Aggression at Dinner Time

Question
Hi - I rescued a male 5 yr old Labrador about 3 months ago and I am having problems with him at feeding time.
Basically he is very possessive over his food & will growl & snap at anyone who approaches him whilst he is eating - this is true whether it is his main meal or a snack/treat. It started off with him just growling at me or my partner if either of us got too near him whilst eating his main meal but yesterday he snapped at me as I walked past him whilst he was eating a treat. Fortunately he didn't make contact with me but it has really unnerved me & I want to address the situation asap as apart from this one thing he is a really fantastic dog & deserves a second chance in life with me. We have actively ignored him as far as possible when eating to try not to provoke the situation but this clearly isn't helping! Any advice you can offer me would be very much appreciated. Many thanks.

Answer
Food aggression is usually an acquired behavior caused by many things, including insufficient nutrition as a neonate.  Dogs who live in mutliple dog households can develop it; dogs in municipal shelters sometimes acquire it; dogs in households with unruly children or people who think they're teaching who is "alpha" by handling food, etc, all can cause this.  Your dog most likely acquired it in much the same way, but there is always the remote possibility that this is also a rank issue.  The treatment to eliminate it does not address the behavior, itself, as doing that will only escalate the aggression.  So the first thing you need do is set aside two (TWO) feeding times a day (to eliminate the frantic hunger and maintain an overall steady blood sugar level).  Give the dog ten minutes in an EMPTY ROOM to eat his meal.  If you have a door on your kitchen, close it; leave the dog alone in the room with his meal.  At the end of the ten minutes, get the dog's attention (if he has not eaten the food) without interacting with his bowl.  You can stand in another room and call his name, throw a ball, etc.  Once the dog has removed himself from his bowl, go into the room without him and pick up the bowl until the next meal time.  This is the first step.

The second step is training this dog using positive reinforcement.  I suggest you use a clicker and you can learn about how to do this by going to Karen Pryor's web site.  Although charging the clicker (teaching the dog the click means a food treat is coming) requires using food, the food can be thrown away from you and the dog and the click can be introduced when the dog gets to, and eats, the food.  Eventually, the clicker BECOMES the reward and food can be offered in much the same way as when charging the clicker.  This eliminates any aggressive response the dog might have over a food reward.  One thing you DO NOT want to do is provoke aggression.  Each time the dog uses aggression, he learns more about it.

Using positive reinforcement, teach the dog one command (start with 'sit' but use a new word) over the course of a couple of weeks.  Once your dog has a 100% reliable response to your command, you will have accomplished two things: you will have partically desensitized him to his resource guarding behavior (growling over food) and you will have given him a behavior he can be REWARDED for.  NOW you can use your reliable "sit" command to make him earn everything NOT food related, thereby promoting yourself psychologically and establishing a firmer emotional connection between you.  The food aggression should begin to extinguish within a few weeks following this new regimen.