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ORIGINAL RESEARCH
published: 11 June 2018
doi: 10.3389/fvets.2018.00115
Frontiers in Veterinary Science | www.frontiersin.org 1June 2018 | Volume 5 | Article 115
Edited by:
Mary M. Christopher,
University of California, Davis,
United States
Reviewed by:
Katherine Albro Houpt,
Cornell University, United States
Carri Westgarth,
University of Liverpool,
United Kingdom
Sara C. Owczarczak-Garstecka
contributed to the review of Carri
Westgarth
*Correspondence:
Jacquelyn A. Jacobs
jjacob01@uoguelph.ca
Specialty section:
This article was submitted to
Veterinary Humanities and Social
Sciences,
a section of the journal
Frontiers in Veterinary Science
Received: 29 December 2017
Accepted: 15 May 2018
Published: 11 June 2018
Citation:
Jacobs JA, Coe JB, Widowski TM,
Pearl DL and Niel L (2018) Defining
and Clarifying the Terms Canine
Possessive Aggression and Resource
Guarding: A Study of Expert Opinion.
Front. Vet. Sci. 5:115.
doi: 10.3389/fvets.2018.00115
Defining and Clarifying the Terms
Canine Possessive Aggression and
Resource Guarding: A Study of
Expert Opinion
Jacquelyn A. Jacobs 1
*, Jason B. Coe 1, Tina M. Widowski 2, David L. Pearl 1and Lee Niel 1
1Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada, 2Department of
Animal Biosciences, University of Guelph, Guelph, ON, Canada
The terms possessive aggression and resource guarding are often used interchangeably
to describe behavior patterns used by a dog to control primary access to a perceived
valuable item. The use of inconsistent terminology may impact the effectiveness of
communication between dog owners and clinicians, affect treatment and management
success for the behavior, and inhibit research progress. The aim of this study was to
explore the opinions of canine behavior experts on the meaning of and preference for
the terms possessive aggression and resource guarding, as well as to develop and
propose an operational ethological definition for the preferential term identified. Eighty-five
individuals met the inclusion criteria and were invited to participate in a two-stage online
survey. Results from the two-stage survey found that the majority of participants preferred
the term resource guarding. Detailed exploration of meaning and definitions required
in-depth discussion beyond traditional survey methods, therefore, respondents from the
second stage of the survey were invited to participate in an online discussion board.
Following content analysis of the data from the discussion board, we conclude that
the majority of participants preferred the term resource guarding. Considering 100%
consensus was not reached regarding terminology among experts in the field, future
authors and clinicians should provide clear definitions where terms are applied to ensure
effective communication between all parties and to ensure consistency in canine behavior
research. Based on expert contributions, we define resource guarding as “the use of
avoidance, threatening, or aggressive behaviors by a dog to retain control of food or
non-food items in the presence of a person or other animal.”
Keywords: canine aggression, possessive aggression, resource guarding, behavior, expert opinion, content
analysis
INTRODUCTION
Canine aggression is the behavior problem most commonly referred to companion animal
specialists (1), at least in part due to the potential danger involved in living with an aggressive
dog and the advanced knowledge typically needed to address the problem. Treatment and
management advice differs between categories of aggression (2,3), and as such, it is important for
clinicians to diagnose the type of aggression correctly. Clear descriptions of the behavior patterns
Jacobs et al. Exploring Canine Behaviour Terminology
involved are essential to proper diagnosis, and clinicians often
must rely on pet owners to provide this information (2,3).
However, pet owners may struggle to effectively relay this
information, given that the language used to describe behavior
between lay people and clinicians may be different (4,5).
Furthermore, the use of inconsistent terminology has been
recognized as a significant impediment to advancing behavioral
science (6,7). Research efforts focused on causation or efficacy of
treatments for aggression may be negatively impacted when the
type of aggression is misidentified or poorly described.
The terms possessive aggression,resource guarding, and food-
related aggression have all been used to refer to a sequence of
behavior patterns that dogs exhibit to gain or maintain primary
access to a perceived valuable item when another animal or
person approaches [e.g., (8,9)]. It is unclear if these terms
are considered to be synonyms or if there are fundamental
differences between the terms that are not explicitly stated in the
literature.
Possessive aggression is used frequently in scientific literature
to describe a category of aggression involved in defense of a
resource [e.g., (3,10,11)]. The descriptions in these sources
share several common and distinct components. For example,
Horwitz and Neilson (10) describe possessive aggression as “dogs
that aggressively guard things (food bowl, rawhides, real bones,
stolen, or found items), or objects (e.g., toys, stolen objects).”
Horwitz and Neilson (12) describe possessive aggression when
“the dog barks, growls, lunges, snaps and or bites when a person
or animal approaches it while it is in possession of or near
something it does not want to relinquish.” The former quote is
specific regarding the objects of apparent interest, whereas the
latter quote focuses on the specific behaviors involved in the
overall sequence. Both sources seem to agree that the behavior
involves aggression around something of perceived value for the
dog. Overall (3) separates possessive aggression and food-related
aggression, distinguishing between the two categories by item
of apparent interest (e.g., food or non-food object). Possessive
aggression is described as “aggression (threat/challenge/contest)
that is consistently directed toward another individual who
approaches or attempts to obtain a non-food object or toy
that the aggressor possesses or to which the aggressor controls
access.” The description for food-related aggression differs by the
behavior being exclusively executed in the presence of something
edible (“dog food, bones, rawhides, biscuits, blood, treats, or
table scraps”). It is of interest that the author remarks that
food-related and possessive aggression should not be considered
“under the umbrella term of resource guarding;” the author
states that this term is deleterious and prevents veterinarians
and clients from evaluating the degree of abnormality of the
behavior and inhibits a discussion on risk assessment for future
aggression (3).
Trends in the scientific literature may not reflect general
consensus or everyday application of preferred terminology.
Comments regarding the term resource guarding in Overall (3)
may be a recognition of the inconsistent application of the two
terms or changing preferences in the dog owner community.
Luescher and Reisner (1) refer to the behavior pattern as
resource guarding (possessive aggression) in their text without
a clear description, suggesting an interchangeable application
between the two terms. An updated edition of Landsberg et al.
(12) refers to the behavior pattern as resource guarding and
includes the original description of possessive aggression with the
addition of “tense” posture in the list of specified behaviors (12).
Furthermore, the term resource guarding seems to be gaining
colloquial popularity and is used almost exclusively in these types
of settings, such as blogs [e.g., (13)]. The lack of standardized
terminology and descriptions coupled with the complexity of the
behavior generates potential issues for dog specialists, owners,
and researchers.
Although a number of editorials have suggested that
discussion and consensus on terminology related to companion
animal behavior is needed (6,7,14,15), to date there has
been little research on this topic. To explore and develop an
understanding of preferences for terminology and definitions
among behavior specialists, an interactive approach is required
where these professionals can share and discuss their perspectives
and examine whether consensus is possible given commonalities
and differences. Several methods can be used to achieve
such understanding, such as online discussion boards, where
participants can openly share their views, opinions, and ideas
while remaining anonymous to each other. Discussion boards
are similar to focus groups in that they are facilitated by a
moderator and data are generated through participant discussion
(16). The extracted data can then be analyzed using qualitative
methodology, which utilize the participants’ words in the context
of the discussion to gain a deeper understanding of the topic.
The objective of this study was to clarify terminology and
develop a definition surrounding the behavior(s) commonly
referred to as resource guarding,possessive aggression, and
food-related aggression. More specifically, the authors sought
to determine whether canine behavior specialists felt the
terms described different behaviors or were interchangeable.
If participants expressed that the terms were interchangeable,
the authors sought to determine if a preferential term
existed and to explore reasons why the chosen term may be
preferred. Additionally, the authors sought to develop and
propose an acceptable ethological definition, broadly focused
on animal behavior and allowing for inclusion of emotional
and motivational states, for the preferential term based on
considerations from participants.
An external and long-term objective of this research is to
encourage further discussions surrounding the various uses of
terminology and definitions for similar topics which lack clarity.
MATERIALS AND METHODS
All procedures were submitted and approved by the University of
Guelph Research Ethics Board prior to the start of this study.
Participants
Experts were identified as having an advanced degree
[either Doctor of Veterinary Medicine (DVM) or Doctor of
Philosophy (PhD) in a related field] with additional professional
requirements that indicated an advanced knowledge of
companion animal behavior [i.e., Diplomat of the American
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Jacobs et al. Exploring Canine Behaviour Terminology
College of Veterinary Behavior (DACVB), Diplomat of the
European College of Animal Welfare and Behavior Medicine—
Companion Animal (DECAWBM-CA), Certified Applied
Animal Behaviorist (CAAB), or Certified Clinical Animal
Behaviorist (CCAB)]. Eighty-five experts met the inclusion
criteria at the start of the study, and were invited to participate
in all stages of the survey. Thirty-six individuals participated
in the first survey stage for a response of 45%. Responses from
the first stage were returned to all responding participants for
comment during the second stage. Twenty-nine of the thirty-six
individuals participated in the second stage of the survey
for a response of 80%. The majority of participants (28/29)
resided in the United States or Canada. Following the second
stage of the survey, the authors determined that developing
a definition and understanding the terminology preferences
required in-depth discussion with experts that extended beyond
the ability of traditional survey techniques. Twenty-nine experts
participating in the previous two stages of the survey were invited
to participate in an online discussion board to provide greater
opportunity for open dialogue. Fourteen individuals participated
in the online discussion for a response of 48%. The majority
of participants (13/14) resided in the United States or Canada.
Table 1 contains educational demographics for participants in
each stage of the survey and discussion board.
Procedure
Initially, a two-stage survey was employed to gather expert
opinion regarding concepts, definitions, treatment, and
prevention methods for the behavioral response(s) commonly
referred to as resource guarding,possessive aggression, or
food-related aggression. The current paper is focused solely
on concepts and definitions. For the first survey stage, all
identified participants were invited in January, 2013 through
an introductory email outlining the project’s objectives and the
TABLE 1 | Educational demographics of participants in each stage of the survey
and discussion board.
Stage Education demographics # Participants
Survey stage 1 (85 invited) DVM +DACVB or DECVBM-CA 21
DVM +DACVB & CAAB 3
PhD +CAAB or CCAB 12
Total 36/85 (45%)
Survey stage 2 (36 invited) DVM +DACVB or DECVBM-CA 15
DVM +DACVB & CAAB 2
PhD +CAAB or CCAB 12
Total 29/36 (80%)
Discussion board (29 invited) DVM +DACVB or DECVBM-CA 7
DVM +DACVB & CAAB 2
PhD +CAAB or CCAB 5
Total 14/29 (48%)
format requiring multiple stages of participation. The email
provided a link to an online survey website (LimeSurvey)
where participants were asked several open-ended questions: (1)
“How do you define resource guarding/possessive aggression?”
(2) “Please outline any behavior or other factors you might
use to identify resource guarding/possessive aggression. How
might you differentiate this behavior from other types of
aggression?” and (3) “Briefly outline the treatment methods
you would recommend to an owner of a dog with resource
guarding/possessive aggression.”
All participants that completed the first survey stage were
invited to participate in the second survey stage in March,
2013, which included closed- and open-ended questions that
were developed from the results of content analysis on the first
stage’s responses (see below for further detail on methods). Thus,
the content in the second survey was participant driven and
provided opportunity for participants to anonymously comment
on responses from the first stage (17). Further, an open-ended
clarifying question was added to the second stage to address
perceived confusion in providing a definition for the behavior:
“Do you prefer the term resource guarding, possessive aggression,
or a different term and why?”
Following the first two survey stages, the authors determined
that identifying a universally accepted definition as well as
exploring reasons for terminology preferences would require
in-depth, dynamic discussion between experts that extended
beyond the ability of traditional survey techniques. Therefore,
participants from the second stage were invited to participate in
an online discussion board website (20|20 research, Qualboard).
After completing the consent form and initial sign-in process, a
unique identifier was automatically assigned to each participant.
This identifier provided them with anonymity during the online
discussion board in order to encourage honest responses and
reduce the potential influence of group pressure (17). The
discussion board initially consisted of two questions related to
terminology: (1) “Do you think the terms possessive aggression
and resource guarding describe different behaviors or are they
appropriate to use interchangeably? Please explain,” and (2)
“What are your thoughts on the use of separate terminology
when referring to this behavior when associated with food only?”
Further, the authors considered all responses and comments
on a definition from the first and second survey stages and
derived the following definition based on a combination of
the most common components proposed: “A dog that is
displaying defensive, threatening, or aggressive behaviors to
prevent a person or other animal from gaining access to a
food or non-food object.” Participants were provided with this
definition in the online discussion and asked (3) to comment
on components of the definition they would like to have
changed, or provide their own complete definitions. All three
questions were released simultaneously to participants at the
beginning of the 1 week study period (September 3rd through
10th, 2013). The discussion board was open for 7 days during
which time participants were encouraged to post comments on
their own schedule. They could either respond directly to the
moderator’s questions, or post responses to other individual’s
comments.
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Jacobs et al. Exploring Canine Behaviour Terminology
In addition to the three initial questions posed by the
moderator, one probing question was added on day 3 during the
online discussion to explore perceived variability in participants’
definitions of aggression. Participants were asked “How do you
define the word ‘aggression’? Please consider specific behaviors
in your response.” On day 6 of the discussion board, the main
points of the discussion were summarized by the moderator and
presented back to all participants for a 24-h period in order
to provide a final opportunity for clarification, confirmation of
the discussion or any final thoughts from participants. The final
completed discussion board was downloaded in text documents
for analysis.
Data Analysis
As results from stage one were incorporated into the questions
for stage two and thus provide no additional information, only
results from stage two and the discussion board are presented
in this paper. For stage two of the survey, we determined the
number of participants that preferred to use the terms resource
guarding, possessive aggression, or an alternative. A Fischer’s
exact test (SAS 9.4, Cary, NC) was performed to determine if
there was a significant difference between expert background and
preference for terminology choice. Qualitative data management
software was utilized for the remainder of the data analysis
(ATLAS.ti, Berlin, Germany). To understand the data and
address the research questions, a qualitative approach was taken.
Data was analyzed descriptively using manifest content analysis
(18–20). Content analysis identifies, counts and attempts to
understand the context in which specific words or ideas are
expressed within the data (21–23). In this way, content analysis
permits both a qualitative and quantitative approach to data
analysis; descriptive coding of the data follows a quantitative
count of the codes (20). Specifically, data were coded by reading
the text of the open-ended responses from the survey and
discussion board several times to become familiar with the data.
Through an iterative process of repeated review of the text,
related data were assigned key words or phrases (i.e., codes)
which were then subjected to quantitative counts of the number
of participants that stated or supported a particular thought or
view, and supportive examples were extracted from the text.
RESULTS
Terminology Preference Among
Participants
The majority of participants in stage two of the survey preferred
the term “resource guarding” (Table 2). No significant difference
was found between expert backgrounds (i.e., CAAB/CCAB vs.
DACVB/DECAWBM-CA) and preference for terminology (p
=0.56). In the discussion board, eleven (out of fourteen)
participants thought the terms resource guarding and possessive
aggression described different behaviors, with the majority of
these people (seven out of eleven) further expressing the belief
that possessive aggression described a more specific version of the
behavior and is only applicable when aggressive behaviors are
involved. Two of the 11 individuals mentioned, unprompted, that
they recognize the terms are often used interchangeably but they
TABLE 2 | Count of terminology preference from participants in survey stage 2.
Preferred term # Participants
Resource guarding 19/29 (66%)
Possessive aggression 6/29 (21%)
Resource guarding or possessive aggression 2/29 (7%)
Neither 1/29 (3%)
do not consider them to be synonyms. Two participants (out
of 14) consider the terms to be synonyms and thus consider it
appropriate to use the terms interchangeably. One participant did
not provide a direct response to this topic.
When asked about the use of separate terminology for the
behavior pattern when associated with food only, the majority of
participants agreed the use of a separate term is unnecessary. A
few participants stated they prefer not to complicate terminology
further by using a separate term specific to one type of
resource. Several other participants stated that they believe the
motivation remains the same regardless of the type of item
being “guarded” and therefore the use of separate terminology
is not meaningful. Three participants discussed that dogs may
consider items other than what we consider to be food edible
(such as a paper towel) and thus, it is inappropriate to ascribe
a specific term when assumptions are being made about the
item category. A little more than half (eight out of fourteen) of
the respondents mentioned that they would use a subheading
with their preferred term to describe the item or context more
specifically for treatment and management purposes, but that
using a completely separate term was unnecessary. Only two
participants thought it was important to use separate terminology
when describing food-related aggression. In support of this view,
these two participants referenced published literature suggesting
the existence of separate brain pathways mediating aggression
around food compared to other objects [example provided: (24)].
Reasons for Terminology Preference
The Influence and Meaning of the Word “Aggression”
Eleven (out of 14) respondents suggested that the word
“aggression” within the term possessive aggression has an
influence on the meaning and application of the term and
describes a behavioral sequence that necessitates an aggressive
response. Specifically, these participants stated that possessive
aggression was not a broad enough term to include the behaviors
of “body blocking” or “grabbing an item and running away with
it.” For example, one respondent stated
“I always use resource guarding, which is a broader term than
possessive aggression. A dog may in fact guard just by staring and/or
body blocking without showing an aggressive response.”
Respondents considered the inclusion of the word “aggression”
to limit the referenced behavior to the aggressive form, and for
some, the use of the word “aggression” in the term implied a
more severe form of the behavior. For example, one respondent
stated
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Jacobs et al. Exploring Canine Behaviour Terminology
“...some animals will guard the resource without overt aggressive
responses but will freeze and hover. I tend to use both terms...
but when the dog becomes more threatening I may use possessive
aggression but at times have also used resource guarding
aggression.”
Three respondents (out of 14) disagreed with other participants’
rationale for distinguishing between terms with and without the
word “aggression,” stating that inclusion of this word should not
be a limiting factor for the meaning of the term as aggression can
include a range of behaviors not limited to snapping or biting.
For example, one respondent stated
“... I don’t think just because the word ‘aggression’ is used in
the category name, that is a good rationale to distinguish it
from resource guarding - which can also include threats and/or
aggression.”
Among participants, a division on the definition of aggression
was evident which seemed to contribute to the disagreement
respondents expressed in relation to using the terms resource
guarding and possessive aggression. Generally, participants’
discussion of the definition of aggression were divided into two
categories: (1) actions that harm or intend to harm the other
participant, or (2) threats and harmful actions that primarily
serve to increase distance between themselves and the other
participant.
Respondents participating in the latter discussion expressed
concern about defining and using the word aggression to only
mean “intent to harm” as it implies planning on the part of
the dog. One individual acknowledged and responded to this
concern by stating,
“Obviously we cannot 100% know an animal’s intent, I use it as
‘obvious intent’ which includes anything from lip lift and growl to
bite.”
When asked to provide specific examples of what distinguishes
between threats and harmful behavior from another participant,
responding individuals generally agreed that “growling, teeth
baring, and freezing” are examples of threatening behavior,
whereas “snapping, lunging, and biting” are all examples of
harmful actions. Two participants admitted that the line between
threatening and harmful behavior is not always distinguishable;
aggression lies on a continuum and the dog’s ultimate response
will be a result of the dogs’ experience, genetics, and the behavior
of the other individual. To validate the two group’s contradictory
opinions on the definition of aggression, one participant cited
numerous quotes from the literature that reflected a similar,
long standing level of disagreement on the definition of the
word “aggression” within the scientific literature. These quotes
included:
“the term aggression has so many meanings and connotations
that in effect it has lost its meaning... it is not a simple unitary
concept and therefore cannot be defined as such (25).”, “The word
‘aggression’ is widely used and misused in a variety of contexts (26),”
and, “The solution to the problem of ‘aggression’ is simply to treat
the word as a convenient, loosely defined aid to communication...
recognizing that we cannot provide an adequate definition and that
we are probably lumping together a number of diverse phenomena
(27).”
Concern for Owner Perception
In addition, several respondents reported that a client’s
interpretation of the words used in a term and their concern for
owner perception of the behavior influenced their term choice.
Concern focused on the potential for the owner misinterpreting
the dog’s motivation to perform the behavior, and ultimately
were about the reaction of the owner. The term possessive
aggression was discussed most often, with some specifically
mentioning concern with the word “possession” and others with
the word “aggression.” According to three participants, the word
“possession” may be interpreted by the owner as an indication
that the dog is vying for inappropriate ownership of the item
resulting in a necessary competition between the owner and dog
for the item. Further, concern for the word “aggression” focused
on misunderstanding of the motivation for the behavior, resulting
in an attempt for the owner to control the dog’s actions. For
example, one participant stated,
“this terminology... may be deleterious in that it may
contribute to inappropriate treatment of aggression problems
(combative/confrontational techniques/punishment).”
And another stated,
“I think that the term ‘possession’ may have misleading meanings
(the same way the term ‘dominance’ does) and may induce the
owner to engage in dangerous confrontations with the dog to
determine who ‘possesses’ something.”
Participants suggested that terms that include the word
aggression might be avoided because of the negative connotation.
For example, one participant stated
“A lot of people seem to want to use ‘resource guarding’ because it
doesn’t sound that bad, that if the dog had ‘aggression’ that the dog
is a bad dog.”
Not all respondents felt it necessary to avoid terminology based
on its potential perception by owners, even though they recognize
that many professional people may do so. For example, one
respondent stated
“Possessive aggression explains the dog is displaying aggression,
which can vary in intensity, etc. I don’t think the word ‘aggression’
is a bad word, but it is often avoided when some people talk with
owners.”
Almost two-thirds of respondents (10 out of 14) stated their
preference for the use of the term resource guarding over
possessive aggression due to the potential for motivation to
be interpreted more accurately by owners. For example, one
participant stated,
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Jacobs et al. Exploring Canine Behaviour Terminology
“I always use resource guarding... the term resource guarding
underlies the motivation for the behavior, making the owner
understand that the dog is protecting a high value item.”
These participants mentioned the importance of understanding
the motivation for the behavior, both for themselves (treatment
and management advice) and for owners. Several participants
provided their interpretations of the motivation behind resource
guarding, which included the following participant definitions: “a
resource that the dog is guarding from other individuals being
able to obtain,” an “attempt to maintain control/ownership of an
item,” and “protection of a high-value item.” Two respondents
warned that it is inappropriate to assume motivation, and that
motivation may be different for each dog even though the
behavior has the same or similar appearance.
Lay vs. Expert Communications
The majority of participants (12 out of 14) identified differences
in the way they relay information between colleagues (e.g., DVMs
or PhDs with behavioral expertise) and clients (i.e., pet owners)
with respect to behavior issues. Participants indicated that
although they may use strict ethological definitions of aggression
when discussing the behavior with colleagues, generally they
find themselves adjusting their definitions and language use
when discussing the behavior with clients and dog owners to
ease communication and attempt to prevent misunderstanding.
Participants who consider aggression to include “harmful or
harm-intending behaviors only” recognized that most dog
owners define aggression more broadly and include behaviors
such as growling and teeth baring when discussing aggressive
behavior and will adjust their language to mirror that of their
clients. For example, one respondent stated
“with colleagues... I use very specific ethological definitions and
descriptions. With clients and DVMs without behavioral expertise,
I use aggression in the way that most people outside the field do—
any behavior that makes people concerned about a bite or an actual
bite. It’s not great to use different definitions, but to be practical, I
always try to speak the language of the listener.”
Seven (out of fourteen) participants stated that they use the
same terminology with presumed laypersons as they do with
experts; however, they take the time to go into more detail with
lay individuals when explaining the behavior. For example, one
participant stated
“I would do a lot more explaining to clients (than colleagues),
pointing out the details of their dog’s behaviors and the context(s)
in which they occur but the language would remain the same.”
For these individuals, the depth of explanation about the behavior
relies on the perceived knowledge level of the audience in
order to communicate more efficiently. In addition, as discussed
previously, a few other participants indicated that they would
avoid using certain terms that might have associated negative
connotations with clients, such as the word “aggression,” in order
to appease clients or avoid misunderstanding.
TABLE 3 | Agreement with components of a definition gathered from survey stage
1 and presented in stage 2.
Definition
Components
# Participants
Component
presented
for
comment
“Display of threatening or aggressive
postures”
28/29 (97%)
Dog is “in control or perceived control
of the object or item”
27/29 (93%)
“The maintenance or defense of
control of the resource”
20/29 (69%)
“Object or item has some value to the
dog”
11/29 (38%)
Participant
suggestions
Make description of behaviors or
postures more specific
3/29 (10%)
Include defensive or fearful postures
in addition to aggression and threats
1/29 (3%)
Eliminate term ‘aggression’ 1/29 (3%)
Developing a Definition
Specifying Behaviors
In the discussion board, the majority of participants (12 of
the 14) suggested changes to the definition proposed for
resource guarding or possessive aggression (Table 3). Half of those
participants suggested that the definition should include specific
behaviors (e.g., “growling, snapping, biting”) instead of using
an inclusive term open to misinterpretation (e.g., “threatening”
or “aggressive”). A variety of specific behaviors were proposed,
including: body blocking (one out of six), rapid ingestion (two
out of six), submissive postures (two out of six), lip lifting (two
out of six), grabbing the item and running away (three out of six),
stiffening (three out of six), barking (five out of six), growling (six
out of six), lunging (six out of six), snapping (six out of six), and
biting (six out of six). All suggestions of specific behaviors were
either preceded by “for example” or concluded with “etcetera”
indicating their proposal represents a sample of the possible
behaviors to be included in the behavioral repertoire.
Defensive vs. Offensive
The use of the word “defensive” in the proposed definition
received a lot of attention from participants. Five participants
discussed the merit of including the word in the primary
definition or using it in a modifier, which could be added or
subtracted from the definition depending on the body posture
of the dog and the context of the behavior. A few of these
participants (three out of five) suggested that threatening and
aggressive behaviors could be offensive or defensive, and one
individual suggested these terms could be applied on a case-by-
case basis to help describe the dog’s body posture. One individual
suggested that the motivation for the behavior is defensive and
suggested that the definition include examples of a defensive
response:
“Resource guarding is a behavior motivated by the defense of
valuable resources, as perceived by the dog. It can be displayed as a
purely defensive response (e.g., running away with valuable items)
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Jacobs et al. Exploring Canine Behaviour Terminology
or as an overtly aggressive response (e.g., growling, barking, lunging
and biting).”
In response, another individual disagreed and stated that the
observed behavioral response may be a reflection of past
encounters in which the dog was previously punished in a similar
scenario and the behavioral response is often more complicated
than the defense of a resource. Another participant agreed with
the latter and mentioned that motivation for the behavior does
not belong in an ethological definition.
Affective States
One-third of the 12 participants who suggested changes to
the initially proposed definition mentioned the importance of
considering underlying affect (e.g., anxiety, as a component
of resource guarding or possessive aggression for some dogs)
and adding a subsequent modifier to describe associated body
postures such as fearful body postures when anxiety is involved.
For example, one participant stated,
“...adding something like, ‘at times fearful, submissive or deferent
body postures may be associated with the behavior when anxiety is
a component.”
Terminology Disagreement
Use of the word “valuable” was debated by a few individuals. Two
individuals preferred incorporating the word into a definition,
suggesting that the item(s) hold some degree of value to the dog
based on their unwillingness to relinquish the item. Two other
individuals felt that this word is anthropomophic and assumes
what the dog might be feeling toward the item or about the
situation in general and suggested that use of the word “valuable”
is either avoided or preceded by the word “perceived” (e.g.,
“perceived to be valuable,” or “perceived threat to maintaining
possession of the object”).
The word “item” was suggested as a replacement for the term
“food or non-food object” by two individuals. Alternatively, two
individuals stated that the term “non-food object” and “item”
are both too vague and instead they should be described in
separate categories as items the dog can physically “take into
possession (e.g., pick up in mouth)” or “possess in another way
(e.g., lying on the couch or sitting near an individual).” There
was some discussion regarding whether resource guarding or
possessive aggression is a sub-category of territorial aggression
as one participant defined a territory as “any defended area,”
and suggested that “people, areas, objects, food, etc.” can all be
defended or guarded. Three participants disagreed with this view,
with one stating they believe aggression in defense of an area
(specified as a “yard, home or car”) or person is not correlated
with aggressive behavior around food, objects or sleeping and
resting places. Another participant remarked they are unclear
about whether people are being “possessed” or “guarded” when a
dog behaves with threats or aggression upon approach by another
person or other animal. One participant supplied an alternate
definition of a territory as,
“a fixed area from which an individual animal excludes rival
intruders by some combination of advertisement, threat and attack
(Brown, 1971),” and stated that “territorial behavior involves a
whole other set of behaviors that don’t belong under the topic of
resource guarding (e.g., scent marking).”
Complicating the development of a definition was the division
in agreement over possessive aggression and resource guarding
being synonyms or terms requiring separate definitions. For
example, one participant provided separate definitions for
resource guarding and possessive aggression, stating:
“Resource guarding involves using a variety of behaviors for
the purpose of maintaining possession of a particular resource.
Possessive aggression is the use of aggressive behaviors in order to
maintain possession of a particular resource.”
Another participant expressed their confusion over the
use of separate definitions as they believe the terms are
interchangeable and refer to the same pattern of behavior. All
suggested modifications to the originally proposed definition are
summarized in Table 4.
DISCUSSION
Terminology Preferences
Based on the survey, participants preferred the term resource
guarding over possessive aggression, and there was no effect
of professional qualification on this preference. Participants
on the discussion board expressed a variety of perspectives
about the use and meaning of the terms resource guarding
and possessive aggression. Most experts initially expressed the
belief that the terms possessive aggression and resource guarding
described two different behavior patterns. However, upon
analyzing the experts’ discussion it became clear that the
majority of experts believe possessive aggression describes a
more specific sub-set of the behavior pattern and is limited to
the expression of aggressive behaviors. Individuals participating
in this discussion preferred the term resource guarding over
possessive aggression for a variety of reasons including a broader
inclusion of behaviors, a greater potential for dog owner
understanding of the motivation and relatively positive dog
owner perception of the behavior [see (3) for a contradictory
argument].
A number of participants expressed the belief that dogs use
strategies other than aggression to maintain control of valuable
items in support of their preference for the term resource
guarding. Examples mentioned include grabbing an item and
running off with it and rapid ingestion of an item (i.e., avoidance
strategies). These types of non-aggressive strategies are rarely
mentioned in the literature when describing the behavioral
response. Perhaps these behaviors are of less concern to owners
(and clinicians) due to their relatively low risk of injury, and
thus are seldom presented to a behavior specialist and not widely
considered in text book descriptions of resource guarding and
possessive aggression. This focus on aggression may be why the
term possessive aggression has been used more frequently in
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Jacobs et al. Exploring Canine Behaviour Terminology
TABLE 4 | Content analysis of agreement and disagreement to the proposed definition by participants.
Category Behaviors #
Agree
Target #
Agree
Underlying Affect or
Motivation
#
Agree
Object/Item types #
Agree
Original
definition
Defensive, threatening
or aggressive
2 Person or other animal 2 Prevention of loss,
desire to maintain
4 Food or non-food
object
2
Proposed
substitutions
“Changes in affect”
(used as a blanket term
for observed behaviors)
1 Another individual 1 Maintaining control of
“valued” resource
2 “item” better than
non-food object
2
Agonistic behaviors 2 “Perceived” valued
resource control
2 Distinction made
between items dog can
hold in mouth or not
hold in mouth (e.g
couch)
2
Avoidance (instead of
defensive)
1“Perceived” potential
loss to possession
1
Proposed
additions
Tense body posture 1 N/A Defense (as the
motivation)
1 People 2
Specific behaviors
(e.g., taking item and
running off, rapidly
consuming item,
stiffening and hovering
over it, lip lifting,
barking, growling,
lunging, snapping,
biting)
6 Resting and sleeping
places (e.g., couches)
2
Territories (i.e., “area”) 1
Proposed
Context-
specific
inclusions
Anxious behaviors
(e.g., lip licking,
yawning, averting gaze,
freezing)
2 N/A Anxiety (as a
component)
2 N/A
Defensive or offensive,
depending on
behaviors observed
3
Deferent or submissive 1
Proposed
deletions
Defensive should not
be included
2 Should not include
motivation in a
definition
1 People and territories
should not be included
2
The original proposed definition was: “A dog that is displaying defensive, threatening, or aggressive behaviors to prevent a person or other animal from gaining access to a food or
non-food object.” The “number agree” represents a count of individuals that either proposed the respective component or agreed with a previous participant regarding the component
proposed (N =14).
reference manuals than resource guarding, and the description of
the behavior almost always includes the use of aggression [e.g.,
(3,10)].
Although anecdotal, experts suggested that many dog owners
react negatively to the term possessive aggression due to the
owner’s perception of both words within the term (28). One of
the topics that received the most discussion was whether the
word “aggression” unduly influences the meaning of the term for
owners, inhibiting their understanding that avoidance behaviors
can also be displayed and that the behavior is often normal (29).
In a focus group described in Orrit et al. (30), professionals
reported their biggest challenge was battling the stereotypes and
misconceptions with owners of dogs that commonly display
aggressive behavior, while in a separate but complimentary focus
group, lay persons were defensive when discussing aggressive
behavior from their own dogs; these contradictory perspectives
likely challenge communication between the two groups. Further,
previous research suggests that dog owners and lay persons may
have more difficulty identifying or describing aggressive behavior
compared to professionals (4,5,31), further exacerbating
communication issues. The findings from these studies support
those observed from our population of participants and suggest
that concerns regarding the owner’s interpretation of words used
in a term have merit.
Furthermore, there was an underlying concern among
participants about owner perception of the behavior when
the word “possessive” or “possession” was applied, fearing
that owners might misinterpret the behavior as a competition
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Jacobs et al. Exploring Canine Behaviour Terminology
with the dog over item ownership, potentially leading to the
application of positive punishment-based training methods.
These concerns seem to parallel some of the discussion
surrounding the labeling of a “dominant” dog. Historically,
confrontational techniques have often been employed to make
a “dominant dog” submit to the owner or to reinforce
the dog’s dominant position to other household dogs (32).
Research suggests that the application of confrontational
training techniques (e.g., using a shock collar or hitting) is
associated with and can exacerbate aggressive behavior [e.g.,
(33,34)]. Recent position statements from a variety of veterinary
organizations disagree with these practices (e.g., American
and Canadian Veterinary Medical Associations, Australian
Veterinary Association, American Veterinary Society of Animal
Behavior) and it seems reasonable to be concerned about the
impression of any word that might inadvertently imply the need
for confrontational techniques.
Concern over term perception likely contributed to several
participants’ belief that the term resource guarding better
communicates the motivation of the behavior, with the aim
of promoting owner understanding about the normal nature
of the behavior and ultimately decreasing the chance that
performance might result in conflict between the owner and the
dog. Several of these participants provided their interpretation
of resource guarding motivation. These suggestions had only
slight variation between them and were generally described as
“guarding,” “protection,” or “control” over high-valued items.
Several other participants were displeased with these suggestions,
stating that motivation cannot be known or at the very least,
generalized to all dogs exhibiting the behavior. It appeared that
these individuals were concerned with knowing the motivation
beyond the desire to maintain access to a resource (i.e., hunger,
primary access).
One area that did not have much variation in response
involved discussion around the use of the term food-related
aggression. This term has been used throughout the literature
to describe an aggressive behavioral response toward a person
or other animal when a dog has a food item [e.g., (3,35)]. The
vast majority of participants believe that using a separate term to
describe resource guarding and possessive aggression around food
is unnecessary and further complicates the issue. Participants
mentioned that food is often narrowly interpreted by humans
and that dogs may find items edible that we would not consider to
be food. This is an interesting point and one that challenges the
literature referenced by another participant that suggests there
is different brain circuitry involved in mediating food-related
aggression from other types of aggression. The cited reference
does suggest there are two distinct neural circuits that mediate
two different kinds of aggression (in rats and cats), “defensive
rage” and “predatory attack” (24). It is unclear which of these
two types of aggression the participant was comparing to food-
related aggression although one might assume predatory attack
as it is the natural method of obtaining food (even though
predation is directed at the food item, rather than a potential
food stealer). Although predation has been listed as one category
of aggression by a few authors (36,37), Archer (29) argues
there are only two broad functional types of aggression: resource
competition and reactions to danger. Neither of these involve
predation.
Developing a Definition
Ethology studies generally focus on the following four main
areas, or questions, as proposed by Tinbergen (38): evolutionary
history, development, causation and function. The apparent
function of a behavior (i.e., the consequences of the behavior) is
often included in operational definitions of animal behavior (39).
For example, Broom and Fraser (40) define competition as “the
striving of two or more individuals to obtain a resource that is
in limited supply.” In this example, the immediate function of
the behavior is the resulting access to a limited resource. The
apparent function of resource guarding or possessive aggression is
the control of an item. Given that the consequence of the behavior
pattern is likely to be the same regardless of the specific behaviors
that occur (e.g., running away with an item vs. snapping or
biting) a complete description of the behavior pattern should
allow for extension of the definition beyond aggression alone.
In a clinical setting, it might be advantageous to distinguish
between behaviors that have been displayed in different contexts
in order to assess and mitigate future risk of aggression; however,
we propose that the operational definition be inclusive of those
behaviors that support the apparent function of the behavior
pattern.
Although half of participants preferred the inclusion of
specific behavior examples in the definition, the use of a finite list
of examples in this context is likely to be too rigid and, therefore,
limiting. It is possible that conflicting behavior patterns or those
not commonly observed may be used by the dog for the same
functional purpose of retaining control of an item; thereby the
dog’s behavior pattern is functionally representative of resource
guarding or possessive aggression but would not be labeled as such
based on the absence of key behaviors. Furthermore, an ethogram
for this behavior pattern does not currently exist in the scientific
literature, so there is insufficient data on which to base inclusion
of specific behaviors in the definition. Indeed, when participants
proposed specific behaviors for inclusion in the definition they
either preceded their list with “for example” or concluded their
list with “etcetera,” which indicates the list was not exhaustive.
For these reasons, we propose to include only broad terms in
the general definition at this time. As more definitive research is
completed, the definition may be augmented with an ethogram
that further defines the specific behaviors that relate to each of
these broad terms.
One area that received much attention by participants was
the discussion around inclusion of the words “defense” or
“defensive” in the definition. Participants seemed to be using
these words in two different ways, with one group considering
“defense of the resource” as a motivation for the behavior, and
the other group considering “defensive” as a way to describe
the behavioral response (i.e., “defensive body postures”). The
latter group debated whether the behavior pattern could also
appear offensive, with the majority of participants agreeing that
aggressive behavior could be either offensive or defensive. It
was suggested that it might be important to identify which was
occurring through the use of a modifier in the definition in order
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Jacobs et al. Exploring Canine Behaviour Terminology
to infer the emotional state in the dog. Historically, offensive
and defensive aggression in animals have been distinguished
by attack patterns and bite locations [e.g., (41)], and are
suggested to have different situational determinants, emotional
and motivational states (42) and therefore differing associated
body postures. However, no scientific studies to date have
assessed the emotional states of dogs in the context of resource
guarding or possessive aggression, so it is not possible to infer
emotional states in this context at this time. In addition,
when put into practice, these modifiers would need to be
added to a definition post-response by the dog, and would
require direct observation to distinguish between offensive
and defensive behaviors or would rely on the ability of the
assessor, often likely to be the dog owner, to accurately
describe or identify body postures. Furthermore, some behavioral
responses may be ambiguous, including both offensive and
defensive components. For these reasons, we felt the terms
defensive and offensive did not belong in a definition of the
behavior.
One of the biggest challenges in developing a definition
that is likely to be widely acceptable to the canine behavior
community revolves around determining which items, objects,
areas and individuals should be included. Participants in the
current study were varied in their preferences with suggestions
to replace “food or non-food object” with the word “item,”
to include a separate indication for food, to limit items
to those that can be physically held [in the mouth], and
to include larger things such as resting areas or people.
However, each change was only suggested by one or two
people. The literature follows with similar variation. Some
authors are non-specific in their descriptions; for example,
“food or other resources” (9,43) and “food” (for food-related
aggression) and “non-gustatory items” (for possessive aggression)
(3). Other authors have shown varying degrees of specificity,
including: “food, rawhide or toys” (8), “territory, owners or
other animals” (44), “food bowls, chew toys, people, pets, or
places” (12), and “food bowls, rawhides, real bones, stolen or
found items, toys and stolen objects” (10). It seems unclear in
both the literature and within participant discussions whether
the behaviors of dogs around people and large areas are
serving a similar function as behaviors around small objects
that can be manipulated. Alternate interpretations (e.g., fear-
related, territorial) may suggest the motivation or function of
those behavior patterns differ from those employed to retain
control of relatively small food and non-food items. This is a
topic in need of further scientific investigation, therefore we
opted to exclude people and areas from the current definition.
With further evidence to the contrary, the definition should be
modified.
Limitations
A range of opinions on the topic were gathered and analyzed
in this study. Due to the nature of the discussion board
it was difficult to obtain depth from all participants; some
individuals provided deeper opinions and a greater number of
comments than others as a result of visiting the discussion
board more frequently than their peers. However, the choice
of a discussion board was preferred in comparison to a focus
group because it allowed for anonymity between a group of
participants that are likely to know of each other due to
their membership in a relatively small pool of professionals,
and it allowed individuals to participate regardless of location
or potential scheduling conflicts. The results may not reflect
the opinions of all experts in the field of canine behavior.
Considering there are ∼60 DACVB Veterinarians and 30
CAABs in North America we achieved representation from
∼16% of this particular population for the discussion board.
However, we had greater representation for the initial survey
stages that were used to inform this discussion, and for the
assessment of term preference. Furthermore, it is unknown
if all participants recognized English as their first language;
differences in word use and understanding may have impaired
some discussions, and regional differences may have influenced
preferences in terminology. However, the unique nature of the
online discussion board format allowed participants to express
themselves freely and anonymously, while qualitative descriptive
analysis allowed for exploration on areas of agreement and
disagreement amongst experts on components of a definition
and terminology used to refer to a relatively common behavior
“problem” that would not have been obtained through other
research methods.
CONCLUSION
As Overall (14) states, “If what we call something affects the
way we think about it—and it does—then what we call it is
essential.” The majority of participants for both the survey and
discussion board indicated that they prefer the term resource
guarding rather than possessive aggression, and the discussion
board analysis suggests that many participants find that the term
resource guarding is less likely to be negatively misinterpreted
by dog owners, is easier to communicate to dog owners, and
better represents the potential for behaviors other than aggression
to be exhibited during the behavioral sequence (e.g., avoidance-
related behaviors). Based on discussion among participants, we
propose the following basic definition for resource guarding:
“The use of avoidance, threatening, or aggressive behaviors
by a dog to retain control of food or non-food items in the
presence of a person or other animal.” As more scientific
research is conducted on this topic we welcome modifications
and expansion to our proposed definition. Employing consistent
definitions and terminology when referencing this behavior
pattern will help ensure consistency and progress for future
research and will help to avoid confusion between clinicians and
clients.
ETHICS STATEMENT
Participants were provided with a consent form prior to
beginning the study which outlined the aims and methods of
the study, as well as any potential risks, and were provided
with contact information for the authors should they have
any questions. Participants were asked to read the consent
Frontiers in Veterinary Science | www.frontiersin.org 10 June 2018 | Volume 5 | Article 115
Jacobs et al. Exploring Canine Behaviour Terminology
form and acknowledge agreement, after which access to
the surveys were allowed. All participants were selected by
the authors due to their expertise and advanced degrees;
therefore no vulnerable populations were included in the
study.
AUTHOR CONTRIBUTIONS
The idea for the paper was conceived by JJ, JC, LN, TW, and
DP. The experiments were designed by JJ, JC, and LN. The
experiments were performed by JJ, JC, and LN. The data were
analyzed by JJ and JC. The paper was written by JJ, JC, LN, TW,
and DP.
ACKNOWLEDGMENTS
The authors would like to thank the Ontario Veterinary College
Pet Trust and the Natural Sciences and Engineering Research
Council of Canada for generous funding support. The authors
would like to thank Melissa Speirs for her research assistance.
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Conflict of Interest Statement: The authors declare that the research was
conducted in the absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
Copyright © 2018 Jacobs, Coe, Widowski, Pearl and Niel. This is an open-access
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the original author(s) and the copyright owner are credited and that the original
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No use, distribution or reproduction is permitted which does not comply with these
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