You will notice that we will not use food toys (like stuffed Kongs) in our missions until we have hit the point of resolution, and never will we sneak out while the dog is busy doing something else. We want the absences to be as natural and organic as possible in the sense that we are not using distractions or secretive measures, destroying their trust.
Eventually, we may choose to use food toys during an absence, but that is down the road and not during the learning process as it can give us an incomplete picture where one of the following things can happen:
the dog is perfectly fine while they have a food toy and then the panic sets in
the dog doesn't even notice the food toy since stress • shuts down the digestive system temporarily so it's a wasted effort
leaving a food toy predicts you leaving, so the dog develops a negative association with the food toy as a result
Save the food toys for mealtimes when you are around and you will find that your dog will enjoy them much more!