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Urine marking in male domestic dogs: honest or dishonest?
B. McGuire , B. Olsen, K. E. Bemis & D. Orantes
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
Keywords
domestic dog; scent mark; over mark; dishonest
signal; competitive ability; male–male
competition; body size; shelter.
Correspondence
Betty McGuire, Department of Ecology and
Evolutionary Biology, Cornell University, Ithaca,
NY 14853, USA. Tel: +1 (607) 279 6405;
Fax: +1 (607) 255 8088
Email: bam65@cornell.edu
Editor: Nigel Bennett
Received 29 May 2017; revised 12 June 2018;
accepted 2 July 2018
doi:10.1111/jzo.12603
Abstract
Scent marking is a common mode of communication in mammals. Such marking is
thought to communicate information about the signaler’s size and corresponding
competitive ability and accurately reflect the signaler’s attributes (i.e., an honest sig-
nal). However, new data suggest that scent marking can be dishonest in certain cir-
cumstances. Via two studies, we tested the hypothesis that urine marking is a
dishonest signal in adult male domestic dogs, which raise a hindlimb when marking
vertical objects. In Study 1, we tested whether raised-leg angle (i.e., during a urina-
tion, the angle between a dog’s raised leg and the axis normal to the ground) is a
proxy for urine mark height (n=15 dogs) and, in Study 2, we tested whether small
dogs exhibit larger raised-leg angles than large dogs (n=45 dogs). We videotaped
urinations of adult male dogs and, afterwards, measured height of urine marks (Study
1) and degree of raised-leg angles (Studies 1 and 2). In Study 1, we found significant
positive relationships between both raised-leg angle and height of urine mark and
body size (using either body mass or height at withers) and height of urine mark;
raised-leg angle was a stronger predictor than either measure of body size. In Study
2, we found a significant negative relationship between body size (using either body
mass or height at withers) and average raised-leg angle. Our findings support raised-
leg angle as a proxy for urine mark height and provide additional evidence that scent
marking can be dishonest. Assuming body size is a proxy for competitive ability,
small adult male dogs may place urine marks higher, relative to their own body size,
than larger adult male dogs to exaggerate their competitive ability. We did not con-
trol for over marking, which also may explain our findings.
Introduction
Scent marking, a common mode of communication in mammals,
conveys several types of information, including individual identity,
sex, age, reproductive status, social status, health, quality, kinship,
and histocompatibility (Sharpe, 2015). Properties of marks, such as
olfactory content (Alberts, 1992; Gosling & Roberts, 2001) and
spatial arrangement (Gosling & Roberts, 2001), convey informa-
tion. With respect to spatial arrangement, many mammals elevate
their scent marks (Sharpe, Jooste & Cherry, 2012).
Increased detection via olfaction and vision may explain
why some mammals elevate their scent marks. The ground
physically restricts diffusion, so both size of mark and likeli-
hood of detection by olfaction are increased when scent marks
are elevated (Alberts, 1992). Elevated marks are disentangled
from other scents that saturate the substrate (Alberts, 1992)
and conveniently located at nose-height of receivers (Gorman
& Mills, 1984). Deposition of scent marks on conspicuous,
elevated landmarks may create visual cues that increase detec-
tion (Eisenberg & Kleiman, 1972).
Increased detectability, however, may not be the sole expla-
nation for elevated scent marks. White, Swaisgood & Zhang
(2002) state that increased detectability should benefit all sex
and age classes. If this is true, then increased detectability can-
not explain dimorphic marking postures in which members of
one class typically deposit elevated scent marks and members
of another class low-lying marks. For example, adult male pan-
das (Ailuropoda melanoleuca) are more likely than adult
females and subadults to deposit elevated scent marks; this
suggests that elevated marks are uniquely beneficial to adult
males (White et al., 2002).
Competitor assessment may explain why adult males, in com-
parison to juveniles and females, are more likely to elevate their
scent marks. Receivers may extract information about a competi-
tor’s size from the vertical placement of their scent marks
(Alberts, 1992). Alberts (1992) cites the handstand marking pos-
ture as evidence because it enables some mammals (see Sharpe
et al., 2012 for species) to place scent marks a full body length
above the ground, thereby directly communicating body size.
Data from White et al. (2002) for pandas and Sharpe (2015) for
dwarf mongooses (Helogale parvula) provide additional support:
in both species, males and females spend more time investigating
higher scent marks. According to these authors, it would be bene-
ficial for male receivers to avoid particularly large conspecifics
and female receivers to catalogue the scent of large prospective
mates. This reasoning assumes that larger individuals have higher
Journal of Zoology (2018) – ª2018 The Zoological Society of London 1
Journal of Zoology. Print ISSN 0952-8369
competitive ability, which is supported for diverse species (Hunt-
ingford & Turner, 1987; Gosling & Roberts, 2001).
Scent marks that convey information about size and corre-
sponding competitive ability of the signaler may be honest
(i.e., accurately portray the signaler’s attributes, including size
and competitive ability) or dishonest (i.e., inaccurately portray
the signaler’s attributes). Gosling & Roberts (2001) hypothe-
sized that, in general, male scent marks are honest. They rea-
soned that females use scent marks to evaluate the quality of
prospective mates and, because females are the higher invest-
ing sex, this would only be evolutionarily beneficial if male
scent marks are honest signals. Additionally, it seems likely
that scent marking is restricted by the signaler’s anatomy and
physiology, just as the frequency of acoustic communication is
restricted by the caller’s size (Fitch & Hauser, 2002), thereby
honestly reflecting the signaler’s attributes. However, more
recent evidence suggests that scent marks can be dishonest sig-
nals: male dwarf mongooses that are small for their age com-
municate their size and competitive ability dishonestly by scent
marking higher than expected (Sharpe et al., 2012).
In domestic dogs (Canis lupus familiaris), urination is the most
common form of scent marking and urinary behavior varies greatly
across sex, age, and size classes (Cafazzo, Natoli & Valsecchi,
2012; McGuire, 2016; McGuire & Bemis, 2017). Adult males typ-
ically use the raised-leg posture, juvenile males use the lean-for-
ward posture during which no hindlimb is raised, and most
females use the squat posture (Sprague & Anisko, 1973). By rais-
ing a hindlimb during urination, adult male dogs are more likely
than adult females and juveniles to deposit an elevated mark. Adult
males urinate more frequently and direct more urinations onto ver-
tically oriented targets than do adult females (McGuire, 2016).
Small dogs urinate more frequently and direct more urinations than
large dogs, which may indicate a preference by small dogs for
communicating through scent marking rather than direct interac-
tions that could be risky (McGuire & Bemis, 2017).
We further explore contexts in which scent marks may be
honest or dishonest and do so for the first time with respect to
urine marking in domestic dogs. We evaluated raised-leg angle
and body size as predictors of urine mark height to determine if
raised-leg angle could serve as a proxy for height of urine mark
(Study 1). Then, using raised-leg angle as a proxy for urine
mark height and body size as a proxy for competitive ability, we
compared height of urine mark and the signaler’s competitive
ability (Study 2). Assuming that urine mark height communi-
cates body size and corresponding competitive ability to con-
specifics, Study 2 tested the hypothesis that urine marking is a
dishonest signal in male dogs. Given that small dogs urinate
more frequently and direct more urinations than large dogs
(McGuire & Bemis, 2017) and would seem to benefit more from
exaggerating their size, we predicted that small male dogs would
exhibit larger raised-leg angles than large male dogs.
Materials and methods
Dogs and housing
We scored the raised-leg marking posture of male dogs at two
animal shelters, Tompkins County SPCA (Ithaca, NY, USA)
and Cortland Community SPCA (Cortland, NY, USA). Dogs
came to the shelters as strays, transfers from other shelters, or
were owner-surrendered; most were mixed-breeds. All dogs
had undergone temperament testing by shelter staff, received
veterinary care, and were in good physical health at the time
of observation. Body mass and estimated age of each dog were
obtained from veterinarian records. We measured height at
withers for each dog.
We analyzed adult males because juvenile males typically
do not raise a hindlimb during urination (Sprague & Anisko,
1973; Gough & McGuire, 2015; McGuire, 2016) and senior
dogs are more likely to experience orthopedic issues such as
hip dysplasia (Lavrijsen et al., 2014), which could hinder the
raised-leg posture. Dogs ranged in age from 10 months to
7 years (median =3.0 years). We excluded from Study 2 two
large 1-year-olds because they displayed juvenile urinary
behavior by predominantly using the lean-forward posture and
included one small (23 cm) 10-month-old because small dogs
undergo puberty earlier than large dogs (Pineda, 2003) and he
displayed adult urinary behavior by exclusively using the
raised-leg posture. Dogs varied in body mass (range: 3.6–
36.3 kg, median =26.3 kg) and height (range: 23.0–70.0 cm,
median =54.0 cm). We included both intact and neutered
adult males because both display the raised-leg posture (Beach,
1974). We observed 15 dogs in Study 1. For Study 2, we
included relevant data from the 15 dogs in Study 1 plus data
from 30 additional dogs (different response variables were ana-
lyzed in Studies 1 and 2).
Housing arrangements for dogs are detailed in Gough &
McGuire (2015); we provide an abbreviated description here.
Tompkins SPCA held dogs in individual cubicles, which ran-
ged in size from 5.2 m
2
to 7.3 m
2
. Dogs were typically
walked or taken to an outdoor enclosure every two or three
hours. We observed dogs that had not been outside for at least
2 h. Cortland SPCA held dogs in individual cages that ranged
in size from 2.3 m
2
to 4.5 m
2
, were divided by chain-link
fences, and accessed via chain-link doors. Dogs were walked
by staff or volunteers once or twice per day and rotated
through two outdoor pens.
Walking procedures
At Tompkins SPCA, the walking area included the shelter’s
yard and a nearby agricultural field (16.6 ha; 42°28020″N,
76°26022″W). Vertically oriented objects such as dense vegeta-
tion (0.3–1.0 m in height), trees, and buildings lined the yard.
Trees, pond reeds, benches, and a chain-link fence were within
the yard. The agricultural field had walking paths lined with
vertically oriented vegetation and trees. At Cortland SPCA, the
walking area included a gravel parking lot and the shelter’s
yard (0.3 ha; 42°34055″N, 76°13001″W). Vegetation (0.3–1.0 m
in height), trees, buildings, and a fire hydrant lined the walking
area. A planter (approximately 0.5 m in height), two metal
posts, and a dumpster were within the walking area.
Given size differences in walking areas, walk duration was
20 min at Tompkins SPCA and 10 min at Cortland SPCA.
Dogs set the pace of walks, explored freely, and investigated
prospective marking targets as they pleased. In Studies 1 and
2Journal of Zoology (2018) – ª2018 The Zoological Society of London
Urine marking in male domestic dogs B. McGuire et al.
2, Betty McGuire (BM) typically walked the dogs and Kather-
ine Bemis (KB) or Destiny Orantes (DO) followed behind the
dogs at approximately three meters and filmed continuously
with an iPhone 7 (model MN9G2LL/A, Apple Inc., Cupertino,
CA, USA). In Study 2, Boomer Olsen (BO) filmed using a
high-speed camera (Exilm FH20) mounted to a monopod
(Quik Pod Ultra; 0.5 m in length). Only one dog displayed an
interest in the camera and/or monopod. BO filmed this dog at
a distance such that it no longer responded to the camera (ap-
proximately 20 m). Due to adoptions during our period of data
collection, we walked some dogs once and some multiple
times (Study 1: 1 walk, 6 dogs; 2–3 walks, 4 dogs; 4–5 walks,
4 dogs; 6 walks, 1 dog; Study 2: 1 walk, 19 dogs; 2–3 walks,
14 dogs; 4–5 walks, 5 dogs; >8 walks, 7 dogs). All procedures
were carried out under protocol 2012-0150, which was
approved by Cornell University’s Institutional Animal Care
and Use Committee.
Video analyses
We used video analysis software (ImageJ) to view footage and
quantify raised-leg angle by drawing a virtual angle on paused
video (Fig. 1). The first ray was drawn from the knee of the
dog’s raised-leg to the vertex at the base of the dog’s tail. The
second ray was drawn parallel to a vertical object in the back-
ground (thus, the second ray was normal to the ground). The
vertical objects used for reference included buildings, light
posts, and fences. If no vertical object existed in the back-
ground, then the urination was not analyzed. The ground itself
was not used for reference because its orientation was not
always obvious from the video recordings. To control for
potentially restrictive effects of target size on raised-leg angle,
only urinations on vertical targets that exceeded the dog’s
height (e.g., walls, posts, trees, vertically oriented vegetation)
were analyzed. We archived a screenshot of each raised-leg
posture and the superimposed angle drawn in ImageJ.
Statistical analyses
All statistical analyses were completed in JMP Pro (version
12.0.1).
Study 1
At least three factors influence the relationship between raised-leg
angle and height of urine mark. First, size of dog affects absolute
height of urine mark (i.e., no matter the raised-leg angle, a large
dog would likely mark higher than a small dog). Second, height
of urine mark depends on distance between dog and target (e.g.,
holding the raised-leg angle constant, dogs that are farther from
the target will deposit urine at lower heights than dogs that are
closer). We could not directly measure distance from planted
hind-limb to target without disrupting marking behavior. We
instead controlled for target shape, which partially affects how
close dogs can stand (i.e., dogs can wrap their legs around poles
and stand very near but, when marking walls, there must be space
between the dog and the wall to accommodate the raised leg). We
classified targets as cylinder-shaped (e.g., poles and tree trunks),
wall-shaped (e.g., walls, fences, stacked pallets), and borders of
tall grass (because grass borders are not solid, we separated this
type of target from wall-shaped). Third, strength of urine stream
affects height of urine mark (i.e., a weak stream will decrease in
height before reaching the target). We could not practically and
reliably measure this variable.
BM, KB, and DO measured heights of urine marks and BO,
who was blind to heights of urine marks, measured raised-leg
angles. Height of urine mark (cm) was measured from the ground
at the base of the object being marked to the highest point of the
mark. We pooled dogs from Tompkins SPCA (n=11) and Cort-
land SPCA (n=4) for statistical analyses due to small sample
size at Cortland SPCA; previous analyses revealed similar pat-
terns of scent marking behaviors at both shelters (Gough &
McGuire, 2015; McGuire, 2016). We ran two general linear
mixed effects models with height of urine mark as the response
variable, size of dog (using body mass in one model and height at
withers in the other because these variables were highly corre-
lated; R
2
=0.91, F
1, 14
=127.37, P<0.0001), raised-leg angle,
and target type as fixed factors, and dog as a random effect. We
did not include neuter status in our models because 14 of the 15
males were neutered at the time of their walks; the remaining dog
was walked twice while intact and twice after neutering. Support-
ing Information Table S1 includes body mass, height at withers,
number of walks, and number of angles by target type for each of
the 15 dogs observed.
Study 2
Measuring urine mark height is challenging because dogs
sometimes miss targets, especially poles and tree trunks of
small diameter, and marks can be hard to locate on tall grass
or targets wet from rain. Thus, we chose to use raised-leg
angle as a proxy for urine mark height in Study 2. Using
raised-leg angle measurements (range: 1–159 angles per dog,
median =5 angles per dog) from video analyses, we calculated
mean raised-leg angle (deg) for each dog, which we refer to as
Figure 1 Screenshot of video analyses as described in Section Video
analyses. The first ray was drawn along the dog’s raised leg to the
vertex at the base of the dog’s tail. The second ray was drawn
parallel to the post (thus, the second ray is normal to the ground).
Journal of Zoology (2018) – ª2018 The Zoological Society of London 3
B. McGuire et al. Urine marking in male domestic dogs
average raised-leg angle. We then conducted linear regressions
with average raised-leg angle (deg) as the response variable
and either body mass (kg) or height at withers (cm) as predic-
tor variables. Body mass and height at withers were highly
correlated (R
2
=0.84, F
1, 43
=223.62, P<0.0001) and there-
fore included in separate models. Residuals were checked for
normality via Shapiro-Wilk test and homogeneity of variance
via Levene’s test using a median split method. Average raised-
leg angle was cubed to meet both normality and homogeneity
of variance assumptions.
For these analyses, we pooled dogs from Tompkins SPCA
(n=19) and Cortland SPCA (n=26) because shelter identity
was not a significant predictor when included in the linear regres-
sion models. We also excluded neuter status because it was not a
significant predictor when included in the models. Note that we
tested the effect of neuter status using 38 neutered dogs, two
intact dogs, and intact data from the five males that were neutered
over the course of our observations; thus, for the analysis, we had
38 neutered males and 7 intact males. Age did not predict average
raised-leg angle, so we excluded age from the models.
Results
Study 1
In the first model, raised-leg angle was a significant predictor
of height of urine mark (F=31.222, d.f. =1, 61.9,
P<0.0001) as was body mass (F=12.727, d.f. =1, 8.8,
P<0.007). Type of target did not predict height of urine mark
(F=1.076, d.f. =2, 87.1, P=0.35). In the second model,
raised-leg angle was a significant predictor of height of urine
mark (F=38.292, d.f. =1, 24.8, P<0.0001) as was height at
withers (F=36.270, d.f. =1, 5.5, P<0.002). Type of target
did not predict height of urine mark (F=1.265, d.f. =2, 91.1,
P=0.29). In these analyses, we had limited ability to control
for distance between dog and target and inability to control for
strength of urine stream. These two factors are best controlled
by analyzing the relationship between raised-leg angle and
height of urine mark during a single urination. Figure 2 com-
pares two raised-leg angles from a video of a single urination
by Patches (Supporting Information Video S1). Patches first
held his raised leg at 115 degrees (Fig. 2a). We calculated the
corresponding height of urine mark to be 15.3 cm. As the
video plays, Patches further elevates his raised leg without
shifting his planted hindlimb or moving closer to the target.
Simultaneously, the urine stream and urine mark on the tree
trunk move upward. Patches then holds his raised leg at 120
degrees (Fig. 2b). We measured the height of the correspond-
ing urine mark, from the base of the tree trunk to the highest
point of the urine mark, to be 17.8 cm. Thus, Figure 2 directly
demonstrates the positive relationship between raised-leg angle
and height of urine mark while best controlling for both dis-
tance between dog and target and strength of urine stream.
Study 2
A male dog’s body mass significantly predicted average raised-
leg angle (cube-transformed; Table 1; Fig. 3a). Similarly, a
male dog’s height significantly predicted average raised-leg
angle (cube-transformed; Table 1; Fig. 3b). For ease of
115° 120°
17.8 cm15.3 cm
(a) (b)
Figure 2 Screenshots from a video of Patches, who was observed in Study 1. Horizontal lines compare height of urine mark and height of
raised-leg. (a) Patches first held his raised leg at 115 degrees, resulting in a urine mark at 15.3 cm. We approximated height of urine mark by
calculation. (b) At a later time during the same urination, Patches shifted his raised leg to 120 degrees, resulting in a urine mark at 17.8 cm. We
measured height of urine mark from the base of the tree to the highest point of this second mark. [Colour figure can be viewed at
zslpublications.onlinelibrary.wiley.com]
4Journal of Zoology (2018) – ª2018 The Zoological Society of London
Urine marking in male domestic dogs B. McGuire et al.
interpretation, non-transformed average raised-leg angle is plot-
ted against body mass (Fig. 3c) and height (Fig. 3d). Although
regression tests using nontransformed average raised-leg angle
did not meet the normality assumption, these regression out-
puts and conclusions were very similar to those obtained using
transformed data (Table 1). In all analyses, the relationship
between body size (using either body mass or height at with-
ers) and average raised-leg angle was negative (Table 1;
Fig. 3). Supporting Information Table S2 contains body mass,
height, number of walks, number of raised-leg angle measure-
ments, and average raised-leg angle (SD) for each dog.
Discussion
We found that raised-leg angle was the strongest predictor of
height of urine mark (Study 1). Consistent with our prediction
that small dogs would exhibit larger raised-leg angles than
large dogs, we found a significant negative relationship
between an adult male dog’s body size (using either body
mass or height at withers) and average raised-leg angle (Study
2).
As body mass negatively predicted average raised-leg angle,
we expect that light dogs place scent marks higher, relative to
their own body size, than heavy dogs. Our results are consis-
tent with Sharpe et al. (2012), who found that particularly light
male dwarf mongooses marked higher than expected. Our find-
ings and those of Sharpe et al. (2012) suggest that vertical
placement of scent marks could be used dishonestly to exag-
gerate the signaler’s body size and competitive ability. This
conclusion differs from that of Gosling & Roberts (2001), who
maintain that scent marking by male mammals is cheat-proof
(i.e., honest).
In Study 1, we found that body size positively predicts urine
mark height. This suggests that conspecifics may derive accu-
rate information about the size of signalers from heights of
urine marks. However, we also showed that raised-leg angle
positively predicts urine mark height (Study 1) and, on aver-
age, small dogs perform larger raised-leg angles than large
dogs (Study 2). Thus, even though height of urine mark does
reflect size of signaler in part, small dogs seem to “cheat”by
using larger raised-leg angles to deposit higher urine marks,
thereby exaggerating their size.
It is possible that scent marking is honest in some contexts
and dishonest in others; this may vary with identity of the sig-
naler, type of information communicated, and property of the
scent mark. For example, the olfactory content of scent marks
appears to be an honest indicator of health status of males:
female mice (Mus musculus) can distinguish between healthy
and parasitized males by differences in the odor of their urine
marks (Kavaliers & Colwell, 1993; Zala, Potts & Penn, 2004).
On the other hand, scent mark height appears to be a dishonest
indicator of the signaler’s body size and corresponding com-
petitive ability of males in some species: small male dwarf
mongooses placed anogenital scent marks higher than expected
(Sharpe et al., 2012) and small male dogs exhibited larger
raised-leg angles than large dogs (present study). Additionally,
even though heights of anogenital marks by male dwarf mon-
gooses were dishonest, heights of those by females were hon-
est (Sharpe et al., 2012), showing that honesty of scent mark
height can vary with sex of signaler.
Height at withers also significantly and negatively predicted
average raised-leg angle, which contrasts with data by Sharpe
et al. (2012) for male dwarf mongooses; they found a non-
significant negative correlation between body length and aver-
age scent mark height. Due to differing marking postures,
body length of male dwarf mongooses is equivalent to height
at withers of male dogs; male dwarf mongooses use the hand-
stand posture to place anogenital marks (i.e., stand on their
forelimbs; see Sharpe et al., 2012) whereas male dogs use the
raised-leg posture when urine marking (i.e., three limbs remain
planted on the ground while a single hindlimb is raised;
Fig. 1). Nevertheless, our findings and those of Sharpe et al.
(2012) are similar in that body mass is a stronger predictor of
average raised-leg angle in male dogs and average scent mark
height in male dwarf mongooses than height at withers or
body length, respectively. This may be because body mass is a
proxy for competitive ability in dogs and other mammals
(Scott & Fuller, 1965; Gosling et al., 1996; Taylor, Reby &
McComb, 2010) but height is not. Furthermore, our finding
that body mass is a better predictor than height at withers of
raised-leg angle suggests that raised-leg angle, and by exten-
sion relative scent mark height, communicates competitive abil-
ity in domestic dogs. This is consistent with the hypothesis
that scent marks provide an important means for competitor
assessment (Gosling & Roberts, 2001).
Our findings add to a growing understanding of the behav-
ioral differences between small and large domestic dogs. Small
dogs are more likely than large dogs to exhibit problematic
behaviors such as separation anxiety, dog-directed fear, owner-
directed aggression, and urine marking in the home (McGreevy
et al., 2013). Small dogs were less motivated than large dogs
to approach audio playbacks of growls (Taylor et al., 2010)
Table 1 Relationship between body mass (kg) and height at withers (cm) of adult male domestic dogs and average angle of the raised-leg
urinary posture. Shown are results from regression analyses in which body mass and height were predictor variables and average raised-leg
angle (either cube-transformed or nontransformed) was the response variable. Body mass and height were included in separate models because
they were highly correlated. Degrees of freedom for all analyses =43; N/A =not applicable; data analyzed in Study 2
Average angle
3
(deg
3
) Average angle
3
(deg
3
) Average angle (deg) Average angle (deg)
Intercept (b;P) 2.390 910
6
;<0.0001 2.596 910
6
;<0.0001 133.135; <0.0001 137.495; <0.0001
Body mass (kg) (b;P)2.492 910
4
; 0.004 N/A 0.559; 0.008 N/A
Height (cm) (b;P) N/A 1.539 910
4
; 0.024 N/A 0.340; 0.039
R
2
0.176 0.113 0.153 0.095
F9.214 5.494 7.761 4.522
Journal of Zoology (2018) – ª2018 The Zoological Society of London 5
B. McGuire et al. Urine marking in male domestic dogs
and a model of a Labrador retriever (Leaver & Reimchen,
2008). During walks outside, small dogs urine mark more fre-
quently than large dogs (McGuire & Bemis, 2017) and exhibit
larger raised-leg angles (present study). Among other explana-
tions for these behavioral differences (McGreevy et al., 2013),
direct social interactions could be particularly costly to small
dogs, given their lesser competitive abilities, thereby prompting
hesitant behaviors (Leaver & Reimchen, 2008; Taylor et al.,
2010); indirect behaviors, such as leaving a scent mark in the
absence of a receiver (McGuire & Bemis, 2017); and larger
raised-leg angles and, by extension, relatively high scent
marks. It may be uniquely beneficial for small dogs to commu-
nicate indirectly (McGuire & Bemis, 2017) and exaggerate
their body size and competitive abilities through relatively high
scent marks if this enables them to avoid direct conflict. In
contrast, large dogs have less incentive to avoid direct conflict
due to their greater competitive abilities.
Alternatively, over marking may explain our findings. Over
marking is used by mammals to cover deposits by conspecifics
in favor of displaying their own scent (Johnston, Chiang &
Tung, 1994) and is a common behavior in dogs that may, in
combination with adjacent marking (i.e., depositing a scent
mark adjacent to that of a conspecific), constitute 63% of all
urinations (Lisberg & Snowdon, 2011). If a large dog places a
scent mark at the height of its hip, a small dog would need to
place its urine higher, relative to its own hip, to over mark the
large dog’s deposit. This requires the small dog to perform a
larger raised-leg angle than the large dog (per Study 1). Com-
pared to large dogs, small dogs will encounter more marks that
are higher in relation to their own body size for them to over
mark; this could explain the negative relationship between
body size and average raised-leg angle.
Physical constraints may prevent heavy dogs from perform-
ing large raised-leg angles, thereby contributing to trends in
Average raised-leg angle (deg)^3
5.0e+5
1.0e+6
1.5e+6
2.0e+6
2.5e+6
3.0e+6
3.5e+6
0 5 10 15 20 25 30 35 40
Body Mass (kg)
Average raised-leg angle (deg)
80
90
100
110
120
130
140
150
0 5 10 15 20 25 30 35 40
Bod
y
Mass (k
g
)
Average raised-leg angle (deg)^3
5.0e+5
1.0e+6
1.5e+6
2.0e+6
2.5e+6
3.0e+6
3.5e+6
20 30 40 50 60 70
Height (cm)
Average raised-leg angle (deg)
80
90
100
110
120
130
140
150
20 30 40 50 60 70
Hei
g
ht (cm)
(a) (b)
(c) (d)
Figure 3 Plots of response variables (y-axis) versus predictor variables (either body mass or height at withers; x-axis); shading depicts 95%
confidence intervals. (a) Average raised-leg angle (cube-transformed) versus body mass. (b) Average raised-leg angle (cube-transformed) versus
height. (c) Average raised-leg angle (non-transformed) versus body mass, which is plotted for ease of interpretation. (d) Average raised-leg angle
(nontransformed) versus height, which is plotted for ease of interpretation.
6Journal of Zoology (2018) – ª2018 The Zoological Society of London
Urine marking in male domestic dogs B. McGuire et al.
our data. For example, heavy dogs may be limited to small
raised-leg angles that counterbalance their body mass. During a
raised-leg urination, the planted hindlimb of the dog will often
lean in the direction opposite the target (see Fig. 1 for an
example). It is feasible that a small raised-leg angle, versus a
large raised-leg angle, would provide a greater counterbalanc-
ing force to offset the lean; this could then be more important
in heavier versus lighter dogs. We did not control for the
potential importance of raised-leg angle as a counterbalancing
mechanism.
Companion animals do not compete for survival and repro-
duction like free-ranging dogs or other wild canids (Bradshaw,
Blackwell & Casey, 2016), perhaps making competitor assess-
ment less relevant for dogs in homes or shelters. However,
even though outcomes of competitive interactions may be of
lesser consequence, companion dogs frequently exhibit agonis-
tic behaviors such as growling and chasing (Bradshaw, Black-
well & Casey, 2009) and intensely investigate each other’s
urine marks (Lisberg & Snowdon, 2009). Data from Lisberg &
Snowdon (2009) indicate that investigation of urine is an
important means of competitor assessment in companion dogs,
as they found that dogs of lower social status spent more time
than dogs of higher social status investigating urine marks of
unknown conspecifics.
Our findings for male shelter dogs add to those of Sharpe
et al. (2012) for free-ranging male dwarf mongooses in show-
ing that some male mammals engage in dishonest signaling via
vertical placement of scent marks. Nevertheless, our study and
that by Sharpe et al. (2012) were observational. Thus, to fur-
ther characterize the relationship between scent mark height
and signaler’s body size, it would be beneficial to conduct
experimental studies across multiple species in which over
marking is controlled. Future studies should also characterize
the responses of dogs to urine marks placed at different
heights, similar to work done by White et al. (2002; pandas)
and Sharpe (2015; dwarf mongooses).
Acknowledgments
We thank Stephen Parry for statistical advice, Stacy Farina for
advice on video cameras and software, and Lauren Ferris for
helpful discussions. Claudia Gerecke, Rebecca Meyer, and
William Fry helped with data collection. We also thank Cort-
land SPCA and Tompkins SPCA for their participation. This
research was supported by the Einhorn Discovery Fund, Col-
lege of Arts and Sciences, Cornell University.
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Supporting Information
Additional supporting information may be found online in the
Supporting Information section at the end of the article.
Table S1. Physical characteristics (body mass and height at
withers), number of walks, and number of angles by target
type for each of the 15 adult male dogs analyzed in Study 1.
Dogs are ordered from smallest to largest in body mass.
Table S2. Physical characteristics (body mass and height at
withers), number of walks, total angles measured, and average
angle SD for each of the 45 adult male dogs analyzed in
Study 2. Dogs are ordered from smallest to largest in body
mass.
Video S1. Relationship between raised-leg angle and height of
urine mark within a single urination.
8Journal of Zoology (2018) – ª2018 The Zoological Society of London
Urine marking in male domestic dogs B. McGuire et al.