Stealing and guarding—from whom?
Resource guarding among dogs is an extremely common and normal behavior. Dogs are pre-programmed not to want to share valued resources with others. For pet dogs, resources may include food, toys, or even the owner's attention. In most households, resource guarding is limited to simple communication, but sometimes the behavior can escalate in frequency or intensity and injuries can occur. If you are ever concerned about aggressive behavior in your dog, related to resource guarding or not, it is best to contact your vet or other qualified professional for help before proceeding on your own.
While there are many protocols to reduce conflict in dogs that guard resources from their humans, guarding from other dogs presents a unique set of challenges. However, the principles for working with a dog that guards resources from humans and a dog that guards resources from dogs are basically the same. The emotion underlying the behavior is usually fear.
For animals in the wild, keeping or losing a meal can be the difference between life and death. So even though beloved pets are never in danger of starving (far from it!), the instinct to protect valuable resources is still intact. The goal of any training method is to reduce or eliminate the fear and conflict so that the dog feels more relaxed with a resource. Using positive reinforcement and counter-conditioning it is possible to change a dog's emotional response and motivation. As a result, the behavior itself goes away.
Steps to success
The main difference between a dog guarding from people and a dog guarding from dogs is that most of the time the human doesn't actually want the slimy, old, rawhide resource, but most of the time the other dog does want it! Working with two dogs in a household, there are two training tasks to address. The first is to teach the guarding dog to feel more relaxed when approached, and the second is to teach the approaching dog not to steal other dogs' belongings.
The first step in modifying resource-guarding behavior is to use good management strategies to prevent the undesired behavior. Practice makes perfect! Make a list of items, spaces, or situations that are likely to provoke the dog's guarding behavior. Then, either change the environment to eliminate the opportunities, or eliminate the dog's access. This may mean removing treasured toys, restricting access to certain rooms or furniture, confining the dogs separately during feeding times, and other management strategies. Crates, baby gates, and pens are great tools that help control your dog's space and prevent undesirable behaviors. Note that in some cases dogs may have to be completely separated except during training times.
After setting up a dog up for success with good management, it is time for the business of training. Before working with two dogs together, it is extremely helpful to teach some solid, positively trained foundation skills individually. Introduce the dogs to clicker training, if they haven't been introduced already. Practice a strong "leave it" behavior and a solid "stay" behavior. It is also helpful to practice relaxation and self-control behaviors like mat work and Doggie Zen.
Train and treat the two
Next start working with the dogs together. You will need two handlers, one for Dog A and one for Dog B. Start by working with a fairly low-value item, something your dog likes, but isn't that crazy about. A typical resource value hierarchy for many dogs might be: stuffed toys (low value), chewies (medium value), food (high value).
The goal is for all interactions to be positive and educational.The goal is for all interactions to be positive and educational. Keep the dog "under threshold" at all times. This means that if everything goes as it should, you'll never see any aggressive behavior.
To begin, both dogs should be leashed for safety; the guarding dog (Dog A) could even be tethered for extra security. The goal is error-free learning, but it's better to be safe than sorry!
Place the resource near Dog A. Next bring in Dog B, stopping far away from Dog A and well outside the point where Dog A might be concerned. This distance is going to depending on the dog, so err on the side of caution. Click and treat Dog A for remaining calm, lead Dog B away, and click and treat Dog B for not going for the resource.
Repeat, decreasing the distance between dogs slightly, again clicking and treating Dogs A and B for appropriate behavior. If at any point either dog shows behavior that is not calm and relaxed, go back to the last distance where they were both successful and repeat. Gradually decrease the distance in small increments until Dog B can walk right past Dog A and neither dog reacts.
At this point, go back to the beginning distance, but use a more valuable resource. Go through the same steps, always keeping both dogs under threshold until Dog B can walk right past Dog A and both dogs are comfortable. Repeat the process with resources that are more and more valuable until you are working with the best stuff. You can also practice this exercise in different locations, especially any location where Dog A has a tendency to guard, like the couch.
One for you, then one for you
Try another fun exercise. Sit the dogs far apart, one on either side of you, tethering if necessary. Say Dog B's name and give him a medium-value treat. Immediately say Dog A's name and give him an even better treat. If either dog appears uncomfortable at all, move them further apart and start again. Repeat until both dogs are holding their "sits" patiently while the other gets a treat. Gradually reduce the distance between the dogs until they are comfortable sitting as little as a body length apart.
Remember, safety first! Both dogs need to feel completely comfortable at all times. The goal of this exercise is to teach Dog A that when Dog B gets a treat, it predicts him getting an even better treat! Dog A will start anticipating Dog B's treat because it means his own goodie is imminent.
What should you do if, between exercises, your dog guards something unexpectedly? First and most importantly, stay calm! Getting upset will only exacerbate the situation. That is easier to say than to do. There's nothing like a growl and a set of flashing teeth to set off an emotional response in a human, but do the best you can. Resist the urge to punish the guarding dog, because that would be unproductive. Calmly remove the dogs from the situation, preferably without touching either one. Sending them to their mats is a good way to diffuse the tension. Separate the dogs for a short time to let everyone calm down.
Meanwhile, try to examine what happened. What resource was the catalyst? If possible, remove the resource or otherwise restrict access to it before letting the dogs back together. Later, add that particular resource, location, or context to your training plan. Eventually you will have the opportunity to reward the dogs for calm behavior in the same situation.
Modifying resource-guarding behavior is not fast or easy! Don't hesitate to ask for help from a qualified professional trainer or veterinary behaviorist. It will take time and attention, and many dogs will always require some level of management for safety and sanity. But, resource guarding is a behavior, and all behavior is modifiable!