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Journal of Applied Animal Welfare Science
ISSN: 1088-8705 (Print) 1532-7604 (Online) Journal homepage: http://www.tandfonline.com/loi/haaw20
Physiological and Behavioral Responses of Horses
to Wither Scratching and Patting the Neck When
Zoë W. Thorbergson, Sharon G. Nielsen, Rodney J. Beaulieu & Rebecca E.
To cite this article: Zoë W. Thorbergson, Sharon G. Nielsen, Rodney J. Beaulieu & Rebecca
E. Doyle (2016) Physiological and Behavioral Responses of Horses to Wither Scratching and
Patting the Neck When Under Saddle, Journal of Applied Animal Welfare Science, 19:3, 245-259,
To link to this article: http://dx.doi.org/10.1080/10888705.2015.1130630
Published online: 09 Mar 2016.
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Physiological and Behavioral Responses of Horses to Wither
Scratching and Patting the Neck When Under Saddle
Zoë W. Thorbergson,
Sharon G. Nielsen,
Rodney J. Beaulieu,
and Rebecca E. Doyle
School of Animal and Veterinary Science, Charles Sturt University, Wagga Wagga, Australia;
Unit, School of Computing and Mathematics, Charles Sturt University, Wagga Wagga, Australia;
Department of Human
Development, California State University, San Marcos
Riding is considered to be an arousing activity for horses. It has been
suggested that wither scratching may be a more useful tool for relaxation
compared with the common practice of neck patting. In the current study, 18
horses were exposed to 3 treatments, including control or no interaction,
neck patting, and wither scratching, for 1 min each following a short obstacle
course. Heart rate, heart rate variability, and a variety of behaviors were
measured in the horses. Wither scratching produced a signiﬁcantly longer
duration of relaxed-type behaviors. Wither scratching could be a useful tool to
help a horse relax while under saddle. Additionally, the study identiﬁed 2 ear
positions that may be useful for future research in horse behavior.
Agitation; behavior; horse;
welfare; wither scratching
Historically, horse trainers have indicated that relaxation of the horse during riding is imperative to
facilitate learning and ease of training, as it allows the horse to be in a state more conducive to respond
to rider aids, which is also important for rider safety (McGreevy & McLean, 2010; Podhajsky, 1975).
Chronic stress may contribute to illness, stereotypies, and conﬂict behaviors if the horse is trained and
ridden in a nearly continual state of tension and stress (McLean & McLean, 2008). Evidence suggests
that riding can be a stressful event, as it may mimic a predator attacking—for example, when the rider
mounts a vulnerable area that is not defendable with either teeth or hooves (Schmidt, Aurich, Möstl,
Müller, & Aurich, 2010).
Sometimes, riding manuals recommend patting the neck as a form of reward or a means to soothe
the horse (German National Equestrian Federation, 2013; Podhajsky, 1975). No comparable horse –
horse behaviors to human–horse patting have been identiﬁed; thus, patting may not be relevant
ethologically (McGreevy & McLean, 2010; Waring, 2003).
Allogrooming, or mutual grooming, is when a horse uses a scratching or nipping motion with their
upper teeth to groom a partner on a preferred area, usually across the withers (Feh & De Mazières,
1993; Waring, 2003). Allogrooming has been identiﬁed as a behavior of biological importance and
is performed by equines toward conspeciﬁcs in a social bonding context and as a comfort behavior
(McDonnell, 2003; Waring, 2003). Equitation scientists suggest that mutual grooming may act as a
form of tactile communication to convey trust between equine participants (McDonnell, 2003), and
VanDierendonck and Spruijt (2012) proposed that allogrooming may further provide long-term
beneﬁts through self-rewarding properties. Incidences where horses have displayed allogrooming
toward heterospeciﬁcs with whom they have some social afﬁliation, such as dogs or goats, have also
been recorded (Fraser, 2010), further suggesting its ethological importance.
q2016 Taylor & Francis
Zoë W. Thorbergson is now at the University of Guelph. Rebecca E. Doyle is now at the University of Melbourne, Australia.
Color versions of one or more of the ﬁgures in the article can be found online at www.tandf.com/haaw.
CONTACT Zoë W. Thorbergson email@example.com Open Learning and Educational Support Main Ofﬁce, University of
Guelph, Johnston Hall, Room 160, Guelph, ON N1G 2W1, Canada.
JOURNAL OF APPLIED ANIMAL WELFARE SCIENCE
2016, VOL. 19, NO. 3, 245–259
Research has suggested that scratching the wither area of a horse seems to imitate allogrooming.
Horses have displayed reciprocal grooming behavior routinely toward the human during wither
scratching (WS; McGreevy & McLean, 2010; Waring, 2003). Research has also shown that grooming
or massaging around the wither area lowers the horse’s heart rate (HR) and produces relaxed
behaviors while in the stable (Feh & De Mazières, 1993; McBride, Hemming, & Robinson, 2004).
WS may therefore have the capacity to induce similar positive states in horses to those in
Often, HR and factors that measure HR variability (HRV), in combination with subtle behaviors,
can indicate the affective state of the horse (Schmidt, Biau, et al., 2010; Young, Creighton, Smith, &
Hosie, 2012). HRV is a reﬂection of the equine’s stress response, as it indicates the balance of the
autonomic nervous system between sympathetic and parasympathetic tone. The standard deviation of
interheartbeat interval (SDR–R), root mean square of successive interheartbeat interval difference
(RMSSD), and proportions of successive beats differing by 50 ms divided by the total number of
interheartbeat intervals (pNN50) are three time-domain factors that measure HRV (Task Force of the
European Society of Cardiology & the North American Society of Pacing and Electrophysiology, 1996).
Dominance of either sympathetic or parasympathetic tone is indicated by a decrease or increase
(respectively) in HRV indexes (von Borell et al., 2007).
Observation of behavior may provide immediate evidence of a nonhuman animal’s affective state
while being noninvasive and easily identiﬁable. Evidence suggests that subtle behaviors of ear, head,
mouth, tail, or leg movement may be used to identify a horse in a relaxed or agitated state (Young et al.,
2012). A variety of subtle behaviors are considered agitated behaviors at liberty (Fraser, 2010; Waring,
2003). Ears turned back (ears back) has been reported to indicate negative affective states, including
fear, discomfort, submission, avoidance, pain, or aggression in horses depending on the circumstance
(Dalla Costa et al., 2014; McDonnell, 2003; Waring, 2003). Research with sheep has also implied that
ears back may indicate an uncontrollable situation for the animal (Boissy et al., 2011). Ears pinned
against the poll area (ears ﬂat back) may indicate a mild to serious threat posture or that an aggressive
act is imminent (McDonnell, 2003). Tail swishing has been implied as a sign of annoyance or pain
(Fraser, 2010; McLean & McLean, 2008; Waring, 2003).
Stepping forward may be a sign of escape or avoidance behavior (McGreevy & McLean, 2010;
McLean & McLean, 2008). Open mouth,reeﬁng on the reins (distinct pull against the reins), and
combined head above the withers and head below the withers (total AB) are three behaviors that may be
interrelated and may indicate that the horse is displaying escape- or avoidance-type behaviors
(McGreevy & McLean, 2010). Reeﬁng on the reins is also an indication of incomplete training of the
stop response (McGreevy & McLean, 2010). Depending upon the context, other behaviors that are
believed to indicate agitation include stepping backward,raised tail,clamped tail,shaking the head, and
exposure of the white sclera around the eye (Fraser, 2010; Klimke, 2000; McLean & McLean, 2008;
Numerous behaviors have been identiﬁed in the horse that are considered to indicate a relaxed
(positive) state at liberty (McDonnell, 2003; Waring, 2003). Both ears with the pinna facing outward
(neutral ear position) appears to be a reliable indicator of relaxation in horses (McGreevy, 2008;
Waring, 2003). Long snorting or sneezing a long, drawn-out snort is considered a sign of relaxation
while under saddle (McLean & McLean, 2008). A horse who stands still when asked to stop, with mouth
closed and without tension, is considered to be relaxed under saddle (German National Equestrian
Federation, 2013; Klimke, 2000; McLean, 2003; Podhajsky, 1975). Scratching or grooming in a
preferred area on a horse may elicit elongation of the upper lip, which may indicate that the horse is
experiencing a pleasurable sensation (Waring, 2003).
Head below the withers is displayed by horses in a relaxed state when at liberty (Fraser, 2010). The
horse may be experiencing some form of relaxation when the head is below the withers during
scratching, which is supported by the ﬁnding of McBride et al. (2004). However, training a horse
to lower his/her head below the withers may not induce a state of relaxation (Warren-Smith, Greetham,
& McGreevy, 2007).
246 THORBERGSON, NIELSEN, BEAULIEU, DOYLE
For the purpose of the current study, behaviors were classiﬁed as ambiguous if previous research
indicated conﬂicting results concerning the horse’s perceived affective state. Further research is needed
to discover whether these ambiguous behaviors are clear indications of the horse’s affective state. For
example, there is conﬂicting research as to whether yawning and licking –chewing indicate a state of
stress or of relaxation, and yawning has also been identiﬁed previously as being associated with the
presence of stereotypical behavior (Fraser, 2010; Fureix, Gorecka-Bruzda, Gautier, & Hausberger, 2011;
Krueger, 2007; Waring, 2003; Warren-Smith et al., 2007). Oral behavior of exposing the tongue (tongue
out) during riding has the implication of stereotypic behavior developed from chronic bit pressure
(McGreevy & McLean, 2010). Ear lateralization in sheep has been shown to indicate the affective
valence of the animal, but little research on this ear positioning has been performed with horses
(Reefmann, Bütikofer Kaszàs, Wechsler, & Gygax, 2009).
The aim of the present study was to determine whether horses respond differently to WS, neck
patting (NP), and no interaction (control [C]) when under saddle. It was hypothesized that WS when
under saddle would be more relaxing to the horse, resulting in a lower HR and the presence of more
subtle relaxed behaviors compared with when the horse experienced NP.
Materials and methods
All procedures involved with horse handling and testing were approved by the Animal Care and Ethics
Committee of Charles Sturt University in Wagga Wagga, New South Wales, Australia (Project Protocol
A total of 18 horses were recruited for the project. Horses used for pleasure or lesson riding were
chosen, and to participate in the current study, horses had to be of good physical health, familiar to the
rider and stable environment, commonly ridden, and 3 years of age or older. Horses were housed in
their home stables for the duration of the experiment, and each horse wore their usual saddle and bit or
bridle. Nosebands were ﬁtted with a minimum width of two ﬁngers between the nasal bone and the
nose band to allow for ﬂexing of the jaw (British Horse Society & Pony Club, 1966). Horses were ridden
in their normal home arena for all three treatments. Each arena was rectangular and fully fenced with
proper footing for equestrian sports. All horses had experienced NP previously. Details of the animals
are provided in Table 1.
The experiment was carried out at ﬁve different stables on 6 different days with six different riders
(Table 1). Prior to each horse being saddled, a health examination was performed where the following
were examined: HR, respiratory rate, back and girth area, any evidence of lameness, hydration, mucus
membrane color, and eye health. One horse was removed from the experiment due to hypersensitivity
in the girth area and the lumbar vertebral region of the spine and was replaced with another suitable
horse. All 18 horses used in the experiment were deemed healthy.
Each horse was saddled and then ﬁtted with a HR monitor (HRM; Polar RS800CX Science Edition,
Polar Electro Oy, Kempele, Finland). Following the instructions of the HRM user’s manual, electrodes
were placed under the saddle pad on the left side and under the girth on the left side. Water-based
electrode gel was applied to both electrodes on each horse to enhance conductivity (von Borell et al., 2007).
Each horse was ridden through a short obstacle course (20 m £40 m) as a washout period, before
each treatment, to minimize possible carryover effects. This period included a short warmup of walking
the inside perimeter of the arena 1.5 times, then proceeding through an L-shaped pole maze 1.2 m wide,
followed by weaving a slalom through four cones and then passing through two barrels spaced 1.1 m
apart (Figure 1).
HORSE RESPONSES TO WITHER SCRATCHING 247
After the completion of the obstacle course, each horse entered the video-recording area (1.5 m
and behavior and HR data were recorded for 1 min while the treatment was applied for a continuous
1-min period. This treatment length was modeled after the research by Tyler (1972), who concluded
that the time spent mutually grooming by mature mares was 56 s. The horse and rider then repeated the
obstacle course before entering the video area to administer the next treatment.
Table 1. Horses and number of stables, days, and riders.
Horse Breed Breed group
Age Stable Day Rider Equipment bit/saddle
1 Quarter Horse 4 G 17 1 1 1 Snafﬂe/Western
2 Icelandic 2 M 10 5 6 6 Snafﬂe/English
3 Icelandic 2 M 8 5 6 6 Snafﬂe/English
4 Arab/Cross 3 M 15 2 2 2 Snafﬂe/English
5 Paint 4 M 15 2 2 3 Hackamore/Western
6 Fjord 4 G 21 2 2 2 Snafﬂe/English
7 Standardbred 1 M 4 3 3 4 Snafﬂe/Western
8 Standardbred 1 M 5 3 3 4 Snafﬂe/Western
9 Standardbred 1 G 13 3 3 4 Snafﬂe/Western
10 Standardbred 1 M 4 3 3 4 Snafﬂe/Western
11 Icelandic 2 M 13 5 6 6 Snafﬂe/English
12 Icelandic 2 M 5 5 6 6 Snafﬂe/English
13 Quarter Horse/Cross 4 M 23 4 4 5 Hackamore/Treeless
14 Arab 3 G 19 4 4 5 Hackamore/Treeless
15 Arab/Cross 3 M 7 4 4 5 Snafﬂe/Western
16 Arab/Cross 3 G 32 2 5 2 Snafﬂe/English
17 Fjord 4 G 5 2 5 2 Snafﬂe/English
18 Lipizzaner/Hanoverian 4 G 15 2 5 2 Snafﬂe/English
Horses were grouped into one of four categories for statistical analysis: (a) standardbred, (b) Icelandic, (c) Arab –Arab cross, or (d)
G¼gelding; M ¼mare.
L-Shaped Pole Maze
Figure 1. Plan of the arena. Dotted lines with arrows indicate the direction of travel.
248 THORBERGSON, NIELSEN, BEAULIEU, DOYLE
Six adult female riders who had ridden consistently for the previous 5 or more years rode the horses in
the experiment. All riders demonstrated a balanced, independent seat and hands when riding. Riders
were familiar with the respective horses they rode. Each rider was provided with the ethics approval
number, research aim, and treatment protocol to help ensure a standard procedure for each treatment
on each horse. Treatments were deﬁned as C, NP, and WS. Each horse was exposed to all three
treatments according to a balanced Latin square design to guard against order effect.
Riders were instructed to scratch the area around the withers for 1 min after the riding activity had
ceased. The speciﬁc area scratched was at the base of the mane between the shoulder blades;
anatomically, this area corresponded with the dorsal anterior thoracic vertebrae 3 to 5 located in front
of the pommel of the saddle. Riders were instructed to scratch the horse with a raking motion of the
ﬁngers with a “ﬁrm”pressure.
Riders were instructed to pat the horses on the neck for 1 min after the riding activity had ceased. The
speciﬁc area was between cervical vertebrae 3 and 6 on the right side of the neck, midway between the
mane and throat. Riders were instructed to pat the horse in a quick and gentle manner using the ﬂat of
Riders were instructed to sit quietly for 1 min after the riding activity had ceased. Riders refrained from
any form of patting or scratching of the horse.
Heart rate measures
During the 1 min of treatment, mean HR and HRV parameters, including SDR–R, RMSSD, and
pNN50, were collected.
HR was recorded at 1-s intervals continuously during the treatments and C periods. A sampling
frequency of 1,000 Hz was used to provide a temporal resolution of 1 ms for each interheartbeat (R–R)
interval. The raw data were later downloaded to a computer using the Polar Pro Trainer 5 Equine
Edition Software (Version 5.41.002, Polar Electro Europe BV, Fleurier Branch, Switzerland). Kubios
HRV software Version 2.0 (Biosignal Analysis and Medical Imaging Group, Department of Physics,
University of Kuopio, Finland) was utilized for correction and detrending of the raw data ﬁles from the
Polar Trainer 5 Equine Edition software ﬁles to prepare data for statistical analysis.
Thirty-two behaviors were identiﬁed for data collection (Table 2,Figure 2). The 32 behaviors were
separated into three groups based on previous research. These groups were agitated behaviors (15),
ambiguous behaviors (10), and relaxed behaviors (7). To assess the behaviors, each 1-min treatment
period was recorded on a digital camera (Canon, EOS 5D Mark II Full Frame CMOS sensor Full HD,
Canon, Tokyo, Japan) for subsequent analysis on a continuous observational basis.
Behaviors were analyzed either according to the total time they were performed or the number of
times they were performed, regardless of duration, during each 1-min treatment. The behaviors
recorded from the video were not evaluated blindly, as each treatment was visible to the observer. All of
the videos were analyzed by the same technician to yield a high degree of consistency.
HORSE RESPONSES TO WITHER SCRATCHING 249
To facilitate statistical analyses, horses were allocated to one of four breed groups: (a) standardbred,
(b) Icelandic, (c) Arab–Arab cross, or (d) other breeds (Table 1).
Heart rate parameters
HRV is typically nonstationary. Slow, linear, or more complex trends in the HRV signal may cause
distortion of HRV analysis (Berntson & Stowell, 1998; Melkonian, Korner, Meares, & Bahramali, 2012;
Table 2. Ethogram for behavioral observations.
Category Behavior Behavioral description
Agitated Clamped tail The duration of time the tail was clamped tight against rump
Ears back The duration of time the ears were backward, pinna facing back while
still visible (Figure 2a)
Ears ﬂat back The duration of time the ears were held back against the poll area
Head above The duration of time the entire head including the muzzle was above
Open mouth The duration of time the mouth was open; lips may be drawn back to
show teeth (Figure 2b)
Raised tail The duration of time the tail was held higher than natural position and
with higher muscle tone
Reeﬁng on the reins The total number of time there was a distinct pull against the reins:
forward, downward, or in combination
Shake The total number of times a period of head shaking, side to side,
occurred: one shake was deﬁned as the head moving center –side–
Stepping backward The duration of time the horse was stepping backward: one step
or multiple steps
Stepping forward The duration of time the horse was stepping forward: either one step,
multiple steps, or pawing
Tail swishing The duration of time the tail was moving side to side (Figure 2c)
Total above and below (Total AB) The total number of times head was above or below withers
Total forward and back (FB) The total of all steps taken forward and backward
Total head movements The total number of head movements above and below the withers and
left and right of the midline
White sclera The duration of time of exposure of the white sclera around the eye
Relaxed Closed mouth The duration of time mouth was closed, no teeth showing
Elongation upper lip The duration of time of lengthening the upper lip (Figure 2d)
Head below The duration of time the entire head including the ears was below
withers in context of relaxation
Head level The duration of time the head was level with ears above the withers
and muzzle below the withers
Long snorting The total number of times there was a long drawn-out snorting/
sneezing (not to be confused with a short, sharp snort)
Neutral ears The duration of time when the pinna of both ears were facing outward
Standing The duration of time standing stationary with no leg movement
Ambiguous Ears forward The duration of time with ears forward; pinna facing forward (Figure 2f)
Head left The duration of time the head, which may include the neck, was turned
to the left
Head right The duration of time the head, which may include the neck, was turned
to the right
Left-ear lateralization The duration of time the left-ear pinna was facing forward and right-ear
pinna was facing backward (Figure 2g)
Licking–chewing The total number of times licking the lips while performing a chewing
Right-ear lateralization Right-ear pinna facing forward and left-ear pinna facing backward (Figure 2h)
Total ear The total of all ear movements during each treatment
Total left and right (LR) The total number of times head turned left or right or both
Tongue out The duration of the tongue protruding straight out or on either side of
the mouth (Figure 2i)
Yawning The number of times the mouth was open to fullest extent, exposing `
incisors and tongue
250 THORBERGSON, NIELSEN, BEAULIEU, DOYLE
Tarvainen, Ranta-aho, & Karjalainen, 2002). Previous studies have shown that HRV measurement is
reliable if the horse is stationary and if detrending is utilized to correct data (Munsters, Visser, van den
Broek, & Sloet van Oldruitenborgh-Oosterbaan, 2012; Parker, Goodwin, Eager, Redhead, & Marlin,
2010). Removal of trend components and correction of missed beat or extra beat artifacts may decrease
misleading HRV results; thus, detrending and data correction were utilized to counteract these
distortions (Marchant-Forde, Marlin, & Marchant-Forde, 2004). The detrending method based on the
smoothness priors approach was set at 500 ms (Tarvainen et al., 2002). Data correction in the Kubios
custom ﬁlter was set at 0.3 to identify R –R intervals that differed by more than 30% as artifacts
(Schmidt, Biau, et al., 2010). HR parameters were analyzed using linear mixed models (LMMs) in
Tibico Spotﬁre S þ(Spotﬁre S þVersion 8.2.2010, Palo Alto, CA).
(a) (b) (c)
(d) (e) (f)
(g) (h) (i)
Open mouth Tail swishing
Elongated upper lip Neutral ears Ears forward
Left-ear lateralization Right-ear lateralization Tongue out
Figure 2. Photos of 9 of the 32 behaviors in the ethogram.
HORSE RESPONSES TO WITHER SCRATCHING 251
The LMM contained the ﬁxed terms of sex, breed, and treatment and interactions between these.
There were no interaction effects found among sex, breed, and treatment; consequently, these were
dropped from the model. Nonsigniﬁcant terms were dropped sequentially from the model. Horse was
ﬁtted as a random effect. All assumptions of constant variance, independent residuals, and normally
distributed residuals for the LMM were met. Variables were considered to be associated signiﬁcantly
with an outcome if p,.05. The predicted values from the LMM analyses were assigned a rank based
on the Tukey family of pairwise differences with a family conﬁdence level of 5%.
The effects for behaviors were analyzed using a generalized linear mixed model (GLMM) in ASReml-R
(VSN International Ltd., Hemel Hempstead, UK). The behavioral variables of clamped tail, elongated
upper lip, shake, and yawn were binary in their occurrences and so were analyzed using a GLMM with a
binomial error distribution and a logit link function. No GLMMs used in this analysis showed any signs
of overdispersion. The remaining 28 variables were Poisson distributed and analyzed using models with
a Poisson error distribution and a log link function.
All models consisted of ﬁxed effects of sex, breed, and treatment, as well as a random effect of horse.
Speciﬁc behaviors were ﬁtted with a reduced ﬁxed-effect model, as there was insufﬁcient information in
the data to ﬁt the full ﬁxed-effect model of sex, breed, and treatment. The reduced ﬁxed-effect model of
treatment was ﬁt on the following behaviors: stepping backward, open mouth, raised tail, tail swishing,
tongue out, and white sclera.
Heart rate parameters
A signiﬁcant difference between the random effect of horse was detected in mean HR, SDR –R, RMSSD,
and pNN50 (
¼75.90, 11.55, 8.60, and 20.79, respectively). No treatment differences were detected
between any of the HR parameters (Table 3).
The duration of ears back showed a signiﬁcant difference (p¼.003) between treatments with ears in
this position longer during NP and C than WS. Horses opened their mouths for longer durations
during C compared with NP; this presentation was the only signiﬁcantly different (p¼.002)
presentation of open mouth. Horses presented reeﬁng on the reins signiﬁcantly (p,.001) more
frequently during C and NP compared with WS. Stepping forward was executed signiﬁcantly more
Table 3. Predicted means and standard errors of measurement (SEMs) for three heart rate parameters for
three treatments: Control, neck patting, and wither scratching.
Parameter Mean ^SEM
Treatment Control Neck patting Wither scratching F
Mean HR (bpm) 48.18 ^13.31 48.32 ^13.90 47.78 ^13.90 0.67 .519
SDR–R (ms) 50.25 ^17.35 57.73 ^20.12 57.31 ^20.12 1.02 .372
RMSSD (ms) 52.15 ^21.86 58.28 ^25.67 58.68 ^25.67 0.69 .504
pNN50 (%) 26.19 ^17.99 27.43 ^20.25 28.83 ^20.25 0.53 .597
Note. HR ¼heart rate; SDR–R¼standard deviation of interheartbeat interval; RMSSD ¼root mean square
of successive interheartbeat interval difference; pNN50 ¼proportions of successive beats differing by 50 ms
divided by the total number of interheartbeat intervals.
Numerator and residual degrees of freedom for all Ftests are 2 and 34, respectively.
252 THORBERGSON, NIELSEN, BEAULIEU, DOYLE
times during NP compared with C (p¼.012), while the effects of WS were not signiﬁcantly different
from C or NP. A signiﬁcant difference (p,.001) was detected in tail swishing, with longer durations
occurring during NP followed by C and ﬁnally WS. Total movements of head above the withers
and head below the withers (total AB) differed signiﬁcantly (p¼.002) between treatments with C
associated with more movement than NP or WS (Table 4).
A signiﬁcant difference (p,.001) was detected in head below withers, with horses more likely to
maintain this position for a longer duration during WS compared with C or NP. The neutral ear
position was displayed for a signiﬁcantly (p¼.009) longer duration in WS compared with NP, while it
was not signiﬁcantly different for C and WS (Table 4).
Head right differed signiﬁcantly (p¼.001); during WS, the horses were more likely to turn their heads
to the right compared with during NP, but neither treatment was signiﬁcantly different from C. There
was a signiﬁcant difference (p,.001) between treatments of left-ear lateralization; during C, horses
held this ear position longer than during NP, followed by WS. The frequency of licking–chewing
behaviors was signiﬁcantly (p¼.007) higher during NP than WS, with neither different from
C. A signiﬁcant difference (p,.001) was detected between treatments of right-ear lateralization, with
WS producing this ear position for a longer duration than C, while NP was not signiﬁcantly different
from either WS or C. Tongue out was displayed for a signiﬁcantly (p,.001) longer duration during
WS compared with C and NP (Table 4).
Table 4. Back-transformed means for all behaviors with statistically signiﬁcant differences across three treatments.
Back-transformed mean (transformed means ^SE)
Behavior category Behavior Control Neck patting Wither scratching Fp
Agitated Ears back (s) 9.31
(2.23 ^0.43) (2.23 ^0.43) (1.99 ^0.44)
(–0.72 ^0.59) (–1.69 ^0.62) (–1.32 ^0.60)
Reeﬁng on the reins (c) 1.04
(0.04 ^0.65) (–0.04 ^0.65) (–1.14 ^0.67)
Stepping forward (s) 0.28
(–1.27 ^0.56) (–0.55 ^0.53) (–1.21 ^0.56)
(–1.09 ^0.48) (–0.16 ^0.43) (–3.65 ^1.08)
Total AB (c) 1.63
(0.49 ^0.50) (–0.09 ^0.50) (0.32 ^0.50)
Relaxed Head below (s) 0.48
(–0.74 ^0.66) (–1.33 ^0.68) (–0.15 ^0.65)
Neutral ears (s) 10.23
(2.32 ^0.29) (2.29 ^0.29) (2.51 ^0.29)
Ambiguous Head right (s) 4.82
(1.57 ^0.26) (1.32 ^0.26) (1.78 ^0.25)
Left-ear lateralization (s) 1.22
(0.20 ^0.45) (–0.48 ^0.47) (–1.43 ^0.52)
Licking–chewing (c) 1.07
(0.07 ^0.31) (0.36 ^0.30) (–0.41 ^0.34)
Right-ear lateralization (s) 0.65
(–0.43 ^0.55) (0.09 ^0.54) (0.49 ^0.53)
(–5.03 ^1.26) (–2.95 ^0.84) (–1.67 ^0.78)
Note. Total AB ¼head above the withers and head below the withers. Transformed means and SEs of the predicted means presented
in parentheses; behaviors are either in seconds (s) or counts (c).
Behaviors with reduced model ﬁxed-effects “treatment.”
a, b, c
Different letters within a row denote a difference at the 0.05% familywise signiﬁcant level.
HORSE RESPONSES TO WITHER SCRATCHING 253
No detectable difference was found between treatments in the behaviors of clamped tail (p¼.792),
head above (p¼.355), raised tail (p¼.176), shake (p¼.919), stepping backward (p¼.092), total
stepping forward and stepping backward (p¼.094), total head movements (p¼.237), and white sclera
(p¼.754). No instances of ears ﬂat back were observed during WS, NP, or C (Table 5).
No detectable effect was found between treatments during closed mouth (p¼.051), elongated upper lip
(p¼.992), head level (p¼.250), long snorting (p¼.530), or standing (p¼.763; Table 5).
No signiﬁcant effect between treatments was detected in the behaviors of ears forward (p¼.666), head
left (p¼.670), total ear (p¼.191), total left and right (LR, p¼.193), or yawning (p¼1.000) (Table 5).
A signiﬁcant difference between breeds was detected in closed mouth (p¼.023), head level (p,.001),
licking–chewing (p¼.009), stepping forward (p¼.023), and total ear (p¼.009). Group 2 (Icelandic)
had a longer time of closed mouth compared with Group 1 (standardbred). Breed Groups 2 (Icelandic)
and 4 (other) tended to hold their heads level more often than Breed Group 1 (standardbred). Licking
and chewing were performed more often in Group 4 (other) compared with Group 1 (standardbred).
Breed Group 1 (standardbred) took more forward steps than Group 4 (other). More total ear
movement occurred in Breed Group 1 (standardbred) than in Groups 2 (Icelandic) and 3 (Arab –Arab
cross). Due to low numbers of horses in all breed groups (Table 1), these ﬁndings will not be discussed
further but may be a consideration in future studies.
Table 5. Nonsigniﬁcant difference between treatments of behaviors.
Behavior category Behavior
Control Neck patting Wither scratching FP
Agitated Clamped tail
(s) 0.17 ^0.12 0 ^00^0 0.47 .792
Head above (s) 18.72 ^6.13 20.72 ^6.29 20.39 ^6.11 2.07 .355
(s) 2.44 ^2.44 3.50 ^2.26 2.83 ^2.60 3.48 .176
(c) 0.05 ^0.05 0.27 ^0.27 0 ^0 0.17 .919
(s) 0.61 ^0.44 1.22 ^0.64 0.66 ^0.35 4.74 .092
Total FB (c) 1.05 ^0.45 1.78 ^0.76 1.05 ^0.52 4.72 .094
Total head movements (c) 7.5 ^1.96 6.56 ^1.02 6.05 ^1.25 2.88 .237
(s) 0.22 ^0.15 0.11 ^0.47 0.22 ^0.22 0.56 .754
Relaxed Closed mouth (s) 57.72 ^1.04 58.72 ^0.78 53 ^3.4 6.00 .051
Elongated upper lip
(s) 0^00^0 4.17 ^2.99 0.51 .992
Head level (s) 37.17 ^6.01 38.11 ^6.25 35.83 ^5.99 2.77 .250
Long snorting (c) 0.5 ^0.14 0.33 ^0.11 0.28 ^0.11 1.27 .530
Standing (s) 58.39 ^0.69 56.72 ^1.49 58.28 ^0.89 1.00 .763
Ambiguous Ears forward (s) 17.61 ^4.25 18.67 ^3.91 18.78 ^4.03 0.81 .666
Head left (s) 1.83 ^1.10 1.89 ^0.74 2.22 ^1.12 0.80 .670
Total ear (c) 9.28 ^1.32 11.22 ^1.57 10.22 ^1.51 3.32 .191
(c) 2.94 ^0.74 4 ^0.82 3.17 ^0.64 3.29 .193
(c) 0.06 ^0.06 0.17 ^0.17 0.17 ^0.17 ,0.00 1.000
Note. Total FB ¼total stepping forward and stepping backward. Means and SEMs from nontransformed raw data; behaviors are
either in seconds (s) or counts (c).
No incidents of ears ﬂat back were measured.
Data converted to binomial data.
Behaviors with reduced model ﬁxed-effects “treatment.”
Total LR ¼Total left and right.
254 THORBERGSON, NIELSEN, BEAULIEU, DOYLE
The present study provides evidence to suggest that horses perform more relaxed and less agitated
behaviors when experiencing WS compared with NP or C. This ﬁnding suggests that WS is more
relaxing to horses and thus supports the current hypothesis. Contradictory to the hypothesis, no
differences in HR measures were detected across the treatments. Results from the three behavioral
groups and HR measures are discussed in more detail in the following paragraphs.
Signiﬁcantly fewer agitated behaviors were seen when horses were receiving the WS treatment,
suggesting that this treatment was perceived by the horse as a positive interaction.
Ears back and reeﬁng on the reins were seen more frequently when horses were experiencing either
C or NP treatments. A similar response was produced in the study by von Borstel et al. (2009) with
horses ridden in hyperﬂexion of the neck where the chin is pulled coercively toward the chest (rollkur),
during which horses displayed ears back and head tossing more frequently when compared with horses
ridden in a natural neck position, indicating a negative experience during hyperﬂexion.
Stepping forward occurred more frequently during NP compared with C, suggesting escape or
avoidance behavior (McGreevy & McLean, 2010). Tail swishing was also more common during NP.
This behavior has been used as a reliable indicator of agitated behavior in a variety of negative situations
in numerous studies (König von Borstel & Glisman, 2014; Munsters, Visser, van den Broek, & Sloet van
Oldruitenborgh-Oosterbaan, 2013; Vitale et al., 2013), thus suggesting a negative affective state in the
horses during NP.
Horses exhibited more movement of the head above the withers and head below (total AB) the
withers during the C treatment, suggesting behavior that is more restless. No hand contact was
administered during C treatments; consequently, horses may have experienced more opportunity to
explore the possibility of movement. Additionally, the horse may anticipate or prepare for movement
when under saddle; thus, standing with no stimulus may cause confusion or apprehension regarding
the rider’s next request.
Halting the horse for rest periods during training is also promoted as a way to encourage a horse to
relax (German National Equestrian Federation, 2013). When combined, the frequency of the behaviors
of tail swishing, ears back, reeﬁng on the reins, and head movement above and below the withers (total
AB) suggest that NP and C treatments did not relax the horse as effectively from the stress of riding as
did WS. Within the limitations of this study, WS may be a useful tool to assist riders in helping their
horses to relax while standing. It is acknowledged that the horses were inexperienced with WS
compared with NP. It is not known whether there would be a change to the numbers and frequency of
negative behaviors if WS was commonly used when horses were under saddle. Further study to
elucidate this point would be required.
Two relaxed behaviors were more commonly observed during WS than the other treatments, further
supporting that WS was more relaxing to the horses. Horses held their heads lower than their withers
for longer durations during WS, suggesting a more relaxed state. A study comparing conventional
and sympathetic training methods identiﬁed longer durations of lowered head postures in the
sympathetic training method and signiﬁcantly lower HR (Visser, VanDierendonck, Ellis, Rijksen, &
Van Reenen, 2009).
WS induced a signiﬁcantly longer duration of the neutral ears position than NP, suggesting that WS
may contribute to a more relaxed behavioral response compared with NP. This result is similar to that
in a study by Harewood and McGowan (2005), showing neutral ear position being displayed more
often in horses housed on pasture compared with horses conﬁned to a stall. Sheep exposed to a positive
HORSE RESPONSES TO WITHER SCRATCHING 255
situation of being fed grain displayed more neutral ear positions than when presented with wood pellets
(Reefmann et al., 2009).
Ear position may suggest either left- or right-hemisphere processing of the brain in response to familiar
or unfamiliar stimuli (Basile et al., 2009). As the study by Basile et al. (2009) indicated, horses showed
right-ear preference for response to whinnies from neighbors and more left-ear response to whinnies
from strangers. As Reefmann et al. (2009) also suggested, left-ear lateralization may convey negative
valence in sheep. In the current study, both left and right lateralized ear positions may be useful
indicators of affect. Left-ear lateralization was more common during NP and C than during WS.
Conversely, right-ear lateralization was more common during WS than C. When interpreted in
conjunction with the agitated and relaxed behaviors, these ear positions may indicate that the horses
were experiencing a stronger negative affective state during NP and C than during WS. As these
differences observed align with the positive and negative behavior results, it is suggested that lateralized
ear posture may provide a useful measure of affective state in horses. It would be valuable to further
validate these ear postures in future studies.
In the current study, tongue out was more common when horses were experiencing WS. Tongue-out
behavior has been linked to undue bit pressure and the formation of an oral stereotypy in previous
studies (McGreevy & McLean, 2010). Stereotypic behaviors appear to develop when welfare is
chronically compromised and are unlikely to form during the short-term WS treatment (Mason &
Latham, 2004). More generally, tongue out does not appear to be a reliable indicator of an agitated state,
as few studies have indicated signiﬁcant displays of this behavior during negative situations (Visser
et al., 2009). Rather, this oral behavior may suggest that the horse is trying to mimic a mutual grooming
behavior, as horses have been seen displaying reciprocal allogrooming with conspeciﬁcs and
heterospeciﬁcs (Fraser, 2010; Waring, 2003).
Due to the positioning of the camera on the right side of the video area in the current study, a bias of
head right was anticipated for all treatments; unexpectedly, only WS and C showed a bias of head right.
Although left lateralization in turning the head has been shown in feral horses during vigilance and
reactivity (Austin & Rogers, 2012), head-left bias was not demonstrated in this study. NP was
administered between cervical vertebrae 3 to 6 on the right side of the horse and thus may have acted as
a barrier to the horses turning their heads to the right as anticipated.
Research indicates that licking –chewing may be a sign of release of tension after a stressful
interaction, as horses display licking –chewing more often after being chased for a period of time in a
round pen (Krueger, 2007). Other research, however, has suggested that licking –chewing may not be a
reﬂection of a state of arousal (Warren-Smith et al., 2007). Various Natural Horsemanship trainers
have described licking–chewing as a sign of submission or relaxation (Parelli, 1993; Roberts, 1996).
In contrast, the current study indicates that licking –chewing was more likely to occur during NP than
WS, suggesting that horses were experiencing a stronger negative affective state during NP than during
WS when compared with other agitated and relaxed behaviors. Further research is needed to determine
if these behaviors indicate clear differences in the affective state of the horse.
Of the 32 behaviors collected, 8 agitated, 5 ambiguous, and 5 relaxed behaviors did not differ
signiﬁcantly according to treatment. These behaviors may not clearly indicate the horse’s affective state
or may not be relevant indicators when horses are under saddle compared with those behaviors that
presented signiﬁcant differences between treatments. This ﬁnding may be attributed to the rider’s
inﬂuence on the affective valence of the horse during the three treatments (König von Borstel, Euent,
Graf, König, & Gauly, 2011). Rider inﬂuence on the affective state of the horse may have a greater effect
compared with when a rider handles the horse from the ground. Further analysis of these behaviors in
256 THORBERGSON, NIELSEN, BEAULIEU, DOYLE
future studies would give a clearer indication of their usefulness for detecting affective states in horses
who are under saddle.
Further studies may beneﬁt from assessing the interobserver reliability of the behaviors measured in
this study. This is due to both the subtle nature of some of the behaviors and the commonly observed
limitation of observer bias in applied ethology research (Meagher, 2009; Tuyttens et al., 2014).
Heart rate parameters
Parameters of HR and HRV indexes showed no signiﬁcant differences between NP, WS, and C,
although signiﬁcant differences were detected in certain behaviors. This lack of results is in opposition
to previous studies that investigated grooming around the wither area in horses not under saddle (Feh
& De Mazières, 1993; Normando, Haverbeke, Meers, Ödbreg, & Ibañez Talegón, 2002). Both Feh and
De Mazières (1993) and Normando et al. (2002) used treatment lengths of 3 min of grooming around
the wither area and thus may have allowed time for physiological parameters to change; however,
behaviors were not studied in either experiment to allow for comparison. Regardless, HR for horses
during all three treatments was within a common reported range consistent with light work while under
saddle (Matsuura et al., 2010; Powell, Bennett-Wimbush, Peeples, & Duthie, 2008).
Other studies have also failed to identify signiﬁcant physiological differences yet produced
signiﬁcant behavioral differences (Munsters, de Gooijer, van den Broek, & van Oldruitenborgh-
Oosterbaan, 2013; Munsters et al., 2012; Warren-Smith et al., 2007). A large degree of HRV in
individual horses was exhibited in this study and may have contributed to a lack of signiﬁcant HRV
indexes, with previous work by von Borell et al. (2007) and Munsters et al. (2012) yielding similar
observations. Work by Vitale et al. (2013) suggested that restriction of free movement of horses may
cause a shift in the autonomic nervous system to higher sympathetic nervous system activity, further
contributing to this lack of difference.
Further studies may be warranted to determine the optimum length of time to induce a relaxed
physiological state while under saddle. A standardized protocol for data correction and detrending
methods for nonelectrocardiogram equipment may prove useful in data preparation for statistical
analysis and the ability to compare HRV research results in horses.
Behavioral results in the current study suggest that WS for a 1-min period may help to increase
relaxation when the horse is standing under saddle. Unexpectedly, horses displayed a similar number of
agitated behaviors during both NP and C treatments, suggesting that NP may be ineffective at relaxing
horses. These ﬁndings may have implications for the management and comfort of horses while under
saddle. Further research in this area is suggested, with particular focus on whether these results are
replicated with different durations of treatments and with horses commonly exposed to WS.
Two behaviors—left-ear lateralization and right-ear lateralization—were identiﬁed as being
potentially useful indicators of the affective states of horses. Although these behaviors show promise,
further investigation is needed.
The authors gratefully acknowledge the technical assistance and ﬁlming provided by Tom Mitchell, P.Eng.
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