(Originally written for DogWatch, a newsletter for the general public from the Cornell University College of Veterinary Medicine)

My two spayed female dogs, 3-year-old Diele and 5-year-old Pepper, generally get along. However, Diele constantly tries to chew on Pepper’s neck or drag her around by her collar. When I try to keep them separated during walks, Diele whines and barks. Although she will stop if corrected, she resumes the behavior within seconds. Pepper tolerates the chewing for an unbelievably long time and only rarely snaps at her. What’s going on here?

Diele’s behavior persists and Pepper accepts it for the same reason: both constitute perfectly normal canine displays. Sometimes our dogs become so much a part of our families, we forget that the dynamics of both a canine and a human-canine pack shape their relationships with us and each other. However, our dogs don’t forget this because they need a stable pack structure in order to feel secure. Put another way, dogs establish packs with leaders and followers toprevent fighting, not to promote it.

Dogs form dynamic pack structures, and some dogs want to be leaders more than others. Those who want to lead will mouth, or try to mouth, the muzzle and neck of the leader dog, place their front paws on that dog’s shoulders, or even steal its food or toys to communicate this message. Although we commonly label these behaviors “dominant,” they don’t necessarily designate a leader animal nearly so much as one who aspires to that position.

Some packs appear to function like old family businesses, with one dog maintaining the leadership position its entire life and the second dog assuming that slot only when the first one dies. However, in these cases the younger or more inexperienced animal most likely did challenge the leader in some way, was rebuffed in a manner the owner either missed or didn’t notice, and the number two dog gave up. In other cases, such as Diele’s, the second dog doesn’t give up. Typically this occurs when the animal perceives itself as at least equal to, if not more capable than, the current leader. Whether a successful take-over occurs and how it occurs depends on the willingness of the current leader to cede its position.

Even though dogs use rank as a method of ensuring peace, some owners resist the notions of top dogs or canine take-overs because human sports and politics rather than solid knowledge of animal behavior often shape our views of leadership. According to these views, leaders claim their position by virtue of their willingness to beat their adversaries into submission. In reality, though, the more confident the leader, the more tolerant, and the less likely to display behaviors typically defined as dominant or aggressive. This makes sense because fighting requires energy and risks injury, and wild animals who routinely resort to this strategy get eliminated from the gene pool.

Thus, Pepper tolerates Diele’s behavior because she feels confident enough about her position that there’s no need to waste energy communicating this unless Diele exceeds her limits. If Diele does, then Pepper brings her back into line with a snap. As Pepper grows older and Diele becomes more insistent, though, it may take more than a snap to make the point. Eventually, the day may come when Diele doesn’t back down and a fight occurs. If Diele pins Pepper and Pepper submits, or vice versa, peace will reign again. If not, the skirmishes will continue until a leader evolves.

Or at least that would be the case if Diele and Pepper only belonged to a dog pack. However, they belong to a human-canine pack, too. And even though dog rules on the subject are very clear, human input can complicate matters enormously. In cases of evenly matched dogs, human interference may increase the amount of interdog tension and cause them to fight harder and longer when given the chance. A primarily ritualistic display then becomes a frustration-driven attempt to get in as many licks as possible before the owner aborts the process. Other times owner screams and smacks will provide sufficient additional stimuli to drive the dogs from pack into predatory behavior, greatly increasing the likelihood they’ll seriously hurt each other. In still other situations, loyalty to an older or weaker animal leads owners to run interference to artificially maintain pack structures that run counter to canine logic.

Leashed dogs who hassle other dogs communicate that they don’t recognize their owners as leaders of the human-canine pack, either. In this situation, rather than the owner’s presence calming the dog, that person functions more as territory which the dog must fight to claim and protect. To resolve this problem, owners must develop their leadership skills first so they can set the standard for canine behavior, just as a good leader dog does for its subordinates.