1. Behavior Genetics of Canine Aggression:
Behavioral
Phenotyping of Golden Retrievers by Means
of an Aggression Test
AUTHORS: L. VAN DEN BERG, M. B. H.
SCHILDER, AND B. W. KNOL
Presented By: Jennifer Driskell and Monica Endy

2. Background- Golden Retrievers
 Originate from Scotland
 They were developed as gundogs to retrieve shot
waterfowl during hunting and shooting parties.
 Early retrievers were crossed with tweed water
spaniel to get today’s golden retrievers.
Image Source: Flickr Joanne Probyn
Image Source: Wikimedia Commons Scotland Map

3. Introduction
 Why study aggression?
 Can cause human injuries
 Common reason for euthanasia
 Canine behavioral disorders can serve as a model for human
mental disorders
 Why study Golden’s?
 Most are friendly pets
 Some can be very aggressive
 Aggression occurs more often in certain family lines therefore
indicating a genetic cause

4. Hypothesis
 Golden retrievers have a lowed threshold for
aggressive behavior under various circumstances
 Aggression can be subdivided into classes based on
the nature of stimuli eliciting the behavior and that
these different classes are controlled by different
genetic mechanisms

5. Methods
 83 Golden Retrievers were used (55 were purebred
and had known pedigree)
 49 males (18 castrated)
 34 females (16 castrated)
 There was no medical reason found for the
aggression
 53 of the 83 were referred to behavioral experts due
to their aggressive tendencies

6. Methods- The Questionnaire
 Owner filled out questionnaire
 History
 Characteristics of aggressive behavior
 They were then classified into two groups:
 Owner-acknowledged non-aggressive (24)
 Never attacked, bitten or showed excessive growling towards dog
or person.
 Owner-acknowledged aggressive (59)
 All other dogs

7. Methods- The Aggression Test
 There were 22 subtest with similar stimulus
situations
 In each subtest 3 people were present:
 2 test persons (1 male, 1 female)
 1 camera man
 Each subtest lasted ~20 seconds
 All test were recorded on video tape and
subsequently analyzed with the help of an ethogram
(tables 1 and 2)

8. Indoor Testing Facility (Utrecht University)

9. Methods- Analysis
 Behavioral Profiles converted to behavioral
phenotype using three methods:
 Snap Attack Score
 Total Aggression Score
 Principal Component Analysis (fear)

10. Results- The Questionnaire
 Aggressive behavior was not similar in all dogs
 20 were only aggressive towards people
 7 were only aggressive towards dogs
 32 were aggressive to both people and conspecifics
 Severity of aggression varied
 Severe biting incidents
 Threatening behaviors (ex. Growling)
 Environmental factors and genetic variation played a
role in these results.

11. General Test Results- Snap Attack Scores
 Subtest 14- The male test person threatens the owner
by yelling and shouting at him/her. That test person
pushes the owner with the artificial hand. The hand
also moves in the direction of the dog several times.

12. General Test Results- Snap Attack Scores
 Reasonable Measurement of Aggression
 Owner acknowledged aggressive dogs had a significantly
higher snap/attack score than owner acknowledged non-
aggressive dogs.
 Discrepancy
 68 percent of owner acknowledged aggressive dogs did not
snap/attack.

13. Total Aggression Scores
 Owner acknowledged aggressive had higher total
aggression scores than owner acknowledged non-
aggressive

14. Total Aggression Scores
 Total aggression scores are more useful than
snap/attack scores because it aggress more with the
owner’s story
 The higher variation in the total aggression scores
also suggests it is a more realistic measure of
aggression

15. Principal Components Analysis (Fear)
 This attempts to identify underlying variables that
explain the pattern of correlations within the
frequencies of behavioral elements
 A drawback of this test is that it is not reliable
because of the small sample size used
 It is suggested to repeat the analysis with a larger sample size

16. Principal Components Analysis (Fear)
 Owner acknowledged aggressive dogs had
significantly higher factor scores on component 1
than owner acknowledged non-aggressive dogs

17. Discussion
 It is hard to standardize behavioral tests like these
 Weather, sound, conditions (air temperature), variations
introduced by the owners
 The total aggression score was the best method
because it showed the best agreement with the
owner’s story and the highest variation with the
study group
 Due to standardization and environmental factors, it
is questioned whether this study is significant in
determining genetic traits

18. Discussion
 The only group with a possibility of having a lower
“overall aggression threshold” is the owner
acknowledged aggressive dogs
 Within this study they found:
 One breed
 Variety of stimuli
 Variety of responses
 Polygenic control

19. Questions?
Image Source: Flickr trainmandan

20. References
 Article:
 Van der Berg, L, M Schilder, and B Knol. "Behavior Genetics of
Canine Aggression: Behavioral Phenotyping of Golden
Retrievers by Means of an Aggression Test." Journal of
Behavioral Genetics 33.5 Sept. (2003): 469-82. Web. 10 Apr.
2012.