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Fights Between Household Dogs

Debra Horwitz, DVM


|December 2003|Peer Reviewed

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How should I proceed in helping clients who are dealing with fights between household dogs?

Fighting between dogs within a household can have several underlying motivations:

• A younger, larger, more agile dog challenges an older, previously dominant dog. If the older dog acquiesces, things will be fine. If the older dog does not relinquish rank, fighting can persist. Owners may intervene to avoid the change, which creates anxiety and/or may exacerbate the fighting.
• Aggression can occur between dogs that were raised together. As they reach social maturity, the relationship can change, or changes within the home can create anxiety that may result in aggression.
• Aggression can occur when the higher-ranking dog leaves or a new dog enters the home and the others try to restructure the social relationships.
• One dog's social communication skills may be impaired. For example, dog A might give deferential signals, but dog B may still attack. Or dog B may not display any preliminary posturing (growl, snarl, stiffening) when challenged but proceeds directly to a full-out attack. In both scenarios, dog B is behaving inappropriately.

Fights usually occur over access to resources considered important to dogs-food, resting places, territory, and favored possessions and people. Common triggers include treats, owner attention, greeting owners, sleeping positions near the owner, entering or exiting the home, high-arousal situations such as fence running, or movement through tight spaces.1 In some cases, aggression between the dogs may be redirected-that is, dog B becomes aroused by an event or stimulus unrelated to dog A (e.g., mail carrier's arrival, separation anxiety) but it vents its aggression on dog A because it is nearby or accessible.

Characterizing the Situation
When taking a history, focus on the following points:

• What is the progression of the aggression? Get detailed descriptions of the first episode and at least the three most recent episodes.
• What circumstances do the owners believe elicit the aggression? Do the contexts determine which dog is the aggressor and which the victim?
• What are the owners doing and how do they respond to the aggression?
• Are reprimands or punishment used? If so, what type, how is it applied, and to which dog?
• How long has aggression been present and have injuries have been sustained? This often helps in determining prognosis. Severe injuries may indicate lack of inhibition and poor prognosis.
• What are the ages of the animals? This may also determine treatment and prognosis.
• Can the owner identify/predict aggressive episodes? This ability as well as understanding and carrying out treatment recommendations affects results.
• What are the body postures/eye contact of the dogs during fights, at rest at home, and while in the consultation room? Which dog stares and which "avoids"? Are social responses appropriate for each, or does one have impaired social communication skills?

Helping Clients to Understand
The first step in treatment is to explain canine dominance hierarchies to pet owners and how their behavior influences the relationship between dogs within the home. Owners often do not understand this concept and try to produce a "fair" situation by allocating resources equally between dogs. This may not be acceptable to the higher-ranking dog. In an effort to keep certain privileges and resources, the higher-ranking dog may become aggressive to the other.

Owners must recognize that social hierarchies help decrease the conflict associated with allocation of critical resources (food, shelter, mates, territory).2 If two normal dogs are just experiencing a shift in hierarchy, inappropriate owner intervention may exacerbate the problem, but if the owner understands what is happening, he or she can facilitate resolution. Owners should learn how to recognize canine body language indicating assertion; deference; and low-level threats, which include eye contact, snarls, or low growls.

Aggression over resources and redirected aggression must be differentiated because
treatment varies. If the problem is redirected aggression due to another highly arousing circumstance or underlying anxiety, that problem must be treated first or the aggression may continue. During the treatment process, owners should be instructed to keep records of threats, attacks, or tension-producing situations and try to avoid them.

Hands-On Treatment
The first goal of treatment is for the owners to prevent further fighting and injury to the dogs and humans by taking total control. The following steps will allow owners to achieve this goal:

• Separate dogs when they are unsupervised or left alone.
• Apply headcollars to each dog (with leashes attached) and muzzles; these allow intervention and prevention of injury, respectively.
• Restrain dogs with a leash to a piece of furniture (i.e., a "tie-down") while owners are present. The dogs must be kept far enough apart so they cannot make contact with each other.
• If the dogs do fight, care must be taken in breaking up fights to avoid owner injury. Loud noises (fog horns), water, or grabbing the dogs by their back legs can help end the fighting. Owners should be warned not to grab the head or collar to avoid being bitten.

If fighting is not due to underlying anxiety/poor communication skills, treatment is often centered on supporting the chosen dominant dog. In some cases, this is the younger, more physically capable dog. At other times, a technique called "elder support" is used, which entails supporting the dog that has been in the home longest.3 If one of the dogs is a bully, has poor communication skills, or has another underlying anxiety, that dog should not be supported as the leader. While owners are ultimately in control, the chosen dominant dog should have first access to everything, including going outside, coming in, food, owner attention, and entry into rooms. Any circumstance that elicits aggression should be avoided. Keep in mind, however, that dominance can be context-dependent-one dog may care about one resource and not another, and this may determine resource allocation.

Owners as Leaders
Another technique, the owner taking the leadership role and controlling both dogs, is especially helpful when one is a "bully" and doesn't allow any other dog to have status or has impaired social skills. In this method, all privileges are withdrawn from all dogs. Owners keep greetings low-key, avoid treats and rawhides unless the dogs are separated or on a leash, and avoid or control movement through tight spaces. They also separately train each dog in the "sit," "stay," and "down" commands to increase their control and give structure to the environment and their interactions with the dogs. The dogs are then put into subordinate positions (sit/stay or down/stay) and allowed to interact with the owner only at owner commands. Owners control all interactions and access to food, resting places, territory, attention, and treats. As mentioned above, dogs are leashed when they are in the house together with the leashes fastened to furniture.

If anxiety and/or fear are being exhibited by either dog, then medication might be appropriate to facilitate treatment. Dogs with impaired communication often benefit from serotonin therapy, as underlying anxiety may be at the root of the improper behavior.

Getting Back to Normal
As treatment progresses, it is helpful for the dogs to interact in neutral situations where they are both happy, such as during a walk. The dogs can also be fed at a distance (if food guarding is not a problem), but far enough apart that no aggression is shown. The dishes are slowly moved closer together as long as the dogs do not react.4 Owners must be instructed to avoid physical punishment to correct aggression. Pain or even the threat of pain can cause aggression.

Prognosis can vary greatly. In some situations, aggressive behavior can persist despite owner control and intervention. In those cases, alternate living arrangements may be necessary. However, in many situations, if the owner follows the treatment plan by taking control of the dogs, resources, and environment and controlling any underlying anxieties, the dogs can coexist in relative peace.  

• Owners must take charge.
• Owners may support a chosen dominant dog and/or be the controlling individual over both dogs.
• Dogs with impaired communication often benefit from serotonin therapy.
• Allow dogs to interact in a neutral environment, such as on a walk.
• Start by feeding dogs at a distance, gradually moving dishes closer together as long as no aggression is displayed.
• Under no circumstances should physical punishment be used.


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