If you've ever pet a dog prior to going home to your own dog, you know what happens.

Your dog does her happy dance until she sniffs the scent of another dog on you. Then the interrogation begins: "You touched another dog! I can't believe you touched another dog! Where have you been? Who is this dog? Is this going to be a thing now?" It's amazing how accusing the eyes of your dog can be and how many questions she can ask without saying a thing, which comes across as jealousy.

Secondary Emotions

But scientists might disagree with you. There are primary emotions, such as fear, happiness, surprise and anger; and secondary emotions, such as jealousy, guilt and shame. Although it's pretty much a given dogs express primary emotions, many scientists don't believe dogs are self-aware enough to have secondary emotions. But most dog owners, especially those with multiple dogs, would disagree with that assessment. If Dog A feels that Dog B is getting too much attention from their owner, Dog B may try to assert herself by either redirecting the attention to her, or by pushing Dog A out of the way.

What Experiments Tell Us

Researchers have tried to examine this in controlled settings. In one experiment, several pairs of dogs (with the same two dogs always being paired together) were taught to shake hands. One dog was always rewarded when she shook hands, and the other dog never was. Not surprisingly, the dog who was never rewarded stopped shaking hands pretty quickly when she saw the other dog was rewarded for doing the same thing she received no reward for. The value of the reward didn't seem to matter. As long as both were rewarded, both performed the task—even if one dog routinely got sausage and the other got bread.

Potential Solutions

So, what should you do if you sense jealousy in your dogs? Assess your own behavior first. Are you showing favoritism to one dog over the other on a regular basis? If so, you need to equalize your behavior. If the dogs know one dog is your favorite, that can cause resentment in your other dog. Don't make unequal treatment into a problem if your dogs don't care. If one of your dogs is particularly needy and demands more attention from you, but your other dog doesn't seem to mind, then don't worry about it. Dogs can get jealous of new humans in the house as well. In the case of a new baby, start getting your dog used to some things before the baby is even born. Once you have decided which room will be the nursery, teach your dog that that room is out of bounds for her. Start by closing the door, but then let the dog know even when the door is open, she is not allowed in. That way when you bring the new baby home and put the baby in the nursery, the dog will know that the baby is higher on the social order. Dogs have an excellent sense of smell, so let your dog smell the baby, but from a distance. This, too, will be another reminder that people always occupy a higher position in the social order than your dog does. Older children and adults should know to firmly but respectfully show their dominance to the dog. They should be encouraged to interact with the dog. You should interact with your dog not only when the new people are around, but also make sure you have some alone time with her. Try to keep her routine as regular as possible, even with additional people in the house. Dogs have different tolerances to new people in their situations. Some dogs have a "the more, the merrier" philosophy, while others don't want to share their owner with anyone else. Most dogs fall somewhere in between. By helping your dog learn her position in your household and reminding her she is important and always will be, you can keep the jealous squabbles to a minimum.