Here a beagle is urinating on a fire hydrant and when the next dog walks up, she smells the beagle's pheromones and she marks the spot. To an extent, this is analogous to a person scrolling down facebook and "liking" a post.
When you give a gift to a pet, you are not giving a material object, you are providing a ticket to an experience between pet and owner. A moment in time that bonds two souls. You are giving them memories that will be cherished for a lifetime. That is an amazingly powerful gift that can cost as little as a few dollars.