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Author Gabor, V.; Gerken, M. pdf  openurl
  Title Shetland ponies (Equus caballus) show quantity discrimination Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords Cognition, numerical capacity, numerosity judgment, Shetland ponys  
  Abstract (up) The complex housing environment and the close contact between humans and horses in equine sports place high demands on the learning capacity of horses. To date only limited information is available on the learning ability of the horse including higher order cognition. A type of higher order cognition is to perceive and discriminate quantities. Several mammals and birds have shown to be capable of discriminating objects due to their quantity (Brannon and Roitman, 2003). With regard to horses, there are only few studies available concerning their numerosity judgment (Uller and Lewis, 2009) and this ability is discussed controversially (Henselek et al, 2012). Possibly, the legacy of ‘‘Clever Hans’’ overshadowed further research on numerical capacity in horses, a horse to whom several psychologists incorrectly attributed the capacity of symbolic calculation (Pfungst, 1907; Rosenthal, 1965). In the present study we wanted to show whether Shetland ponies are able to transfer a previously learned concept of sameness to a numerosity judgment. The base of the test design was a “matching to sample” task, where the ponies had learned to relate abstract symbols to another which were presented on a LCD screen. Three Shetland ponies, which previously solved the matching to sample task, were tested in two test phases. In the first test phase different quantities of dots were presented (1 vs. 2; 2 vs. 3; 3 vs. 4; 4 vs. 5). To exclude discrimination due to the shape of the stimuli, the dots were varied in size and arrangement. The stimuli were presented in a triangular arrangement on the LCD screen; the sample stimulus was presented in the middle above and the discrimination stimuli in the two lower corners (S+ and S-). The pony received a food reward, by choosing the positive stimulus (S+). When the negative stimulus (S-) was chosen, the pony entered the next trial. Each learning session consisted of 20 decision trials. To investigate whether the numerosity judgment was transferable to mixed geometrical symbols (tri-, rectangle, rhomb, dot and cross) a second test phase was designed. All of the three Shetland ponies met the learning criterion of the first test phase (80% correct responses in two consecutive sessions) within the first eight sessions. One pony could transfer all judgments to the mixed symbols (up to 4 vs. 5), another pony up to 3 vs. 5 and the third on the level 2 vs. 3. These are the first reported findings that ponies are able to discriminate up to five objects. The numerosity judgment seemed to be easier for the ponies when homogenous objects were presented, than in the case of heterogeneous symbols. The reaction of the ponies occurred within few seconds, suggesting that the animals used subitizing for their numerosity judgment.

Keywords:

Cognition, numerical capacity, numerosity judgment, Shetland ponys

References:

Brannon E, Roitman J (2003) Nonverbal representations of time and number in animals and human infants. In: Meck WH (ed) Functional and neural mechanisms of interval timing. CRC Press, Boca Raton, pp 143–182

Henselek Y, Fischer J, Schloegl C (2012) Does the stimulus type influence horses’ performance in a quantity discrimination task? Front Psychol 3:504

Pfungst O (1907) Der Kluge Hans. Ein Beitrag zur nicht-verbalen Kommunikation. 3rd edn. (reprint of the original 1983) Frankfurter Fachbuchhandlung für Psychologie, Frankfurt

Rosenthal R (1965) Clever Hans: the horse of Mr. Von Osten. Holt, Rinehart and Winston, New York

Uller C, Lewis J (2009) Horses (Equus caballus) select the greater of two quantities in small numerical sets. Anim Cogn 12:733–738
 
  Address  
  Corporate Author Gabor, V. Thesis  
  Publisher Xenophon Publishing Place of Publication Wald Editor ; Krueger, K.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 978-3-95625-000-2 ISBN Medium  
  Area Expedition Conference  
  Notes Id - Approved no  
  Call Number Equine Behaviour @ team @ Serial 5894  
Permanent link to this record
 

 
Author Winwright, D.; Elston, H.; Hall, C. pdf  openurl
  Title The impact of paddock design on the behaviour of the domestic horse (Equus caballus) Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords Horses, social behaviour, management, housing, paddock  
  Abstract (up) The design of a captive environment should facilitate the expression of the natural behavioural repertoire of the species concerned. The domestic horse (Equus caballus) is a social, herd dwelling species that is often housed in isolation from con-specifics or kept in groups in paddock enclosures. Although the latter allows for social interaction and does not restrict movement per se, it may not promote natural activity patterns or group cohesion. The aim of the current study was to assess the impact of two different paddock designs on the behaviour of a stable group of horses (n=6: 2 mares, 4 geldings).

The paddock designs tested were adjacent and grassed similarly, but configured differently. A central paddock (75 x 75m) designated NT, was surrounded by a track 1.6-5.5m wide, designated T. The horses were turned out in their group into T or NT for 3 consecutive days. Their behaviour was recorded for one hour three times each day (10.00, 13.00, 16.00 hrs). Within each observation period of one hour focal sampling was used, each individual horse being observed for a 10 minute period. They were then moved to the other enclosure type for a further 3 consecutive days, followed by a repeat of each condition. When turned out the horses were fitted with a global positioning system device (Garmin Forerunner 305) to monitor distance travelled and speed for the period 10.00-17.00 hrs. The mean percentage of time spent in each behavioural state (standing alert, standing resting, walk/trot, grazing, lying, social interaction) during the periods observed was calculated. Behaviour during social interactions was classified as either affiliative (approach, follow, friendly contacts, mutual grooming) or agonistic (approach and retreat, bite, chase, head threat).

The horses travelled significantly further in T than in NT (paired samples t-test: t (5) = 11.74, p<0.001) and moved significantly faster (Wilcoxon signed rank test: z = -2.21, p=0.03). See Table 1. When the percentage of time spent in each behavioural state in T and NT was compared some significant differences were found. A significantly higher percentage of time was spent active (walking /trotting) in T than in NT (paired samples t-test: t (5) = 5.74, p=0.002). Standing alert was only recorded in T (paired samples t-test: t (5) = 3.48, p=0.02). A significantly higher percentage of time was spent grazing in NT than in T (paired samples t-test: t (5) = -3.58, p=0.016). Significantly more social interaction occurred in T than in NT (paired samples t-test: t (5) = 5.93, p=0.002). See Figure 1. In T, 91% of social interactions were affiliative and 9% agonistic, whereas in NT 29% were affiliative and 71% agonistic. No difference was found in the percentage of time spent standing resting or lying down in T and NT.

The benefits of housing horses in groups as opposed to individually have been demonstrated in previous studies. In addition to better satisfying the behavioural needs of the horse it has been found that group housed horses adapt more easily to training and display less undesirable behaviour than those housed individually (Rivera et al. 2002; Søndergaard and Ladewig 2004; Visser et al. 2008). However, individual housing is frequently selected by horse owners in preference to group housing to avoid the risk of injury during agonistic encounters. Fureix et al. (2012) suggest that management practices may well contribute to aggressiveness in horses and that the conditions under which we keep horses should be reviewed. The findings of the present study indicate that the design of the enclosure in which groups of horses are kept affects the nature of social interactions. The T paddock design resulted in reduced intra-group aggression. However, this paddock design also reduced the time spent grazing and increased vigilant behaviour. Although the results demonstrate that a paddock system including tracks may facilitate group cohesion and more natural movement patterns, the long-term impact on behaviour and welfare requires further investigation.

References:

Fureix C, Bourjade M, Henry S, Sankey C, Hausberger M. (2012). Exploring aggression regulation in managed groups of horses (Equus caballus). Applied Animal Behaviour Science 138: 216-228.

Rivera E, Benjamin S, Nielsen B, Shelle J, Zanella AJ. (2002). Behavioural and physiological response of horses to initial training: the comparison between pastured versus stalled horses. Applied Animal Behaviour Science 78: 235–252.

Søndergaard E, Ladewig J. (2004). Group housing exerts a positive effect on the behaviour of young horses during training. Applied Animal Behaviour Science 87: 105-118.
 
  Address  
  Corporate Author Hall, C. Thesis  
  Publisher Xenophon Publishing Place of Publication Wald Editor ; Krueger, K.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 978-3-95625-000-2 ISBN Medium  
  Area Expedition Conference  
  Notes Id - Approved no  
  Call Number Equine Behaviour @ team @ Serial 5895  
Permanent link to this record
 

 
Author Krueger, K. pdf  isbn
openurl 
  Title Social learning and innovative behaviour in horses Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords social learning, innovative behaviour, Equus caballus, cognitive capacities  
  Abstract (up) The evaluation of important parameters for measuring the horses’ cognitive capacities is one of the central topics of the equine behaviour team at Nürtingen-Geislingen University. Social complexity has been said to be one of the settings in which needs for cognitive capacities arise in animals. A variety of studies throughout the last two decades proved the horses’ social complexity to be far more elaborate than previously assumed. Horses form social bonds for the protection of offspring, intervene in encounters of others, identify group mates individually and easily orientate in a fission fusion society.

In such socially complex societies, animals will benefit from learning socially. In many bird and primate species the degree of social complexity correlates nicely with the species abilities for social learning. Social learning was, therefore, argued to be an indicator for elaborate mental capacities in animals. We were delighted to prove that horses actually copy social behaviour and techniques for operating a feeding apparatus from older and higher ranking group members. In a recent study we found young horses, at the age of 3 to 12, to copy the operation of a feeding apparatus from a human demonstrator. Social learning seems to work nicely in horses when the social background of the animals is considered.

The degree to which individual animals adapt to changes in their social or physical environment by finding innovative solution appears to be the other side of the coin, of whether animals adjust to challenges by social learning. It is not very astonishing, that along with the animals’ social complexity and their ability to learn socially also the degree to which they show innovative behaviour was claimed to be one of the most important demonstrations of advanced cognitive capacities. In a recent approach, we started to ask horse owners and horse keepers in many countries to tell us about unusual behaviour of their horses via a web site (http://innovative-behaviour.org). To date, we received 204 cases of innovative behaviour descriptions from which six cases were clear examples of tool use or borderline tool use. We categorized the innovative behaviours into the classes, a) innovations to gain food, b) innovations to gain freedom, c) social innovations, d) innovations to increase maintenance, and e) innovations that could not be clearly assigned to a category. About 20% of the innovative horses showed more than one innovation. These animals could be termed “true innovators”. Again, young horses were more innovative than older ones with the age group 5 – 9 showing the highest number of innovative behaviour descriptions.

In a nutshell, the horses’ cognitive capacities appear to be underestimated throughout the last decades. The horses’ social complexity is far more elaborate than previously assumed, horses learn socially from conspecific and humans, some of them demonstrate innovative behaviour adaptations to their environment and even simple forms of tool use.
 
  Address  
  Corporate Author Krueger, K. Thesis  
  Publisher Xenophon Publishing Place of Publication Wald Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume in prep Series Issue Edition  
  ISSN ISBN 978-3-95625-000-2 Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5848  
Permanent link to this record
 

 
Author Pick, D. Kendra, B.; Steciuch, C. pdf  openurl
  Title The Familiarity Heuristic in the Horse (Equus caballus) Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords color perception, learning theory, prospect theory  
  Abstract (up) This study replicated an unreported finding observed in a color perception experiment (Pick, Lovell, Brown, & Dail, 1994) where, after using the method of successive approximations to train a blue-gray discrimination, red-gray trials were initiated without further training. Although a gray choice had never been reinforced, the subject chose gray on the first 20 trials (p < .000001). In the study reported here, a horse was trained to approach a red feed bucket and not a green feed bucket. After the subject mastered the discrimination, a blue bucket was substituted for the previously reinforced red bucket. With double-blind controls in place, the subject chose the unreinforced green bucket on 15 out of the first 20 blue-green trials yielding a binomial p = 0.0148 that this outcome could be due to chance alone. These results are contrary to all behavioristic psychological learning theories, but consistent with prospect theory (Kahneman & Tversky, 1979). Prospect theory predicts that given a choice between two previously unreinforced stimuli, one familiar and the other novel, humans will choose the familiar. It is argued that the bias toward the familiar is the basis to a heuristic that has a genetic origin and should exist in other animals on the phylogenetic scale. The results of this study indicate that the heuristic is available at least as far down the scale as the horse. Conceptual replications using shape stimuli and sound stimuli are in progress.  
  Address  
  Corporate Author Pick, D. Thesis  
  Publisher Xenophon Publishing Place of Publication Wald Editor ; Krueger, K.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 978-3-95625-000-2 ISBN Medium  
  Area Expedition Conference  
  Notes Id - Approved no  
  Call Number Equine Behaviour @ team @ Serial 5899  
Permanent link to this record
 

 
Author Viksten, S.; Blokhuis, H.; Visser, K.; Nyman, S pdf  openurl
  Title Equine welfare assessment and feedback to owners Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords  
  Abstract (up) To assess horse welfare and develop a system for feedback to horse owners is the aim of the present study. A protocol developed in line with the Welfare Quality® project was used to assess 26 stables and 497 horses. Questionnaires were used to investigate what kind of feedback horse owners wanted and where they currently got their questions about horse welfare answered. The questionnaire was sent to participating stables and made available to the public via websites and social media.

Questionnaires revealed that 38% retrieved information from popular science articles, 77% from discussions with peers while 8% generally perceived their peers to lack knowledge on horse welfare. Factors affecting decision making were horse health (85%) and economy (38%). 85% wanted exhaustive information and advice on improvements, 69% preferred to get feedback as a digital document and 92% were interested in benchmarking.

Answers from participating stables lead to the development of a feedback consisting of results, scientific background of used measures, copies of assessment protocols for each horse, supportive telephone calls regarding decision making and benchmarking from all participating stables.

Questionnaires to the public had 688 respondents of which 54% were amateur riders/drivers. Main questions respondents had regarding horse welfare were within feeding regimes (62%), housing (57%) and field size (54%). Main motivational factors in decision making was horse health (83%) and behavioural problems (71%). 81% got information about horse welfare and support for changes from discussions with peers and 63% based decisions on their own personal opinion. 91% were interested in benchmarking scores to compare themselves with other stables.

The results highlight the need for independent assessment and feedback with a scientific base to horse owners. This will enable horse owners to make informed decisions with a scientific background that will result in increased horse welfare.

Lay persons message

A developed protocol was used to assess horse welfare and horse owners were questioned regarding how they wanted the results presented. This resulted in the development of a feedback system that will aid horse owners to make informed decisions about horse welfare.
 
  Address  
  Corporate Author Viksten, S. Thesis  
  Publisher Xenophon Publishing Place of Publication Wald Editor ; Krueger, K.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 978-3-95625-000-2 ISBN Medium  
  Area Expedition Conference  
  Notes Id - Approved no  
  Call Number Equine Behaviour @ team @ Serial 5901  
Permanent link to this record
 

 
Author Maros, K.; Kovács, R.; Nagy, K. pdf  isbn
openurl 
  Title Questionnaire survey personality assessment of horses of different use Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords horse, personality, questionnaire,  
  Abstract (up) We collected data from 248 horses of different breeds, age, sex and use, forming four groups: 74 trotters, 70 gallop horses, 60 horseback archery horses and 44 police horses. All horses were trained and ridden/driven in a regular base. Caretakers or owners who were familiar with the target animals were asked to assess their horses’ temperament. The temperament scores were obtained with the 7-point scale questionnaire according to the Horse Personality Questionnaire which has 25 items and has previously been shown to be reliable for the assessment of personality in horses. It measures six personality components in horses: Dominance, Anxiousness, Excitability, Protection, Sociability and Inquisitiveness.

Component scores were calculated according to Lloyd, A.S., Martin, J.E., Bornett-Gauci, H.L.I., Wilkinson, R.G. (2008) Horse personality: Variation between breeds. Applied Animal Behaviour Science 112. 369–383. The component scores were compared across the four examined groups using the Kruskal–Wallis test. Post hoc multiple comparisons tests were then carried out to explore specific breed differences on each component. The value of alpha was set at 0.05 for all statistical tests.

Groups differed significantly regarding Anxiousness and Excitability, but no significant differences were found regarding Dominance, Protection, Sociability or Inquisitiveness among groups. This finding is in line with the findings of Lloyd et al. (2008) who showed that Anxiousness and Excitability components have the highest level of variation between breeds.In our study, gallop horses had the highest rank regarding Excitability and they differed significantly from police horses which had the lowest rank for this personality component. Interestingly gallop horses had the lowest rank regarding Anxiousness, and trotters got the highest rank in in this component.

According to our results gallop horses are the most extreme in their personality. It is conceivable that being excitable is a more favourable trait for a race horse than for a working police horse. However, it is interesting that trotters are more anxious than gallop horses since they also have a high thoroughbred ancestry. The effect of work and training on these horses needs further surveys.
 
  Address  
  Corporate Author Maros, K. Thesis  
  Publisher Xenophon Publishing Place of Publication Wald Editor Krueger, K.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN 978-3-95625-000-2 Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5904  
Permanent link to this record
 

 
Author Berger, A. pdf  openurl
  Title Evaluation of living conditions in free running animals by chronobiological analysis of continuously recorded behavioural data Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords non-invasive, stress detection, chronobiology, activity  
  Abstract (up) We developed a biorhythmical method to assess behaviour patterns and to evaluate living conditions of animals. All kinds of continuous and equidistant long-term recordings of behaviour are suitable for this method. As simple behavioural parameters, such as motor activity, can be conveniently recorded by telemetry from wild animals now, it is possible to investigate stressors by analysing its biorhythmic structure. It is the purpose of this report to describe the basic idea, and the procedure, and to give some examples of application measured on Przewalski horses in an Semireserve.  
  Address  
  Corporate Author Berger, A. Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5880  
Permanent link to this record
 

 
Author König von Borstel, U.; Küllmar, A. pdf  openurl
  Title A pilot study on horses‘ behaviour and distance travelled in a “Paddock Trail” husbandry system Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords  
  Abstract (up) With most modern horse husbandry systems, horses’ locomotory behavior is quantitatively as well as qualitatively considerably altered, compared to the slow and continuous movement shown by horses living under conditions similar to those they have evolved under. This lack of locomotion as well as the change in quality of locomotion is thought to be responsible for a number of health issues seen in present day horses. The aim of the present study was to assess behaviour and particularly locomotion in horses kept in a husbandry system specifically designed to stimulate locomotory behaviour in horses. This type of husbandry system is named “Paddock Trail”, (PT) but is also known as “Paddock Paradise”, and the key concept of this husbandry system involves strategic placement of small portions of feed along a track which is an integral part of this husbandry system. For the present study, 11 horses, not used for riding or other activities and kept in one Paddock Trail husbandry system were available. Seven horses used in equine assisted therapy lessons and housed individually in conventional paddock-boxes (IB) served as a control group. Both groups of horses were composed of a similar mixture of horses with regard to age and breeds. Using time-sampling, behaviour of the horses was observed in 8 bouts (4 morning and 4 afternoon sessions) of 5 hours each. In addition, the average speed and distance covered was assessed in 3 (PT) and 5 (IB) horses, respectively, using a GPS system. Since the GPS signal is blocked by buildings and reliable recording would not be possible indoors, the IB horses were recorded only during their work in the therapy sessions. The behavioural observations revealed that the PT horses allocated a larger proportion of time to locomotory behaviour compared to the IB horses (on average 12 vs 3% of the 5 h observation periods; P<0,05), and in turn resting behaviour was reduced in PT horses compared to IB horses (30 vs. 46%; P<0,05). Time spent grazing (10 vs. 8%) and feeding other than grazing (47 vs. 44%) did not differ significantly between the two groups of horses in the two different husbandry systems (P>0,1). In addition, resting and feeding behaviour was influenced by social rank, such that higher ranking horses spent more time feeding and less time resting compared to horses of lower ranks (both P<0,05). Within the 5 hour observation periods, horses of the PT system covered on average a distance of 2,7 km at an average speed of 0,5 km/h. In comparison, IB horses covered during their work in the therapy sessions on average a distance of 2,1 km at an average speed of 3,6 km/h for a duration of 35 minutes. Although the confounding of groups of horses with husbandry system and although the GPS data does not allow for a direct comparison of the husbandry systems and does not cover the entire 24 hours of a day, these data indicate along with the behavioural observations that the PT system stimulates the horses to increase their locomotory behaviour.

Keywords horse, husbandry, paddock trail, locomotion, behaviour
 
  Address  
  Corporate Author König von Borstel, U. Thesis  
  Publisher Xenophon Publishing Place of Publication Wald Editor ; Krueger, K.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 978-3-95625-000-2 ISBN Medium  
  Area Expedition Conference  
  Notes Id - Approved no  
  Call Number Equine Behaviour @ team @ Serial 5898  
Permanent link to this record
 

 
Author Hintze, S.; Smith, S.; Patt, A.; Bachmann, I.; Würbel, H. pdf  openurl
  Title What eye wrinkles in horses tell us about their emotional state Type Conference Article
  Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg  
  Volume Issue Pages  
  Keywords  
  Abstract (up) Wrinkles above the eye ball are common in domestic horses but may differ in number and shape both between and within individuals. They are caused by contraction of the inner eye brow raiser, and some people working with horses call them “worry wrinkles”, considering them to reflect emotional states. However, as yet no study has formally investigated the relationship between eye wrinkles and emotional state in horses.

The aim of the present study was to induce states of different emotional valence and to assess whether positive emotional states would reduce the expression of eye wrinkles while negative emotional states would increase it. Sixteen horses were confronted in a balanced order with two presumably positively and two negatively valenced situations each. Positive situations included anticipation of a food reward (FA) and petting (P), negative situations included food competition (FC) and waving a plastic bag (PB). Each situation lasted for 60s (TRT) and was preceded by a 60s control phase (CON). Throughout CON and TRT pictures of the eyes were taken, and for each horse four pictures per situation (FA, P, FC, PB) and phase (CON and TRT) were randomly selected (n = 512) and scored in random order and blind to treatment for six outcome variables: overall impression (qualitative), number, angle and markedness of eye wrinkles, presence of eye white, and shape of eye lid.

Data were analysed separately for the right and left eye using linear mixed effects models (angle, number), generalised linear mixed models (eye white, markedness), and ordered logistic regression (qualitative, shape of eye lid), with “situation” (FA, P, FC, PB), “phase” (CON, TRT) and their two-way interaction as fixed effects.

Expression of eye wrinkles did not vary consistently across “situation” and “phase”. Independent of phase, eye white appeared less frequently during P than during FA (z=-3.15, p=0.009), FC (z=-2.94, p=0.02), and PB (z=4.17, p<0.001) in the left eye and during PB (z=4.10, p 0.001) in the right eye. Similarly, wrinkles were less marked during P compared to the other situations in the left eye (FA: z=3.15, p=0.009; FC: z=-2.94, p=0.017; PB: z=4.17, p<0.001) and compared to PB in the right eye (z=4.10, p=0.001), while no differences between situations occurred in number of wrinkles, overall impression and shape of eye lid for both eyes. Consistent with our hypothesis, P induced relaxation of the underlying muscle in the right eye resulting in a wider angle compared to its control phase (interaction situation*phase: F3,10=3.71, p=0.055; post-hoc comparison: z=-3.57, p=0.009), while FC induced muscle contraction, resulting in a sharper angle in the left eye (interaction situation*phase: F3,11=6.57, p=0.011; z=3.73, p=0.005).

We conclude that emotional valence may affect characteristics of eye winkle expression in horses which might therefore be a promising indicator of horses’ emotional states, but further research is needed to validate the relevant outcome variables.
 
  Address eye wrinkles, emotional valence, positive and negative emotions, welfare assessment  
  Corporate Author Hintze, S. Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5875  
Permanent link to this record
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