Straight from the horse’s mouth : What we can learn about rein tension by observing horse behaviour

Horse-rider-interaction is largely dependent on rein tension signals which, through pressure and release, communicate with the horse about pace, direction of travel and appropriate head posture. However, the pressures applied on the horse’s mouth and/or head via the reins can cause pain and discomfort, leading to evasive behaviour and oral injuries. This thesis investigated rein tension signals from the perspective of equine behaviour and learning. Rein tension data were collected while backing up the horse from stand-still, with the handler standing next to the horse, comparing a bitted bridle with a soft halter, and in the ridden horse, making transitions from trot to walk using a bitted bridle. The results showed that rein tension signal magnitude could be reduced in a single training session through applying classical and operant learning principles. The rein tension signal was characterised by an increase in rein tension of less than 10 N (less than ~1kg) in each rein, regardless of baseline rein tension. Bit pressure elicited more evasive head/neck/mouth behaviour, with the main function to reduce oral pressure, compared with pressure on the nose from a soft halter. In terms of learning, the horses performed equally well with the halter and the bitted bridle. Thus studying horse behaviour can reveal the rein tension magnitude at which a horse feels comfortable and rein tension can be effectively reduced using the principles of classical and operant learning

Rein tension in 8 professional riders during regular training sessions

AbstractRein tension signals are commonly used to communicate the intended speed, direction, and head carriage to the horse during horseback riding. Rein tension has previously been recorded relative to gait, exercises, and turning maneuvers. The aim of this study was to target the between-gait and between-exercise variation in rein tension, controlling for riders and horses within riders, the between-rein variation, and the general within-gait or exercise variation, during entire riding sessions. Eight riders with 3 horses each were included in the study and each horse was fitted with a custom-made rein tension meter fastened on leather reins. Rein tension data and video films were collected during the riding session, and the video films were scrutinized and categorized according to ridden exercises. Statistics used to model rein tension in mixed models were “median”, area under curve, averages of 2 and 25 percentiles (“low”) and of 75 and 98 percentiles (“high”), and the difference between 98 and 2 percentiles (“range”). Fixed effects were rein, gait, rider's position, horse level, and type of ridden exercise, and random effects were horse-side, rider, horse, and trial within horse. The analyses demonstrate substantial variation between gaits, rider position within gait, and between riders and horses. Considering data on short reins, the major determinants found for amount of rein tension was gait (walk [median 12 N both reins] <trot [median 14-19 N left/right rein and sitting/posting] <canter [median 13-24 N left/right rein and sitting/light seat]) as well as the rider's position in the saddle for trot (posting [median 14 N both reins] <sitting [median 17 N/19 N left/right rein]) and canter (light seat [median 13-17 N left/right rein and left/right canter] <sitting [median 20-24 N left/right rein and left/right canter]). Regarding the 2 reins; the right rein was the highest in comparisons in the “high” and “range” models, whereas the inside rein was the highest in canter. Riders contributed to most of the variation in the “median” and “low” models, whereas horses contributed the highest relative variance estimates in the models associated with high rein tension (“high” and “range”). Our results suggest that variables to consider in rein tension studies are the gait of travel, the rider's position in the saddle, the ridden exercise performed, the educational level of horse, the rider and horse per se, and to some extent the left or right rein

The effects of the rider's rein signals on the horse's behaviour and the pressure on the reins

This essay derives from the concern that horses ridden with a bit in their mouth can be subjected to strong pressure from the bit if the horse and rider do not understand each other. The horse's mucosa membrane and the tongue are very sensitive tissues (Cook, 1999; Manfredi, 2005; Oliveira, 2005; Terada, 2006) and the bit can then be a source of pain and discomfort. The training of the horse should therefore always be a step by step process and as the horse develops difficulties are increased. Oliveira (2005) suggested that high demands can be placed on the horse but to be successful in the training it is essential to be content with small progress and reward the slightest desired response from the horse. This corresponds with the principles of operant conditioning with negative reinforcement. On this basis an interest was formed to study the rider's rein signals to the horse with the focus on the horse's behaviour and the pressure created through the reins. According to the learning theory negative reinforcement, essential concerning the signals to the horse are the time period the signal is applied and the timing when the signal disappears. On this foundation we decided to test and compare two different methods to slow down the horse from trot to walk. One method (1) consisted of the riders slowing down the horses gradually through a decrease in tempo releasing the reins at the slightest obedience from the horse. The other method (2) consisted of the riders slowing down the horses to the walk more abruptly, not giving on the reins until the horse was walking. The purpose was to study how the riders rein signals affect the horse's behaviour and the tension in the reins and if the rein tension and unwanted behaviours from the horse differ between the two treatments. For the experiment four riders and four horses where used. The horses were started under saddle 3-7 months before the experiment began. All horses were tested with all riders and with both treatments during four days. Each horse was only tested once a day, but with both methods. For data collection we used a rein tension meter (Signal Scribe) and a video camera, manually synchronised with each other. During the processing of the material the horse’s behaviour and the rider's signals were recorded as well as the rein tension that was created during the transitions. Our results show that when the riders asked the horses to slow down gradually, according to treatment 1, the horses showed fewer unwanted behaviours and there was a lower rein tension compared to when asked to make the transition immediately, treatment 2. The rider pulling back on the reins turned out to be a factor that also created unwanted behaviour. This study shows that if one wants to care for the welfare of the horse one should be concerned to follow the principles of learning theory and reinforce the horse a lot by removing the rein signal at the slightest response from the horse and to avoid pulling back on the reins

The movement of the rider’s hand related to the horse’s behaviour and the stride cycle

One way of signalling commands to the horse during riding is through applying tension on the reins to create bit pressure in the horse‟s mouth (Terada et al., 2006; Clayton et al., 2011). The skilfulness of the rider in using the hands when applying bit pressure has consequences both for the horse‟s performance and welfare (Manfredi et al., 2010). At the trot there are large vertical deviations of the horse‟s body which the rider must adjust and adapt to (Terada et al., 2006) and an unsteady hand due to inability to follow the horse‟s movement can be a source of discomfort and conflict behaviour in the horse (Heleski et al., 2009). By examining the rider‟s signals and the horse‟s behavioural expression, clues can be received about the horse‟s experience of its training. The aim of this project was to describe the rider‟s hand movement and the horse‟s head movement during sitting trot and to find relationships between these variables, the horse‟s behaviour, the rein tension and the stride cycle. The hypothesis was that the rider‟s hand will interact with the horse through the reins in a regular pattern correlated to the horse‟s head movement and stride cycle and that the horse will show behavioural responses to these interactions. Seven dressage horses were ridden in trot on a treadmill with an integrated force measuring system and infrared cameras registering the position of reflective markers on the horse‟s head and the rider‟s hands. Three horses wore a rein tension meter and all horses were studied for behavioural responses. Behavioural responses included changes in head-, ear- and tail position as well as gestures with the mouth. Ground reaction forces (GRF) were used to define the stride cycle. All data were normalised into 101 data points, 0-100 % of a stride cycle. From the normalised stride curves, range of motion, mean values and variation were calculated. The kinematic, behavioural and rein tension data were related to the stride cycle and examined for their general activity. The rider‟s hand movement and the horse‟s head movement followed the same movement pattern in the X- and Z-axis. Increased proportion of mouth behaviours, increased distance between the rider‟s hand and the horse‟s head as well as increased rein tension were all associated with the suspension phase at the trot. Behavioural registration combined with biomechanical measurement yields information about the horse‟s response to rider actions and is beneficial when evaluating training techniques and rider performance.Ryttarens hand kan, genom tygeln, skapa ett tryck från bettet i hästens mun och detta är ett sätt att signalera sin vilja till hästen under ridning. Hur pass skicklig ryttaren är på att utföra denna signal med sin hand har konsekvenser för hästens välfärd och prestation. Vidare rör sig hästens kropp under trav i ett rörelsemönster som innebär stora vertikala förändringar och detta måste ryttaren anpassa sin kropp och framförallt sin hand till. Om handen inte följer hästens rörelser kan det skapa obehag för hästen och leda till konfliktbeteenden. Genom att analysera ryttarens signaler och hästens beteenderespons under ridning kan man hitta ledtrådar till hur hästen upplever träningen. Syftet med denna studie var att beskriva ryttarens handrörelser och hästens huvudrörelser under nedsutten trav och att hitta samband mellan dessa två variabler samt hästens beteende, tygeltrycket och stegcykeln. Hypotesen var att ryttarens hand interagerar med hästen genom tyglarna i ett regelbundet mönster korrelerat med hästens huvudrörelser och stegcykeln och att hästen kommer att visa beteenderespons på dessa interaktioner. Sju dressyrhästar reds i trav på en rullande matta med ett integrerat kraftmätningssystem. På hästarnas huvud och ryttarens händer fästes markörer vars position registrerades med hjälp av infraröda kameror. Tre hästar reds med tygeltrycksmätare och alla hästar studerades för beteenderespons, vilka inkluderade förändring i huvud-, öron- och svansposition samt uttryck med munnen. Markens reaktionskraft (GRF) användes för att definiera stegcykeln. All data normaliserades till 101 datapunkter, 0-100 % av stegcykeln. Utifrån de normaliserade stegkurvorna beräknades rörelseomfång, medelvärden och variation. Ryttarens handrörelser och hästens huvudrörelser följer samma rörelsemönster i X- och Z-led. En ökad proportion munbeteenden, ett ökat avstånd mellan ryttarens hand och hästens huvud samt ett ökat tygeltryck hörde alla samman med svävningsfasen i trav. Beteenderegistrering kombinerat med biomekaniska mätningar ger information om hästens respons på ryttarens signaler och är värdefullt vid utvärdering av träningstekniker samt ryttarens prestation

Hur man bygger en tygeltrycksmätare

A large part of the interactions between horse and rider during horseback riding takes place through the reins and the bit and devices for measuring the tension on the reins, rein tension meters, has fairly recently been developed. To safeguard the welfare of the ridden horse riders need to be aware of the rein tension they apply and actively work to decrease it. Furthermore, there is a need to develop the study of rein tension through new techniques and refined analysis procedures. A good-quality rein tension meter should be small in size, sensitive, durable and as accurate for light rein tension as for strong forces. Rein tension meters used in research on horse and rider interaction commonly depend on strain gauge technique for generating rein tension data. Strain gauges are electrical resistances and when subjected to tension or compression the resistance change. By connecting the strain gauges in a Wheatstone bridge circuit the sensitivity of the measure is increased and the circuit is compensated for temperature changes. The aim of this project was to create a durable rein tension meter at a low cost that would be as accurate for high loads as for small changes of tension. The rein tension meter was made from bent stainless spring steel, strain gauges, a custom made amplifier and electric cable. Three different sizes of steel, 140*40*1 mm (large), 110*35*1 mm (medium) and 90*30*1.5 mm (small) and two different types of strain gauges, pairs of parallel strain gauges and pairs of perpendicular strain gauges, were tested. Power and logging of data was supplied through an Inertial Measurement Unit. The rein tension meters were calibrated by lifting known weights and were tested at local riding schools as well as with privately owned horses. The maximum force the steel could withstand was calculated and the stability of the output voltage to the same weight was tested. A polynomial regression calculation was used to convert the voltage output received from the ridden tests into rein tension in kilograms. The results show that the pairs of parallel strain gauges were most appropriate to use, the small size meter was most durable due to being thickest and the small size meter also had the most appropriate measuring range of 285 g to >30 kg. Repeated calibrations of the small rein tension meter with the same weight yielded similar values. The mean of the mean rein tension received from the school horses were 1.2 kg for the left rein and 1.11 kg for the right rein. The maximum rein tension registered was with a horse that was difficult for the rider to control and would run off frequently during the ride and its highest rein tension peak reached 31.58 kg. In conclusion, the rein tension meters created were found to be both durable and accurate and well suited for rein tension measurements and the small size rein tension meter with a measuring range of >30 kg is likely enough to register rein tension in most horses and riders. This rein tension meter can also potentially synchronize the rein tension data with the stride cycle. To safeguard the welfare of the horse, training techniques and rider performance need to be measured and evaluated and a tool like this rein tension meter makes it possible to monitor, at least in part, the interactions taking place between horse and rider.En stor del av kommunikationen mellan häst och ryttare sker via tyglarna och bettet och relativt nyligen har instrument som kan mäta kraften i tyglarna under ridning börjat användas inom forskningen, så kallade tygeltrycksmätare. Som ryttare bör man vara medveten om det tygeltryck man använder under ridning och för att säkerställa hästens välmående bör man aktivt sträva efter att minska tygeltrycket. Vidare bör forskningen på tygelkrafter under ridning utvecklas genom ny teknik och förbättrade analysmetoder. En tygeltrycksmätare av god kvalité bör vara liten, känslig, hållbar och lika exakt i sina mätvärden för små som stora krafter. De tygeltrycksmätare som tidigare har använts inom forskning på ridning bygger på trådtöjningsgivare. När en trådtöjningsgivare utsätts för töjning eller kompression ändras dess elektriska motstånd och genom att koppla ihop trådtöjningsgivarna i en s.k. Wheatstone brygga ökar mätningens känslighet och den elektriska kretsen kan kompensera för temperaturskillnader utan att det påverkar de elektriska värdena. Syftet med detta projekt var att skapa en hållbar tygeltrycksmätare till en låg kostnad med exakta mätvärden för såväl små som stora tygelkrafter. Som material användes böjt rostfritt bandstål, trådtöjningsgivare, en förstärkare och elektrisk kabel. Tre olika storlekar på stål, 140*40*1 mm, 110*35*1 mm och 90*30*1,5 mm, och två olika typer av trådtöjningsgivare (parallella par och vinkelräta par) testades. En Inertial Measurement Unit gav tygelmätaren ström och lagrade tygeltrycksdata. Tygeltrycksmätarna kalibrerades genom att lyfta kända vikter och testades även under ridning. Den maximala kraften stålet kunde tåla beräknades och stabiliteten i voltutslagen testades. Genom en beräkning av polynomförhållandet mellan kända vikter och voltutslag under kalibrering kunde tygeltrycksdata från ridningen omvandlas till kilogram tygeltryck. Resultaten visade att par av parallella trådtöjningsgivare är mest lämpliga att använda, att den minsta storleken på stål var mest hållbar, då den också var tjockast, och att denna minsta mätare även hade det mest lämpliga mätområdet på 285 g till >30 kg. Vidare gav upprepad mätning av samma vikt under kalibreringen liknande värden. Medeltygeltrycket var 1,2 kg för vänster tygel och 1,11 kg för höger tygel då ridskolehästar reds med mätarna. Det maximala tygeltrycket som uppmättes under ridningen var med en häst som var svårkontrollerad och drog iväg med ryttaren och tygeltrycket nådde då som högsta 31,58 kg. Sammanfattningsvis blev tygeltrycksmätarna både hållbara och exakta i sina mätvärden och fungerade väl för tygeltrycksmätningar på häst. Den minsta storleken på mätare med ett mätområde på >30 kg är troligtvis nog för att registrera tygeltryck hos de flesta ekipage. Denna tygelmätare kan troligtvis även användas för att synkronisera tygeltrycksdata med stegcykeln. För att säkerställa hästens välfärd under ridning bör träningsmetoder och ryttarens interaktion med hästen mätas och utvärderas och ett verktyg som denna tygeltrycksmätare gör det möjligt att, i alla fall delvis, följa samspelet mellan häst och ryttare

Rein Tension Signals Elicit Different Behavioral Responses When Comparing Bitted Bridle and Halter

When a rider maintains contact on the reins, rein tension will vary continuously in synchronicity with the horse's gait and stride. This continuous variation makes it difficult to isolate the rein tension variations that represent a rein tension signal, complicating interpretation of rein tension data from the perspective of horse-rider interaction. This study investigated (1) the characteristics of a rein tension signal and (2) horse response to a rein tension signal for backing, comparing pressure applied by a bit (bridle), or by a noseband (halter). Twenty Warmblood horses (10 young, 10 adult) wearing a rein tension meter were trained to step back in the aisle of a stable. The handler stood next to the horse's withers, applying tension on the reins until the horse stepped back. This was repeated eight times with the bridle and eight times with the halter. Data analysis was performed using mixed linear and logistic regression models. Horses displaying behaviors other than backing showed significantly increased response latency and rein tension. Inattentive behavior was significantly more common in the halter treatment and in young horses, compared with the bridle treatment and adult horses. Evasive behaviors with the head, neck, and mouth were significantly more common in the bridle treatment than in the halter treatment and the occurrence of head/neck/mouth behaviors increased with increasing rein tension and duration of the rein tension signal. When controlling for behavior, the horses responded significantly faster and to a lighter rein tension signal in the bridle treatment than in the halter treatment. By scrutinizing data on rein tension signals in relation to horse behavior and training exercise, more can be learnt about the horse's experience of the pressures applied and the timing of the release. This can assist in developing ways to evaluate rein tension in relation to correct use of negative reinforcement

Horse mouth behaviour related to selected kinematic variables representing horse-rider interaction

The objective of this pilot study was to investigate the influence of rein contact and the movement of the rider’s hand on the horse’s behaviour, analysing data on horses ridden in two different head and neck positions. We hypothesized that the rider’s hand movements and rein tension generate behavioural responses from the horse, and more so when ridden on the bit compared to free and unrestrained. Data were collected from seven dressage horses/riders in sitting trot on a high-speed treadmill. Kinematics were recorded using a 12-camera, infrared-based opto-electronic system. Behavioural recordings were made from video and three horses wore a rein tension meter. After stride split, data were standardised to 0-100% stride duration. Mixed models were used to analyse how the behaviours varied over the stride cycle; trial within horse was treated as a random effect, while percentage of stride, rein tension and kinematic variables mainly related to the rider’s hand were entered as fixed effects. Behaviours discerned were lip movement, mouth movement, open mouth, ear position, head tilt and tail movement. Mouth movements were associated with the suspension phase of the trot and percentage of stride was highly significant (P<0.0001). Head and neck position was non-significant in the final models, while rein tension and the distance between the rider’s hand and the horse’s mouth affected the amount of mouth movements. The results from this preliminary study convey the large variations between horses and riders, as well as the complexity of the interaction

Hästen (Equus caballus), hästträning och rollkur

Det första hästdjuret utvecklades för ungefär 55 miljoner år sedan (Ståhlberg, 2003). De tidigaste fynden av domesticeringen, som texter och konst med hästar, dateras till slutet av 3000 f.Kr. (Postgate, 1986; Zarins, 1986; Piggott, 1992; Kuz´mina, 1994a,b, 1996; Littauer & Crouwel, 1996). Eftersom hästen inte har varit domesticerad mer än ett par tusen år finns det vilda beteendet kvar hos hästen vilket kan skapa problem då människan vill träna sin häst (Bekoff, 2004). Hästens naturliga beteende, som ligger djupt rotat i generna, jämfört med hur vi önskar att hästen ska bete sig, kan vara ganska olika (Bekoff 2004). Som människa måste man lära sig om och ta hänsyn till hästens naturliga beteende för att samarbete mellan häst och ryttare ska fungera. När man tränar en häst kan man dra nytta av hästens beteende, vilket ofta är bättre än att bortse från det, eftersom hästen mår bäst av att uttrycka sig naturligt (Mills & Nankervis, 1999). Hästens rörelsemönster beror på hur dess muskler och skelett är uppbyggt. Musklerna är hästens "motor" samt fungerar som stöd och stötdämpare och är anpassade till snabba, kraftfulla rörelser, medan skelettet ger stöd och stadga (Attrell et al, 1994). Muskler i rygg (ryggsträckarmuskeln) och i buk hjälper till att stadga bålen vid rörelse (Attrell et al, 1994). Den långa ryggmuskeln sammankopplar framben och bakben och vidarebefordrar, genom sammandragning och avslappning, energi till benen. Energin som bakbenen producerar förs via ryggen till frambenen genom musklerna (de Némethy, 1990). Träning kan definieras som en medveten modifikation i frekvens eller intensitet av ett speciellt beteende. Sådana modifikationer kan skapas genom olika former av positiv eller negativ förstärkning och/eller bestraffning (McLean & McGreevy, 2005). Det som man eftersträvar i träning är en mjuk kontakt med bettet, en häst som slappnar av och utvecklar bra hållning (Podhajsky, 1965). I utbildningen av hästen används olika träningsmetoder. Rollkur är ett exempel på det. FEIs definierade rollkur, eller hyperflexion, som en träningsteknik med överböjning i halsens mittregion som inte är möjlig för hästen att bibehålla under en längre period utan att det påverkar hästen negativt. Då hästarna går i rollkur får de en rak, platt rygg, bakbenen släpar efter och leder i bakdelen dras inte ihop så de förblir bakom hästen (de Némethy, 1990). Att bakbenen inte kliver under hör ihop med att för mycket spändhet i ryggen, vilket förhindrar bakbenens rörelser framåt (Heuschmann, 2007). Hästarna hamnar istället med vikten på framdelen (de Némethy, 1990). Om rollkur orsakar hästen smärta kan det vara svårt att upptäcka. Eftersom hästen är ett bytesdjur och inte gärna visar sig sårbar, då detta signalerar att de är ett lätt byte (Grandin, 2005). Det kan också vara svårt att skilja på smärta, nedstämdhet och stress (Björck, 2004). Det finns många olika åsikter om rollkur. Ryttare som tävlar på hög nivå använder sig av denna träningsmetod, trots att den kan vara skadlig för hästen, och då kan den uppfattas som ett accepterat sätt att träna hästen. Många anser dock att detta är en brutal metod för att få hästen att bli eftergiven. Vi tycker att det behövs mer forskning om rollkur och dess effekter på hästen.The first animal that resembled a horse was developed about 55 billions years ago. The earliest findings of domestication, like texts and art of horses, was dated till the end of 3000 B.C. Since the horse hasn’t been domesticated more than a couple of thousand years, the wild behaviour of the horse is still there, and can create problems in horse training. The natural behaviour of the horse, that is deep seated in the genes, compared to how we wish the horse to behave, can be quite different. Humans have to learn about and respect the natural behaviour of the horse in order to find a working relationship. In training the horse you should take advantage of the horse’s natural behaviour rather than to ignoring it, since it’s better for the horse to be able to behave in a natural way. Training can be defined as a modification in frequency or intensity of certain behaviours. Such modifications can be created through different forms of positive and negative reinforcement and/or punishment. What is wished for in training is soft contact with the bit, a relaxed horse and development of a good posture. In the training of the horse, different training methods are used. An example is rollkur. Federation Equestre Internationale’s defined rollkur, or hyperflexion, as a training technique that overbends the mid-region of the neck and that it can not be maintained for a prolonged time without welfare implications. When the horse is in rollkur the back becomes flat and straight, the hind legs are trailing which leads to the horse being camped. The horse being camped is connected to, too much tension in the back, which prevents the hind legs from moving forwards. The weight of the horse is transferred to the front legs instead of the hind legs. If pain is involved in the training method rollkur it can be hard to detect. The horse is a prey animal and doesn’t want to present itself as vulnerable, since this would signal being an easy target for predators. It can also be difficult to distinguish between pain, depression and stress. There are a lot of opinions about rollkur. Riders competing on a high level use this method, in spite of its possible injuries to the horse. It is thus acknowledged as an acceptable way of training horses by some people. On the other hand, some people considered rollkur to be a brutal method to get the horse more submissive. We think that a lot more research needs to be done on rollkur and its effect on the horse. Also knowledge about the horse and training methods needs to be spread in our society, which we are trying to show in this text

A rein tension signal can be reduced by half in a single training session

Rein tension signals are, in essence, pressures applied on the horse's mouth or nose, via the bit/noseband, by a rider or trainer. These pressures may feel uncomfortable or even painful to the horse and therefore it is important to reduce rein tension magnitude to a minimum. The aim of this study was to investigate the magnitude of a rein tension signal for backing up, using negative reinforcement. We wanted to assess how much the magnitude of rein tension could be reduced over eight trials and if the learning process would differ depending on headstall (bridle/halter). Twenty Warmblood horses were trained to step back from a rein tension signal with the handler standing next to the horse, holding the hands above the horse's withers. As soon as the horses stepped back, rein tension was released. The horses were either trained with a bridle first (first treatment, eight trials) and then with a halter (second treatment, eight trials), or vice versa in a cross-over design. All horses wore a rein tension meter and behavior was recorded from video. The sum of left and right maximum rein tension from onset of the rein tension signal to onset of backing (signaling rein tension) was determined for each trial. Mixed linear and logistic regression models were used for the data analysis. In both treatments, signaling rein tension was significantly lower in trial 7-8 than the first trial (p < 0.02). Likewise, signaling rein tension was significantly lower (p < 0.01), and the horses responded significantly faster, (p < 0.001) in the second treatment compared to the first, regardless of headstall. The maximum rein tension was reduced from 35 N to 17 N for bridle (sum of left and right rein) and from 25 N to 15 N for halter in the first eight trials. Rein tension was then further reduced to 10 N for both bridle and halter over the eight additional trials in the second treatment, i.e. to approximately 5 N in each rein. There was no significant difference in learning performance depending on headstall, but the bitted bridle was associated with significantly more head/neck/mouth behaviors. These results suggest that it is possible to reduce maximum rein tension by half in just eight trials. The findings demonstrate how quickly the horse can be taught to respond to progressively lower magnitudes of rein tension through the correct application of negative reinforcement, suggesting possibilities for substantial improvement of equine welfare during training

Gaping for relief? Rein tension at onset and end of oral behaviors and head movements in unridden horses

Pressure from the bit in the horse's mouth, rein tension, likely feels unpleasant to the horse due to sen-sitive oral tissues. Through trial and error, the horse may learn how to adjust their behavior in order to avoid, diminish or cease uncomfortable sensations from the bit. We hypothesized that oral behaviors and head movements in response to rein tension have the function to avoid or escape the rein tension. The study objective was to assess in what way oral behaviors and head movements affect rein tension and determine the magnitude of rein tension at the onset and end of these behaviors. Twenty Warm-blood horses were fitted with a bitted bridle and subjected to 8 trials of backing up in response to a rein tension signal with the handler standing next to the horse's withers. The rein tension signal was grad-ually increased and then immediately released when the horse stepped back. A rein tension meter and video recordings were used for data collection. Linear mixed models were used for the statistical analysis. There was a decrease in mean rein tension (sum of left and right rein) from onset to end for open mouth ( P < 0.001, from 19 to 11 Newtons (N), biting on the bit ( P = 0.004, from 11 to 5 N), and head upward ( P = 0.024, from 16 to 12 N), while there was an increase in rein tension associated with head forward ( P = 0.015, from 27 to 37 N) and head downward ( P < 0.001, from 17 to 46 N). Our results suggest that horses will open their mouth, or bite on the bit, to alleviate the oral tissues from pressure; move the head upward to avoid rein tension and move the head forward or downward to increase rein tension, likely in a presumed attempt to break free from the pressure applied. The horse's oral behaviors and head movements during training can be used to gain a greater understanding of how the horse perceives the magnitude of rein tension. (c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/