Growling, lip lifts, snarling, snapping, freezing, staring, hovering around items are potential signs of resource guarding in dogs.

Food bowls, bones, toys, beds, stolen items, people and spaces are common targets for resource guarding by dogs.

Use reward-based training to teach "drop it" and "leave it" commands. Hand feed meals. Swap items for high-value treats.

Pick up valued items when unsupervised. Feed separately. Give dogs separate sleeping areas. Supervise play with toys. 

An experienced force-free trainer can help assess your dog's body language, implement a training plan, advise on safety. 

Stop guarding before it starts by handling dogs and their items positively from a young age. Teach give and take games.