Here are some tips: I got it from this website:
http://www.veterinarypartner.com/Content.plx?P=A&A=1462&S=1&SourceID=47
Rehabilitation
If your dog already has a problem with food guarding, you will certainly need to continue the prevention exercises and management for the life of the dog. Initially, it may be too dangerous to walk up to the dog's dish at all while the dog is eating, and we certainly don't want you hurt. In such cases, enlist the help of a behavior specialist in person, to evaluate the dog and the situation and to add an extra measure of safety for the people involved.
For the food-guarding dog, remove the dog dish from the floor between meals. Leaving the dish out gives the dog something to guard, and our goal is to lull the whole food-guarding instinct to sleep.
If this is a fairly moderate problem, start by putting the food dish on the floor at mealtime-with nothing in it! Walk several feet away, and have the dog's food with you. Also have some means of giving the food to the dog in small bits. For a dog who reacts to a hand reaching toward the dish, get the help of a behavior specialist. But one way to work it would be to use something long to put the food into the dish, rather than your hand. A reaching tool for people with disabilities may be an option, depending on the food you're using. These tools are not expensive.
When the dog realizes there is no food in the dish and looks at you, walk up to the dish and put a small amount of food in it before walking away again. When the dog finishes that bit and looks at you again, walk up and place another bit in the bowl and go back to your position several feet away from the dish.
You're conditioning the dog to accept having a person approaching the dish and putting a hand down to the dish. You don't want to just stand next to the dish dispensing food. You want to include an approach to the dish each time, in order to turn the approach of a person at mealtime into a positive event in the dog's mind. A good way to end the meal would be to give the dog an especially tasty treat as you pick the bowl up off the floor. This is to condition the dog that having the bowl removed is a good thing, too, and also to let the dog know the meal is finished.
If your dog is extra-touchy about the person's approach or some other aspect of the exercise, you can start by taking a step back from doing it as described above, or more than one step back. Here are some ideas for "back up steps":
1. For the dog who has become defensive about the dish itself, you could start with no dog dish, and feed the dog from your hand. In order to switch the dog to safely eating from a dish, you would gradually include the dish. After the dog gets used to eating from your hand, you could place the dish on a surface nearby and gradually move the hand with the food closer to the dish for successive bits of food.
Start holding the dish in your other hand, and gradually move the dish to the floor level. Eventually set the dog dish on the floor, and continue gradual steps until the dog is ready for you to start setting the empty dish on the floor and moving several steps away.
Take these steps slowly. You want to do the whole process over as long as period of time as it takes, as slowly as necessary, to avoid triggering the dog into a food-guarding or dish-guarding reaction. Such a reaction is a big setback to training. Slower is faster in this case, because taking the steps slowly will achieve the desired effects much more quickly than if you rush things.
2. You could hold the dog dish in your hand rather than setting it on the floor, and have the dog come to you for food rather than you walking up to the dog. You may want to move around, stepping away from the dog, having the dog come with you to a new spot for each bite.
A next step would be to teach the dog a simple "stay" and have the dog hold the "stay" while you walk up with the dish and still hold it for the dog to eat. Now you're introducing the approach, but the dog has nothing to guard as you approach, because you still have the dish and the food with you.
Gradually you would put the dish closer to the floor, and then eventually on the floor. When using a "stay" with training on food guarding, avoid creating a situation that rewards the dog at the release from the "stay." This can make a dog somewhat explosive, exactly what you do not want.
Always bring your dog out of a "stay" command calmly. Do the same whenever you bring a dog out of a crate or other confinement. Exploding dogs can be dangerous, and we sometimes unknowingly condition this reaction by making the release too rewarding. Give the dog something calm to do immediately on release from the "stay" or the confined area.
3. It could enhance an adult's safety to place the dish on a raised surface for early training, so that you're not bending down and putting your face near dog teeth, and so that you're less physically off balance when you deposit food into the dish. A raised dish and a reaching tool to add the food would be additional safety. Note that raising the dish could put it closer to a child's face, and therefore not be a good idea. You wouldn't be including the child in the conditioning process at the early stages anyway, though. The child should not be brought into the exercises until the dog is completely steady with adults.
4. You could tether the dog before putting down the dish, so that the dog cannot nail you with teeth as long as you stay out of reach. Again, if you feel this is necessary, get a behavior specialist to help you with the dog rather than going it alone.
5. For extra safety, you could use a head halter or muzzle that allows the dog to eat but prevents the dog from biting you. If you want to try this option, work with a behavior specialist-and have that person help you fit the mouth-controlling device so that you don't get a nasty surprise if it accidentally comes off at the worst possible moment.
Remember, too, that conditioning might quickly seem complete with the mouth-controlling device on, and fall apart appallingly quickly when the device is removed. Don't try to take short cuts on the conditioning. If a dog has this big a problem with food-guarding, it's going to be a long process to make that dog safer.
6. Keep confrontation and punishment strictly out of this process. No matter how difficult the dog or how serious you might consider a particular transgression the dog has committed, human aggression toward the dog over food or toys is virtually guaranteed to make the problem worse. It is quite often what causes the problem in the first place.
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