Veterinary Clinics of North America: Small Animal Practice
Review articleDifferential diagnosis and management of human-directed aggression in dogs
Section snippets
General principles
Aggressive behavior includes threats and unsuccessful attempts to injure as well as biting. Threatening behavior includes stiffening, staring, growling, baring teeth or snarling, lunging and charging, and aggressive barking. For example, a dog that growls when it is approached while eating is probably exhibiting food-related aggression, regardless of whether it lunges at or bites an interloper.
The dog owner who, perhaps defensively, does not consider his or her pet to be vicious (or aggressive)
Management of aggression
The treatment of behavioral problems in general and of canine aggression in particular does not tend to follow a “cookbook” format, because each case is unique and includes a tremendous amount of individually defined characteristics. Among these characteristics are historical behavioral information, the medical history of the patient, family makeup, and the specific situational details associated with aggression, including identification of provocations (however subtle) and other circumstances
Safety issues
No matter how carefully designed the treatment plan is, there can be no relationship to work with if safety issues are not addressed. How can the clinician help the family to avoid being bitten or to protect neighbors and visitors from being threatened?
First, it is critical to avoid the circumstances and provocations that have historically been associated with aggression. This should include avoidance of specific targets, especially if they are not family members; for example, if the dog tends
Medical problems contributing to aggression
Behavioral problems are generally considered to be diagnoses of exclusion. In practical terms, this would indicate that a primary behavioral diagnosis depends on the clinician's reasonable confidence that medical problems are not the predominant reason for the presenting complaint; however, not all medical problems must (or realistically can) be ruled out in many cases. For this reason, it is important to consider physical and neurologic examination findings, a minimum database of laboratory
General principles of behavior modification
Few behavioral problems can be sufficiently addressed with lasting results without modification of the dog's behavior through learning. Problems with roots solely in physiology and with little or no consequential learning may respond satisfactorily to surgical or chemical (drug therapy) intervention alone. Most behavioral cases, however, involve at least some learned component and therefore require learning—modification of behavior through operant (or at times classic) conditioning—as part of
Drug therapy
Drug therapy may be helpful as an adjunct to behavior modification and safety counseling in the management of canine aggression. Indications for drug therapy include fear or anxiety, particularly because stress can override the effects of behavior modification, and impulsive or explosive (disinhibited) behavior, which may be effectively blunted by serotonergic agents [47]. Duration of drug therapy ranges from relatively short term (eg, 6 months for cases in which anxiety must be reduced to
Castration
Castration can effectively reduce urine-marking, mounting, and roaming behavior [57], [58]. It would make intuitive sense that only sexually dimorphic behaviors (eg, dominance-related and territorial aggression but not fear- or food-related aggression) would be affected by castration. Testosterone may have an intensifying effect on aggression of all types; in a pair of studies, intact male dogs were involved in 70% to 76% of reported bites [5], [30]. Hopkins et al [59] reported that castration
Summary
Canine aggression directed to human beings is a common presenting complaint and requires attention to safety issues and behavior modification to minimize the risks of future aggression. Dogs may bite familiar people, including family members, or unfamiliar people for a variety of reasons. Anxiety plays an important role in aggression regardless of its target or circumstances. Effective management of aggression may include education and safety counseling for owners, lifestyle changes for dogs
Acknowledgements
The author thanks Alison Seward and Jenny O'Connor, CVT, for assistance in review of the manuscript.
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