Canine aggression poses a major concern to dog owners due to the risk for injury, financial loss, and damage to the human-animal bond. A number of predisposing factors influence a dog\u2019s general threshold for aggression: genetic predisposition, prenatal environment, exposures during early socialization, and environmental circumstances. There are a number of possible motivational factors, but fear and stress are often the underlying factors.<\/p>\n
A comprehensive treatment plan for canine aggression involves a risk assessment, client education, addressing any health concerns, environmental management, behavior modification, and appropriate therapeutics to address underlying fear or anxiety. Environmental management is arguably the most important factor, and this article describes a number of basic guidelines that may be implemented at the general practice level to set up success for patients and households.<\/p>\n
Take-Home Points<\/strong><\/p>\n The term \u201caggression\u201d encompasses a wide range of behaviors and can be seen in many contexts. In dogs, severity can range from a hard stare and stiff body to prolonged biting attacks. Canine aggression poses a major concern to dog owners due to the risk for injury, financial loss, and damage to the human-animal bond<\/a>. Aggression may also be an indicator of the dog\u2019s poor mental and\/or physical wellbeing. Although veterinarians can be instrumental in properly diagnosing and treating the behavior and educating clients about canine aggression, most primary practitioners report that they do not feel qualified to do so.1<\/sup> Nevertheless, significant improvements can often be made through relatively simple steps achievable in the general practice setting.<\/span><\/p>\n Aggression can be defined as a threatening behavior intended to cause harm to or increase distance from the recipient.2<\/sup> It can also be described as the facial expressions, body postures, and vocalizations used to communicate these intentions. Overt behaviors with threatening intent are growling, snarling (baring teeth), head-whipping, snapping, biting, harsh barking, hard stare, and stiff body. Some of these behaviors can be also be observed in nonaggressive contexts, like play. Critical, yet underrecognized, precursors to aggression are fear and stress behaviors; therefore, subtle signals of distress (e.g., lip licking, dilated pupils, ears held to the side or flat to the head, tucking tail, avoidance by turning head or body)(<\/span>FIGURE 1<\/b><\/span>) usually precede overt aggression.<\/span><\/p>\n Figure 1. Example of a fearful dog displaying subtle signs of stress (e.g., lip licking, pinned ears).<\/p><\/div>\n All animals are capable of aggressive behaviors when feeling sufficiently threatened, and there are many causal layers that determine why a particular animal behaves aggressively in a specific situation. An individual dog\u2019s general threshold for aggression is heavily influenced by genetic predisposition, prenatal environment (e.g., maternal stress or disease), and exposures during early socialization (approximately 4 to 14 weeks of age). Factors present immediately (seconds to weeks) before an event can also have an additive effect and drive a dog over its threshold. For example, a painful dog that is approached by an unfamiliar person in a loud environment is more likely to escalate to aggression than is a nonpainful dog approached by its preferred person in a quiet home setting. As veterinarians, our role is to identify as many of these <\/span>factors as possible, particularly physical health concerns.<\/p>\n Medical issues (e.g., mentation-changing neurologic diseases, acute pain) can directly lead to aggression. In addition, endocrine diseases, organopathies, or any source of discomfort (ranging from pruritus to chronic osteoarthritis) can create irritability and push a dog closer to its threshold for aggression. Recent publications argue that underlying pain is often correlated with problem behaviors.3,<\/sup><\/span>4<\/sup><\/span><\/p>\n Although aggression is a normal part of canine behavior signaling, certain attributes may be more strongly associated than others with aggressive responses. The probability seems to increase with age, which may in part result from increased risk for painful comorbidities in older dogs.5,6<\/sup> International survey studies have shown that the dogs at consistently high risk for displaying aggression are small dogs, fearful dogs, dogs with poor early socialization, and dogs of first-time owners.5-8<\/sup> Owners of small dogs may not seek the help of a behavior professional after aggression is observed because small dogs seem less threatening and easier to manage. Behavior and temperament may not influence breeding decisions with regard to small dogs as strongly as for their larger counterparts because small size has been linked to a range of fear and anxiety behaviors with and without aggression.5-8<\/sup> Owner reports of aggression are more consistently associated with fearful dogs and poor owner education than with any specific breed or sex.6,7,9-11<\/sup><\/span><\/p>\n Fear<\/b><\/p>\n Fear leads to aggression when a dog feels it cannot avoid a threatening or a fear-producing stimulus. The so-called ladder of aggression describes how the physiologic fight-or-flight response often plays out in dogs.12<\/sup> Behavior escalates from mild stress displacement (fidget) to escape (flight) before intensifying to threats and injurious aggression (fight). Common situations in which a dog may display fear or defensive aggression include encountering startling stimuli (e.g., loud sudden noise, person moving from sitting to standing at close distance), being approached or reached toward, and encountering stimuli while on leash or otherwise confined. <\/span><\/p>\n Novelty and lack of familiarity with the stimuli are additional layers that can amplify fear and push a dog past its threshold for aggression. For example, an unfamiliar person reaching out to pet a dog is much more likely to trigger intense aggression than the same action by a familiar family member. However, when a family member or other familiar person consistently triggers aggression, learned aversion to that person from a previous interaction is usually part of that dog\u2019s history. Aversive interactions from people include verbal or physical correction, but actions intended to be affectionate (e.g., hugging, reaching out to pet) can also be perceived as threatening. In many cases, the subtle stress behaviors may become fleeting or even absent with repetition as the dog learns that only the most obvious aggressive behaviors are effective for ending the unwanted interaction.<\/span><\/p>\n Possessive Aggression<\/b><\/p>\n Possessive aggression is a display of threatening behaviors in the presence of a high-value resource, such as a food bowl, long-lasting chew (e.g., rawhide, bone), favorite person, special toy, or comfortable resting area. Although any person or dog can be a target, those most likely to encounter the dog in these circumstances are family members. Conversely, the target (person or animal) of territorial aggression, or agonistic behavior directed toward a perceived threat to a dog\u2019s territory, is usually unfamiliar or outside of the dog\u2019s social group. Terminology for diagnosing aggression is inconsistent, but additional types may include, but are not limited to, social conflict; redirected aggression; impulse control; maternal aggression; and aggression induced by frustration, play, stress, or pain (see <\/span>Additional Resources<\/b><\/span>).<\/span><\/p>\n Overall KL. Manual of Clinical Behavioral Medicine for Cats and Dogs<\/em>. Mosby; 2013.<\/div><\/div>\n Multiple Motivations<\/b><\/p>\n Aggressive behavior can have multiple motivations (diagnoses) at any given moment. Consider the following situations. A dog may show obvious fear and avoidance to unfamiliar people or dogs off property but may rush aggressively at the same targets if they approach the house. The territorial motivation can combine with the underlying fear to create a very intense aggressive response. Likewise, a dog may normally avoid an adult male owner or child in the home due to fear of their actions or physical attributes, but if the same person approaches the dog while it is resting on a couch with the preferred family member, the dog may exhibit aggression instead of avoidance because of some degree of possessiveness over the person or resting spot. Note also that confined physical space amplifies the fear and defensive aggression.<\/span><\/p>\n A comprehensive treatment plan for canine aggression involves treating any underlying health conditions, educating clients, managing the environment, and applying behavior modification and appropriate therapeutics for any underlying fear or anxiety. In a typical general practice setting, a veterinarian can help the family of an aggressive dog identify and manage all contributing factors<\/a>.<\/span><\/p>\n Because any medical conditions, especially painful conditions, can lead to irritability and decrease the threshold for aggression, a minimum database for a patient presented for aggression should include a thorough medical and behavioral history, physical examination to the extent the patient\u2019s temperament allows, complete blood count, chemistry panel, free T4 (thyroxine) level, and urinalysis to help screen for and address contributing medical conditions. Note that some signs may be missed on initial presentation to the clinic (e.g., musculoskeletal pain in stoic or distressed dogs), and reassessment or empirical medication trials may be warranted. Holistic wellbeing also encompasses mental health, and adequate physical and mental stimulation (e.g., food puzzles, scent games, reward-based training) for that specific dog and family should be discussed.<\/span><\/p>\n Arguably the most important step in a canine aggression plan is environmental management (setting up the environment to prevent aggression). The most obvious reason is to reduce the risk for injury, but avoidance also improves the success rate of behavior modification. The best training plan exposes the dog to the triggers in controlled situations only and prevents rehearsal of the aggressive behavior or strengthening of any negative association with the target. From a neurobiological standpoint, a dog that is constantly showing aggression has unhealthy levels of stress neurochemicals (e.g., glucocorticoids, inflammatory cytokines), which can have both short- and long-term health and welfare consequences.13<\/sup> Dogs experiencing chronic stress are much closer to their threshold for aggression. Conversely, dogs in low-stress states are less likely to show aggression because they are far below their aggression threshold and can also focus more effectively during training sessions.<\/span><\/p>\n Below are some typical aggression-triggering situations and possible environmental modification tactics for avoiding aggression. Strict environmental management is recommended until a reputable behavior professional can be consulted. In all circumstances, when there is a chance that a physical interaction or bite injury will occur, using a basket muzzle (with appropriate acclimation before use) is recommended to decrease the risk for injury.<\/span><\/p>\n Visitors entering the home<\/b><\/span><\/p>\n Figure 2. Use of window films in the home can reduce a dog\u2019s stress by blocking its view of people outside.<\/p><\/div><\/li>\n Person approaching while dog is on furniture<\/b><\/span><\/p>\n Person approaching and intends to pet the dog<\/b><\/span><\/p>\n Encountering people or dogs while on walks<\/b><\/span><\/p>\n Aggression between dogs in the same household<\/b><\/span><\/p>\n Environmental management is a necessary but insufficient step for optimally reducing canine aggression. Many factors coalesce to create aggressive behavior; therefore, a treatment plan should be multimodal. Behavior modification is 1 important aspect of a complete treatment plan. Good training changes not only the behavior but also the underlying emotional association with the aggression target. In other words, we want to treat the cause of the aggression. However, a detailed plan is beyond the scope of a typical general practice appointment.<\/span><\/p>\n Behavior modification sessions can be implemented by the veterinary team in longer, behavior-focused appointments, or the client can be referred to a board-certified veterinary behaviorist<\/a> or an outside trainer. A reward-based approach is best, but identifying the right professional can be challenging.14<\/sup> Pharmaceuticals and nutraceuticals that address fear and anxiety can be helpful in many cases but are limited when used alone.15<\/sup> The prognosis for complete resolution of canine aggression is always poor. However, aggression is akin to any chronic disease, and a realistic favorable outcome is minimization of aggressive episodes to a degree that all people and pets in the household experience a state of wellbeing.<\/span><\/p>\n\n
What is Aggression?<\/h2>\n
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<\/a>Which Dogs Show Aggression and Why?<\/h2>\n
Health<\/h3>\n
Demographics<\/h3>\n
Motivations<\/h3>\n
How Should We Treat Aggression?<\/h2>\n
Environmental Management<\/h3>\n
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Additional Treatment Steps<\/h3>\n
How Should Clients Respond During an Aggressive Episode?<\/h2>\n