Not good. That is called resource guarding.
Not a good idea to pet an eating dog, though.
You do need to work with him trading, as suggested above, so that he does not feel threatened when you touch his food.
Also, try hand feeding his meals this week.
Do you have him sit and wait before you feed him?
PS-- no cooked bones, I hope
Last edited by Sunflowers; 12-10-2012 at 11:08 AM.