How can I stop a German Shepherd from resource guarding?

I have recently rescued a German Shepherd. He is male and approximately 15 months old. I have had the dog for two months and we are bonding fine and he is responding well to marker training, however, he becomes aggressive when approached during feeding, and this morning he growled at me after being put in his crate. He had not finished his food, (unusual) and crated himself (he usually does this once he finishes his meal). When I went to pet him (while he was in his crate) and invite him back out to finish his food, he snarled at me and showed his teeth. He sometimes becomes aggressive when chewing on his bone, but this is less frequent and less intense. I want to stop these behaviors immediately before it becomes any worse. What do you suggest?

Cindy's Answer:

There are several things to keep in mind with dogs that resource guard. First of all, I would be working on obedience and impulse control away from any RG (resource guarding) issues, every day.

I would not allow him to eat his food in a bowl- I might try putting individual pieces on the ground and if I did keep using the bowl I would put him in an area drop the food in a piece at a time, let him eat and then call him to you afterwards. I would not give him access to freely enter the crate as it appears the crate is also a resource he wants to guard. Keep the crate door closed and he goes in when you allow it, not when he wants to.

The absolute worst thing you can do is mess with a dog's resources when you know they have this tendency. For now, I would not give him bones at all and if you do, give them in a crate and don't try to reach in and take it. Wait until the dog is outside or somewhere else.

If you try to test this by reaching in or encroaching on his space when he's eating you are going to make it get worse.

Resource guarding is often something that needs to be managed to some extent with certain dogs, for the long term. Set the dog up for success by not "poking the bear" so to speak. Use your time with him to do obedience and teach him impulse control. Make him sit and wait before you give him treats (for him I'd place them on the floor one at a time and then release him to get the treat)