Breeders can help prevent this too by feeding pups in their own dishes or maybe only 2 pups per dish rather than the entire litter out of the same dish. We always teach they get more and better treats when hands are by the food dish from the time the pup gets to your house. But if the dog is freezing and growling from 5 feet away, you're not there yet. Peach on a Leash has an awesome video on teaching the Drop it cue where the GSD drops a whole hot dog out of his mouth. You have to practice ahead of time, without any object, but eventually you'll be able to say it without the use of treats. I never teach a trade as you then can get a dog that is bad to be good. Like they'll grab an object then run to the fridge. Chirag Patel's resource guarding resolved video is also awesome! Susan Garrett has a whole resource guarding series of videos. Her TEMP video also helps you really tune in to their body language. Hope that helps.
Oh and although the video is for jumping, Chirag Patel's video on talk to your shoe has helped so much even for off courses in Rodeo Dog class. Hope that helps.
This way you're not begging or bribing your dog, you're rewarding their decision to get back to you, without having to actually call them - especially if they are ignoring you.
