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Medill, S. A., Janz, D. M., & McLoughlin, P. D. (2015). Hair testosterone and cortisol concentrations and their relationships to physiological and social status in feral horses (Equus ferus caballus). In Proceedings of the 3. International Equine Science Meeting.
Abstract: Determining steroid hormone concentrations in hair has been frequently performed in humans, and increasingly in wildlife and domestic animals. Hair hormone concentrations may provide insight on how individuals are responding to their physiological condition or social situation. Cortisol is most frequently measured in hair as a biomarker of long-term stress, while testosterone may be linked with reproductive status in males. These hormones are commonly measured in substances that reflect either current (e.g. blood) or very recent (e.g. saliva, urine, feces) circulating levels. However, these hormones are also incorporated into hair during hair growth and provide a chronological record of circulating hormone levels. Thus, analysis of steroid hormones in hair provides a much longer representation of an animal’s endocrine status than other tissues frequently targeted for non-invasive monitoring.
The feral horse (Equus ferus caballus) population on Sable Island, Nova Scotia, Canada, has been annually censused during the mid-late summer since 2008 to track individual life histories and population dynamics. We collected tail hair (n = 144 females, n = 162 males) from known individuals either opportunistically or from natural or artificial snags to investigate how hair cortisol and testosterone might be associated with physiological state (e.g. lactating vs. non-lactating, body condition, age), as well as their social situation (e.g. dominant band stallion, subordinate band stallion, or bachelor) and measures of sociality. The proximal 5 cm of hair (excluding first 4mm or root region) were ground to a fine powder and hormones extracted with methanol and analyzed by using enzyme-linked immunoassay.
Preliminary analyses of the data showed a general sex based difference in hair cortisol concentrations (females lower than males; t = 3.16, df = 317, P=0.002). Among females, the presence of nursing foals was accompanied by an increase in hair cortisol (z = 2.93, df =140, P = 0.003); however, no significant difference was found in hair cortisol concentrations based on sex of the foal (t = -0.06, df = 82, P = 0.95). Horses in poor body condition tended to have higher hair cortisol than those in good or excellent condition (slope= -0.203, df = 312, P = 0.003). We also observed an increased concentration of hair cortisol as horses increased in age from 3-6 or entered into reproductive maturity. Adult male dominant band stallions did not have significantly less cortisol than bachelors or subordinate stallions but these three groups were significantly greater than young males (aged 3 and 4) who generally do not challenge the older males for reproductive opportunities.
Additionally, we looked at hair testosterone concentrations for n=46 males. Testosterone is known to influence traits and behaviours that enhance sexual selection. Often there is an inverse relationship between cortisol levels and testosterone; in particular, being able to maintain high testosterone and not have elevated cortisol related to the metabolic costs of sexual trait production ensures that traits or behaviours honestly signal the quality of the individual. For this reason we’d expect to see band stallions (those males in a position to mate) have a lower value in the ratio Cortisol: Testosterone. Early indications suggest we see this phenomenon in feral horses.
As a relatively new approach in wildlife research, the use of hair hormone analysis shows promise in contributing to our understanding of physiological aspects of sexual selection and other processes. Additionally, hair hormone analysis may have applications in advancing knowledge of animal husbandry and in particular, welfare.
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Vidament. M. (2015). Laterality and emotions : behavioural response to an approach of a novel object by young ridden horses. In , & K. Krueger (Ed.), Proceedings of the 3. International Equine Science Meeting. Proc. 3. Int. Equine. Sci. Mtg. Wald: Xenophon Publishing.
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Hintze, S., Smith, S., Patt, A., Bachmann, I., & Würbel, H. (2015). What eye wrinkles in horses tell us about their emotional state. In Proceedings of the 3. International Equine Science Meeting.
Abstract: 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.
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Ahmadinejad, S. M., & Asgari, Z. (2015). Facial expressions of the Caspian pony to its own picture, mirror and a combination of these two. In Proceedings of the 3. International Equine Science Meeting.
Abstract: Abnormal behaviors of the horses are among the most important problems, in the ridding clubs. Digestive and somatic abnormal behaviors are the two most important abnormal behaviors in the horses, with the loneliness and boredom the two most important causes of these abnormal behaviors. Many study showed that spending times ( increasing the exercise and training time) would stop such abnormal behaviors. The man power scarcity is the important reason many ridding clubs face and this is the reason why the abnormal behavior are mostly observed in such clubs.
Current study is the first report regarding facial expressions of the Caspian Pony to different objects. Totally 10 Caspian ponies were used in this study. The pictures were taken both in the calm and in the furious (nervous) situation The pony’s pictures were the alternatives we used in this research to combat the man power scarcity!. We also used mirror to compare the expressions of the ponies to the pictures and mirror. The results of this study showed that the ponies showed more attention to the picture in calm position when compared with the picture in nervous position. In the box with the mirror and the picture (in calm position) in it, the ponies paid much more attention to the mirror than the picture.
We conclude that despite of resistant of ponies for leaving outdoor and entering to indoor (paddock to box), installing mirror can prevent (almost completely) the horse’s boredom and loneliness, a very cheap (but not wise! alternative for manpower). The results of this research were applicable and were suggested to many ridding clubs with the horses with stereotypic behaviors, received almost completely positive results.
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Briefer Freymond, S., Piovesana, L., Briefer. E. F., Beuret. S., Zuberbühler, K., Bshary, R., et al. (2015). Crib-biting behaviour of horses: stress and learning capacity. In Proceedings of the 3. International Equine Science Meeting.
Abstract: Crib-biting is a stereotypy in horses that is potentially linked to both chronic stress and genetic predisposition. Chronic stress can cause neurobiological changes such as alteration of the dopaminergic modulation of the basal ganglia [1]. These neurobiological changes could alter and modify the learning profile of the horses [2,3]. We tested 19 crib-biters and 18 non-crib-biting horses (controls) in five challenging spatial tasks, in order to test if differences in dopaminergic modulation impair learning capacities. The tests were performed in two time periods, in a small arena (8 x 10 m) that was familiar to the horses. For each trials, the horses were led to the start zone in front of a four-meter-long solid fence and were then left alone in the arena. Their task was then to find a bucket containing food, which was situated in different positions around the fence, depending on the tests. The time to reach the food bucket, the trajectory taken by the horse (left or right side of the fence) and the ECG trace were recorded continuously. Additionally, salivary cortisol was collected before the tests (baseline), after the first time period, and after the second time period. We found that crib-biters and controls behaved similarly during the learning tasks. However crib-biters that did crib-bite on the solid fence during the task (group A; 10 horses) behaved differently than crib-biters that did not crib-bite (group B; 9 horses) and controls (group C; 18 horses) for some tests, in their trajectory or time to reach the bucket. These differences are more likely explained by the time taken to crib-bite, than by differences in learning capacity. We did not find any difference between groups in their heart-rate variability (RMSSD). Yet, we found a difference in salivary cortisol after the first time period between groups A, B and C. Indeed, the crib-biters that did not crib-bite had higher salivary cortisol values than all the other horses (mean±SE: A, 0.51±0.16ng/ml, B, 0.78±0.17ng/ml, C, 0.59±0.20ng/ml; Linear mixed model (LMM), p<0.05). Our results suggest that crib-biting horses that did not crib-bite during the learning tasks were more stressed than all other horses. This difference could be due to higher stress sensitivity in crib-biters, which could be reduced by the opportunity to crib-bite. These results replicate our previous findings testing differences in cortisol levels between crib-biters and control horses during an ACTH challenge test. Therefore, crib-biting behaviour might be a coping strategy helping stereotypic horses to reduce their stress during frustrating situations [4].
Keyword:
stereotypy, chronic stress, learning task
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Bouskila, A.,, Lourie, E., de Vries, H., Hermans, Z. M.., & van Dierendonck, M. (2015). Sex, but not relatedness nor age, affect the social network of horses in a semi-natural reserve. In Proceedings of the 3. International Equine Science Meeting.
Abstract: For some time now, social network analysis provides tools to describe concisely the social structure of animals. Nevertheless, the factors that shape the social network and determine the frequency of different types of affiliations are often unclear. For example, the effects of relatedness on social networks have been only studied on relatively few species. Both among social or sub-social species the effects ranged from no effect to a substantial effect. Here we test the hypothesis that relatedness has an effect on the social network of horses (Equus caballus) that live freely in semi-natural conditions, and specifically, that individuals with high values of relatedness to their neighbors in the network will have fewer links Wolf et al, 2011). This hypothesis is based on the notion that related individuals have common interests and are likely to assist each other, and may need less links to other, unrelated individuals. In addition, individuals of similar age and sex are likely to have common needs, and thus are more likely to be associated. We thus tested a second hypothesis: homophily to individuals with similar age and sex will have a role in determining the associations within the social network. The field study was conducted on 27 horses in the Blauwe Kamer reserve in the Netherlands (1.1 sq km). We videotaped horses and their groups and used the information from 22 horses, after excluding the five foals from the analysis. Relatedness was calculated from the pedigree, which was based on parentage, determined by DNA analysis. The social network was constructed based on spatial proximity data. We assessed the influence of relatedness, age-homophily and sex-homophily on the network structure with Multiple Regression Quadratic Assignment Procedure (MRQAP) (Krackhardt 1988), with the R package sna. The results show that there was no significant effect of relatedness on the network, nor an effect of age-homophily. Nevertheless, we found a significant effect of sex-homophily, the tendency of individuals to associate with individuals of the same sex. We argue that the lack of a relatedness effect is not likely to have been caused due to the inability to detect who is kin. The structured social system in horses includes strong associations between often unrelated individuals, alongside with young individuals leaving their natal harem as part of the inherent inbreeding avoidance (Linklater & Cameron 2009; Boyd et al. in press). The significant effect of sex-homophily could stem from the protection females get from associations with other females, e.g., in the reduction of harassment from males. Previous studies on feral horses showed that mares that were better connected with other females in their harem benefited from higher survival rates to their foals (Cameron et al. 2009). The associations among bachelor males could also contribute to the strength of the sex-homophily effect.
In order to generalize from our results, one needs to examine additional populations of horses, because the conditions in the Blauwe Kamer reserve may not be representative, mainly due to the limited opportunity for dispersal in a restricted area.
Keywords: Long-term affiliation; spatial proximity, kin detection
Boyd, L., Scorolli, A. L., Nowzari, H., & Bouskila, A. (2016). Chapter 2: Social organization. In J. I. Ransom, & P. Kaczensky (Eds.), Wild equids. Baltimore, Maryland (in press): The Johns Hopkins University Press.
Cameron, E. Z., Setsaas, T. H., & Linklater, W. L. (2009). Social bonds between unrelated females increase reproductive success in feral horses. Proceedings of the National Academy of Sciences, 106(33), 13850-13853
Krackhardt, D. (1988). Predicting with networks: Nonparametric multiple regression analysis of dyadic data. Social Networks, 10(4), 359-381.
Linklater, W. L., & Cameron, E. Z. (2009). Social dispersal but with philopatry reveals incest avoidance in a polygynous ungulate. Animal Behaviour, 77(5), 1085-1093.
Wolf, J. B., Traulsen, A., & James, R. (2011). Exploring the link between genetic relatedness r and social contact structure k in animal social networks. The American Naturalist, 177(1), 135-142.
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Ahmadinejad, S. M., Pishkar, J., Anisi, T., & Babayee, B. (2015). Verbal expressions of the horses to the pain. In Krueger. K. (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: For communicating with the environment (other horses, foals, owner, etc.), horses have to use different methods. In contrast with the human, for whom talking is the most important way of communication, the horses can’t talk. In the years 1990s and before, the imagination was such that the infants do not express verbally to the pain either (like horses).
To communicate, horses use their body language. Vocalization (if not the body language), seems to be the most important way of communication in horses, though it seems they use the same tone when exposing to different events.
In this study which was performed in collaboration with the electronic institute of Sharif technical university (the top most technical university of the country), totally 25 horses were used. The horses were exposed to different events (hunger, pain, loneliness, mating, parturition and separation of the 1-2 weeks old foals from their dams). The verbal expressions of the horses were studied using spectrogram.
The results of this study showed that there were significant differences between the spectrograph of the voices of the horses, exposed to hunger, and the separation of the foals from dams. This was the same (no significant differences) when horses were exposed to loneliness, separation and hunger. There were no significant differences between the verbal expressions of the horses while exposed to mating, parturition.
One of the most important reasons why the horses do not have verbal expressions when exposing to the pain, might be the absence of the part of the brain, responsible for the pain interpretation. Morse research has to be performed to prove this.
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Ahmadinejad, S. M., Pishkar, J., & Bahmen, M. (2015). Comparisons of behavioral and physiological state in Caspian pony before and after stress. In Krueger. K. (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: Behavioral scores (BS) offer an non-invasive, objective and easy to use way of assessing welfare in horses. Their development has, however, largely focused on behavioral reactions to stressful events (often induced), and so far no use of physiological measures has been made to underpin and validate the behavioral measures in the Caspian ponies. This study aimed to develop a physiologically validated scale of behavioral indicators of stress for the purpose of welfare logically validated scale of behavioral and physiological data assessment in the stabled Caspian ponies. To achieve this , behavioral and physiological data were collected from 16 Caspian ponies that underwent routine husbandry procedures. The ponies were divided into two groups, a control and a treatment group (8 each). The ponies in the treatment group took part in a 700 meter race. Analysis of the behavioral data were undertaken by a panel of equestrian industry professionals. Physiological measures (salivary and serum cortisol level) were significantly correlated with the behavioral scores confirming that the scores were meaningful and reflected the physiological stress. The scores offer an easy to use tool for rapid, reliable non-invasive welfare assessment in Caspian ponies, and reduce the need for potentially invasive physiological measures.
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Jacquot, M., Grosjean, A., Emrot, C., Van-Erck-Westergem, E., Schwartz, C., & Tomberg, C. (2015). Effects of a walk phase at the warm up onset on physiological and behavioural parameters of ridden horses (Equus caballus). In , & K. Krueger (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: For human athletes, any physical performance classically begins with a warm-up including a phase of cardio-respiratory activation as well as a phase of neuro-muscular mobilization. For the equine athletes similar routines are widely followed despite limited scientific studies addressing its effectiveness. Although physiological bases are of a similar nature in humans and horses, the latter are showing a different “telos” related to their status of prey. Indeed, their survival depends on their ability to detect any predator or potential danger in their environment and to estimate the need to run away. Therefore warm-up techniques should be adapted to this specificity and we added a walk phase preceding the usual warm-up during which the horse was allowed to visually assess its environment without constraint imposed by its rider, reins being long. We assumed that this walk phase would allow a more relaxed mental state and then a decrease in cognitive resources involved in environmental monitoring. Consequently this would release cognitive resources then available for the communication between the horse and the rider.
The autonomous nervous system (ANS) regulates the heart rate via the sympathetic and the parasympathetic nervous systems. The sympathovagal balance and the heart rate variability are considered as good indicators of an acute stress state as well as emotional states. These measures are frequently used to estimate well-being in animals. During the walk phase, we observed a significant decrease of the heart rate (HR), a significant increase of its variability and a significant modification of the sympathovagal balance in favour of a higher contribution of the parasympathetic control. We also measured the non-linear correlation dimension which reflects the degree of freedom of a system. To the best of our knowledge, this method was used until now only in humans to whom it was shown that its decrease is related to stressful events and is associated with a bad prognosis for survival. During the walk phase in horses, the dimension of correlation of cardiac activity was increased.
From a behavioural point of view, we observed a significant decrease of side movements related to head orientation as well as significant changes in ears position, the latter being preferentially directed forwards at the beginning of the walk phase and laterally at the end. As previous research suggests that ears position and head orientation can be involved in attentional mechanisms in horses, our results suggest a decrease of the attention focused on the environment. Furthermore, a significant lowering of the neck was observed as well as a significant decrease of behaviours related to stress.
To conclude our results suggest that a walk phase preceding the usual warm-up of horses would contribute to improve their mental state in favour of more relaxation and of a decrease of the attentional resources invested in environmental monitoring.
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König von Borstel, U., & Küllmar, A. (2015). A pilot study on horses‘ behaviour and distance travelled in a “Paddock Trail” husbandry system. In , & K. Krueger (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: 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
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