Food aggression is very common and can often be quite scary, however its not impossible to combat.
Dogs with food aggression may stiffen, show teeth, growl,/snap, or bite when they are approached by a person or animal when they are around food, they are likely to behave in an aggressive manner around items that they consider of high value (a bit like us when we are offered a Banana or a Galaxy Chocolate bar, hands off my chocolate!), this means dogs are more likely to behave aggressively over a raw chicken wing than over a bowl of dry food because the raw chicken is seen as the tastier option to them. Similarly something as small as a dropped food wrapper may be considered as high value and trigger the aggressive food guarding behaviour.
Quite often food aggression is overlooked or dogs are inadvertently rewarded for this behaviour, for example jumping up to ‘beg’ for the food faster, in this instance we should not put the food down until we teach the dog this behaviour is not acceptable, by putting the food down we are teaching that it is ok. When this behavior is successful, the dog experiences negative reinforcement and the behavior is more likely to be repeated.
Some dog trainers recommend taking food away during the bad behaviour however with regards to food aggression this is not the best method of teaching your dog to be calm and that their food is safe, their worry is that the food will be stolen from them hence the need to urgently and aggressively protect it, so taking away the food you have just given only reinforces the need to protect and gorge before the food is removed. If your dog feels food will be taken away each time a human comes near then they are going to become stressed and defensive.
With consistent rules in place your dog will learn they do not need to resource guard their food, that they will be rewarded for sitting nicely and waiting and that the human is there to protect the food with the rules in place therefore they don’t need to worry and can have a stress free meal time.
Rather than giving food to our dogs for free, we need to make them work for it, by ignoring unwanted behaviors and rewarding good behaviors with food.
Whilst preparing food teach your dogs they must sit calmly and wait, if they do so they get their food quicker therefore are rewarded. However if they show unwanted behaviour whilst you prepare food such as jumping up, nipping, growling at the other dogs then stop preparing food and request they sit calmly and wait again. Do not put the food down until each dogs is calm and waiting for their turn. Alternatively teach your dogs tricks to perform before being rewarded with their meal.
If stealing food from each other is an issue you should give your dogs separate safe areas to eat, maybe in a crate (if correct training has been done beforehand, otherwise the crate may be seen as a punishment) or just in opposite rooms/behind a gate.
Reward training and hand feeding may help to reduce food aggression issues because while doing these things we can teach our dogs proper eating manners including bite inhibition and patience. When hand feeding we need to again get ours dog to be calm and take the food in a gentle calm manner if my dogs use teeth when taking food from my hand i say ‘ouch’ and stop feeding them at that moment, this teaches them that if they are gentle the food will keep coming, but if they are rough and take too eagerly they are going to hurt you and you will stop feeding them. (Please do not try this method if your dog is biting for food, you must be certain it is a safe method for your dog and yourself, if you do not feel comfortable doing this from the start you may be able to once you have begun teaching calm behaviour before dinner time and see it in progress.)