Journal of Veterinary Behavior (2010) 5, 180-186
RESEARCH
Over-flexing the horse’s neck: A modern equestrian
obsession?
Paul D. McGreevya, Alison Harmanb, Andrew McLeanc, Lesley Hawsona
a
Faculty of Veterinary Science, University of Sydney, New South Wales, Australia;
Mount Hawthorn ESC, Mount Hawthorn, Western Australia, Australia; and
c
Australian Equine Behaviour Centre, Broadford, Victoria, Australia.
b
KEYWORDS:
horse;
equitation science;
dressage;
hyperflexion;
vision;
rollkur;
respiratory stress;
equitation practices and
regulations
Abstract We used an opportunistic review of photographs of different adult and juvenile horses
walking, trotting, and cantering (n 5 828) to compare the angle of the nasal plane relative to vertical
in feral and domestic horses at liberty (n 5 450) with ridden horses advertised in a popular Australian
horse magazine (n 5 378). We assumed that horses in advertisements were shown at, what was
perceived by the vendors to be, their best. Of the ridden horses, 68% had their nasal plane
behind the vertical. The mean angle of the unridden horses at walk, trot, and canter (30.7 6 11.5;
27.3 6 12.0; 25.5 6 11.0) was significantly greater than those of the ridden horses (1.4 6 14.1;
25.1 6 211.1; 3.1 6 15.4, P , 0.001). Surprisingly, unridden domestic horses showed greater angles
than feral horses or domestic horses at liberty. We compared adult and juvenile horses in all 3 gaits and
found no significant difference. Taken together, these findings demonstrate that the longitudinal neck
flexion of the degree desirable by popular opinion in ridden horses is not a common feature of unridden
horses moving naturally. Moreover, they suggest that advertised horses in our series are generally
being ridden at odds with their natural carriage and contrary to the international rules of dressage
(as published by the International Equestrian Federation). These findings are discussed against
the backdrop of the established doctrine, which states that carrying a rider necessitates changes in
longitudinal flexion, and in the context of the current debate around hyperflexion.
Ó 2010 Elsevier Inc. All rights reserved.
Introduction
The rules of dressage issued by the sport’s peak body,
the Fédération Equestre Internationale (FEI), state on 9
occasions that the nasal plane should at all times be in front
of the vertical (FEI, 2009). So it is fair to assume that this
posture is desirable if horses are being prepared in a way
Address for reprint requests and correspondence: Paul D. McGreevy,
Faculty of Veterinary Science (B19), University of Sydney, NSW 2006,
Australia; Phone: 161-2-9352810; Fax: 161-2-93513957.
E-mail: paul.mcgreevy@sydney.edu.au
1558-7878/$ -see front matter Ó 2010 Elsevier Inc. All rights reserved.
doi:10.1016/j.jveb.2010.03.004
that aligns with the FEI rules. Paradoxically, to most
dressage riders these days, ‘‘on the bit’’ means that the
horse travels with its neck arched and nose tucked in, on
or behind the vertical. This degree of neck flexion is not
advocated by leading equestrian manuals, such as the
Official Instruction Handbook of the German National
Equestrian Federation and the British Horse Society’s
Manual of Equitation. However, theoretically, a vertical
nose does not necessarily mean that the horse is ‘‘on the
bit,’’ especially if it is being held in that position by
the rider’s hands (McGreevy et al., 2005). By definition,
the horse that carries itself ‘‘on the bit’’ is adjusting to
McGreevy et al
Over-flexing the horse’s neck
the additional weight of the rider by caudally shifting its
nose, shortening and arching its neck to some extent, bringing its hocks underneath it, and thereby shifting its centre of
gravity caudally (FEI, 2007) with minimal contact or pressure from the reins. This postural change seems to have
been predicated on the assumption that the rider cannot
align his weight over the horse’s centre of gravity.
It is worth considering how the concept of being ‘‘on the
bit’’ may have been corrupted by common equestrian
parlance. It is a poor translation from the French mise en
main which literally means, put in the hand, and refers to
the relaxation of the jaw and of the poll (Decarpentry,
1949) so that the horse ‘‘releases the mouth softly and
loyally accompanies the hand wherever it moves’’
(Karl, 2008). The mise en main does not imply that the bit
is necessary, or that the nasal plane should be vertical, or
that behind the vertical is desirable. The neck and head
position of the horse, in what is considered to be correct
schooling, where dorsoventral flexion of the proximal cervical vertebrae and atlanto-occipital joint (flexing at the poll,
poll flexion, or roundness) results in the nasal plane being
approximately 6 in front of the vertical or 12 at walk
(McGreevy et al., 2005). In addition, the poll should always
be the highest point of the neck, and the horse should be
trained for this self-maintained posture by achieving what
is known as self-carriage (FEI, 2009). This self-maintained
posture is intended to optimize the balance of the ridden
horse and its readiness to respond to the signals transmitted
by the rider. Alterations to this carriage correlate with the
horse’s level of training. As the dressage horse’s capacity
to collect develops, his poll raises further and the neck
arches more, which brings his nose somewhat closer to his
chest than in those of less trained horses. This results in
changes in the topline physique of the horse over a period.
These alterations are achieved through the anabolic effects
of changes in velocity (McLean and McLean, 2009). It is
likely that such changes facilitate the constant accelerations,
decelerations, and changes of line that characterize the horse
in the sport of dressage as opposed to the horse at liberty.
Hyperflexion (extreme overbending of the neck; i.e.,
flexion of the neck toward the chest of the horse, thus
narrowing the angle toward the vertical from the normal
extended position) is seen in many dressage horses, especially
during warm-up, and may be extreme as in the rollkur debate,
where the nose sometimes remains adjacent to the horse’s
pectoral region for some time (FEI, 2010). Head position can
be readily moderated by bit pressure but doing so mixes 2
responses (deceleration and neck-flexing) with 1 signal (bit
pressure) and as such is a violation of the principles of learning
theory (McGreevy and McLean, 2007). In addition, neck flexion is controversial because it can most easily be achieved by
relentless pressure on the mouth and when excessive seems to
have the potential to compromise pulmonary ventilation
(Petsche et al., 1995) and vision (Harman et al., 1999).
Increased airway resistance during exercise could be expected
to reduce alveolar ventilation. However, the effect on
181
oxygenation of the arterial blood, heart rates, and blood lactate
concentrations during exercise has not been described. The
effect on vision is subject to current debate since
Bartos et al., (2008) drew attention to the ability of the horse
to rotate its eyeball to maintain the pupil in a horizontal
position. These authors claimed that the horse maintains the
‘‘horizontal eyeball position regardless of head position,’’ suggesting that this rotation overcomes any deficit in vision that
might otherwise arise from the horse having its nose pointed
caudally by the rider. We wished to consider this broad claim
in the context of extreme neck flexion and extensions.
We used an opportunistic review of photographs to audit
the nasal angle in feral and domestic horses at liberty and
compare them with those of Australian horses advertised in
the Australian print media.
Materials and methods
We examined the first author’s 5-year archive of photographs
of domestic and feral horses (in the Guy Fawkes National
Park, NSW, Australia, and Tanna Island, Vanuatu) at liberty,
along with all photographs appearing in the November 2009
edition of Horse Deals magazine (Agricultural Publishers
Pty Ltd, Mount Gambier, South Australia). From a total
pool of 7,469 photographs (2,532 of domestic horses at
liberty, 177 of feral horses, and 4,760 of advertised horses),
828 (291 domestic, 55 feral, 378 advertised ridden, and 104
advertised unridden) were selected for further scrutiny, if the
horses were within the following criteria:
a. were moving at the walk, trot, canter, or gallop (the gait
in each case was determined from the arrangement of
the legs and the number of feet touching the ground),
b. had their longitudinal axis of the head and neck perpendicular to the camera,
c. had all 4 hooves apparent.
These criteria were used to do the following:
a. avoid measuring horses that were flexing their necks for
a reason that could be expected to compromise forward
vision (e.g., during bucking),
b. permit an accurate assessment of the vertical inclination
of the nasal plane,
c. permit an accurate assessment of the horizontal inclination of the weight-bearing surface.
For each horse satisfying these criteria, the gait was noted
and the following measurements were taken (see Figure 1):
angle from the vertical of the nasal plane (vertical references were taken opportunistically from fence posts and
tree trunks),
angle from the horizontal of the ground surface.
Nasal angle is the angle formed between the dorsal flat
part of the nose (i.e., in imaginary line formed by the
frontal and nasal bones of the skull) and the vertical.
182
Journal of Veterinary Behavior, Vol 5, No 4, July/August 2010
Figure 1 Lines used to determine angles of the nasal plane and
the weight-bearing surface in a typical photograph from the
domestic cohort.
Analysis
We used a Linear Mixed Model within a residual
maximum likelihood (REML) analysis, which took account
of unequal replication. We used the Wald statistic for testing
interactions and main effects. For the current analysis, this
was based on an F distribution. The analysis proceeded in 3
steps. First, we tested for the 3-way interaction. If this was
not significant, we then tested for the 3 two-way interactions
when each variable was entered last in the analysis. Finally,
we tested for a main effect, only if that main effect did not
appear in a significant 2-way interaction at step 2.
Results
The distribution of nasal angles appears in Table 1. In 68% of
the ridden horses, nasal planes were behind the vertical (40%
at the walk, 71% at the trot, and 58% at the canter).
We tested for the effect of age (juvenile, adult), horse
type (advertised – ridden; advertised – unridden; domestic
– at liberty; feral – at liberty), and gait (canter, trot, walk) in
a single analysis (see Figure 2), Clearly, there were no
juvenile advertised ridden horses but a REML showed no
Table 1
significant interaction between gait and age on nasal angle.
However, it did reveal a strongly significant 2-factor interaction between gait and the 4 types of horse (F statistic 5
4.58, d.d.f. 5 815, P , 0.001) reflecting differences in the
REML predicted means, as shown in Table 2.
In step 1 (of the steps in our analysis described above),
3-way interaction was not significant (F statistic 5 0.76,
d.d.f. 5 807, P 5 0.051). In step 2, the pattern of the angles
among horse types changed significantly (F statistic 5
3.19, d.d.f. 5 811, P 5 0.004) across gaits. There were
no significant interactions that included age. In step 3, the
interaction between gait and type was strongly significant
(F statistic 5 4.58, d.d. f. 5 815, P ,0.001) but, again,
age had no influence.
The difference in angle of the nasal plane of ridden versus
unridden horses was highly significant in all cases for each
gait (canter 5 30.87, P , 0.001; trot 5 36.63, P , 0.001; and
walk 5 18.04, P 5 0.001). The angles for advertised
unridden horses were all significantly larger than those for
domestic and feral horses for all gaits (domestic canter difference from advertised unridden horses 5 27.90, P , 0.001;
trot 5 33.31, P , 0.001; walk 5 17.75, P 5 0.001; and
feral canter difference from advertised unridden 5 22.00,
P , 0.001; trot 5 31.73, P , 0.001; walk 5 12.46,
P 5 0.003). Among feral and domestic horses, the angle
associated with walking gait was significantly smaller than
in other gaits (P , 0.001).
Discussion
Our results show a significant trend in unridden horses to
moderate their nasal angle according to speed or gait, with
the nose tipping up as the horse accelerates. This is also
repeatedly prescribed by the FEI to occur in the ridden
horse with increasing speed through increasing stride length
(FEI, 2009). However, this trend is violated in our series of
photographs of ridden horses, which shows radical departure from what is normal in unridden horses and what is
considered correct in dressage. The significant increase in
the nasal angle in unridden advertised horses when compared with domestic and feral horses at liberty is of interest
because it most likely reflects the tendency for unridden
horses to be chased during presentation for sale. This seems
The distribution of ridden and unridden horses studied for nasal angle at 3 gaits
Canter
Trot
Walk
Groups
n
Average
S.D.
n
Average
S.D.
n
Average
S.D.
Advertised - ridden (n 5 378)
Advertised - unridden (n 5 104)
Domestic - at liberty (n 5 291)
Feral - at liberty (n 5 55)
All unridden (n 5 450)
45
16
136
9
161
1.4
32.1
28.8
25.4
30.7
14.1
8.8
12.9
5.9
11.5
318
82
89
29
200
25.1
30.8
26.1
23.5
27.3
211.1
9.8
15.3
10.5
12.0
15
6
66
17
89
3.1
31.3
25.0
19.9
25.5
15.4
10.6
10.6
12.0
11.0
McGreevy et al
Over-flexing the horse’s neck
Figure 2
183
Angle of nasal planes in photographed horses (n 5 828).
to be derived from an attempt to showcase the horse’s
paces. This is unfortunate because chasing is contraindicated in any training system designed to make horses safe
around humans (McGreevy et al., 2009).
The current findings demonstrate that the marked neck
flexion of the degree desirable in the popular equestrian
domain is not advocated by the FEI (2009), nor is it a
common feature of unridden horses moving naturally.
Arguably, this latter finding could be because of age in
that more ridden horses in advertisements are adults.
However, a comparison of all unridden horses clustered
according to age showed no significant difference resulting
from age. Although in feral and domestic horses, nasal plane
angle positively correlates with gait (and/or speed), no such
correlation is seen in the ridden horses. In fact, the nasal
plane angles are significantly less at trot than at walk.
Biomechanical studies show that horses stabilize the 3
segments of their body (i.e., head, neck, and trunk) in all
planes during all 3 gaits, but walk is known to show the
greatest angular displacements of the head (Dunbar et al.,
2008). Thus, at trot, there is less longitudinal movement of
Table 2 Table of predicted means for type ! gait
interactions
Advertised ridden
Advertised unridden
Domestic
Feral
Canter
Trot
Walk
0.95
32.50
29.34
23.72
25.59
31.62
28.19
26.35
2.64
21.00
20.82
15.38
the neck compared with walk and canter, so it may well
be that riders are taking advantage of this lowered neck mobility to shorten the neck more than at other gaits and that
the horse is held in a shortened posture by the rider’s hands.
Regardless, the results show that, if they are ridden as they
are advertised in trot (the most common gait in horses advertised under saddle), horses in the current Australian sample
are generally being ridden more incorrectly than at other
gaits, according to the FEI directives (2009).
Although FEI rules prescribe some arching of the neck,
this is limited by the directive to maintain the nose in front
of the vertical line. It seems that advertisers tend to favor
photographs of horses with arched necks and it seems
apparent that over time, over-arching of the neck and
ignoring the angle of the nasal plane must have become
fashionable. Yet many engravings since the renaissance
depict highly arched necks in horses trained in dressage. It
seems plausible that if trainers and riders followed the
principle of self-carriage, where the horse’s head and neck
posture is a learned response rather than a forced one, overarching and nasal planes behind the vertical would have
been prevented. This supports previous calls for trainers
and riders to be educated in the principles that arise from
learning theory (McGreevy, 2007; Warren-Smith and
McGreevy, 2008). Our results reflect a tendency for humans
to mistakenly assume that horses are educated and ‘‘on the
bit’’ because they have their noses tucked in (especially at
the trot). Many equestrian authorities suggest that increasing amounts of neck flexion are counterproductive and
put the horse ‘‘on the forehand’’ (so it is heavier on the forequarters) and that is presumably why flexion behind the
vertical is penalized in competition dressage. That said, it
184
is perhaps perplexing that in a sport aimed to exhibit
optimal training, riders warm-up their horses in neck
postures at odds with optimal performance. This suggests
that psychological or biomechanical advantages are to be
gained through this contrary practice, which is a widely
held belief. However, any increased curvature of the upper
respiratory tract increases turbulence and so is likely to
compromise athletic performance. As workload reaches
maximum in oxygen-deprived horses, lactic acid and
beta–endorphin concentrations show a marked increase
(Mehl et al., 2000). This may also provide fertile ground
for future research that explores the physiological effects
of neck-flexing.
This trend toward hyperflexion may also have unwelcome
implications for rider safety if, in response to rein tension, the
horse neck-flexes, rather than decelerates. Safety is further
compromised if this confusion generates conflict behaviors
that manifest as dangerous hyper-reactive behaviors
(McGreevy and McLean, 2007).
Although neck flexion can be forced/trained for collection, dressage exponents regard it as a natural response
(they point to similar postures in horses at liberty when
excited by the presence of a new conspecific or mating
possibility). Here the stride shortens and the trot elevates
(as in collected trot) and there is a significant concomitant
elevation of the poll and shortening of the neck. Dressage is
said to mimic these natural postures so that during collection the neck shortens and the poll is raised, whereas in all
gaits the neck lengthens and the poll lowers as the stride
lengthens. Furthermore, it is also believed that the added
weight of the rider necessitates a caudal shift in the horse’s
centre of mass to achieve balance. Indeed, in the FEI (2009)
guidelines for dressage judging, the stated aim of collection
is to improve the balance and equilibrium of the horse,
which has been more or less displaced by the additional
weight of the athlete (FEI, 2009). However, this may represent a legacy from the long-held belief that a horse, when
mounted, regains some mechanical advantage by a caudal
shift in its centre of gravity when it is moving forward in
collection (FEI, 2007). A recent study by Buchner et al.
(2000) shows that the approximate body centre of mass
of unmounted horses is on a line approximately 2 cm below
the true hip joint, 1 cm left lateral of the centre line and
level with T12–13 (i.e., in a position consistent with the
anticlinal in the dorsal spinous processes). This is more
caudal than previously thought but fortuitously aligns
directly under the rider’s body centre of mass, apparently
obviating the need for any shift. So, moving the horse’s
centre of mass further caudally than the rider’s centre of
mass may actually be mechanically inefficient.
Instead of bestowing a biomechanical advantage for the
horse, true collection may simply be a demonstration of
advanced training and provides the additional bounce that
makes horses somewhat more comfortable to ride.
Holmstr}
om and Drevemo (1997) showed that Grand Prix
horses have a higher compression of hindlimb joints with
Journal of Veterinary Behavior, Vol 5, No 4, July/August 2010
longer stance phase as collection increases. That said, in
at least 1 study, (Holmstr}om et al., 1995) the placement
of the hindfeet more cranially under the horse’s body did
not increase with higher collection, and over-track is known
to decrease with collection in trot (Clayton, 1994).
In so-called classical training (which nowadays refers to
a multinational post-Middle Ages approach to horse training, principally for the purposes of war), the correct
position of the nasal plane when riding a horse ‘‘on the
bit’’ is always in front of the vertical and with the head
more or less raised, according to the level of training (FEI,
2009). In classical texts, the height of the poll (the atlantooccipital junction) is given considerable attention because it
changes according to stride length: when the horse makes
short strides, the poll rises (and comes a little closer to
the withers), and when the stride lengthens, the poll lowers
(and the neck lengthens a little). Collection (characterized
by the higher poll, more arched neck as well as lowered
croup) develops as a result of repeated transitions of lengthening and shortening the stride over time, and the topline
(the cervical and thoracolumbar) muscles develop as a result of this (Podhajsky, 1966). Horse trainers who adhere
to an older ‘‘classical’’ approach claim that these alterations
in poll height (and to a lesser extent neck length) cause the
necessary shift in centre of gravity back and forward as
strides shorten and lengthen (Karl, 2008). As already noted,
the need for this has recently been refuted. It seems likely
that this dogma began at the end of the Middle Ages when
the weight of armor added significantly to the rider’s
weight. In addition, the front end of the horse was also
covered by metal armor (e.g., the chanfron, crinet, peytrel,
and flanchard were all metal covers for the head, neck,
shoulders, and sides of the horse) and this extra weight
may well have necessitated the transfer of some weight to
the hindquarters of the horse for it to be balanced and locomote optimally. Accordingly, classical training emphasizes
that collection is purely the result of the physical development of the horse’s body as a result of transitions that
enabled weight to be transferred to the hindquarters.
In contrast, contemporary dressage training focuses on
bringing the nose behind the vertical, which is believed to
make the horse work ‘‘correctly’’ and ‘‘over the back’’
where the lowering of the head lifts the vertebral column
(Van Weeren and Schrijer, 2003). Equitation Science
(McGreevy et al., 2009) should be able to clarify this issue
by showing how a strong lumbar musculature in which
the muscles raise the back relates to the softer back the
‘‘classical’’ masters describe. Similarly, future research
should explore how and when the trend toward permitting
and even promoting carriage behind the vertical emerged.
In 2010, the FEI claimed to have resolved the issue by
redefining hyperflexion/rollkur as flexion of the horse’s
neck that is the product of aggressive force (FEI, 2010).
The same statement went on to assert that flexion without
undue force, a technique they referred to as low, deep,
and round, is acceptable. The group unanimously agreed
McGreevy et al
Over-flexing the horse’s neck
Figure 3
185
The apparent orientation of the pupil in a pony with its neck relaxed, extended, and hyper-flexed.
that any form of aggressive riding must be condemned but
made no mention of how this might be defined or measured.
If the only force that is unacceptable is characterized by the
intention of the rider (i.e., the rider’s aggression), then
stewards will struggle to be sure that a breach has occurred.
The International Society for Equitation Science (ISES) has
written to the FEI suggesting that this statement makes the
need to collect rein tension data more pressing than ever.
Policing action against aggressive force relies on a universally accepted definition of aggressive force, which can be
achieved only by ensuring that objective measures are made
to confirm or refute the observations made by stewards.
The effect of neck-flexing on vision is controversial.
Harman et al. (1999) indicated that horses ridden behind the
vertical have compromised vision. In contrast, Bartos et al.,
(2008) noted that neck arching is seen by stallions approaching one another and questioned why horses would ‘‘handicap
themselves visually during stressful social interactions that
can lead to a fight causing injury or death or in an uncertain
situation that might be dangerous for the subject.’’ The reality
is that parallel prancing is an important feature of inter-male
interactions (i.e., when stallions approach one another, rather
than merely advancing directly head-on, they do so with
lateral and diagonal displays that include neck-flexing).
When horses cavort, their noses occasionally point very
much in the direction of the ground they have just covered
but this would be maladaptive only if it were maintained.
By way of an example, neck-wringing in play may have the
same effect on vision but we should not assume that vision
is always prioritized by horses. Brief displays may be of
sufficient proximate importance to horses that surveillance
may be sacrificed, but only very briefly.
The Bartos et al. (2008) study reported that the pupil
maintained its horizontal position relative to the ground
regardless of head position. However, they did not report
the head positions they examined, and their photographs
seemed to imply that the nose was always somewhat in
front of the vertical. They were not concerned with forward
binocular vision and did not use any technique such as
ophthalmoscopy to determine visual field (Harman et al.,
1999) or alignment of the pupil relative to the corpora
nigra, so it is difficult to comment on their findings. Our
own preliminary data indicate that in extreme head positions the pupil is not parallel to the ground (Figure 3),
but further work is needed to confirm this. The ideal study
would apply ophthalmoscopy during radical neck flexion
and extension to a cohort of horses with different head
shapes (Evans and McGreevy, 2006a) because it is known
that the distribution of ganglion cells differs with skull
length (Evans and McGreevy, 2006b).
When horses are grazing, the head is well in front of the
vertical and the binocular field is directed toward the
ground in front of the nose. However, with their laterally
placed eyes, they have excellent, extensive lateral vision,
which enables them to scan the environment in this position
(Harman et al, 1999). By contrast, when the horse is
186
moving through space, it needs to use the binocular visual
field, necessary for seeing in 3 dimensions. This field is
located down the nose of the horse, not directly in front
of the animal as it is in humans (Harman et al., 1999).
This explains why the horses at liberty in the current series
of photographs travel with the head well in front of the
vertical. The current trend for over-flexing the neck significantly compromises forward vision. This head position
produces a horse that, because it cannot see in front, is
rendered somewhat powerless, which may be necessary
for riders of modern, vigorous competition horses. It is
clearly contraindicated in jumping horses in whom forward
vision is crucial.
Conclusions
Inappropriate neck-flexing behind the vertical is surprisingly common in ridden horses advertised in Australia and
only very rarely seen in horses at liberty. In contrast, true
collection by horses at work (with the poll raised and the
neck moderately flexed) may be a demonstration of
appropriate training for particular locomotory requirements
and may therefore be desirable, even without meeting a
perceived need for a shift in the horse’s centre of gravity.
However, artificial collection is easily mimicked by simple
neck-flexing through increased rein tension, an approach
that is clearly contraindicated on training and welfare
grounds because it exposes the horse to 1 pressure signal
for 2 responses (neck-flexing and deceleration), increased
turbulence in the upper respiratory tract, and compromised
forward vision. It may also have implications for rider
safety if the horse shows less deceleration in response to
rein tension. The trend toward a focus on incorrect neckflexing in contemporary elite dressage may account for the
popularity of this ill-advised practice in the wider dressage
rider population.
Acknowledgments
Pierre Malou and Dr Mick O’Neill are warmly thanked
for their contribution to measurements of nasal angles and
statistical analyses, respectively.
References
Bartos, L., Bartosová, J., Starostová, L., 2008. Position of the head is not
associated with changes in horse vision. Equine Vet. J. 40, 599-601.
Buchner, H.H.F., Obermüller, S., Scheidl, M., 2000. Body centre of mass
movement in the sound horse. Vet. J. 160, 225-234.
Journal of Veterinary Behavior, Vol 5, No 4, July/August 2010
Clayton, H.M., 1994. Comparison of the stride kinematics of the collected,
working, medium and extended trot in horses. Equine Vet. J. 26,
230-234.
Decarpentry, A.E.E., 1949. Academic equitation. J.A. Allen, London, UK.
Dunbar, D.C., MacPherson, J.M., Simmons, R.W., Zarcades, A., 2008.
Stabilization and mobility of the head, neck and trunk in horses during
overground locomotion: comparisons with humans and other primates.
J. Exp. Biol. 211, 3889-3907.
Evans, K.E., McGreevy, P.D., 2006a. Conformation of the equine skull: a
morphometric study. Anat. Histol. Embryol. 35, 221-227.
Evans, K.E., McGreevy, P.D., 2006b. The distribution of ganglion cells in
the equine retina and its relationship to skull morphology. Anat.
Histol. Embryol. 35, 1-6.
Fédération Equestre Internationale, 2007. Dressage handbook guidelines
for judging. FEI, Lausanne, Switzerland.
Fédération Equestre Internationale, 2009. Rules for dressage events, 23rd
Ed.. FEI, Lausanne, Switzerland.
Fédération Equestre Internationale, 2010. FEI round table conference resolves
rollkur controversy. Available at: http://www.fei.org/disciplines/dressage/
press-releases/fei-round-table-conference-resolves-rollkur-controversy.
Accessed February 18, 2010.
Harman, A.M., Moore, S., Hoskins, R., Keller, P., 1999. Horse vision and
the explanation of visual behaviour originally explained by the ‘ramp
retina’. Equine Vet. J. 31, 384-390.
Holmstr}om, M., Drevemo, S., 1997. Effects of trot quality and collection
on the angular velocity in the hindlimbs of riding horses. Equine
Vet. J. Suppl. 23, 62-65.
Holmstr}om, M., Fredricson, I., Drevemo, S., 1995. Biokinematic effects of
collection on the trotting gaits in the elite dressage horse. Equine
Vet. J. 27, 281-287.
Karl, P., 2008. The twisted truths of modern dressage. Cadmos, Brunsbek,
Germany.
McGreevy, P.D., 2007. The advent of equitation science. Vet. J. 174,
492-500.
McGreevy, P.D., McLean, A.N., 2007. The roles of learning theory and
ethology in equitation. J. Vet. Behav.: Clin. Appl. Res. 2, 108-118.
McGreevy, P.D., McLean, A.N., Warren-Smith, A.K., Waran, N., Goodwin,
D. (Eds.), 2005. Defining the terms and processes associated with
equitation. Proceedings of the 1st International Equitation Science
Symposium, Broadford, Victoria, Australia, Post-Graduate Foundation
in Veterinary Science, Sydney, pp. 10–43.
McGreevy, P.D., Oddie, C., Burton, F.L., McLean, A.N., 2009. The
horse-human dyad: can we align horse training and handling activities
with the equid social ethogram? Vet. J. 181, 12-18.
McLean, A.N., McLean, M., 2009. Academic horse training: equitation
science in practice. McLean Andrew & Manuela. Australian Equine
Behaviour Centre, Broadford, Victoria, Australia.
Mehl, M.L., Schott, H.C., Sarkar, D.K., Bayly, W.M., 2000. Effects of
exercise intensity and duration on beta-endorphin concentrations in
horses. Am. J. Vet. Res. 61, 969-973.
Petsche, V.M., Derksen, F.J., Berney, C.E., Robinson, N.E., 1995. Effect of
head position on upper airway function in exercising horses. Equine
Vet. J. Suppl. 18, 18-22.
Podhajsky, A., 1966. The complete training of horse and rider in the principles of classical horsemanship (E. Podhajsky and V.D.S. Williams,
Trans.). Doubleday, Bantam Doubleday Dell, New York, NY.
Van Weeren, R., Schrijer, S., 2003. Auf dem falschen rucken ausgetragen.
Reiterrevue. 7, 13-15.
Warren-Smith, A.K., McGreevy, P.D., 2008. Equestrian coaches’ understanding
and application of learning theory in horse training. Anthroz}oos. 21,
153-162.