Some dog breeds—typically guarding breeds and herding breeds—appear to have a low threshold for developing excessive territorial aggression.1 This may be compounded by inadequate or inappropriate socialization, leading to a comorbid diagnosis of fear aggression. However, behavior—aggressive or otherwise—is always a reaction to some aspect of the dog’s environment, rather than an aspect of the dog itself. Genetics and perinatal experiences do affect the likelihood with which some behaviors develop, but appropriate environmental conditions must exist for the behavior to be expressed.
Testosterone can mediate offensiveness, competitiveness, and aggression in some contexts. However, many intact male dogs do not show behavior problems. In fact, a slowly growing body of research suggests that gonadectomized dogs may be at higher risk for expressing certain behavior (eg, anxiety, aggression) than intact dogs.2-4
Territorial behavior is not a result of dominance or pack hierarchy and is, actually, normal in dogs. Even extremely sociable dogs will generally bark to announce the arrival of someone onto the owner’s property. In domestic dogs, the territory generally encompasses the owner’s house and yard. Dogs may also defend the space in and around a vehicle or cage. Territorial behavior tends to be most intense directly along boundary lines. Unlike fear aggression, which often manifests at an early age, territorial and protective behaviors generally begin at around 8 to 10 months of age5 and escalate over the next 12 to 24 months, particularly if the dog’s environment is not carefully managed.
The primary concern in this case was the time Ruger spent outside unsupervised rehearsing aggressive territorial reactions. Every behavior serves a function for a dog; when the dog barks and chases someone or something along the fence and it leaves, the territorial behavior is reinforced. Barriers tend to escalate these reactions.
Many dogs have intense reactions at the front door. The level of arousal rehearsed there can lead to biting behavior, even in otherwise friendly dogs.
During Ruger’s bite episode, he performed the same behavior that he did every day but was able to reach the trigger by breaking through the fence. There is a higher risk for bite by an escaped dog that spends a lot of time patrolling the perimeter of the property, fence running, and barking at humans and other animals from the home.