Aggression: Triggers, Flashpoints, and Diagnoses

Karen L. Overall, MA, VMD, PhD, DACVB, ABS Certified Applied Animal Behaviorist


The association between anxiety and aggression: Canine aggression is the most common behavioral problem seen in dogs visiting behavioral practices and is the most dangerous one seen in pet dogs.

Overview of dominance aggression: The necessary condition for canine dominance aggression include: abnormal, inappropriate, out-of-context aggression (threat, challenge, or attack) consistently exhibited by dogs towards people under any circumstance involving passive or active control of the dog's behavior or the dog's access to the behavior. The sufficient condition for this diagnosis to be made include an intensification of any aggressive response from the dog upon any passive or active correction or interruption of the dog's behavior or the dog's access to the behavior . This is a very discrete definition of dominance aggression and has the advantage of not coupling the challenge to food (food related aggression), toys (possessive aggression), or space (territorial aggression). These aggressions can all be correlates of dominance aggression and when associated with it may be indicative of a more severe situation. The sentinel issues in the diagnostic criteria are control and access -- most of the problems with diagnosing the condition arise from people's misunderstanding of canine social systems, canine signaling, and canine anxieties associated with uncertainly about contextually appropriate responses.

The diagnosis of dominance aggression cannot be made on the basis of a one-time event. Once the dig begins to show signs of this problem they will become more visible and consistent permitting the diagnosis to be made. Data on early signs, patterns of change with experience, and changes in intensity are lacking. Note that the necessary and sufficient conditions are radically different from the common descriptions of dominance aggression that specify that the dog will often react to being pushed on, to being corrected with a leash, or to being pushed from a sofa or a person. The number of situations in which the dog reacts inappropriately or the intensity with which he or she reacts do not affect the necessary and sufficient conditions, although these factors may affect ability to treat the condition, prognosis, and risk to people.

Implicit in this diagnosis is that, unless explicitly stated, is that there is no known underlying physical or physiological reason for the behavioral problem and that physical and physiological "causes" have been ruled out. It is also important to remember that this type of classification represents diagnoses of problem behaviors, not just descriptions of a behavioral event (i.e., dominance aggression can ONLY be a diagnosis for an abnormal behavior, but interdog aggression can be both a diagnosis and description).

Dominance aggression is a description for a complex of multi-factorial disorders. Because of the association with social contexts, dominance aggression (like all other aggression) is probably representative of a canine anxiety disorder. Dogs demonstrating dominance aggression can be divided into two broad groups: (1) those who have no doubt that they are in control and can compel their clients to do their bidding), and (2) those who are unsure of their social role and use the aggressive behaviors to deform the social system to get much needed information about what is expected of them. They define their social and behavioral boundaries using the response to their aggression. This is analogous to teenage children with behavioral disorders who are disruptive, and sometimes aggressive. These dogs appear to be less sure of their relative hierarchical status and to express more ambiguity in their vocal and physical responses about the intensity of their aggression. The aggression is not applied equally to all humans in the second class of dominance aggression because the dog responds to the social environment in a differential manner based on individual social interactions. A retrospective analysis of the dominantly aggressive dogs seen at the Behavior Clinic at VHUP since 1987 revealed that the vast majority of these dogs also exhibited attention seeking behavior. These are dogs that are very needy and are constantly setting people up to defer to them, not simply because they have an abnormal urge to control, but also because this is the only mechanism they have for getting information about their role in the social environment. It should be implicit that this need for information about their role in the environment has less to do with that dog's particular social environment than it has to do with an inherent abnormality. Response to anti-anxiety medication supports this categorization: dogs in the second group do well with ancillary anxiolytics (e.g., amitriptyline) to help with their behavior modification. These two behavioral profiles also help to explain the different human groups that may be victimized by dogs exhibiting these different forms of dominance aggression.

Role of Hormonal Facilitation: The role of hormones in canine aggression has been discussed largely on the basis of correlational data. Most dominantly aggressive dogs are male. Testosterone acts as a behavior modulator. It makes dogs react more intensely. When an intact dog decides to react to something, he reacts more quickly, with greater intensity, and for a longer period of time. Castration decreases aggression in about 2/3 of the cases involving interdog aggression; however, few data exist for any effect on other types of aggression. Male dimorphic aggressions may be disproportionately represented in such studies. One study has made a good first attempt to quantify behavioral influences of early neutering for dogs both with and without a history of behavioral problems. In a preliminary study examining the effects of neutering on the behavior of dogs less than 6 months of age and 12 months of age or older, one group stood out. Females younger than 6 months of age who were already showing signs of dominance aggression became more aggressive post-ovariohysterectomy (Gadj = 5.95, p # 0.05; my analysis). All other statistical comparisons indicated that aggression either did not change, or decreased with age, regardless of hormonal status, although a slight trend towards increasing aggression was noted for bitches as they became socially mature. Data from VHUP indicate that androgens may be implicated in dominance aggression in females. Although less common in males that in females, when dominance aggression does occur in females, the patients tend to be very young (less than 1 year and usually less than 6 months of age compared with 18-36 months of age for males), present with profound aggression that gets rapidly worse, and may have delayed heat cycles. This form of dominance aggression may not be the same as dominance aggression that appears at social maturity, nor may it have the same catalogue of behaviors seen in dominance aggression that appears at social maturity. The concept of multi-factorial causality is only recently being accepted in medicine. This is another area that warrants better description of the symptomology, more specific diagnoses, and more experimental research.

Prognosticators: Prognosis is worse with: a. the earlier the age of onset, b. the longer the duration, c. the more intense or frequent the bouts of aggression, especially if intensity or frequency is increasing with time.

Cure v. control: Aggression, like diabetes, is not curable, but, may be controllable in the majority of cases. In a retrospective analysis of prognosticators of aggressive cases seen at VHUP, client compliance and extent of effort was the single best determinant of success. A dog that both the behavioral specialist and the owners feel is greatly improved and with whom the owners are comfortable and content to live is a success. Because of the potential danger and liability involved, everyone involved in treating an aggressive animal must be realistic about what to expect, and what they want and can handle. Requirements vary from one household to the next. A dog that could live safely and non-aggressively in a childless household may not be able to do so safely in one with children. It would be unfair and perhaps, dangerous to guarantee absolute reliability in any dog, including those treated for aggression. A dog could appear "cured", but relapse if clients cease to reinforce the dog's appropriate behaviors. In the case of dominantly aggressive dogs, such reinforcement may mean never letting the dog succeed with subtle, non-aggressive signs of control, like pushing.

Until clients can seek qualified help, they should avoid circumstances known to precipitate the specific aggression. With therapy it may be possible to desensitize the dog to circumstances to which it reacts aggressively, but avoidance is key in minimizing danger.

References:

1.  Beach F, Dunbar I, Buehler. Competitive behavior in male, female, and pseudohermaphraditic female dogs. J. Comp. Physiol. Pysch. 1982; 96:855-874.

2.  Borchelt, PL. Aggressive behavior of dogs kept as companion animals: classification and influence by sex, reproductive status, and breed. Appl. Anim. Ethol. 1983;10:45-61.

3.  Borchelt PL. Development of behavior in the dog during maturity. In: Nutrition and Behavior of Dogs and Cats, ed. RS Anderson. Pergamon Press, New York, 189-197, 1984.

4.  Brain PF, Haug M. Hormonal and neurochemical correlates of various forms of animal "aggression". Psychoneuroendocrinology 1992;17:537-551.

5.  Coyle JT, Puttfarken P. Oxidative stress, glutamate, and neurodegenerative disorders. Science 1993;262:689-695.

6.  Hopkins SG, Schubert TA, and Hart BL. Castration of adult male dogs: effects on roaming, aggression, urine-marking, and mounting. JAVMA 1976;168:1108-1110.

7.  O'Farrell V, Peachey E. Behavioral effects of ovariohysterectomy on bitches. J Sm Anim Pract 1990;31:595-598.

8.  Overall KL. Clinical Behavioral Medicine for Small Animals, At. Louis, Mosby, 1997.

9.  Overall KL. Canine aggression: Part I. Canine Practice 1993; 18(2):40-41.

10. Overall KL. Animal behavior case of the month. Use of fluoxetine (Prozac) to treat complicated interdog aggression. JAVMA 1995;206:629-632.

11. Voith VL, Borchelt PL. Diagnosis and treatment of dominance aggression in dogs. Vet Clinics NA. 1982;12:655-664.

12. vom Saal FS. Sexual differentiation in litter-bearing mammals: influence of sex and adjacent fetuses in utero. J. Anim. Sci. 1989;67:1824-1840.

Diagnostic Correlates of Aggressive Signs: Canine Aggression Screen

NR=no reaction; SL=snarl/lift lip; BG=bark/growl; SB=snap/bite; NA=not applicable

Please note if the reaction is consistent or only to one person or in one circumstance. Also note if the dog has been worsening in one category.

NR

SL

BG

SB

NA

DX

1. take dog's food dish with food

FOOD

2. take dog's empty food dish

FOOD

POSS

3. take dog's water dish

FOOD

POSS

4. take food (human) that falls on floor

FOOD

5. take rawhide

FOOD

6. take real bone

FOOD

7. take biscuit

FOOD

8. take toy

POSS

9. human approaches dog while eating

FOOD

10. dog approaches dog while eating

FOOD

11. human approaches dog while playing with toys

PLAY

POSS

12. dog approaches dog while playing with toys

INTER

DOG

REDIR

13. human approaches/disturbs dog while sleeping

DOM TERR

14. dog approaches/disturbs dog while sleeping

INTER

DOG

15. step over dog

DOM

16. push dog off bed/couch

DOM

17. reach toward dog

DOM

18. reach over head

DOM

19. put on leash

DOM

20. human pushes on shoulders

DOM

PAIN

21. dog mounts, pushes on shoulders

INTER

22. human pushes on rump

DOM PAIN

23. dog mounts, pushes on rump

INTER

24. towel feet when wet

DOM FEAR

25. bathe dog

DOM FEAR

PAIN

26. groom dog's head

DOM

27. groom dog's body

DOM PAIN

28. human stares at

DOM

29. dog stares at

INTER

30. take muzzle in hands and shake

DOM FEAR

31. push dog over onto back

DOM PAIN

FEAR

32. stranger knocks on door

TERR

PROT

33. stranger enters room

PROT

TERR

34. dog in car at toll booth

PROT

TERR

35. dog in car at gas station

PROT

TERR

36. dog on leash approached by dog on street

INTER

DOG TERR

37. dog on leash approached by person on street

PROT

38. dog in yard -- person passes

PROT

TERR

FEAR

39. dog in yard -- dog passes

INTER

DOG TERR

40. dog in vet's office

FEAR PAIN

DOM

41. dog in boarding kennel

FEAR

TERR

42. dog in groomers

FEAR PAIN

43. dog yelled at

FEAR DOM

REDIRE

44. dog corrected with leash

DOM FEAR

REDIRE

45. dog physically punished -- hit

DOM FEAR

46. someone raised voice to owner in presence on dog

PROT

47. someone hugs-touches owner in presence of dog

PROT

48. squirrels, cats, small animals approach

PRED

49. bicycles, skateboards

PRED

TERR

50. crying infant

PRED

51. playing with 2-year-old children

DOM PAIN

FEAR

TERR

52. playing with 5-7-year-old children

DOM FEAR

53. playing with 8-11-year-old children

DOM

54. playing with 12-16-year-old children

DOM