your dog and someone else will be feeding your dog, they will need to know the verbal cue if you get your dog trained well enough in the discipline.