Evaluating the Reaction to a Complex Rotated Object in the American Quarter Horse (Equus caballus) - MDPI
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animals
Article
Evaluating the Reaction to a Complex Rotated Object in the
American Quarter Horse (Equus caballus)
Megan Elizabeth Corgan, Temple Grandin * and Sarah Matlock
Department of Animal Science, Colorado State University, Fort Collins, CO 80523, USA;
mecorgan@colostate.edu (M.E.C.); sarah.matlock@colostate.edu (S.M.)
* Correspondence: cheryl.miller@colostate.edu
Simple Summary: Horses are prey animals and exhibit behaviors that help them adapt and survive
in their environment. These reactions are often referred to as spooking and they have the potential to
be dangerous to the horse, handler and rider. Spooking consists of avoidance reactions that include
suddenly moving away or running away from the perceived danger. It is dangerous for both riders
and horses when a horse suddenly startles. Sometimes horses do this in familiar environments
because familiar objects may look different when rotated. The purpose of this study was to determine
whether horses that had been habituated to a complex object (children’s playset) would react to the
object as novel when rotated 90 degrees. Twenty young horses were led past the playset 15 times by
a handler. Next, the rotated group was led past the rotated playset 15 times. Each time the horse
was led by the object was counted as a pass. An increasing reactivity scale was used to quantify
behavioral responses. Being aware of potential reactions to changes in the orientation of previously
familiar objects can help keep the handler safer.
Abstract: It is dangerous for both riders and horses when a horse suddenly startles. Sometimes
horses do this in familiar environments because familiar objects may look different when rotated. The
Citation: Corgan, M.E.; Grandin, T.;
purpose of this study was to determine whether horses that had been habituated to a complex object
Matlock, S. Evaluating the Reaction to
(children’s playset) would react to the object as novel when rotated 90 degrees. Twenty young horses
a Complex Rotated Object in the
were led past the playset 15 times by a handler. Next, the rotated group was led past the rotated
American Quarter Horse (Equus
caballus). Animals 2021, 11, 1383.
playset 15 times. Each time the horse was led by the object was a pass. The behavioral responses
https://doi.org/10.3390/ani11051383 observed and analyzed were ears focused on the object, nostril flares, neck raising, snort, avoid by
stopping, avoid by moving feet sideways, and avoid by flight. An increasing reactivity scale was
Academic Editor: Barbara Padalino used to quantify behavioral responses. A two-sample t-test was performed on the reactivity scores
comparing the first pass by the novel object to the first pass by the rotated object. The horses in the
Received: 28 March 2021 rotated group reacted to the rotated orientation similarly to the first exposure (p = 0.001, α < 0.05).
Accepted: 11 May 2021 Being aware of potential reactions to changes in previously familiar environments can help keep the
Published: 13 May 2021 handler safer.
Publisher’s Note: MDPI stays neutral Keywords: horse; safety; training; behavior; novel object; habituation
with regard to jurisdictional claims in
published maps and institutional affil-
iations.
1. Introduction
Spooking was associated with 27% of horse accidents [1]. Researchers have described
“spooking” as “horse reacted in fear of something, unseating the rider” [1]. Another study
Copyright: © 2021 by the authors.
showed that injuries to riders were more likely to occur “when the horse behaved in an
Licensee MDPI, Basel, Switzerland.
unexpected manner” [2]. Some of the more severe injuries occur when a rider falls of a
This article is an open access article
horse. Data collected from hospital emergency rooms indicated that falling off a horse
distributed under the terms and
resulted in more injuries than injuries that occurred when the rider was not mounted [3].
conditions of the Creative Commons
Attribution (CC BY) license (https://
Another study showed that “danger to the rider increases as the horse’s speed increases” [4].
creativecommons.org/licenses/by/
When riders fall of a horse, their head is more likely to be injured compared to other parts
4.0/).
of the body [5]. Riders have reported that sometimes they do not know what caused their
Animals 2021, 11, 1383. https://doi.org/10.3390/ani11051383 https://www.mdpi.com/journal/animals
Animals 2021, 11, 1383 2 of 9
horse to spook. Experienced horse trainers know that it is important to habituate young
horses to new things in their environment. One study showed that gradually desensitizing
horses to stimuli such as a moving white nylon bag had fewer flight responses than horses
where it was suddenly introduced [6]. Several studies have also indicated that a sudden
stimuli such as an umbrella that opens suddenly can startle a horse [7–11]. A sudden novel
stimulus such as a waving flag or a bell will raise a horse’s heart rate [12]. Researchers
have also reported the intensity of a horse’s reaction was influenced by horse genetics [13].
Sudden novel stimuli will startle many different species of animals [14]. The dangerous
and usually unexpected “spook” reaction is likely to be a startle response.
A review of the horse behavior literature showed that there are different ways that
horses are introduced to new objects. They consist of voluntary approach in an open field,
led towards the object, or ridden toward the object [15–17]. Open field tests are usually
conducted in an arena. In these experiments a free moving horse is allowed to voluntarily
approach novel objects [15]. In many of these studies the horse learns to associate a
particular novel object with a food reward [18,19]. These studies are extremely useful for
the study of horse cognition and learning. However they do not provide information on
the conditions that may cause a dangerous “spook” reaction that could seriously injure a
rider. One study showed that horses that were more willing to investigate a novel object
were able to learn more quickly [20]. There may be differences in a horses reaction to a
novel object when the way it is presented is changed. Research has shown that a horses
reaction to a novel object is different during a voluntary approach compared to being led
or ridden [17]. The authors found that when including a rider in temperament tests and
performance tests, results were more reliable and repeatable. When positive reinforcement
such as food is used, horses are able to choose the correct object and be presented with a
reward. This type of learning and test does not often include a handler and is referred to as
discrimination [18].
The purpose of this research was to conduct a study to identify a possible situation
where a large complex novel object may have the potential to cause a serious horse accident.
The object we chose was a child’s colored plastic playset with a small slide and swing. It
is a large object and large objects may be more frightening stimulus compared to smaller
objects [21]. The playset is an object that a horse could possibly see during riding near
residences. It is known that horses can learn to discriminate between different colors and
shapes [18,22]. In our experiment, no attempt was made to control for color or shape, but a
playset was chosen that had approximately the same dimensions when it was rotated.
The purpose of this preliminary study was to determine if a habituated horse may
react differently when the playset was rotated. Both its shape and color would change. A
non-voluntary approach was used. All horses were led at a walk for both habituation and
the test after the playset was rotated. For safety reasons, we conducted all experiments at a
walk and measured behavioral reactions used by Leiner and Fendt [7]. Their study may
provide insights into a situation that might trigger dangerous “spooking”. If the rotated
playset is associated with increased mild behavioral reactions when a horse is being led
towards it, there is the possibility that it might trigger a more dangerous sudden reaction
if a horse and rider was trotting towards it. A high speed study would be too dangerous
and would be unethical. This study may help identify one cause of spooking when a rider
is not able to identify an obvious possible trigger. It will also provide a starting point for
further studies into horse perception.
2. Materials and Methods
The sample population consisted of twenty-two 2 and 3-year-old American Quarter
Horse horses (15 fillies and seven gelded colts) in a university horse training program. The
horses had 4 months of handling training at the time of this study, all trained at the same
place. The horses were taught using methods of pressure and release training to halter,
lead, lunge, and acclimate to being groomed and handled. Of the twenty-two horses, one
posed a safety concern for the research handlers by its continued attempt to pull away and
Animals 2021, 11, x 3 of 10
Animals 2021, 11, x 3 of 10
Animals 2021, 11, 1383 3 of 9
halter, lead, lunge, and acclimate to being groomed and handled. Of the twenty-two
horses, one posed a safety concern for the research handlers by its continued attempt to
halter, lead, lunge, and acclimate to being groomed and handled. Of the twenty-two
pull away and was excluded from the study. Another horse was removed from the study
horses,
was one posed
excluded a safety
from concern
theissues.
study. for thehorse
Another researchwas handlers
removed by
fromits continued
the attempt 4to
on
pull
day
away
4 for
and
soundness
was excluded
Twenty
from the
horses
study.
continued
Another horse
through
was
thestudy
removed
entire
from
on day (n
study
the study
for
= 20).
soundness
All horses issues.
were Twenty
housed at horses
the continued
Colorado Statethrough the
University entire
Equine study (n =
Teaching 20). All
and horses
Research
onwere
day housed
4 for soundness issues. Twenty
at the Colorado State horses continued
University Equine throughand the Research
entire study (n = (CSU
20).
Center
All horses(CSUwere ETRC)
housed in at
outdoor
the pens
Colorado with
State libitumTeaching
adUniversity water
Equine and access to
Teaching and
Center
shelter.
ResearchHorses
ETRC) in outdoor pens with ad libitum water and access to shelter. Horses were fed a mix
were fed
Center a mix
(CSU of grass and alfalfa hay once per day on a feed bunk.
of grass andETRC)
alfalfainhayoutdoor
once perpensdaywith
on aad libitum
feed bunk.water and access to shelter. Horses
were fedThe test
a mix environment was an alley (4.57 meters wide)
feedinbunk.
an indoor horse barn in front
The test of grass and alfalfa
environment was an hayalley
once(4.57
per day on awide)
meters in an indoor horse barn in
offront
empty
The stalls
oftest
empty
with
environment the doors
stalls withwasthean
closed. The
alleyclosed.
doors
barn
(4.57 meters had
wide)
The barn
concrete
in an
had
flooring
indoor
concrete horse and
flooring barn electric lights
andinelectric
front
above
of empty
lights the
abovealleyway.
stalls with
the Thedoors
the
alleyway. horses were The
Theclosed.
horses led
were in
barnthrough
led had
in the entrance,
concrete
through theflooring walked
entrance, and down
electric
walked the the
lights
down alley-
way,
above past
the the novel
alleyway. object
The and
horses led
were out
led inof the
through testthearea through
entrance, the
walked
alleyway, past the novel object and led out of the test area through the exit (Figure 1). Two exit
down (Figure
the 1).
alley- Two
Hero
way,
Hero 55video
pastvideo cameras
the novel
cameras (GoPro,
object and led
(GoPro, Sanout
San Mateo,
of the
Mateo, CA,
CA, testUSA) were
areawere
USA) through placed
placed in
thethe
theinexit test
(Figure
test environment
1). Two
environment
Hero
for 5 video
forlater
later cameras of
observation
observation (GoPro, San Mateo,
of behavioral
behavioral CA, USA) were placed in the test environment
responses.
responses.
for later observation of behavioral responses.
Figure
Figure
Figure 1.1.1.
TheThe
The test
test
test areaconsisted
area consisted
consisted ofofGoPros
of GoPros
GoPros ( (( ) and) the novel
andthe
) and the object
novel
novel placed
object
object during
placed
placed habituation
during
during to the
habituation
habituation novel
theobject
to novel
to the novel and
object
object
and
and rotation
rotation
rotation days.
days.
days.
Thenovel
The
The novelobject
novel objectwas
object wasa aachildren’s
was children’s
children’s plastic
plastic
plasticplayset
playset
playset (Little
(Little Tikes
Tikes
(Little Hide
Hide
Tikes and
and
Hide Seek
Seek
and Climber
Climber
Seek Climber
and
and Swing-Brown
Swing-Brown and
and Tan)
Tan) (Table
(Table 1).
1). The
The object
object was
was 134.62
134.62 l l
×
and Swing-Brown and Tan) (Table 1). The object was 134.62 l × 132.08 w × 104.14 × 132.08
132.08 ww× × 104.14
104.14 hh cm.
cm.h cm.
This
This object was used because, in both orientations, its outer dimensions are similar. The
This object
objectwas
wasused
usedbecause,
because,ininbothboth orientations,
orientations,its its
outer dimensions
outer dimensionsare similar. The The
are similar.
playset hada adifferent
playset different shapewhen whenrotated
rotatedninety
ninetydegrees.
degrees.RopeRopehalters
halterswith
with2 2mmlead
lead
playset had
had a differentshape
shape when rotated ninety degrees. Rope halters with 2 m lead
ropes
ropes were used to lead the young horses past the playset.
ropeswere
wereused
usedtotolead
leadthe
theyoung
young horses
horses past thethe
past playset.
playset.
On day 1–3 of the study (habituation to the test area) (Table 1), the horses were led
through the test area five passes each day without the novel object to habituate the horses
to the test area. Each time a horse was led past the object was counted as a pass. The
horses were given 15 total passes through the test area based on Christensen et al. [15]. The
authors found that horses needed 4–13 exposures before meeting habituation criterion.
On day 4, the novel object was placed in the test area in the original position. Days
4–6 of the study (habituation to the novel object) consisted of the same procedure for the
first three days with the novel object in its original position (Table 1). Each horse passed
the original position of the object fifteen times over three days.
To assess the effect of object rotation on the horses’ behavior, the horses were random-
ized into a control group and a rotated group. On days 7–9 (test days), the control group
had five passes each day through the test area, with the novel object in the original position
(Table 1). The control group passed the original position of the object fifteen times over the
three days. The rotated group was led through the test environment for five passes each
day with the novel object rotated 90 degrees clockwise (Table 1). The rotated group passed
the rotated position of the object fifteen times over the three days.Table 1. TestingTable
Procedure:
1. Testing
Outline
Procedure:
of testing
Outline
procedure
of testing
to provide
procedure
details
to provide
of the Control
detailsand
of the
Ro-Control and Ro-
nimals 2021, 11, x tated group procedures.
tated group procedures. 4 of 10
Control and Rotated Controlgroups
and Rotated groups
Animals 2021, 11, 1383 Habituation to test
Habituation
area to test area 5 passes each day 5 passes each day 4 of 9
DaysTable
1–3 1. Testing
Days 1–3
Procedure: Outline of testing procedure to provide details of the Control and Ro-
(novel object absent)
(novel object absent) 15 total passes 15 total passes
tated group procedures.
test area (Figuretest1) without
area (Figure
novel1)object
without novel object
ControlControl
and Rotated
Controlgroups
and Rotated
and Rotated groups groups
Table 1. Testing Procedure: Outline ofHabituation
testing procedure to provide details
to test area of 5the
5 passes eachControl
day
passes 5each and
dayRotated
passes each daygroup procedures.
Days 1–3
(novel object absent) 15 total 15passes
total 15 total passes
passes
Control and Rotated groups
test area (Figure
test test
1) with
area area novel
(Figure
(Figure 1) object
1) with
withoutin novel
original
novelobject
object in original
Habituation to test area 5 passes eachposition
day
Days 1–3 position
Control and Rotated groups
(novel object absent) 15 total passes
5 passes each day
test area (Figure 1) without novel object
Habituation to the
Habituation
novel to the novel Control15and total passes
Rotated groupsin original
Days 4–6 Days 4–6 test area (Figure 1) with novel object
object object
position
5 passes each day
15 total passes
test area (Figure 1) with novel object in original position
Habituation to the novel
Days 4–6
Days 4–6 Habituation to the novel object object
Days 7–9 Days 7–9Test days Test daysControl group Control group Rotated group Rotated group
5 passes each day 5 passes each day each day
5 passes 5 passes each day
test area (Figuretest
1) with
area (Figure
test area1)(Figure
with test
1) with
area (Figure 1) with
Days 7–9 Test days Control
object group
in originalobject
posi-in original
object inposi-
rotatedobjectRotated
posi- group
in rotated posi-
Days 7–9 Test days 5 passes each
tion day
Control group tion tion 5 passes
Rotated group each
tion day
test area (Figure5 1) with each
passes objectday
in 5test area each
passes (Figure
day1) with object in
original position rotated
test area (Figure 1) with test area (Figure 1) with position
object in original posi- object in rotated posi-
tion tion
Two handlers were used and both led the horses at a slow walk. Each handler had
On day 1–3 an ofOn the day
equal study1–3(habituation
number of the studyto(habituation
of horses the test area)
randomly to (Table
assignedthe test 1),area)
from the
both horses
(Table 1),
were
the control theled
horses
and were group.
rotated led
through the test through
area
Eachfive thepasses
horse test
was areaeach
ledfive
atday
apasses
without
walk eachthe
through day novel
thewithout
testobject
areathetobynovel
habituateobjectthe
the same to horses
habituate
handler for thethe horses
entire study.
to the test area.toEach
the test
time area.
a horse
Each was
time leda horse
past thewas object
led past
was the
counted
object
The handlers wore the same clothes every day (black overalls, jacket, hat and black boots). aswas
a pass.
countedThe horses
as a pass. The horses
were given 15were total
The given
passes
handlers15through
total
were passes
the test
instructedthrough
area tobased
the test
walk onarea
the Christensen
horse based
with on a etChristensen
leadal. rope
[15]. through
Theetau-al. the
[15]. The au-
center of the
thors foundOn thatday
thors
horses1–3
found of the
needed
that study
horses
4–13 (habituation
exposures
needed 4–13 to
before the
exposures test
meeting area)
before (Table
habituation
alley (1 m away from the object), and move with the horse, only stopping or turning when meeting 1), the horses
criterion.
habituation were led
criterion.
Onthrough
day 4, thethethe test
On
novel area
day
horse 4,five
object
stopped passes
thewas novel each
orplaced
object
turned day
in thewithout
was
towards test
placed area
the the
in novel
inthe
object.thetest object
Iforiginal
thearea to habituate
inposition.
horse the original
stopped, the
Days
the horses
position.
handlerDays waited
to the
4–6 of the study test area.
4–6(habituation
3ofsecondsEach
the study time a horse
to(habituation
before thegently was
novelencouragingled
object) past
to theconsisted the
novelthe object
object)
of the
horse was counted
consisted
same procedure
forward as
of the
by a pass.
same
walking The
forforward horses
procedure
the andforslightly
the
were
first three daysgiven
first
with 15the
three
pulling totalonpasses
days
novelthe with
leadthrough
object therope. its the
innovel To test area
original
object
facilitate in
position
itsbased
original on Christensen
(Table
habituation, position
1).
if aEach (Table
horse et
horse al.
1).[15].
passed
stopped Each The
when au-
horse passed
it was either
thorsposition
the original found that
theapproaching
original horses
of the position
objectorneeded
fifteen
of the
passing 4–13
times exposures
object
the over
novel fifteenthree
object, before
times days.
it was meeting
over threehabituation
allowed to stop for criterion.
days. a period of 3 seconds. If
To assessOn the
daytheTo4,horse
effect theofnovel
assess object
did thenotobject
stop,was
effect
rotationofthe placed
object
on the
handler incontinued
rotation the on
horses' test area
behavior,
the inthe
tohorses'
lead the original
it behavior,
horses
past thewereposition.
theran-
novel horses
object.Days
were ran-
domized 4–6into
of the study
domized
a control (habituation
into
group a control
and ato the
rotated
group novel
and
group. object)
a rotated
On consisted
days group.
7–9
The horses’ behavioral responses to the object exposure was analyzed based of
(test
On thedayssame
days), 7–9 procedure
the(test
control
days),for the
the control
on the
first three
group had fivegroup days
passes
video had with
eachfive the
day
recordings. novel
passes
through
One object
each the in
daytest
observer its
through original
area,
recorded with
the eightposition
test
the area,
novel (Table
with
different object 1). Each
theinnovel horse
the original
behavioral object
signs inpassed
the original
during each pass
positionthe original
(Table position
1).on position
The eachcontrol
(Table
day. of1).
the
group
The Theobject
control
passed
behavioralfifteen
the
group times
original over
passed
responses three
position
the
recorded days.
original
ofwere
theposition
object fifteen
of thetimes
ears focused object
on thefifteen
object,times
nostril
over the three Toover
assess
days.
flares, the
theThe neckeffect
threerotated of group
days.
raising, object
The
snorting,rotation
rotated
was avoid on
ledgroup the
through
stop, was horses'
the
avoid ledtestbehavior,
through
side, environment
avoid thethetest
back, horses
for were flight
environment
and five
avoid ran-for(Table
five 2).
passes domized
each day into
passes
with athe
Behavioral
eachcontrol
novel
day group
responses
with
object theand
were
rotated
novel a adapted
rotated
object
90 degrees group.
fromclockwise
rotated On
[7]. days(Table
90 degrees 7–9 (test
clockwise days),
1). The the 1).
(Table
rotated control
The rotated
group had
group passed group five
the rotated Apasses
passedreaction each
position
the day
scale
rotated
of thethrough
was created
position
object the
fifteentesttimes
offrom
the area,
the
object with
behaviors
over
fifteenthetimes
the novelover
observed
three object
days. theain
on the from
scale
three original
days.0–3 (Table 3).
position
Two handlers(Table
ThisTwo
were 1).handlers
The control
reaction
used scale
andwere group
was
both led passed
adapted
used the from
andhorses theChristensen
both original
led
at athe slow position
horses et al.
walk. of
[15]
at Each the
a slow object
walk.fifteen
tohandler
evaluate times
reactivity
Each
had handler based
had on
over
an equal number the three
an behaviors
equal days.
of horsesnumber The
observed
randomly rotated
of horses group
inassigned
this study.
randomly was
from The led
assigned
both through
reactivity
thefromcontrolthe
scores
both test
and environment
increase
therotated with
control for
a bigger
group.
and five
rotated response
group. to
passes
Each horse was each
Each
ledtheday
at
horse with
object,
a walkwas the
lednovel
score
through 3 showing
at a theobject
walk test rotated
the
through
area biggest
bythe 90test
the degrees
response.
same area clockwise
handler
by the forsame the(Table
entire1).study.
handler The
for therotated
entire study.
group passed the rotated position of the object fifteen times over the three days.
Two handlers were used and both led the horses at a slow walk. Each handler had
an equal number of horses randomly assigned from both the control and rotated group.
Each horse was led at a walk through the test area by the same handler for the entire study.Animals 2021, 11, 1383 5 of 9
Table 2. Behavioral responses and definitions used for behavioral analysis.
Definitions of Behavioral Responses
Behavioral Responses Definition
ears focused on the object ears are pointed toward the novel object
nostril flares nostrils overly expanded (nose elongation)
neck raising neck raised above normal headset and/or neck muscles tense
snorting “short powerful exhale” [23]
avoid stop avoiding the object by stopping, feet stop moving
avoid side avoiding the object by evasive steps to the side, away from the object
avoid back avoiding the object by evasive steps backwards, backing up
avoid flight avoiding the object by jumping away in a sudden movement, feet moving faster a walk
Table 3. Reaction Scale used to quantify behavioral responses (adapted from Christensen et al. [15]).
Score 0–3 Behavioral Responses Observed
0 No behavioral signs observed
1 Ears focused, nostril flares, and/or neck raising
2 Snorting and/or avoid stop
3 Avoid side, avoid back, avoid flight
To assess whether the horses’ behavior was affected by the object rotation we compared
difference in the reaction score per individual horse using a two-sample t-test (α < 0.05) (R
with R Studio, PBC, Boston, MA, USA). Christensen et al. and Tidyverse (www.tidyverse.
org, accessed on 28 March 2021) was used for the figures [15,24,25]. This test was done
for each pass 1–15 comparing the corresponding passes from the original position to the
rotated position.
Animals 2021, 11, x 3. Results 6o
The control and rotated group showed significant differences between the change in
reaction score from the first pass by the novel object to the first pass on the Test days (t-test
p-value = 0.001) (Figure
reacted 2). Horses
similarly on the that
first reacted
pass by to
thethe novel position
rotated object inof
the
theRotated group,
object as they did on
reacted similarly on the first pass by the
initial pass by the novel object. rotated position of the object as they did on the
initial pass by the novel object.
Figure 2. Boxplot of differences in Reaction Score for pass 1 by the novel object to pass 1 by the
Figure 2. Boxplot of differences in Reaction Score for pass 1 by the novel object to pass 1 by the rotated object. The Control
rotated object. The Control group mean (bold line) showed a decrease in reaction. The Rotated group
group mean (bold line) showed a decrease in reaction. The Rotated group mean showed no change in reaction. There was
mean showed no change in reaction. There was a significant difference between the means of the
a significant difference between the means of the two groups.
two groups.
Passes 1–4 after rotation in the rotated group showed a significant difference betwe
the two groups change in reaction (p-values = 0.001, 0.010, 0.004, 0.001). After pass 4
the rotated object, there was little significant difference between the rotated and cont
groups (p-values > 0.05). As noted in Table 4, some later passes also showed signific
differences in the change in reaction between the two groups (Passes 1–4, 8, 9, 12: p-vaAnimals 2021, 11, 1383 6 of 9
Passes 1–4 after rotation in the rotated group showed a significant difference between
the two groups change in reaction (p-values = 0.001, 0.010, 0.004, 0.001). After pass 4 by the
rotated object, there was little significant difference between the rotated and control groups
(p-values > 0.05). As noted in Table 4, some later passes also showed significant differences
in the change in reaction between the two groups (Passes 1–4, 8, 9, 12: p-value > 0.05).
Figures 2 and 3 show the significance in the change in reactions for the rotated group when
the horses were exposed to the rotated object.
Table 4. Values for differences in reaction score for corresponding passes 1–15 by the novel object to
rotated object.
Control Rotated
Pass # Mean Min. Max. Mean Min. Max. p-Value
1 −1.75 −3 0 0.083 −2 2 0.001
2 −0.875 −2 0 0.25 −1 2 0.010
3 −0.875 −2 0 0.167 −1 1 0.004
4 −1 −2 0 0.333 −1 1 0.001
5 −0.375 −2 1 -0.083 −2 0 0.312
6 −0.375 −1 0 -0.25 −1 1 0.719
7 −0.5 −2 0 0.167 −1 1 0.062
8 −1 −2 0 0.333 −1 2 0.005
9 −0.875 −2 0 0.583 −2 2 0.002
10 −0.125 −1 1 0.167 −1 2 0.537
11 0 0 0 0.167 −2 2 0.656
12 0.125 −1 1 -0.333 −1 0 0.010
13 −0.125 −1 1 0.333 −2 1 0.226
Animals 2021, 11, x 7o
14 −0.25 −1 2 0.083 −2 2 0.554
15 0 −1 1 -0.167 −2 2 0.700
Figure 3. Graph of reaction scores from pass 1–30 for the control and rotated groups. The colored
Figure 3. Graph of reaction scores from pass 1–30 for the control and rotated groups. The colored triangles indicate indi-
triangles indicate individual horses’ reactivity scores. The colored lines depict mean reaction score by
vidual horses’ reactivity scores. The colored lines depict mean reaction score by group over passes (control = red, rotated
= blue). group over passes (control = red, rotated = blue).
4. Discussion
4. Discussion
When a previously familiar complex novel object is rotated, the rotated object may
When ato
cause reactions similar previously
the initialfamiliar
exposurecomplex
to the novel
novel object
object.is This
rotated, the rotated
confirms what object m
handlers and riders have described anecdotally. Understanding horses’ reaction to a what h
cause reactions similar to the initial exposure to the novel object. This confirms
dlers and riders have described anecdotally. Understanding horses’ reaction to a rota
object is important for the safety of riders and handlers. If handlers expect horses no
react to subtle changes in a familiar environment, they are less prepared for a horse spo
ing which could lead to an accident. Additionally, studies have shown that investigat
behavior is correlated with learning [20]. Allowing a horse to investigate and becomeAnimals 2021, 11, 1383 7 of 9
rotated object is important for the safety of riders and handlers. If handlers expect horses
not to react to subtle changes in a familiar environment, they are less prepared for a
horse spooking which could lead to an accident. Additionally, studies have shown that
investigative behavior is correlated with learning [20]. Allowing a horse to investigate
and become familiar with all orientations of an object can help to avoid spooking. Future
studies are needed to evaluate if allowing a horse to fully investigate a novel object will
help with habituation and decrease spooking.
As shown in Figure 3, there was a decline in the horses’ reactions with each successive
pass by the rotated object. Table 4 shows the significant decrease in the horses’ reaction
to the object with each successive pass, for the first four passes. After pass 4, the changes
in reactions between the rotated and non-rotated groups seem to be less consistent. This
inconsistency in changes in reactions between the two groups shows the unpredictable
nature of the horse [26]. Even subtle changes to a familiar object can cause horses to react
again. These subtle changes can cause the horse to need more exposure until they are
habituated or until no reactions are shown again. Handlers need to be aware of this for
safety of themselves and the horses.
This study shows that despite findings from previous research [19], horses may
not recognize different orientations of previously familiar objects, when being led by a
handler. While assumptions cannot be made about the horse’s recognition of the rotated
object from the present study, there is an obvious reaction to the rotated object. This
reaction is important to note and important for anyone handling horses to be aware of.
There are possible differences in personality and reactivity by breed [27]. The traits that
showed the most variability between breeds were excitability and anxiousness [27]. This is
thought to be because of the purpose each breed has been bred for over time. For example,
Thoroughbreds tend to show a bigger flight response because they are bred to race and
are expected to leave the gate quickly [28]. Age has also been shown to have an effect
on reactivity. In a study comparing horses ranging in age from two months to two years,
younger horses were more reactive [29].
Training methodologies are worth further exploration when researching equine percep-
tion of novel objects. Humans can have an impact on how the horse reacts and behaves [16].
There may be a difference between a voluntary approach, as compared to being led by
a handler. Marsboll and Christensen [30] and Hartmann et al. [31] found that a familiar
handler can have a calming effect on the horses response to a novel object as well as a
change in fear response. The present study used unknown handlers to evaluate how
horses will react to a rotated object with a handler. Christensen et al. [20] showed that
fearfulness was not correlated with learning, whereas investigative behavior was correlated
with learning. While their study did not use handlers, the present study allowed some
investigative behavior and kept the handler involved, creating a more practical scenario.
The present study did not use food or positive reinforcement when evaluating recognition
or reactivity, as compared to [19]. Using food as a reinforcement in training is similar to
using latency to eat in research. It is important to note, that most trainers do not use food
as reinforcement in their training.
The purpose of this study was to evaluate how horses being led and habituated to a
previously familiar complex object would react after it was rotated ninety degrees. This
study showed that horses’ reaction to a rotated orientation of a familiar complex object was
similar to its reaction when it first saw it.
5. Conclusions
Horses may have a greater reaction to new orientations of previously familiar objects.
This may cause accidents that lead to injury of the horse or handler. If handlers and
riders can be prepared for how a horse may react, they may be able to help reduce risk by
adjusting training methods to allow for investigation of all sides of an object. Additionally,
while horses show a decrease in reactions to novel objects and novel orientations of familiar
objects, there is the possibility for reactions during habituation. Further research needs toAnimals 2021, 11, 1383 8 of 9
be conducted to evaluate how different methods of handling and training affect the horses’
reaction to changes in their environment.
Author Contributions: Conceptualization, M.E.C., T.G., and S.M.; methodology, M.E.C. and T.G.;
formal analysis, M.E.C.; investigation, M.E.C. and S.M.; resources, M.E.C. and T.G.; data curation,
M.E.C.; writing—original draft preparation, M.E.C.; writing—review and editing, M.E.C., T.G., and
S.M.; visualization, M.E.C., T.G., and S.M.; project administration, M.E.C.; funding acquisition, T.G.
All authors have read and agreed to the published version of the manuscript.
Funding: This research was funded by Grandin Livestock Handling Systems, Inc., Fort Collins,
CO 80523, USA.
Institutional Review Board Statement: This study received ethical approved by the Colorado State
University Animal Care and Use Committee [IACUC #: 1349].
Informed Consent Statement: No applicable because no human subjects were involved.
Data Availability Statement: The data presented in this study are openly available in FigShare at
[10.6084/m9.figshare.14256512.v1].
Acknowledgments: The authors would like to thank John Snyder and the Legends of Ranching
Program for use of the horses in the study and the Equine Teaching and Research Center for use of
the facility. The authors would also like to thank Ben Sharp for assistance in statistical analysis.
Conflicts of Interest: The authors declare no conflict of interest.
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