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Behavioural assessment of pain in 66 horses, with and without a bit


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Horses can be ridden with or without a bit. Comparing the behaviour of the same horse in different modes constituted a ‘natural experiment’. Sixty‐nine behaviours in 66 bitted horses were identified as induced by bit‐related pain and recognised as forms of stereotypic behaviour. A prototype questionnaire for the ridden horse was based on 6 years of feedback from riders who had switched from a bitted to a bit‐free bridle. From a template of 69 behavioural signs of pain derived from answers to the questionnaire, the number of pain signals shown by each horse, first when bitted and then bit‐free, was counted and compared. After mostly multiple years of bit usage, the time horses had been bit‐free ranged from 1 to 1095 days (median 35). The number of pain signals exhibited by each horse when bitted ranged from 5 to 51 (median 23); when bit‐free from 0 to 16 (median 2). The number of pain signals for the total population when bitted was 1575 and bit‐free 208; an 87% reduction. Percentage reduction of each of 69 pain signals when bit‐free, ranged from 43 to 100 (median 87). The term ‘bit lameness’ was proposed to describe a syndrome of lameness caused by the bit. Bit pain had a negative effect on proprioception, i.e. balance, posture, coordination and movement. Only one horse showed no reduction in pain signals when bit‐free. The welfare of 65 of 66 horses was enhanced by removing the bit; reducing negative emotions (pain) and increasing the potential to experience positive emotions (pleasure). Grading welfare on the Five Domains Model, it was judged that – when bitted – the population exhibited ‘marked to severe welfare compromise and no enhancement’ and – when bit‐free – ‘low welfare compromise and mid‐level enhancement.’ The bit‐free data were consistent with the ‘one‐welfare’ criteria of minimising risk and preventing avoidable suffering.
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Original Article
Behavioural assessment of pain in 66 horses, with and without a bit
W. R. Cook
* and M. Kibler
Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton,
Massachusetts; and
Department of Mathematics and Computer Science, Washington College, Chestertown,
Maryland, USA
*Corresponding author email:
Keywords: horse; bit; pain; pain-related behaviour; proprioception; stereotypic behaviour; welfare; poor performance
Horses can be ridden with or without a bit. Comparing the
behaviour of the same horse in different modes constituted a
natural experiment. Sixty-nine behaviours in 66 bitted horses
were identied as induced by bit-related pain and
recognised as forms of stereotypic behaviour. A prototype
questionnaire for the ridden horse was based on 6 years of
feedback from riders who had switched from a bitted to a
bit-free bridle. From a template of 69 behavioural signs of
pain derived from answers to the questionnaire, the number
of pain signals shown by each horse, rst when bitted and
then bit-free, was counted and compared. After mostly
multiple years of bit usage, the time horses had been bit-
free ranged from 1 to 1095 days (median 35). The number of
pain signals exhibited by each horse when bitted ranged
from 5 to 51 (median 23); when bit-free from 0 to 16 (median
2). The number of pain signals for the total population when
bitted was 1575 and bit-free 208; an 87% reduction.
Percentage reduction of each of 69 pain signals when bit-
free, ranged from 43 to 100 (median 87). The term bit
lamenesswas proposed to describe a syndrome of
lameness caused by the bit. Bit pain had a negative effect
on proprioception, i.e. balance, posture, coordination and
movement. Only one horse showed no reduction in pain
signals when bit-free. The welfare of 65 of 66 horses was
enhanced by removing the bit; reducing negative emotions
(pain) and increasing the potential to experience positive
emotions (pleasure). Grading welfare on the Five Domains
Model, it was judged that when bitted the population
exhibited marked to severe welfare compromise and no
enhancementand when bit-free low welfare compromise
and mid-level enhancement.The bit-free data were
consistent with the one-welfarecriteria of minimising risk and
preventing avoidable suffering.
Pain in animals is dened as an aversive sensation caused by
actual or threatened tissue damage; a negative mental
state. Pleasure is dened as fullment of a biological drive for
comfort and safety; a positive mental state. Current animal
welfare thinking (Mellor 2015a) refers to pleasureas a
positive affective experience(Table 1). The term affect
describes emotion (feeling), either positive or negative. It
encompasses motivation; an animals urge to move
towards or away from a stimulus, i.e. stereotaxis.
Used since the Bronze Age, metal bits have been
accepted as part of the furniture of horsemanship and not
subjected to scrutiny until quite recently (Cook 1999). In a
review of equine pain assessment, the absence of data on
abnormal bit behaviour[sic] was noted by Ashley et al.
(2005). Since then, three studies have compared ridden horse
behaviour, with and without a bit. First, two unschooled 2-
year-old horses in a 10-day period of foundational training
performed at least as well, if not betterwithout bits as two
matched horses in snafe bridles (Quick and Warren-Smith
2009). Second, four mature horses, in their maiden bit-free
test, exhibited statistically improved ridden behaviour (Cook
and Mills 2009). In two concurrent four-minute tests, rst bitted
then bit-free, ridersscores increased from a mean of 37
(fairly bad)to64(satisfactory). Finally, a study of 16
therapeutic riding horses showed signicantly more negative
behaviours when bitted and positive behaviours when bit-
free (Carey et al. 2016).
Pain studies in animals have not generally included
removal of the pains source. The arrow of direction in
assessing most management interventions (e.g. castration) is
from painless to painful. In the current study, the direction
was reversed. Bit usage is an elective and almost daily
intervention during many horsesworking lives. Assessment of
its effect on welfare is overdue.
As bits have been standard equipment for millennia, they
are widely assumed to be indispensable and ethically
justied. This being so, an opinion by welfare researchers is
cited ... Most horses exhibit clear behavioural evidence of
aversion to a bit in their mouths, varying from the bit being a
mild irritant to very painful(Mellor and Beausoleil 2017). The
same authors observe that evidence of aversion is available
to all who seek by comparing the open mouth, head tossing
and restricted jaw angle of many bitted horses clearly
apparent on YouTube videos with the absence of these
behaviours in videos of wild horses and of domestic horses
when ridden bit-free or bridleless. The need for a list of ridden
horse behaviours to be developed was noted by Hall et al.
The study objective was to start answering six questions:
What behaviours are caused by the bit?
How prevalent are they?
How many bit-induced behaviours might one horse
Are they reversible when the bit is removed?
Is a horses welfare improved by removal of the bit?
Can a horse be controlled without a bit?
The null hypothesis was that removal of the bit would
cause no behavioural change.
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
This is an open access article under the terms of the Creative Commons Attribution License, which permits use,
distribution and reproduction in any medium, provided the original work is properly cited.
Equine vet. Educ. (2018)  ()-
doi: 10.1111/eve.12916
TABLE 1: Prevalence of 69 pain indices in 66 horses, when bitted and bit-free. The mean reduction when bit-free was 85% (range 43
100) with a median of 87%. Many of the bit-induced pain indices jeopardised the safety of both horse and rider
Number of
number of
bit-free (%)
Inferred likelihood of horse having POSITIVE AFFECTIVE
EXPERIENCES e.g., pleasures of safety, condence, comfort,
compliance, enthusiasm, motivation following removal of
the bit and cessation or easement of pain
1 Hates the bit 53 0 100 The relief, pleasure and comfort of being without pain
2FRIGHT: 46 4 87 One of the ve major categories of fear (the ve Fs),
replaced by calmness, ease and comfort
3 Stiff-necked 45 7 84 Freedom of the head: Ability to balance; smoothness
and uidity in the way of going
4 Lack of control 43 6 86 Horse/rider high accident hazard replaced by willing
cooperation, harmony and partnership
5=Resents bridling 41 3 93 Drops head eagerly into bridle; exhibits enthusiasm for work
5=Above the bit 41 3 93 Able to select the physiologically most comfortable (optimally
balanced) head position
6 Muzzle rubbing 40 9 77 Relief from the persistent irritation and distraction of facial
7=Head shaking 37 8 78 As above for muzzle rubbing- the relief from nerve ache
7=Unfocused 37 1 97 Focused; not distracted; listensto and complies with
riders signals
8FLIGHT 35 1 97 Contentment; energy conservation; no propensity to bolt,
rush or run away
9=FIGHT 34 2 94 Calm, quiet, cooperative and willingly offers compliance
9=Pig-rooting 34 2 94 See ghtabove: Does not grab the bit and snatch reins
from riders hands
10 Difcult to steer 33 8 76 Ability to balance; steers straight and turns comfortably
(also see lack of controlabove)
11=Stiff or choppy stride 32 2 94 Enjoys the natural rhythm of motion (also see
11=Reluctant to rein-back 32 10 69 Return of normal agility; one of many signs of reduced
bit lameness
12 Tail swishing 31 1 97 Removal of discomfort; tail movement in synchrony with
spinal movement
13=Hair-trigger response
to bit
29 0 100 Calm and condent as opposed to highly strung,anxious
and apprehensive
13=Sneezing & snorting 29 13 55 Restoration of normal breathing pattern; reduction of nasal
irritation (facial neuralgia)
14 Yawning 28 4 86 Absence of yawning suggestive of reduced need to
ease/interrupt pain signals (see facial neuralgia above)
15 Slow learner 27 1 96 Return of ability to learn - a vital survival strategy (see
unfocussed above)
15 Uncooperative 27 3 89 See ghtabove
15 Heavy on the forehand 27 6 78 Unhampered ability to balance, return of normal agility,
elimination of stress and pain
16 Fails to stand still 26 0 100 Return of species specic default behaviour of calmness
and contentedness
17 Pulling on bit 26 0 100 No need to defend itself from the bit and become unbalanced
in the process
18=Grazing on the y
at exercise
25 11 56 Less need to interruptpain signals (see yawningabove)
18=Inverted frame 25 5 80 No pain - no high head carriage - return of ability to balance
19=Dislikes wind/rain/sunlight 24 10 58 Relief from trigeminal hypersensitivity
19=Tilts head at exercise 24 5 79 Proper balance with no need to try and avoid bit pain
19=Fails to maintain
trot or canter
24 4 83 Engaged, lively, energised, exhibits vitality of tness
20=Difcult to mount 23 3 87 Reduced anxiety and apprehension
20=Grabs the bit 23 0 100 No need for defensive behaviour at exercise
20=Lacks courage 23 5 78 Condent, engaged and curious about its environment
21=Napping 22 4 82 Reduction of fear; reduced pain increases comfort
(see Freeze)
21=Stumbling 22 7 68 Reduction of bit lamenesswith unfettered proprioception
enabling a horse to keep itself upright and safe
22=FREEZE 21 4 81 Keen to explore. Relief from the frozenstate of a prey animal
when attacked by a predator
22=Resents unbridling 21 1 95 Optimism rather than pessimism (see hates the bitabove)
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
2 Ridden horse pain
Study design
Owner/rider assessment of horse behaviour, with and without a
bit; a longitudinal, retrospective, questionnaire-based study. The
number of behavioural signs of pain in each of 66 horses when
bitted was compared with the number of signs when bit-free.
The questionnaire (Supplementary Item 1) was based on
6 yearsfeedback from 605 riders who had switched from a
bitted to a bit-free bridle (Cook 2003). As recommended,
questions were posed using vernacular terms (Wemelsfelder
et al. 2001). At the end of an 8-page manual for a bit-free
bridle, riders were informed that a questionnaire was
available for documenting behavioural changes. The
questionnaire was mailed on request or, more commonly,
downloaded online. The 6-page questionnaire comprised
signalment; 106 yes/noquestions about horse behaviour
and signs of disease; and 10 questions describing a riders
feelings about riding. It was completed twice; once when
bitted and again when bit-free. From the answers, the
change in prevalence of 69 behaviours, occurring in not less
than 4 of 66 horses when bitted, was assessed (Table 1).
TABLE 1: Continued
Number of
number of
bit-free (%)
Inferred likelihood of horse having POSITIVE AFFECTIVE
EXPERIENCES e.g., pleasures of safety, condence, comfort,
compliance, enthusiasm, motivation following removal of
the bit and cessation or easement of pain
22=Behind the bit 21 1 95 Adopts head position based on proprioceptive signals (see
above the bit)
22=Head shyness 21 12 43 Abatement of trigeminal hypersensitivity, hyperalgesia or
22=Salivates excessively 21 2 90 A relatively dry mouth betokens contentedness at exercise
23=Bucking or bounding 20 3 85 Less pain, more comfort
23=Lazy or dull 20 4 80 Engaged aliveness
23=Heads for the stable 20 6 70 Relishes exercise, fulls biological drive and need for movement
23=Jigging 20 1 95 Walks quietly and contentedly
24=Unfriendly in stable 18 2 89 Return of normal (social) behaviour
24=Anxious eye 18 2 89 Soft(rounded) eye - an indicator of comfort
25=Ear pinning at exercise 17 4 76 Non-aggression equates with the default social behaviour of
the species
25=Open mouth (gaping) 17 2 88 Closed mouth and sealed lips; oral vacuum restored; default
condition for unobstructed airway at exercise
25=Lolling tongue 17 0 100 Another return to physiological and behavioural norm
25=Reluctant to change lead 17 5 71 Return of normal agility with correction of bit lameness
26 Bites at tack or
other horses
16 0 100 Reduced facial neuralgia enables disposition to move beyond
neutral to a more positive emotional state
27 Scuffs hind hooves 15 7 53 Soundness of limb returns with correction of bit lameness
28 Backing-up 14 1 93 See fails to stand still
29 Multiple wrinkles
around muzzle
13 2 85 Relaxation of tension with elimination of pain
30 Crossing the jaw 13 1 92 As above - return to normalbehaviour when on the move
31=Evades capture
in paddock
12 2 83 Accepts rider as a member of its herdor band
31=Sweats excessively 12 1 92 No stress, less sweat
31=Over bends 12 0 100 Proprioceptively and physiologically comfortable head position
31=Tongue over bit 12 0 100 No need for defensive behaviour following removal of the bit,
unobstructed breathing
31=Interfering 12 4 67 Another aspect of bit lamenesscorrected
32 Rears 11 2 82 Reductionof bit-escape behaviour
33=Runs wild on bitted lunge 10 1 90 More comfortable
33=Lower lip slapping 10 3 70 More comfortable
33=Incoordination. 10 1 90 Unhampered proprioception corrects bit lameness
34=Eyes water 9 2 78 Reduction of corneal pain (facial neuralgia)
34=Exercise triggers cough 9 2 78 Reduction of pharyngeal angina (trigeminal neuralgia) and/or
inammatory airway disease
34=Back problems 9 2 78 Relief of bit-lameness
35 Retracts tongue
behind bit
7 0 100 Return of default tongue position at exercise, oral vacuum,
soft palate stability, unobstructed airway
36 Drops food 6 0 100 Elimination of sore mouth(mandibular gingivitis)
37 Reluctant to drink
during endurancetest
4 0 100 Ability to create an oral vacuum and relief of sore mouth
prevents dehydration
Upper case letters mark the ve major categories of fear-induced behaviour (the ve Fs) in the questionnaire; i.e. fright, ight, ght,
freeze and facial (trigeminal) neuralgia. Pain indices specic to the bit are shaded grey.
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
W. R. Cook and M. Kibler 3
Population selection
Owner/riders volunteered their participation in the study.
Each horse served as its own control, inasmuch as its
behaviour was compared before and after removing the bit.
Between 2002 and 2016, 96 questionnaires were received.
Sixty-six were completed correctly; a usablerate of 69%. The
inclusion criterion was that for each of the 69 behaviours
selected for analysis, a yes/no answer must have been
entered for both bitted and bit-free periods.
Statistical analysis
A matched pairs t-test was used to determine if there was
change in the number of pain signals (pain indices) when bit-
free. An alpha level of 0.05 was set for signicance.
Welfare assessment
A numerical grading of behaviour was eschewed in favour of
the Five Domains Model (Mellor and Beausoleil 2015; Mellor
2017). Welfare compromise was graded on a ve-tier scale
from A (no compromise) to E (very severe compromise).
Welfare enhancement was graded on a four-tier scale from
zero (no enhancement) to +++ (high-level enhancement).
The age of the population ranged from 3 to 24 years, with a
mean of 10 years and a median of 8 (Table 2). Including half-
breds, the breeds comprised Thoroughbreds (n =21),
Arabians (n =11), Warmbloods (n =7), Tennessee Walking
Horses (n =5), Appaloosas (n =4), Clydesdales (n =3) and
others (n =15). Gender distribution was male (n =40; 39
geldings and one stallion) and female (n =25). Categories by
predominant use were dressage (n =22), pleasure (n =21),
trail (n =13), eventing (n =5) and jumping (n =5). All owners
rode Englishstyle. Twenty-eight horses had been bitted for
ve or more years. The time a horse had been bit-free before
the second assessment ranged from 1 to 1095 days (median
35; mean 108). Questionnaires were returned from North
America (n =46), UK (n =14), Australasia (n =3), Austria
(n =1), France (n =1) and Holland (n =1).
Bits used were snafes, Pelhams and double bridles. The
bit-free bridle used throughout was a crossunder (Dr.Cook
Results are displayed in Tables 13and Figure 1. Answers
to the six questions are summarised as follows:
All 69 behaviours were caused by the bit, as judged by
their signicant reduction in prevalence when the bit was
removed. Excessive salivation was the only behaviour not
caused solely by bit-induced pain, being also a reex
response to an oral foreign body.
Bit-induced behaviours, as a group, were highly prevalent. The
total number of pain signals for the population when bitted
was 1575 and, when bit-free, 208; an 87% reduction. From 66
horses, the number of horses exhibiting each behaviour
ranged from 53 (80% of the population) to 4 (6%) (Table 1).
The median number of behaviours per horse when bitted
was 23 (range 551); when bit-free 2 (range 016).
Most bit-induced behaviours were eminently reversible and
the change was statistically signicant (Table 2). The
matched pairs t-test gave a P-value of less than 0.005,
supporting a causal link between the bit and pain-induced
behaviour (Table 3).
The welfare grade for the population when bitted was
judged to be D/0 (marked to severe compromise and no
enhancement) and, when bit-free B/++ (low compromise
and mid-level enhancement).
None of the riders experienced loss of control when bit-
free, quite the opposite. In only one horse was control
The null hypothesis was refuted: 65 out of 66 horses
showed a change in behaviour following removal of the bit.
The data support previous observations based on anecdotal
evidence (Cook 2003).
Horses exhibit stereotaxis; a word derived from the Greek
stereo, hard, solid. This fundamental property of (even)
primitive life forms, also known as thigmotaxis, is dened as
the positive (or negative) response of a freely moving
organism to cling to (or avoid) a solid object. Indisputably, a
bit is a solidobject. A horse is innately programmed to (try
and) move away from (evade) the bit, i.e. to display
negative stereotaxis. A denition for thigmotaxis (Greek:
thigmo,touch) emphasises the point the motion or
orientation of an organism in response to a touch stimulus.
When the touch is painful, stereotaxic stimuli are stronger. It
follows that the equitation mantra requiring a horse to
accept the bitis misconceived. Expecting a horse to
accept an oral foreign body is a biologically unrealistic
Mason (2006) proposed a denition of stereotypical
behaviour based on three causal mechanisms, i.e. repetitive
behaviours induced by frustration, repeated attempts to
cope and/or CNS dysfunction. The reversibility of 69
behaviours in 65 of the bitted horses indicates that CNS
dysfunctionwas not their cause but frustrationand
attempts to copeare mechanisms consistent with the data.
In Masons words again, stereotypical behaviours are
generally responses of normal animals to abnormal
environments. In captive animals, they stem from adecit in
housing or husbandry, where a decit means something that
the animal would change if it could (e.g. a motivational
decit linked with frustration; a health decit linked with
nausea or pain; or a safety decit causing fear).
Observational evidence constitutes the foundation for
animal welfare assessment and this evidence carefully
observed is objective, not subjective. Contemporary
animal welfare science understandingaccepts the need to
focus on subjective experiences, known as affects, which
collectively contribute to an animals overall welfare status
(Mellor 2017). Inferences based on such observational
evidence derive credibility from the underlying affective
neuroscience in a process that involves cautiously exercising
scientically informed best judgement(Mellor and Beausoleil
2017). Thus, it is asserted that improvements in behaviour
following removal of the bit enable inferences to be made
about the aversive experience of bit-induced pain. The
improvements cannot be dismissed as merely subjective.
Collectively, the behaviours were predominantly
manifestations of pain experience, expressed by aberrant
movements of the head, spine and limbs. They ranged from
too little movement (e.g. stiffening, freezing) to too much
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
4 Ridden horse pain
TABLE 2: Results for 66 horses switched from bit to bit-free, sorted on number of days bit-free. The number of pain indices when bit-free
was signicantly (P<0.005) reduced in 65 of the 66 horses
Case # Age (yrs) BREED Gender USE
# of pain
indices bitted
Time bit-free
% reduction in pain
indices bit-free
39 4 TWH G Trail 7 1 86
24 5 Arab/TB F Dressage 23 1 100
15 6 TB G Pleasure 5 1 60
22 6 Arab F Trail 30 1 83
29 23 3/4 TB G Dressage/trail 22 1 100
3 8 WB G Dressage 16 4 62
7 9 TB F Equitation/jumper 39 5 53
32 5 Welsh G Trail/Pony Club 24 7 96
57 8 QH/App G Trail 24 7 96
9 12 WB G Dressage/eventing 6 7 100
44 19 Arab F Trail 32 7 84
35 6 TB F Pleasure/endurance 23 8 87
1 5 TB G Trail 34 14 100
10 7 TB/QH F Pleasure 17 14 35
51 7 cob F Trail 13 14 100
55 8 TB G Pleasure 24 14 96
50 4 App G Jumping/hunter trials 26 19 88
48 4 WB F Dressage 37 20 100
12 6 QH G Western pleasure 24 21 83
27 3 WB F Dressage/eventing 19 30 100
42 7 TB/Trotter G Pleasure 12 30 100
45 7 Arab/Pinto G Dressage/trail 39 30 100
60 9 Paint G Trail 23 30 57
26 10 Gaited G Pleasure 5 30 80
43 10 Arab/QH F Pleasure/dressage 42 30 98
64 12 Arab G Endurance 23 30 100
23 13 QH G Hunter 16 30 0
52 22 TB G Pleasure 23 30 78
5 ? TWH ? Pleasure 21 30 76
56 ? Andalusian G Classical riding 27 30 67
40 6 TB F Pleasure 15 35 100
25 16 App F Pleasure/trail 27 35 100
47 11 Morgan/WB F Dressage 29 40 100
49 12 cob G Jumping, dressage 21 42 90
13 14 TB G Dressage/pleasure 23 42 33
59 3 Draft/X F School horse 7 60 71
58 6 Draft F Trail 21 60 62
4 8 TWH G Trail 11 60 100
53 8 TB G Dressage/jumper 42 60 100
16 15 App G Dressage 43 60 93
31 ? TB F Dressage/trail 13 60 54
8 4 TB G Dressage/eventing 34 64 97
11 11 SDB G Pleasure/trail 24 64 77
2 11 Arab G Dressage/trail 31 72 94
28 5 TB F Dressage/eventing 10 90 70
18 7 WB F Dressage 29 90 100
17 8 WB G Dressage 29 90 100
19 9 WB G Dressage 27 90 100
62 11 Draft G Mounted patrol 9 90 35
63 18 WB F Dressage/jumping 34 90 97
34 8 TB/Paint G Eventing/pleasure 23 120 74
46 8 Arab F Pleasure/endurance 28 120 100
54 11 TB G Trail/ dressage 23 120 69
41 14 Saddlebred G Dressage/jumping 42 150 90
20 12 Arab/Pinto G Trail 18 180 83
65 14 TWH M Dressage/pleasure 28 180 89
6 22 Arab F Trail 12 180 83
61 3 Draft G Mounted patrol 17 240 87
14 13 TB/WB F Dressage/eventing 9 240 100
37 6 TB (OTTB) F Dressage 32 300 75
30 11 WB G Pleasure/trail 7 300 86
38 24 Arab/Welsh G Eventing/trail 43 330 93
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
W. R. Cook and M. Kibler 5
movement (e.g. bucking, bolting). That some horses may
exhibit a few aversions to the bit is widely acknowledged.
That every horse is programmed to be averse to the bit and
that aversions are numerous is not. The current study showed
that at least 65 of 66 horses exhibited aversion to the bit and
that horses have not less than 69 ways of exhibiting
frustration, attempts to cope and efforts to avoid bit contact.
In a review of poor performance, 48 (72%) of these same
behaviours were recognisable among 67 behavioural signs of
pain compiled by Dyson (2016). Clearly, even though both
lists are incomplete, the mandible and tongue (a sense
organ in its own right) gure prominently as the seat of
musculoskeletal manifestations of pain experience in the
bitted horse. To this must be added pain from the lips, a
particularly sensitive area of another sense organ skin.
A bit stimulates nociceptors mediated by the trigeminal
nerve in lips, tongue, teeth and bone. Gingiva is periosteum,
the most sensitive part of bone. A principle of saddle-tting is
that saddles should not press on bone. A bit breaches this
principle. In the male horse, the peridontium of the canine
tooth roots lies immediately ventral to the dorsal edge of the
so-called interdentalspace. In the female, unerupted,
vestigial canine teeth are common (Sisson and Grossman
1938). In both sexes, wolfteeth (erupted and unerupted)
may be present in this space. In cross-section, bits are circular
and make point contact with the knife edgeof bone at the
bars. This can be assumed to cause a horse pain, just as it
causes us pain if we press the barrel of a pencil sideways into
our gums. When the edges of the tongue are pinched
between bit and bone, this too is likely to be painful. Pain is
also likely when lips are stretched longitudinally to twice their
normal length by the bits retractor effect. Finally, cuts at the
commissures will cause pain.
In common with other mammals, the vestibular labyrinths
and receptors in skin, muscle, tendon and temperomandibular
joints of the horses head mediate perception of orientation
and motion in three planes; i.e. proprioception. Head
proprioception controls not only movement and posture of the
head but also dominates that of the trunk and limbs
(Sherrington 1907). In the ridden horse, imbalance can result in
a fall with potentially fatal consequences. Head
proprioception constitutes a central balancing mechanism
and is key to a horses agility and athleticism. Painful restraint of
the head by a bitted rein interferes with a horses ability to
balance. As a horses head movement is synchronised with
limb movement for energy economy in the work of breathing
and locomotion, proprioception unfettered by nociception is
crucial. A bit also obstructs breathing and probably triggers the
negative affective experiences of breathlessness, i.e.
respiratory effort, air hunger and chest tightness (Mellor and
Beausoleil 2017). These unpleasant physical and emotional
consequences of bit pain are also antithetical to athleticism.
Thus, the bit represents an impediment to welfare, safety and
performance. Noxious stimuli from the bit are proposed to be
incompatible with the unimpeded function of at least four
systems critical to performance: the nervous, musculoskeletal,
proprioceptive and respiratory systems.
Dyson et al. (2018) observe that, since 2013 there is an
increasing awareness that horses can exhibit lameness when
ridden, while appearing sound when trotted in hand.In
common usage, the word lamedenotes a gait abnormality
caused by pain in a limb. Another sense of the word is not
limited to limbs and carries the wider meaning of disabled,
imperfect and lacking in smoothness(Webster). In this sense,
at least 65 of the 66 horses when bitted were shown to be
disabled. When trotted-up in a halter, they were not limb-
lame, but when bitted and ridden they developed an
abundance of gait abnormalities. The term bit lameis
proposed to describe a syndrome of bit-induced disability, i.e.
the 69 pain indices here studied. As bit usage is the norm in
Englishequitation and still frequent in Westernequitation, it
seems likely that bit lameness will be found to be common in
the ridden horse.
A provisional diagnosis of bit lamenessis testable. If, by
removing the bit, a gait abnormality is corrected this conrms
a diagnosis of bit lameness and differentiates it from primary
limb and thoraco-lumbar-sacral lameness or the
incoordination of equine protozoal myeloencephalitis (EPM).
As the denitive diagnosis of EPM and other subtle gait
abnormalities can be difcult, removal of the bit is
recommended as an early step in the differential diagnosis of
lameness and the evaluation of poor performance. Such a
step is especially indicated to help interpret the ndings of
computerised gait analysis, a diagnostic methodology that
has introduced a dilemma over dening the term lameness
(Van Weeren et al. 2017).
TABLE 2: Continued
Case # Age (yrs) BREED Gender USE
# of pain
indices bitted
Time bit-free
% reduction in pain
indices bit-free
21 10 Arab G Dressage/pleasure 21 365 67
36 10 TB/Conn F Dressage/eventing 51 720 85
33 8 TB/Paint G Dressage/jumping/trail 42 730 93
23 TWH F Trail 24 1095 100
App =Appaloosa; Conn =Connemara; QH =Quarter Horse; STB =Standardbred; TWH =Tennessee Walking Horse; TB =Thoroughbred;
WB =Warmblood.
TABLE 3: Results of the matched pairs t-test for means
Bitted Bitless
Mean 23.86 3.15
Standard deviation 10.88 3.99
Observations 66 66
Actual mean difference 20.71
Hypothesised mean difference 0
Degrees of freedom 65
tStat 14.50144
Two-tailed P-value 4.75E-22
tcritical two-tail 1.997138
The test was signicant (P<0.005).
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
6 Ridden horse pain
After owning a horse for years, riders discovered that
many unwantedbehaviours they had assumed to be
immutable character traits were corrected by removing the
bit. They were sometimes aware that their horse was
exhibiting signs of pain but, until they removed the bit, did
not recognise the source. Often, the signs themselves were
not even noticed until, following bit removal, they
disappeared. Norm theory explains how signs of bit lameness,
being so familiar, fail to elicit surprise and are assumed to be
normal. What ultimately did surprise owners was the
unexpectedly large number of pain indices each discovered.
It follows that riders need to carry out a bit-free test before
asserting that their horse shows no sign of bit pain.
The most prevalent pain index was hates the bit,a
family of behaviours shown by 53 horses (80% of the
population) (Table 1). The full line in the questionnaire read,
Hates the bit, chomping, chewing or clenching the bit,
grinding the teeth (bruxism), constant fussing with the bit,
busy mouth,evading contact(Supplementary Item 1).
The second most prevalent index was fright, shown by
46 horses (70% of the population). In the questionnaire, the
line read Fright: Anxious, unpredictable, hot,nervous,
painful, shy, spooky, panicky, tense, stressed. It seems
reasonable to assume that at least a quarter of the 69 pain
indices imperil the safety of horse and rider (Table 1). The
data support the opinion that bit-induced fear is the cause of
many horse-related accidents (Jahiel 2014). Removal of the
bit in 65 horses appeared to minimise risk and prevent
avoidable suffering,in accord with the concept of one-
welfare(Campbell 2013; Pinillos et al. 2016). In the feral
horse, pain or the anticipation of pain (fear) is adaptive and
promotes survival. In the ridden horse, pain is inimical to
performance. A bolting horse can be in such fear and panic
that it behaves as though blind and can run straight into
standing objects. Case No. 36, with 51 pain indices when
bitted, was described as dangerous to ride (Table 2,Fig 1).
Astiff neckwas the third most prevalent behaviour and
shown by 45 horses (68% of the population). Its 84% reduction
when bit-free is important for reasons over and above the
relief of pain. Bitted-rein tension restricts movement of the
head and neck, handicapping a horses ability to breathe,
stride and balance. Bedouin horsemen apparently
understood this long ago. When their very lives depended on
their horses peak performance, Bedouins rode bit-free
(Hanson and Cook 2015). Over half of the 69 pain indices
when bitted were expressed by abnormal positions of the
head and neck at exercise. Unfettered movement of the
head-and-neck pendulum is a vital locomotory mechanism.
Freedom of the neck is key to freedom of gait. Except when
ridden by a master horseman (someone who rides with a
loose rein and does not apply rein tension) a bitted horse
can be unbalanced by rein tension and is likely to stumble.
The fourth most prevalent sign of pain when bitted was
lack of control(65% of the population). Its reduction by 86%
when bit-free questions the rationale of competition rules
which mandate bit usage on the grounds that bits control
Twelve horses were assessed for the second time after
having been bit-free for 14 days or less. Five riders completed
the second assessment on day one (Table 2). Because of this
and the persistent nature of neuropathic pain compared with
nociceptive pain, the number of horses documented as
having recovered from facial (trigeminal) neuralgia may not
reect the populations full potential for recovery from what
0 10203040506070
CaseNo. 23istheonly horse
thatshowed nochange
Fig 1: Individual value plot of pain index numbers in 66 horses when bitted and bit-free. When bitted, all 66 horses (100%) exhibited
pain, with a range of indices from 5 to 51 (median 23). When bit-free, for a median time of 35 days, 66% still exhibited some pain but
the range of indices was from zero to 16 (median 2).
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
W. R. Cook and M. Kibler 7
was listed in the questionnaire as Facial neuralgia (the
headshaking syndrome). The percentage reduction in the
prevalence of this syndrome in the population was the lowest
of the ve major categories of fear (Supplementary Item 2).
Yet the reduction was still encouraging compared with results
from other treatments for headshaking (Mills et al. 2002). The
headshaking syndromeline item was checked for 37 of the
66 horses when bitted; eight when bit-free a 78% reduction
(Table 1). The word bitderives from the word bite.Clearly,
bits bite. It is considered no coincidence that the
headshaking syndrome includes many of the same
behaviours caused by biting ies.
Space does not permit a paragraph on every one of 69
pain indices but the positive affective experiencescolumn
of Table 1 provides a pr
Cognitive bias was recognised in the population. Mellor
(2015c) describes the bias as follows negative emotional
states may be accompanied by greater attention to
threatening stimuli and more pessimistic interpretations of
ambiguous information, whereas positive states may be
accompanied by more optimistic judgments. The
behavioural changes matched such a description; for
example, the greater frequency with which bitted horses
shied and spooked compared with their calmness when bit-
free (see FrightTable 1).
The 69 pain indices assessed in this study represent only a
fraction of possible bit aversions. If, for example, a study was
done on racehorses, it is predicted that many more bit-
induced, pain-related indices (diseases and disabilities) would
be identied. From a performance perspective, the most
critical years in the working life of a Thoroughbred racehorse
are those between the ages of one and four. These are the
years in which canine teeth are developing in the interdental
space. Bit-induced mandibular periostitis (sore mouth) is the
aetiological equivalent of metacarpal periostitis (sore shins).
Both sides of the mouth are traumatised on a daily basis. The
mouth is even more sensitive than the shin. Bit pain can
trigger a cascade of locomotor and respiratory
consequences; separation of the jaws open lips loss of the
intraoral vacuum instability of the soft palate asphyxia
followed by fatigue, sprains, dislocations, fractures and falls
and/or negative pressure pulmonary oedema (bleeding)
and sudden death (Cook 2002, 2014, 2016; Mellor and
Beausoleil 2017).
A horse learns to defend itself from the bit by gripping it
between the premolars (grabbing the bit); trapping it under
the tongue (tongue over bit); or placing it against the rostral
edge of the rst mandibular cheek teeth. Horses that try to
disarm the bit in these ways are unfairly blamed for being
hard-mouthedor pullers. The strategies result in bone spur
development at the interdental space and/or dental erosion.
Both defects are highly prevalent (Van Lancker et al. 2007;
Cook 2011; Mata et al. 2015).
Odberg and Bouissou (1999) reported that many horses
are slaughtered at a young age, perhaps because of
unresolved behavioural problems. McGreevy and McLean
(2005) stressed the need for physical causes of undesirable
behaviour to be ruled-out before behavioural therapy was
adopted. They noted that bits are ...a potential source of
tremendous discomfort.
The horse is motivated to avoid pain and seek comfort.
Mankind has an obligation to promote positive emotions for
the horse the neuroscience-supported concept (see
Table 1)ofpositive affective engagement(Mellor 2015a).
Contingent on the absence of pain a horse can probably
derive pleasure from being ridden, similar to that derived
from playwith conspecics (Mellor 2015b). Bonding
between horse and rider seems optimal when rein cues are
devoid of pressure, painless and proprioceptively supportive
(Hanson and Cook 2015).
Limitations of the study
Study design
The case-study population was not a random population.
The prototype questionnaire does not meet recently
developed standards for questionnaire-based research (Hall
et al. 2013; Muir 2013; Reid et al. 2013). A future questionnaire
could be based on the Five Domains Model (Mellor and
Stafford 2001; Jones and McGreevy 2010; Mellor and
Beausoleil 2015; Mellor 2017). Future questionnaires might also
include input from the work of Mullard et al. (2017) and
Dyson et al. (2017) who have developed a ridden horse
ethogram based on facial expression. Most recently, Dyson
et al. (2018) have developed a pain scoring ethogram for
the ridden horse with the objective of differentiating lame
from nonlame horses.
Assessors were not blinded
Nevertheless, as recommended by current welfare science,
the assessors were the people most familiar with the animals
studied, having triple credentials as owners, caretakers and
Data grading
A simple count of pain indices represents the most basic of
welfare grading systems. As a result, the homocentric lack of
controlcarried no more weight than, for example,
yawning. Absence of relative weighting will have
underestimated the harm of the bit. That said, current welfare
science thinking recommends non-numerical grading (Mellor
and Beausoleil 2015; Mellor 2017).
Lack of standardisation prevents this study from being
compared with others, e.g. Hockenhull and Creighton (2013).
To permit comparisons, a standard glossary (McGreevy et al.
2005), ethogram and protocol is needed. None of the 24
behavioural markers of pain in the ridden horse ethogram
developed by Dyson et al. (2018) were identical in wording
to the 69 markers of pain in the current study. However, many
were clearly descriptions of the same behaviours.
Comparisons cannot be made because of the terminology
differences and because none of Dysons37 horses were
assessed when bit-free. The authors concluded None of the
horses ... had evidence of oral pain.
Crib-biting, wind-sucking and other stereotypic
behaviours in stabled horses
A footnote to the questionnaire read: To date there is no
evidence to link wind-sucking or crib-biting as problems that
might be caused by the bit but it would be worth noting the
occurrence of such items in case a pattern of correlation
could be demonstrated. Six out of 66 horses (9%) were
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
8 Ridden horse pain
reported as showing stable-based stereotypic behaviour
when bitted; four windsuckers, one wood-chewer and one
self-mutilator. Information was not collected on whether this
behaviour changed when the bit was removed. In a survey
of stereotypic behaviour in a randomly selected population
of 650 riding-school horses, 46 exhibited stereotypies
(Normando et al. 2002). A statistically signicant difference
was recognised in the prevalence of stereotypies between
stabled horses ridden Western style (9 out of 348 horses 3%)
and English(37 out of 302 horses 12%). The authors noted
that the latter employs more hand to bit contact.
When bitted, the median number of behavioural signs of
pain per horse was 23. After being bit-free for a median
period of 35 days, the median was 2. Removal of the bit
reduced the prevalence of pain signals by 87%; showing the
bit to be a predominant cause of pain in the population.
The null hypothesis was refuted. Following the criteria
proposed by Campbell (2013) for distinguishing use from
abuse, removal of the bit in 65 horses minimised risk (for the
rider) and prevented avoidable suffering (for the horse). In
sum, 65 horses out of 66 benetted from removal of a
foreign body.
Authorsdeclaration of interests
No current conict of interests have been declared.
Ethical animal research
No ethical review was required.
Source of funding
There was no formal funding for this research. The data were
collected by W.R. Cook during a period of years when he
was the CEO of a small company, Bitless Bridle Inc. The costs,
small as they were, were part of the general running costs of
the company and did not gure in any line item for research
in the annual accounts.
Pioneering owners made the study possible.
The study design was conceived by W. R. Cook, as was the
execution, data entry and preparation of the manuscript. The
statistical data analysis was carried out by M. Kibler. Both
authors approved the nal manuscript.
Manufacturer's address
PHS Saddlery, Colorado Springs, Colorado, USA.
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Supporting information
Additional Supporting Information may be found in the online
version of this article at the publishers website:
Supplementary Item 1: Questionnaire.
Supplementary Item 2: Prevalence of ve major categories of
fear in 66 horses compared by their order when bitted.
©2018 The Authors Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd
10 Ridden horse pain
... Horses can also be controlled without a bit (McMiken, 1990;Cook and Kibler, 2019). Bitless bridles can be used to allow oral lesions to heal (Bennett, 2010) and they have been proposed as a solution for bit-related conflict behaviors or behaviors that might indicate pain (Easley, 2010;Cook and Kibler, 2019). ...
... Horses can also be controlled without a bit (McMiken, 1990;Cook and Kibler, 2019). Bitless bridles can be used to allow oral lesions to heal (Bennett, 2010) and they have been proposed as a solution for bit-related conflict behaviors or behaviors that might indicate pain (Easley, 2010;Cook and Kibler, 2019). However, some studies have not found a difference in horses' conflict behavior rates when ridden with bitless vs. bitted bridles (Scofield and Randle, 2013;Condon et al., 2022). ...
... The horse is an obligatory nose-breather and in exercise it normally keeps its mouth closed (Cook, 1999). Mouth opening, tongue moving in and out, tail swishing (lateral, vertical, or circular tail movements), head movements (tilting, rising, lowering, tossing, or going behind the vertical), teeth grinding, ear pinning, evasive behaviors (shying, rearing, bolting, fleeing), and braking the gait are behaviors that can be related to pain avoidance, frustration, or fear, indicating that the horse is experiencing mental or physical discomfort (Cook, 1999;McGreevy et al., 2005;Górecka-Bruzda et al., 2015;Hall and Heleski, 2017;Cook and Kibler, 2019;Fenner et al., 2019b;Dyson and Van Dijk, 2020;Christensen et al., 2021). It has been suggested that horses expressing discomfort, and thus, from a human point of view, seemingly resisting commands, be labeled as 'problem horses' and described with such anthropomorphic terms as 'lazy', 'mad', or 'stubborn' and exposed to punishment in training ...
Full-text available
Bit-related oral lesions are a common and painful welfare issue in horses. Even though horses have been ridden and driven with a bit and bridle for 6000 years and bit sores have been described already in the 19th century in the veterinary literature, scientific reports on bit-related lesions and their risk factors in horses remain scarce. The aim of this thesis was to (i) determine the occurrence of oral lesions in the bit area in Finnish trotters and event horses after competitions, (ii) create a scoring system for oral lesions in the bit area and demonstrate different lesion types and locations with photographs, (iii) investigate risk factors for bit-related lesions in trotters and event horses, (iv) further investigate different stakeholders’ attitudes towards bit-related lesions in trotters. The rostral part of the mouth of 469 horses (261 trotters, 208 event horses) was examined systematically after a competition. Trotters were examined in 10 racing events in 2017 and event horses in 8 competition events in 2018–2019. Many horses had multiple lesions, and therefore, a lesion scoring system was created in which points were given to each lesion depending on its size, type (bruise or wound), and depth (superficial or deep). Points for each lesion were summed such that each horse received a total lesion score that reflected the overall lesion status. No acute lesions were found in 42 trotters (16%), and lesion status was mild in 55 trotters (21%), moderate in 113 trotters (43%), and severe in 51 trotters (20%). In event horses, no lesions were found in 99 horses (48%), and lesion status was mild in 45 (22%), moderate in 55 (26%), and severe in 9 horses (4%). The most common lesion location was the inner lip commissure. Lesions were also found in the bars of the mandible in front of the first lower cheek tooth, in the buccal area near the first upper cheek tooth, and in the outer lip commissures. Only a few horses had mild lesions involving the tongue and one horse in the hard palate. Although 109 event horses and 219 trotters had oral lesions in the bit area, none of the event horses and only six trotters showed external mouth bleeding. Additionally, one event horse and 26 trotters had blood inside the mouth or on the bit when it was removed from the mouth. Associations between a horse’s moderate-severe oral lesion status and potential risk factors were analyzed with multivariable logistic regression analysis. The association between bit type and lesion location was examined with Fisher’s exact test. Risk factors for moderate-severe oral lesion status in trotters were the use of a Crescendo bit, a mullen mouth regulator bit, or an unjointed plastic bit (model Happy Mouth) and female sex (mare). In event horses, the risk factors were thin (10–13 mm) and thick (18–22 mm) bits, female sex (mare), and other than pony breed. In both disciplines, unjointed bits were associated with lesions in the bars of the mandible. Single-jointed snaffle bits were the most common bit type in trotters and the least associated with moderate-severe lesions. In event horses, double-jointed 14–17 mm bits were most common. Bit thickness of 14–17 mm was the least associated with moderate-severe lesion status. However, these results may at least partly reflect driveability or rideability issues, and thus, rein tension differences because drivers/riders may change to distinctive bit designs if they have difficulty eliciting an appropriate response with rein cues. In the pilot questionnaire study, imaginary scenarios and photographs of lesions from horses’ mouths were presented to different stakeholders (veterinarians and race veterinary assistants, trainers, and others). They were asked in multiple choice questionnaires whether they allow the horse to start in the race, stipulate a health certificate before the next race, or remove the horse from the race. The association between stakeholder groups and their answers was examined with the Pearson Chi-square test. The results of this study indicated differences in attitudes towards bit-related lesions between stakeholder groups but also within a stakeholder group. This might reflect differences in conflicts of interests, moral values, empathy, or over-exposure to oral lesions. Not removing horses with severe oral lesions from the race may compromise horse welfare and society’s trust in the surveillance system. In this study, oral lesions in the bit area were common after a competition, although only few horses showed external bleeding. Oral examination and an oral lesion scoring system with an assistant recording the findings were suitable for field conditions and horses seemed to tolerate the examination well. Even though changing the bit to the bits least associated with lesions may be beneficial, horses with oral lesions might benefit from training modifications. Given the higher risk observed for mares in this study, mare oral health warrants special attention. Results of this thesis encourage adopting bit area monitoring as a new routine by horse handlers and as a welfare measure by competition organizers in order to minimize pain and negative experiences by early diagnosis and treatment of mouth lesions.
... A bit that does not fit can potentially cause too much pressure, pinching or rubbing of oral tissues (12) or restrict tongue movement (7). An ill-fitting or inexpertly used bit can cause oral trauma (13)(14)(15)(16)(17) and thus discomfort or pain for the horse (3,18). Oral discomfort can lead to undesirable behavior such as avoiding the bit pressure by opening the mouth and protruding the tongue, or resisting bit pressure by grasping the bit between the teeth (1,4,7). ...
... Based on the radiographic study of the bit position within the horse's oral cavity, it is recommended that the center link should be short to avoid placing the joints directly over the bars of the lower jaw (6). Large variability in the surface morphology of the bars of the lower jaw has been noted, with some horses having rounded and others sharp-edged bars, which may predispose to injury (18,37). The orientation of the center link of the Bristol/French-link-type double-jointed bit affects the severity of the bit, a narrow surface on top of the tongue causing more pressure (5,10). ...
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A bit that fits is essential for horse welfare and good communication with the ridden, driven or led horses. The bit causes pressure on the sensitive structures of the horse mouth. The aim of this study was to investigate variation in oral dimensions related to bit fit in adult horses and ponies and to evaluate bit fit by comparing oral dimensions with the currently used bit size selected by the horse owner. The study population consisted of 554 horses and ponies, 308 geldings and 246 mares, age 5-29 years, presented for routine dental care. Oral dimensions: mouth width, distance between upper and lower jaw, tongue thickness and lower jaw width, were measured under sedation. Oral dimensions were compared with the most used bit mouthpiece size presented to the researcher by the owner. Bit type and material were recorded. All oral dimensions in adult horses and ponies varied by breed and sex. Mouth width and distance between upper and lower jaw correlated positively with age. Oral dimensions were significantly smaller in mares than in geldings. In coldblood Finnhorses, oral dimensions were greater than in other breeds; in ponies they were smaller. The majority of the oral dimensions correlated positively with each other. Lower jaw width did not correlate with tongue thickness. It was common to use a bit that did not fit the horse: the bit was either too short or too long (over 10 mm longer) compared to mouth width, compressed the tongue in between the upper and lower jaw, or the center link was of similar length compared to lower jaw width, thus possibly causing pressure points or a nutcracker effect on the bars of the lower jaw. Horses had, on average, space for a 14 mm thick bit without compressing the tongue. The results of this study can aid in choosing a horse bit size that fits correctly and does not cause discomfort. It is recommended that the fit of the bit is evaluated regularly as the horse ages.
... The equipment used in equestrian sports-such as bits, spurs, nosebands and whips-are often utilized in conjunction with aids from the rider/driver that apply pressure to various parts of the animal's body to amplify or refine the signal to the equid. Whilst these do not always incur pain or distress, they are still instruments of negative reinforcement or punishment and function through creating an inherently aversive stimulus to which the animal responds [186] and, thus, have the potential to impair welfare (see, for example, [187][188][189][190][191][192][193]). This risk may be increased if equipment is used by people who are inexperienced, uninformed about the manner in which these artificial aids function or lack knowledge of equine behavioural needs; conversely, when users are experienced, knowledgeable and compassionate, negative welfare implications should be minimised. ...
... Despite bits having been used for thousands of years as the primary means of control during riding and driving, it is often assumed they are both essential and ethical; however, research indicates that they can cause discomfort, pain, oral lesions, behavioural inhibition and, thus, also create fear and distress [188,191]. Any bit can create poor welfare if used incorrectly such as with excessive pressure, or by inexperienced riders/drivers [187,200]. However, risks are magnified with 'stronger' types of bit, which exert greater pressure or more severe action on the animal and, therefore, have more capacity to inflict pain and injury [77]. ...
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Equestrian sports, including racing (e.g., flat, steeple-chasing, harness or donkey derby); show-jumping; cross-country; dressage; polo; polocrosse; endurance; carriage driving; vaulting and hunting; are hugely popular in the UK, and they involve a significant number of people, both as participants and spectators, and tens of thousands of equids. In this paper, we discuss animal welfare as a complex and disputed issue, clarifying what the term means and how it can be measured. We review many aspects of welfare risk to equids used for sport, addressing issues encountered throughout their lives, including housing, feeding, veterinary intervention, shoeing, handling, training, breeding and equipment. This is followed by a unique exploration of the institutions and social processes influencing equine welfare. The institutional components comprise the rules of competition, the equids, attributes of the stakeholders and the space where participants strive to achieve a common purpose. We endeavour to untangle the most significant elements that create barriers or provide opportunities for equine welfare improvement. We expose the challenges faced by a broad range of stakeholders with differing ethics, attitudes and values. Evidently, there are many welfare risks to which equids used in sports continue to be exposed. It is also evident that significant improvements have occurred in recent times, but there remains a barrier to reducing the risks to an acceptable level. We conclude with recommendations regarding a process for change, involvement of stakeholders and management of knowledge to improve equine welfare that involves identifying and prioritising the risk factors and ultimately leading to interventions, further research and/or education.
... Animal advocacy informants in the same study additionally identified routine training and husbandry practices, human-horse interactions and the "everyday life of horses" as "where the real welfare issues are" in thoroughbred racing [3]. These are issues discussed in the general equine welfare literature and include topics such as housing [4][5][6][7], feeding [8,9], equine behaviour [10], equine emotions [11], equine welfare assessment [12,13], the application of equipment [14][15][16][17][18][19][20][21], equine learning and training [22,23], the impact of equine activities on the horse [24], human handling during various forms of human-horse interactions [25,26], impacts of riding on behaviour and welfare [27][28][29][30], horse-human relationships [31][32][33][34] and people's ability and inability to recognise behavioural signs of equine distress and pain [35][36][37][38]. A theme that unites these issues and that allows one to make assessments as to the welfare impact is naturalness, i.e., what is natural for the horse and what is in the horse's nature in relation to their species-specific, as well as individual, physiological; emotional; cognitive; social and behavioural characteristics, abilities and boundaries. ...
... They suggest "the non-recognition of clear behavioural evidence of horses' aversion to bits in their mouths arises because the indicative behaviours have been and are observed so commonly that, except in more extreme cases, they are considered to be normal" [17]. Cook and Kibler [20] (p. 551) suggest that, because bits have been standard equipment for millennia, they "are widely assumed to be indispensable and ethically justified". ...
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The idea of what is natural has particular relevance in the thoroughbred racing and breeding discourse. It guides breeding regulations; influences how the thoroughbreds’ behaviour is perceived and has implications for husbandry, handling, training and racing practices. This study investigates how key industry and animal advocacy informants based in the US, Australia and the UK conceptualise naturalness within the context of common racing practices that potentially impact the horses’ welfare. The informants were interviewed using semi-structured interviewing and photo-elicitation. Four common images of thoroughbreds on race day were presented to elicit the informants’ responses. Differences emerged between how the two groups tended to describe the images and the role naturalness played in their conceptualisations. The findings were analysed using an updated version of the Layers of Engagement with Animal Protection developed by Bergmann to situate the informants’ conceptualisations of naturalness within the wider thoroughbred protection discourse. In conclusion, the industry informants tended to defend the status quo of common racing practices. They tended to naturalise and normalise these practices and downplay their welfare impact. This poses risks for thoroughbred welfare, which are amplified by misrepresentations of what is natural. With the public’s understanding of welfare and racing practices growing, racing’s legitimacy may be further questioned. Opportunities to leverage the potential of the notion of naturalness for thoroughbred protection are discussed. [Available open access at]
... There is considerable controversy about the use of potentially restrictive nosebands (Fenner et al. 2016;Doherty et al. 2017;Uldahl and Clayton 2019) and the use of a bit as opposed to a bitless bridle (Cook and Kibler 2019;Mellor 2020). In a study of 148 ridden horses, those wearing crank cavesson nosebands compared with cavesson nosebands had significantly higher RHpE scores, but there was no effect of other noseband types (Dyson et al. 2020c). ...
The Ridden Horse Pain Ethogram (RHpE) comprises 24 behaviours, the majority of which are at least 10 times more likely to be seen in lame horses compared with non‐lame horses. The observation of ≥8/24 behaviours is likely to reflect the presence of musculoskeletal pain, although some lame horses score <8/24 behaviours. A marked reduction in RHpE scores after resolution of lameness using diagnostic anaesthesia proves a causal relationship between pain and RHpE scores. Horses should be assessed for approximately 10 min in walk, trot (including 10 m diameter circles), canter and transitions. The validity of the RHpE has been verified for use in horses which perform dressage‐type movements, and which have been trained to work with the front of the head in a vertical position. It has not, as yet, been used in horses while jumping, racehorses, western performance or endurance horses. The RHpE provides a valuable tool for riders, trainers, veterinarians and other equine professionals to recognise the presence of musculoskeletal pain, even if overt lameness cannot be recognised. Riders with a higher skill‐level may improve gait quality, but cannot obscure behavioural signs of pain, although specific behaviours may change. Tight saddle tree points, the rider sitting on the caudal third of the saddle and rider weight may influence RHpE scores. Accurate application of the RHpE requires training and practice. The RHpE is a powerful tool for the assessment of ridden horses and the identification of likely musculoskeletal pain. Such pain merits further investigation and treatment, to improve equine welfare and performance. The RHpE provides an additional means of evaluating the response to diagnostic anaesthesia. It provides a mechanism for client education and a diplomatic way of communicating with clients about equine discomfort related to saddle‐fit, rider size, their position in the saddle and ability to ride in balance.
... Horses can be controlled without a bit during exercise [10], but bitting is considered an obligatory safety measure in harness racing. Successful bit use is based on the principles of negative reinforcement, and problematic behavioural consequences of erroneously applied pressure or pain are common and well described elsewhere (see for example [11,12]). ...
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Background: Bit-related lesions in competition horses have been documented, but little evidence exists concerning their potential risk factors. Objectives: To explore potential risk factors for oral lesions in Finnish trotters. Study design: Cross-sectional study. Methods: The rostral part of the mouth of 261 horses (151 Standardbreds, 78 Finnhorses and 32 ponies) was examined after a harness race. Information on bit type, equipment and race performance was collected. Results: A multivariable logistic regression model of Standardbreds and Finnhorses showed a higher risk of moderate or severe oral lesion status associated with horses wearing a Crescendo bit (n = 38, OR 3.6, CI 1.4-8.9), a mullen mouth regulator bit (n = 25, OR 9.9, CI 2.2-45) or a straight plastic bit (n = 14, OR 13.7, CI 1.75-110) compared with horses wearing a snaffle trotting bit (n = 98, P = 0.002). Bar lesions (67 horses) were more common in horses wearing unjointed bits than in horses wearing jointed bits (Fisher's exact test P < 0.001). Lesions in the buccal area and the inner lip commissures were not associated with bit type. Using a tongue-tie or an overcheck, galloping, placement in the top three or money earned in the race were not associated with lesion risk. Main limitations: The sample size for certain bit types was insufficient for statistical analysis. Conclusions: Moderate and severe oral lesion status was more common in horses wearing a Crescendo bit, a mullen mouth regulator bit or a straight plastic bit than in horses wearing a single-jointed snaffle trotting bit. However, lesions were observed regardless of bit type. Further studies on rein tension, the interaction between bit type and rein tension, and prevention of mouth lesions in trotters are warranted.
Globally, calls for change in the horse industry to prioritise the health and well-being of domestic horses (Equus caballus) are reaching a critical threshold. Horse behaviour deemed undesirable or inconvenient by owners (henceforth referred to as undesirable behaviour) is reported across all aspects of a horse’s life and may indicate a welfare issue. This study proposes a reconceptualisation of undesirable horse behaviour as a complex challenge based on systems thinking. Emerging from the natural sciences, systems thinking is an interdisciplinary approach to complex challenges (such as undesirable behaviour) as dynamic, highly interconnected networks of components and feedback relationships. This critical literature review examined the undesirable behaviours studied, the disciplines conducting research and their underpinning assumptions to identify opportunities for approaching research differently. Four themes emerged from the literature: undesirable behaviour is typically studied with unarticulated assumptions and in individual disciplines; behaviours are typically studied in isolation with the complexity of horse-human interactions generally not considered; management of behaviour typically has an anthropocentric linear ‘cause and effect’ focus; and solutions to undesirable behaviour are often short-term ‘fixes’ resulting in poor horse outcomes. From these, we outline the opportunities that each provide the next generation of horse research in terms of interdisciplinarity, systems thinking and management. Undesirable horse behaviour in a horse-human system is conceptually mapped in terms of factors associated with the behaviour (eg housing, stress, diet), and the relationships between them. Systems thinking offers a way to integrate multiple disciplines and identify and navigate new solutions to promote horse welfare.
There is an increasing trend towards the use of bitless bridles within the equine industry, but a lack of quantitative literature on their effects. This study aimed to measure the pressures underneath the noseband and headpiece of two designs of bitless bridle in comparison to a bitted snaffle bridle, and to measure trot kinematics in all three bridles. Five horses were each ridden in three different bridles, a snaffle bridle with cavesson noseband (SN), a side pull bitless bridle (SP), and a cross under bitless bridle (CU), over three days in a Latin square design. The SP bridle showed a significantly higher average noseband pressure (4.42 ± 1.52 N/cm2; median ± IQR) than the SN (2.67 ± 1.00 N/cm2) with the CU sitting between the two (2.96± 1.00 N/cm2). The pressures exerted by the SP design could be capable of causing tissue damage if sustained for long periods of time. The pressure increase is likely due to the attachment of the reins directly to the noseband in the SP bridle, meaning rein tension is concentrated on the frontal nasal plane, rather than being distributed more evenly across the head. There was no significant difference in headpiece pressures between the bridles. In the CU bridle a significant reduction in carpal flexion (98.10 ± 7.98o) and a more extended head and neck angle (112.04 ± 3.01o) were seen compared to the SN (93.58 ± 7.32o and 105.94 ± 6.98o respectively). These changes are associated with an extended back posture and reduced performance, and may be a result of avoidance behaviors arising from pressures underneath the jaw due to this bridle design. Removal of the bit from the horse's mouth means that rein tension forces are distributed to other facial structures. This study demonstrates that these forces are sufficiently high to possibly have detrimental effects. The design and use of bitless bridles should be carefully considered in light of this finding.
Nonspecific performance and rideability issues are more likely a manifestation of pain in the ridden horse rather than a true behavioural problem. A systematic and thorough investigation focusing on the potential presence of pain‐related conditions is thus crucial in horses with such complaints. It can, however, be challenging to determine whether the complaint is indeed related to pain, where the pain is located, and what the underlying cause is. This review describes the challenges of pain recognition in ridden horses and summarises the recently developed ridden horse ethograms that might enable pain to be assessed in an objective, valid and reliable way. Furthermore, the differential diagnosis and diagnostic approach to horses presenting potentially pain‐related performance and rideability issues are discussed.
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A proposition addressed here is that, although bitted horses are viewed by many equestrians as being largely free of bit-related mouth pain, it seems likely that most behavioural signs of such pain are simply not recognised. Background information is provided on the following: the major features of pain generation and experience; cerebrocortical involvement in the conscious experience of pain by mammals; the numerous other subjective experiences mammals can have; adjunct physiological responses to pain; some general feature of behavioural responses to pain; and the neural bases of sensations generated within the mouth. Mouth pain in horses is then discussed. The areas considered exclude dental disease, but they include the stimulation of pain receptors by bits in the interdental space, the tongue, the commissures of the mouth, and the buccal mucosa. Compression, laceration, inflammation, impeded tissue blood flow, and tissue stretching are evaluated as noxious stimuli. The high pain sensitivity of the interdental space is described, as are likely increases in pain sensitivity due to repeated bit contact with bruises, cuts, tears, and/or ulcers wherever they are located in the mouth. Behavioural indices of mouth pain are then identified by contrasting the behaviours of horses when wearing bitted bridles, when changed from bitted to bit-free bridles, and when free-roaming unbitted in the wild. Observed indicative behaviours involve mouth movements, head-neck position, and facial expression (“pain face”), as well as characteristic body movements and gait. The welfare impacts of bit-related pain include the noxiousness of the pain itself as well as likely anxiety when anticipating the pain and fear whilst experiencing it, especially if the pain is severe. In addition, particular mouth behaviours impede airflow within the air passages of the upper respiratory system, effects that, in their turn, adversely affect the air passages in the lungs. Here, they increase airflow resistance and decrease alveolar gas exchange, giving rise to suffocating experiences of breathlessness. In addition, breathlessness is a likely consequence of the low jowl angles commonly maintained during dressage. If severe, as with pain, the prospect of breathlessness is likely to give rise to anxiety and the direct experience of breathlessness to fear. The related components of welfare compromise therefore likely involve pain, breathlessness, anxiety, and fear. Finally, a 12-point strategy is proposed to give greater impetus to a wider adoption of bit-free bridles in order to avoid bit-induced mouth pain.
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In accord with contemporary animal welfare science understanding, the Five Domains Model has a significant focus on subjective experiences, known as affects, which collectively contribute to an animal's overall welfare state. Operationally, the focus of the Model is on the presence or absence of various internal physical/functional states and external circumstances that give rise to welfare-relevant negative and/or positive mental experiences, i.e., affects. The internal states and external circumstances of animals are evaluated systematically by referring to each of the first four domains of the Model, designated "Nutrition", "Environment", "Health" and "Behaviour". Then affects, considered carefully and cautiously to be generated by factors in these domains, are accumulated into the fifth domain, designated "Mental State". The scientific foundations of this operational procedure, published in detail elsewhere, are described briefly here, and then seven key ways the Model may be applied to the assessment and management of animal welfare are considered. These applications have the following beneficial objectives-they (1) specify key general foci for animal welfare management; (2) highlight the foundations of specific welfare management objectives; (3) identify previously unrecognised features of poor and good welfare; (4) enable monitoring of responses to specific welfare-focused remedial interventions and/or maintenance activities; (5) facilitate qualitative grading of particular features of welfare compromise and/or enhancement; (6) enable both prospective and retrospective animal welfare assessments to be conducted; and, (7) provide adjunct information to support consideration of quality of life evaluations in the context of end-of-life decisions. However, also noted is the importance of not overstating what utilisation of the Model can achieve.
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Simple Summary Horses have superior athletic capabilities due largely to their exceptional cardiorespiratory responses during exercise. This has particular relevance to horses’ potential to experience breathlessness, especially when their athletic performance is reduced by impaired respiratory function. Breathlessness, incorporating three types of unpleasant experiences, has been noted as of significant animal welfare concern in other mammals. However, the potential for breathlessness to occur in horses as usually ridden wearing bitted bridles has not yet been evaluated in detail. Accordingly, key physiological responses to exercise and the consequences of impaired respiratory function are outlined. Then the physiological control of breathing and the generation of the aversive experiences of breathlessness are explained. Finally, the potential for horses with unimpaired and impaired respiratory function to experience the different types of breathlessness is evaluated. This information provides a basis for considering the circumstances in which breathlessness may have significant negative welfare impacts on horses as currently ridden wearing bitted bridles. Potential beneficial impacts on respiratory function of using bitless bridles are then discussed with emphasis on the underlying mechanisms and their relevance to breathlessness. It is noted that direct comparisons of cardiorespiratory responses to exercise in horses wearing bitless and bitted bridles are not available and it is recommended that such studies be undertaken. Abstract Horses engaged in strenuous exercise display physiological responses that approach the upper functional limits of key organ systems, in particular their cardiorespiratory systems. Maximum athletic performance is therefore vulnerable to factors that diminish these functional capacities, and such impairment might also lead to horses experiencing unpleasant respiratory sensations, i.e., breathlessness. The aim of this review is to use existing literature on equine cardiorespiratory physiology and athletic performance to evaluate the potential for various types of breathlessness to occur in exercising horses. In addition, we investigate the influence of management factors such as rein and bit use and of respiratory pathology on the likelihood and intensity of equine breathlessness occurring during exercise. In ridden horses, rein use that reduces the jowl angle, sometimes markedly, and conditions that partially obstruct the nasopharynx and/or larynx, impair airflow in the upper respiratory tract and lead to increased flow resistance. The associated upper airway pressure changes, transmitted to the lower airways, may have pathophysiological sequelae in the alveolae, which, in their turn, may increase airflow resistance in the lower airways and impede respiratory gas exchange. Other sequelae include decreases in respiratory minute volume and worsening of the hypoxaemia, hypercapnia and acidaemia commonly observed in healthy horses during strenuous exercise. These and other factors are implicated in the potential for ridden horses to experience three forms of breathlessness—”unpleasant respiratory effort”, “air hunger” and “chest tightness”—which arise when there is a mismatch between a heightened ventilatory drive and the adequacy of the respiratory response. It is not known to what extent, if at all, such mismatches would occur in strenuously exercising horses unhampered by low jowl angles or by pathophysiological changes at any level of the respiratory tract. However, different combinations of the three types of breathlessness seem much more likely to occur when pathophysiological conditions significantly reduce maximal athletic performance. Finally, most horses exhibit clear behavioural evidence of aversion to a bit in their mouths, varying from the bit being a mild irritant to very painful. This in itself is a significant animal welfare issue that should be addressed. A further major point is the potential for bits to disrupt the maintenance of negative pressure in the oropharynx, which apparently acts to prevent the soft palate from rising and obstructing the nasopharynx. The untoward respiratory outcomes and poor athletic performance due to this and other obstructions are well established, and suggest the potential for affected animals to experience significant intensities of breathlessness. Bitless bridle use may reduce or eliminate such effects. However, direct comparisons of the cardiorespiratory dynamics and the extent of any respiratory pathophysiology in horses wearing bitted and bitless bridles have not been conducted. Such studies would be helpful in confirming, or otherwise, the claimed potential benefits of bitless bridle use.
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Adopting the concept of One Welfare could help to improve animal welfare and human wellbeing worldwide, argue Rebeca García Pinillos, Michael Appleby, Xavier Manteca, Freda Scott-Park, Charles Smith and Antonio Velarde Toll free link to the full text -
There is evidence that more than 47% of the sports horse population in normal work may be lame, but the lameness is not recognized by owners or trainers. An alternative means of detecting pain may be recognition of behavioral changes in ridden horses. It has been demonstrated that there are differences in facial expressions in nonlame and lame horses. The purpose of this study was to develop a whole horse ethogram for ridden horses and to determine whether it could be applied repeatedly by 1 observer (repeatability study, 9 horses) and if, by application of a related pain behavior score, lame horses (n = 24) and nonlame horses (n = 13) could be differentiated. It was hypothesized that there would be some overlap in pain behavior scores among nonlame and lame horses; and that overall, nonlame horses would have a lower pain behavior score than lame horses. The ethogram was developed with 117 behavioral markers, and the horses were graded twice in random order by a trained specialist using video footage. Overall, there was a good correlation between the 2 assessments (P < 0.001; R² = 0.91). Behavioral markers that were not consistent across the 2 assessments were omitted, reducing the ethogram to 70 markers. The modified ethogram was applied to video recordings of the nonlame horses and lame horses (ethogram evaluation). There was a strong correlation between 20 behavioral markers and the presence of lameness. The ethogram was subsequently simplified to 24 behavioral markers, by the amalgamation of similar behaviors which scored similarly and by omission of markers which showed unreliable results in relation to lameness. Following this, the maximum individual occurrence score for lame horses was 14 (out of 24 possible markers), with a median and mean score of 9 (±2 standard deviation) compared with a maximum score of 6 for nonlame horses, with a median and mean score of 2 (±1.4). For lame horses, the following behaviors occurred significantly more (P < 0.05, chi-square): ears back, mouth opening, tongue out, change in eye posture and expression, going above the bit, head tossing, tilting the head, unwillingness to go, crookedness, hurrying, changing gait spontaneously, poor quality canter, resisting, and stumbling and toe dragging. Recognition of these features as potential indicators of musculoskeletal pain may enable earlier recognition of lameness and avoidance of punishment-based training. Further research is necessary to verify this new ethogram for assessment of pain in ridden horses.
Poor performance in horses is often attributed to rider or training problems or behavioural abnormalities. Riders often fail to recognise lameness. We need to determine if there are differences in facial expression in lame and non-lame horses when ridden, which may facilitate the identification of horses experiencing pain. A previously developed facial expression for ridden horses ethogram (FEReq) was applied blindly by a trained analyst to photographs (n=519) of the head and neck of lame (n=76) and non-lame (n=25) horses acquired during ridden schooling-type work at both trot and canter. These included images of seven lame horses acquired before (n=30 photographs) and after diagnostic analgesia had abolished lameness (n=22 photographs). A pain score (0-3; 0=normal, 1-3=abnormal) was applied to each feature in the ethogram, based on published descriptions of pain in horses. Pain scores were higher for lame horses than non-lame horses (p<0.001). Total pain score (p<0.05), total head position score (p<0.01), and total ear score (p<0.01) were reduced in lame horses after abolition of lameness. Severely ‘above the bit’, twisting the head, asymmetrical position of the bit, ear position (both ears backwards, one ear backwards and one to the side, one ear backwards and one ear forwards) and eye features (exposure of the sclera, the eye partially or completely closed, muscle tension caudal to the eye, an intense stare) were the best indicators of pain. Application of the FEReq ethogram and pain score could differentiate between lame and non-lame horses. Assessment of facial expression could potentially improve recognition of pain-related gait abnormalities in ridden horses.
Many horses presumed to be sound by their riders are not. Facial expression ethograms have previously been used to describe pain-related behavior in horses, but there is a need for a ridden horse facial ethogram to facilitate identification of pain in ridden horses. The objectives of this study were to develop and test an ethogram to describe facial expressions in ridden horses and to determine whether individuals could interpret and correctly apply the ethogram, with consistency among assessors. An ethogram was developed by reference to previous publications and photographs of 150 lame and non-lame ridden horses. A training manual was created. Thirteen assessors (veterinarians of variable experience, n=4; equine technicians, n=3; equine studies graduates, n=2; amateur horse owners, n=2; equine veterinary nurse, n=1; a British Horse Society Instructor, n=1) underwent a training session and, with reference to the training manual, evaluated still lateral photographs of 27 Training heads. Features were graded as Yes, No or ‘Cannot see’ (when it was not possible to determine the presence or absence of a feature). The ethogram was adapted and, after further training, the assessors blindly evaluated 30 Test heads from non-lame and lame horses. Intra-class correlation (ICC) and free-margin Kappa tests were used to assess consensus among assessors. For the Training heads, single ICC matrix among observers resulted in an overall ICC of 0.50 (95% Confidence Intervals [CI], 0.40-0.62). Four assessors consistently scored differently from the others, with ranges of ICC of 0.20-0.50 (mean 0.41). There was no difference in assessors’ scoring related to their professional backgrounds. For the Test heads, mean inter-rater agreement among assessors was 87%. Two assessors still scored consistently differently (0.28-0.50 ICC agreement; mean 0.40) from the remaining 11 assessors (0.44-0.69 ICC agreement; mean 0.56). The mean percentage of overall agreement was 80% and the mean free-marginal Kappa value was 0.72, standard deviation (SD) ± 0.22. The large SD was the result of inconsistency in assessments of the eyes and muzzle. It was concluded that the developed ethogram could reliably be utilised to describe facial expressions of ridden horses by people from different professional backgrounds. Future work needs to determine if non-lame and lame horses can be differentiated based on application of the ethogram.
An ethological survey was based on 605 written reports from horsemen who had switched from a bitted bridle to a new bitless bridle. The comparison of equine behaviour was between an invasive and painful method of control (a bitted bridle) and a non-invasive and painless method (a bitless bridle). The unprecedented opportunity to switch a horse, overnight, from painful to painless control revealed many new and serious manifestations of the syndrome 'aversion to the bit.' The survey demonstrated that the bit method of control caused 58 adverse behavioral effects. All 58 effects could be classified under four major effects; to instill fear, to trigger flight, to make the horse fight back, and to cause facial neuralgia (the headshaking syndrome). These effects could all, in turn, be categorized as responses to oral pain. The sensory pathway for registering pain caused by the bit is the trigeminal nerve but the motor pathways involved many systems, with the nervous, respiratory and musculoskeletal systems predominating. The behavioral responses interfered, in particular, with attitude to exercise, breathing and locomotion. A survey of 65 horse skulls revealed painful, bit-induced exostoses on the mandibular diastema in 49 (75%). It was concluded that a bit is harmful to the health and safety of horse and rider, and an impediment to performance.