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Initial approach to the aggressive canine (Proceedings)


Aggression is the most common reason that dogs are seen at behavior referral practices.

Aggression is the most common reason that dogs are seen at behavior referral practices. Primary care veterinarians are also asked to deal with this issue on a regular basis. When clients present a patient with an aggression problem, it is important to identify what their definition of aggression is. For some clients, aggression only means biting so when they state that their dog suddenly became aggressive, they may not voluntarily inform you that the dog has been growling in similar contexts for weeks, months, or years. For purposes of this lecture, aggression will include threatening barking (versus alarm barking), lunging, growling, snapping, and biting. Freezes and hard stares are also considered aggressive but most owners will only recognize these in conjunction with more overt expressions of aggression.

Aggression may be normal or abnormal, adaptive or maladaptive. Aggression is complicated and its expression is influenced by many parameters including breed, early development, socialization, hormones, stress, diet, health status, social interactions, and reinforcement history (learning). Rarely is there a simple explanation for an aggression disorder. Therefore, it is extremely important that the clinician get an excellent history from the owner that includes the above factors as well as the development/progression of the problem, the targets, the triggers, the dog's bite severity, and how easily the dog is triggered. Although many owners claim their dog's aggression is unprovoked or unpredictable, the history typically disproves both of these. It is also important that owners specifically describe the dog's behavior just before, during and after an aggressive outburst. Statements such as "he was being dominant" are not useful. Instead the client should describe the dog's body posture, head/ear/tail position, etc. in an unbiased, objective manner. Observing videotape of the dogs is extremely useful if the owner can acquire it safely. Although owners' interpretations of what their dogs are doing, and why, is sometimes useful, many owners are clueless regarding the true motivation and purpose of their dog's aggressive response.

The most commonly seen forms of aggression in dogs include fear, conflict ("dominance-related"), territorial, resource guarding, predatory, and intraspecific (fear, dominance/resource guarding, predatory, territorial). While aggression issues can be serious, it is important to realize that many aggression problems are very amenable to behavior modification. Aggression is not, and should not, mean an automatic death sentence for the animal. It is easy to judge owners that harbor aggressive animals; the fact that they do so is a testament to the strength of the human-animal bond. From both personal and professional experience, I can verify that is not easy to choose euthanasia for an outwardly healthy animal even when logic tells you that the animal poses a risk to people or another animal. As counseling veterinarians, it is not our job to make that decision for the owners. Our job is to provide the owners with the information necessary to make the choice that is best for their situation, whether we agree with it or not.

As with medical disorders, identifying a specific diagnosis is usually helpful in devising a tailored treatment program for aggressive dogs. However, not all dogs fit neatly into a predefined "category". Additionally sometimes categorical labels (as opposed to functional assessments) can actually hamper treatment by eliciting emotional judgments regarding the owner, the animal, and the animal's behavior. It is often sufficient to merely describe the behavior in its functional terms. For example, rather than "labeling" a dog as territorial, a functional approach merely identifies that the dog barks, growls and snaps at unfamiliar people that enter the home. Once the behavior is clearly defined in its topography, context, duration, intensity, triggers, etc., then a preliminary treatment plan can be developed.

Management and Behavior Modification


Management is a crucial step in controlling and treating behavioral disorders. It is often the most overlooked step as well. In some cases, managing the problem is more practical than trying to actually "cure" it. For some owners, the improvement obtained from management steps alone is sufficient to make the animal agreeable and safe enough with which to live.

Management consists of meeting the dog's physical and psychological needs including adequate physical exercise (for medium to large dogs this means 40 or more minutes of aerobic exercise per day), mental stimulation, and social contact. More importantly, it means controlling access to stimuli that trigger inappropriate/undesirable behavior. Owners should avoid placing the dog in situations that trigger aggressive behavior. Each time the dog displays aggressive behavior, neurochemical and behavioral reinforcement systems are activated. Additionally, both the target and the dog are placed at risk of injury (the target from the dog and the dog from retaliation).

Most dog owners and even many trainers take a reactive approach to problem behavior – they are always correcting the dog during or after the fact, but do not take steps to prevent the dog from engaging in inappropriate behavior in the first place (management). In many cases, owners and trainers miss subtle warning signs that a bite is going to occur, or the bite actually occurs with little or no warning. In these cases, it is impossible for a human to react rapidly enough to actually stop the attack midway or, ideally, before it occurs. Thus any correction that is applied is typically done after the threat/bite has ended and often at the time when the dog is actually starting to show reconciliatory behavior. Once the dog is engaged in a threat display or aggressive attack, no manner of training will influence that display – it has happened and so has the reinforcement for it. The only episodes of aggressive behavior that can be influenced at this point are future ones.

Although it does work in some cases, the concept of specifically triggering aggression just so the trainer or owner can correct the dog for the aggressive display is flawed in many ways. First, very few owners or trainers have the skill to judge the appropriate level and timing of such a correction (i.e. strong enough to instantly abort the behavior but not so strong as to frighten the dog or trigger a defensive attack). Second, the entire process is extremely stressful for the dog. Not only is the dog forced to engage in a distressing encounter, the dog is also being punished for showing the only coping strategy that it knows. Additionally, if the owner applies this punishment, it seriously erodes the dog's trust in the owner's leadership ability (and causes significant damage to their relationship). Third, there can be significant risk of redirected or punishment-induced aggression toward the handler. Finally, aggression is like scratching, it is the symptom of an underlying problem. Focusing just on the actual aggressive display will not necessarily address the underlying "disease" process.

Dogs aggressive to people entering the home or yard should not be left outside unattended (to run and bark along the fence line), nor should they be allowed at the front door when visitors arrive. These dogs should be placed in a crate or bedroom away from the entrance to the house, preferably before the visitor even arrives at the home. Any items (e.g. rawhides, certain toys, food bowl) that a dog guards should be removed from the dog's environment at least temporarily. If the dog shows aggression when on the furniture, then the dog should not be allowed on the furniture. Dogs with intraspecific aggression should be kept away from other dogs and certainly should not be taken to the dog park! Fighting and scuffling with other dogs is not socialization. This reprieve from exposure gives both the owner and the dog time to "chill out" and not worry about reacting to trigger situations. It allows the dog's threat response system and HPA axis to tone down. This intervention also forces the owner to be more proactive and take charge of the dog's environment more effectively, and this step alone can improve some dogs to a significant degree.

Finding the appropriate equipment to control the dog is also important. Aggressive dogs should be trained to wear a muzzle, so that when one is needed for safety, the dog does not become even more upset and aroused. Various head collars (e.g. Gentle Leader, Newtrix, Halti) and harness (e.g. Sen-Sation, Easy Walk) are available to give owners humane control over large, unruly, and/or aggressive dogs. Head collars in particular are useful as they give the owner control over the dog's head and mouth, which provides an increased level of safety over regular harnesses and collars.

Other products such as Dog Appeasing Pheromone, the Anxiety Wrap (www.anxietywrap.com) and the Calming Cap (available from Premier Pet Products, www.premierpet.com) are often extremely helpful in reducing arousal in aggressive and reactive dogs.

Behavior Modification

Behavior modification implements steps to actively change the dog's behavior long term. Clients must understand that in order to change the dog's behavior, they must change their own. Behavior modification can create rapid alternations in a dog's behavior in some circumstances, but in most cases improvement occurs slowly over a period of weeks to months. For many cases, therapy must be implemented on some level for 1-2 years or even the life of the dog. The initial phase concentrates on dealing with general unruliness and establishing basic foundation skills. Foundation skills include basic obedience, leadership programs, and relaxation tasks.

Basic obedience training should teach, at minimum, response to cues for sit, down, come, stay and walking politely on leash (no pulling). Dogs with resource guarding should also be taught an object release word (e.g. "Give) and a "Leave it" cue. Owners should also practice rewarding dogs for orienting to the owner when the dog's name is called. Most dogs actually have poor response to their names. This behavior should be practiced and rewarded similar to any other cued behavior to produce reliability even under distractions.

Implementing a leadership program (frequently identified by various names such as No Free Lunch, Nothing in Life For Free, Deference, etc.) is crucial to resolving most aggression disorders (and most other behavioral disorders as well). Some experts advocate these programs as "alpha reduction" programs and most of these programs focus on requiring the animal to respond to a command before interacting with the animal or providing the animal access to any resource (e.g. petting, treats, food, bones, leashing the dog for walks, allowing the dog to pass through barrier-ways [doors, dog crate], etc.). I prefer to view such programs more as an exercise in teaching the dog focus (on the owner) and self-control, as well as an additional opportunity to reinforce calm behavior. Furthermore these programs help owners learn how to manipulate the dog's life rewards beyond just the use of food. If they control the dog's resources, they have better control over the dog. The leadership program establishes a bargain between the owner and the dog. In order for the owner to do anything for the dog, to the dog, or allow the dog to interact with any life reward, the dog must meet four behavioral criteria: 1) respond to a (previously trained) obedience cue within 1-3 seconds without any physical prompting 2) remain calm and quiet, 3) remain focused (making eye contact) on the owner for the duration of the interaction, and 3) remain politely outside the owner's personal space for the duration of the interaction (unless the owner specifically invites the dog into that space). Owners also should learn to be aware of attention-seeking and manipulative behaviors that the animal may show. In some cases these are obvious, but in other situations they may be subtler. Owners must learn to ignore such behaviors; any directed, focused reaction with reinforce the behavior and the animal will continue to show it. Owners should look for calm, relaxed behaviors and make a point to interact with the dog at those times, thereby reinforcing those behaviors instead.

Emotional arousal is the one underlying consistent issue with aggressive dogs. As helpful as basic training is, obedience does not really address the dog's underlying emotional reaction to a trigger stimulus. Relaxation exercises are critical to teach dogs to essentially relax on command. Most owners and many trainers pay attention to what the dog is doing but not how the dog is doing it. A dog that sit-stays like a coiled spring is better than one that lunges, but a dog that sit-stays with a relaxed body in the presence of a trigger is almost "cured." Teach the dog various relaxed postures such as sit, down, and the "play dead" position in a distraction free environment. Distractions (not the trigger stimulus) are gradually added until the dog is proficient in a variety of environments and distractions. It is also helpful to place condition these behaviors to a certain dog bed or rug such that eventually just asking the dog to go to this area and sit or lie down triggers relaxation. This bed or rug becomes a "safety zone" for the dog. Massage and TTouch are also useful in attaining this goal.

Once owners have completed the above foundation exercises, desensitization/counterconditioning (D/CC) exercises are begun for specific problem stimuli. It is crucial that the dog is kept below threshold during each session. For example, if the dog previously reacted aggressively to an approaching stranger 40 feet away, then D/CC sessions start with the strangers 45-50 feet away. The stranger walks perpendicular to the dog (not directly toward the dog) and the dog is rewarded for remaining calm. This is repeated until the dog consistently remains calm and then the stranger moves a few feet closer as he/she passes by. During any D/CC procedure, there are four general criterion groups: distance to the stimulus, duration of exposure to the stimulus, number of stimuli present, and behavior of the stimulus. The trainer/owner should never alter more than one criterion at a time; for example, the stranger never moves closer to the dog AND stays there longer. D/CC is time consuming and, if done properly, extremely boring to watch, but this process produces long lasting positive changes in the animal's behavior. It takes many, many repetitions of each task for new behavioral patterns to be established. Owners should never think the dog is "fixed" just because it stays calm 5 times in a row in a previously problematic situation.

Drug therapy is useful for some cases and contraindicated for others. Drugs should never be used as the sole treatment approach! Drug therapy does have the potential to make the dog worse and increase the risk of biting. Cases must be carefully chosen and owners must demonstrate an ability to adequately manage the dog to ensure public safety before drug therapy is begun. Drug therapy may be most useful for cases with concurrent anxiety/fear, impulse control problems, and/or reactivity.

Further Reading

Crowell-Davis SL, Veterinary Psychopharmacology, Blackwell Publishing: Ames, Iowa (2006).

Horwitz DF, Mills DS, Heath S, BSAVA Manual of Canine and Feline Behavioural Medicine, British Sm Anim Assoc: Gloucester (2002).

Lindsay SR, Applied Dog Behavior and Training Vols.1-3, Iowa State University Press: Ames, Iowa (2000-2003).

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