Dogs and humans have several behavioral traits that are similar. One easily recognizable trait is jealousy. Some dogs, like some humans, become extremely possessive of their owners and other family members, striking out aggressively at rivals. A jealous dog wants exclusive access to its owner's attention and affection. Such a dog will exhibit angry aggressive behavior toward any person or animal that the dog perceives is intruding upon its relationship with the owner. Bringing a new baby into a home is often a cause for jealously in dogs.
Jealous dogs exhibit behaviors such as barking at the object of jealousy, barking at you when you are giving your attention to the object of jealousy, always being underfoot, tearing things up, and regression from learned housetraining behaviors.
A dog's guarding instinct is a mechanism similar to jealousy wherein the dog's jealousy extends to expecting exclusive access to the entire household in which it lives. Dogs can react viciously whenever a person or dog is allowed access to the home, even if is done with the obvious approval of the dog's owner.
This jealousy is an exaggerated manifestation of a dog's innate need to guard its possession of items like bones or chew toys. Dogs will aggressively guard them against use by both humans and other animals. This behavioral characteristic of some dogs is not a serious a problem as jealousy or the guarding behavior, except where children are involved in inadvertently touching a dog's possessions.
One common manifestation of jealousy in dogs results from the complex relationship with a mother dog, her puppies, and her owner. Unlike humans, a canine mother does not maintain the maternal instinct for her children for the remainder of her life. As soon as the puppies are able to survive on their own, particularly when the mother is again in heat, her maternal instinct for the current litter wanes. During this period, owners try to treat all the dogs with equal care and attention, but to no avail. The mother dog sees her owner's attention being diverted away from her toward the puppies, and becomes jealous. This can escalate to the point where she might actually become aggressive toward the pups.
She may begin ignoring the pups and trying to exclude them from the maternal nest. Continued efforts by her owner to treat the puppies as coequal members of the household exacerbate the mother dog's jealousy. Her jealousy may actually cause her to direct her aggressiveness toward the owner.
As the puppies age and becomes more mature, the mother no longer recognizes them as "family." The growing puppies become strangers - interlopers. A conscientious owner will train the dogs to behave while he or she is present. When the owner is away, however, the mother may revert to aggressive behavior in order to drive the youngster away from the nest where her new litter will be cared for. Woe be it to the maturing puppy who deigns to take one of the mother's toys or other guarded possessions.
If the owner intends to keep the maturing pups as a permanent part of the household, he will have to treat them as non-related dogs, and train them and socialize them to live together as well socialized dogs, not as mother and pups. The owner should give the jealous dog a little of extra attention to show the dog that it is important to the owner. He should also determine what actions are actually causing the jealousy, and try to mitigate it.
Never tolerate bad behavior. As owner, it is your responsibility to train the dog to adjust to whatever new situation arises in the home.