Canine aggression: Getting to a good walk


When the nightly walk becomes a nightmare for pet owners and their dogs, it's time for veterinary technicians to intervene.

What does canine aggression on a walk look like? For Bella, her tail drops and her ears fall back. She licks her lips, squints her eyes, and growls. In Buddy's case, his hackles rise, his ears go erect and back, his body tenses, and he lunges forward barking. Both of these dogs may be demonstrating signs of fearfulness and aggression toward a trigger. These behaviors can make it difficult or impossible for pet owners to manage and enjoy walks with their dogs.

Aggression toward unfamiliar pets or people generally arises from fear and anxiety, perhaps because of inadequate socialization, genetic factors, or previous unpleasant experiences. Regardless of the initial cause, the problem is further aggravated by each further exposure if a positive outcome is not achieved. If the owner is angry, upset, or uses corrective training, fear and anxiety are increased. If the person or pet that approaches is aggressive or fearful, fear is aggravated. And if aggression successfully removes the threat, the behavior is rewarded.

While a similar treatment approach can be used for most cases, the level of improvement that can be achieved will vary with the environment, the owner, and the dog's temperament. The approach should include:

  • Developing safe, effective management of the problem through preventive measures

  • Implementing a program of positive training to achieve focused and calm behaviors in the absence of any stimuli

  • Using humane control products such as head halters or chest attachment body harnesses to maintain physical control

  • Using drugs or other therapeutics to reduce fear, anxiety, and impulsivity where indicated.

Gradually, the pet might then be exposed to increased intensity of stimuli and given high-value rewards during each successful exposure. Using this form of desensitization and counter-conditioning can result in more pleasant walks, ideally eliminating unpleasant outcomes. This will be discussed in more detail later in the article.

As a technician, you can play an important role in the following ways. If you work in a clinic that offers behavior consulting with the veterinarian, you are central to identifying cases and advising clients that help is available in your practice. During the consultation, you can play an important role in working with the veterinarian to demonstrate reward-based training, the fitting and use of control products such as head halters, and techniques such as clicker training and shaping. You can also serve as the point person for follow up, supporting and clarifying where necessary for the client and liaising with the veterinarian. In addition, if you have sufficient training in reward-based behavioral modification, it might be practical to schedule follow-up visits at the clinic or in the home (if legally permitted) to help guide the owner with the implementation of the program.

If you work in a practice that does not provide behavior consultations, your role should be to work with your veterinarian to help identify pets with problems, provide advice and guidance on training strategies and management, and encourage referral to a veterinary behaviorist if recommended by the veterinarian. So it's important to know the qualified behaviorists and appropriate trainers in your area that your veterinary practice prefers. After the behavior referral, you may also serve as liaison with the specialist to ensure adequate follow up and client support.

History and prospective prognosis

Assuming that underlying medical problems have been ruled out, the behavioral history along with any video of the undesirable behavior (including owner responses) are used to diagnose, develop management strategies, and provide the owners with realistic expectations of what might be achieved. While you may also gain information from observing the dog and its interactions during the consultation, the primary focus will need to be on these factors:

  • Interviewing the owner and reviewing video to get a complete and accurate description of the problem from its outset to the present

  • Asking how the owner has responded to the problem to date

  • Learning the dog's response

  • Understanding the dog's training background

  • Evaluating the dog's temperament

  • Understanding the owner and environmental factors. For example, if the dog displays fear aggression toward unfamiliar dogs and the owner lives in a building complex in which other dogs cannot be avoided, safety is an ongoing concern, and graduated exposure might not be practical. In addition, the ability and willingness of the person who walks the dog to be able to implement the program is an important consideration in safety and success.

  • Exploring the ABCs—antecedent (what precedes), behavior (a description of the behavior itself), and consequence of the behavior, including any change from the first occurrence to the present.

With respect to prognosis, the first question is whether the owners can effectively manage the situation to prevent injury. This also requires being able to identify each and every situation that might lead to fear or aggression, since if the behavior is not predictable then it cannot be reliably prevented. If the management and treatment plan is something the owners are unable or unwilling to implement, then improvement will not be achieved. Even if the problem is preventable and substantive improvement might be possible, the owner must have realistic expectations about what is achievable considering the dog's temperament, the environment they live in, and the underlying cause. For example, some owners may not be able to accept that their dogs will always require on-leash walks and will need to be kept out of off-leash dog parks. In cases in which owners are unable or unwilling to safely manage the aggression, relinquishing the pet may be necessary. In some cases, a suitable environment or home may be found in which problems can be effectively avoided, managed, or improved. However, the safety and well-being of people, other animals, and the dog in question must be the priority. Euthanasia is a last resort in cases where injuries have occurred and further injuries cannot be effectively prevented. In one study of dogs that were aggressive toward unfamiliar dogs, 76 percent could be around other dogs on leash outdoors after treatment.1

Prevention and safety

Before instituting behavior modification, the owner must first put in place a preventive management program. This is essential not only to prevent potential injuries but also to avoid further learning that would perpetuate and aggravate the problem. When aggression is successful at removing the threat, the behavior is reinforced, further increasing the problem. This may also lead to a decrease in threats and posturing as the pet gains confidence that aggression will be successful. Therefore, evaluation of the case from the first incident might be necessary to be able to use body language as a primary diagnostic tool. Another consequence of each aggressive interaction is that if the owner is anxious or upset or uses punishment (corrections) to suppress the behavior, or if the stimulus (person or pet) is fearful or threatening in any way, the association with the stimulus becomes increasingly more unpleasant. In addition, when owners punish pets that are displaying aggressive signals, they might suppress the warning threats that precede the aggression.

Leave out the punishment

For dogs that are aggressive to people or other pets on walks, stimulus avoidance can be achieved by avoiding walks and limiting play, exercise, and training to the home or yard. Alternatively, it might be possible to walk the dog at times or in locations where stimuli can be avoided or at sufficient distance from the stimulus that the dog does not react. Pet owners might even drive their dogs to a location where they can walk their dogs without exposure to any fear-evoking stimuli. Some dogs can be walked when they are focused on a positive activity, such as jogging or cycling, or when they are together with people or other dogs that keep them distracted or help calm them. Pet owners can also practice stimulus avoidance by keeping their dogs away from doors or windows or running free in the yard, if fear and aggression might be incited.

Since safety is the first concern, a leash and head halter, an easy walk harness (front control), a basket muzzle, or physical confinement (e.g., to a room, crate, or secure yard or kennel) will most likely be required during parts of the program. Control devices such as the leash and head halter or front-control harness also allow the owner to immediately but calmly redirect the pet away from a situation should problems begin to arise. Owners should be taught how to monitor, read, and communicate with their dogs to identify any body language or signals that precede threats or aggression and to immediately remove their dogs should any of these signs arise.

During the preventive program, the owners will also need to work on the foundation exercises that will be used to control the dog and achieve desired outcomes (response substitution) during future exposure. This can only be accomplished when the pet is in a sufficiently low state of arousal that allows it to focus and learn. Pets in a high state will react reflexively and without the ability to consciously assess and respond to situations. Pets that cannot be effectively calmed during this early training may need to have some one-on-one sessions with a trainer or revisit the behavioral specialist. Various medications to help reduce anxiety can also be recommended in this situation or if the aggressive behavior is excessive, prolonged, or out of control.

Preparing for exposure to stimuli: foundation exercises

During the preventive part of the program, the owner should teach the pet the foundation behaviors that will be needed for future exposure to stimuli. The pet and owner will need to become familiar with any new control or restraint devices used such as head halters and muzzles. The veterinarian will need to decide if the pet and the problem might require medication (and determine the medications given) to reduce anxiety, arousal, and impulsivity so that the pet might better focus and learn. And if therapeutics are prescribed to reduce the pet's anxiety or reactivity to the stimulus, they sometimes need to be administered for several weeks before stimuli exposure begins to determine if they have the desired effect. In addition, even if significant improvement can be achieved, there are still likely to be situations in which management will be required. So for most cases, the ongoing use of a head halter is usually the best option for ensuring control and safety during walks. Taking time to properly fit and adapt the pet to the head halter with positive associations, such as treats, walks, play, and toys, can help ensure long-term success.

It's important to discuss the principles of training with pet owners. Develop a reward list and gradient, and discuss predictability and consistency of all rewards both to reduce anxiety and conflict and to train the behaviors that we want to the dog to learn. Remind owners that a few training sessions a day with favored rewards, such as toys and treats, can be incorporated into a pet's walks, play, and exercise times. In addition, each time the pet wants anything of value—whether it's a walk, food, going outdoors, attention, a toy, or a chew—these should be viewed as rewards and should only be given for desirable behaviors. Highest-level rewards should be saved for each new increment of training, and intermittent rewards or lesser rewards should be used for those behaviors that have been learned. With fear and anxiety, the goal is to gradually shape more relaxed behaviors by focusing on body postures and breathing.

Desired behaviors can be achieved through observation and reward as long as timing is immediate and consistent. Clicker training can be an excellent way to explain reward timing and shaping. Lure reward training or the use of a leash and head halter can be used to prompt desirable behavior as long as rewards are given only when the desired behavior is observed. With the head halter, the immediate release of pressure is used to mark what is desirable. Owners must be cognizant of reinforcing desirable behaviors whenever they are observed or offered by their pets. However, eliciting behaviors on cue is also essential so that desirable behaviors can be taught as a substitute for the undesirable behaviors. For aggression on walks, the focus of foundation exercises should be on relaxed, loose-leash walks with short slack; a relaxed sit; a focus on the owners; and the ability to back up or turn and walk away from a stimulus that the pet perceives as a threat. Working with a behavioral technician or appropriate trainer can help with owner understanding, implementation, and compliance.

Treatment of fear aggression

Once loose-leash walks, sit focus, or back up or turn are reliably trained, drugs or other therapeutics have been appropriately administered, and any recommended control devices are being effectively used, the owner can begin to focus on ensuring relaxed and calm outcomes in situations with greater distractions. A good pre-exposure goal would be for the owner to be able to successfully achieve the foundation behaviors in situations where the dog is meeting and greeting people and dogs that are familiar, building up to those the dog would be most excited to greet. Initially, these situations can be set up so that the owner is prepared with favored rewards in hand and the leash and head halter attached, if one is being used. Training could begin with greeting people at the door with a calm sit, walking up to familiar people or dogs in the yard or on the street, and sitting, walking by, or turning in the other direction. In other words, ensure that response substitution and calming can be effectively achieved in situations that might cause arousal or excitement but not fear or aggression.

When these steps can be predictably achieved, a follow-up visit with the specialist should be scheduled to assess the level of success and determine whether appropriate outcomes have been achieved with any prescribed medications. At this point, the ability of the owner and dog to proceed to exposure exercises can be reevaluated, and further suggestions, adjustments, or other alternatives, such as drugs, products, training, and methods, can be discussed.

To achieve effective response substitution, the focus is on getting a desirable behavior during stimulus exposure—a relaxed sit or calmly walking past the stimulus rather than showing aggression. The type of stimulus for initial training and the threshold at which success can be ensured will need to be individually determined. Generally, success will best be achieved by setting up exposures in order to control all parameters—the stimulus, the dog, and the environment. Repeatedly exposing the dog to a formerly fear-evoking stimuli at low enough levels and pairing with highly valued rewards each time the dog looks at the target to make a positive association is known as desensitization and counter-conditioning. Remaining below the threshold to ensure that each exposure ends with a positive pairing is the goal. The ability to control and calm the dog with commands and the use of a head halter can help ensure that the owner also remains calm and that the dog can be settled or turned away and removed from the situation. Each situation should always conclude with a relaxed, safe outcome. Developing a stimulus gradient and finding a way to expose the dog in a controlled and measured manner can be difficult to implement for many owners.

It's important to establish realistic and practical short- and long-term goals. Continue to monitor progress with follow-up appointments to adjust goals and expectations. A behavioral technician or trainer is often the best option to help owners with hands-on guidance and to provide ongoing feedback.

If the final goal is for direct contact between the dog and stimulus (e.g., stranger giving a treat or petting, dogs playing), remember that fear-evoking stimuli can be visual, auditory, olfactory, and, in some cases, tactile. Stimuli can be muted in a variety of manners, including distance, location of exposure, stimulus characteristics (e.g., uniform, height, age), and intensity (e.g., motion, volume) as well as by exposing the dog to individual components of the fear-evoking situation one at a time. The stimulus should be approached slowly and calmly, and progress should cease if the pet is no longer interested in food or treats or shows any signs of fear, anxiety, or aggression. In the case of aggression toward other dogs, initial greetings could take place with the stimulus dog standing still and the dog walking past, the stimulus dog walking in one direction with the dog walking in the opposite direction, or the dog sitting and the stimulus dog walking past, in front of the dog and back again (always at sufficient distance from the stimulus to ensure success). A DVD can also be used to begin exposure if it incites a reaction from the pet. If any signs of anxiety begin to emerge, and the dog cannot be quickly and safely calmed, the dog should be backed up or turned away to a sufficient distance that it calms, perhaps with the aid of a command, food lure, or gentle pull on the head halter. At this point, positive reinforcement should be immediately given, thus ending the exposure with a positive outcome. This type of exposure should be repeated until each exposure results in a positive (no aggression, no fear) outcome.


Pet owners are more likely to succeed with the support of the veterinary team. Setbacks happen and that is when the most encouragement is needed. Technicians can be an invaluable resource for client follow-up, feedback, guidance, and support. In addition, with training, technicians can work directly with clients in reward-based training, product use, and exposure exercise to help owners achieve the best possible results.

As a technician, if you're interested in doing more behavioral work, start by joining the Society of Veterinary Behavioral Technicians. You don't have to pursue certification to receive guidance and learn about what makes good training as well as the products that support your pet-training efforts.

Gary Landsberg, BSc, DVM, Dipl. ACVB, Dipl. ECVBM-CA, practices at North Toronto Animal Clinic, Thornhill, Ont., Canada.


1. Sherman CK, Reisner IR, Taliaferro L, et al. Characteristics, treatment, and outcome of 99 cases of aggression between dogs. Appl Anim Behav Sci 1996;47:91-108.

Additional reading

1. Pryor K. Don't shoot the dog! The new art of teaching and training. Gloucestershire: Ringpress Books Ltd., 2002.

2. Rogerson J. Canine fears and phobias; a regime for treatment without recourse to drugs. Appl Anim Behav Sci 1997;52:291-297.

3. Horwitz D. Classical counterconditioning as a treatment modality for dogs (Canis familiaris) showing aggression toward other dogs on walks. In: Mills D, Levine E, Landsberg G, et al., eds. Current issues and research in veterinary behavioral medicine. West Lafayette, Ind: Purdue University Press, 2005;207-210.

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