Gatta, D., Baragli, P., Ferrarini, N., Ciattini, F., Sighieri, C., & Colombani, B. (1998). Fitness evaluation in endurance horses by standardised exercise test on treadmill. Valutazione dello stato di allenamento del cavallo da endurance mediante test standardizzato su trea, 9(4), 57–69.
Abstract: Endurance horses, like marathon runners, undertake sub-maximal, longterm physical exercises and in both cases thermoregulation plays a critical role. A standardised sub-maximal treadmill test was used to assess fitness and training state in endurance horses. Literature reports that trained human athletes dissipate head load better than not trained ones; in this study parameters related to thermoregulation were recorded together with other haematologic and metabolic ones. Six endurance horses, divided into two groups according to their training state, performed two submaximal tests at a distance of one week. Blood samples were collected at rest, during exercise, at the end and during recovery (10, 30 and 60 minutes after work). Heart rate (HR), respiratory rate (RR), rectal (RT) and skin (ST) temperatures were monitored through the exercise (and recovery for HR). HR resulted significantly lower (P<0.01) in trained horses than in untrained ones, especially during recovery. Also rectal and skin temperatures resulted significantly lower (P<0.05) in trained horses and ST increased more gradually during exercise. The values of haematocrit and haemoglobin resulted significantly lower (P<0.05) at rest, during exercise and recovery samples. In this study, the parameters related to thermoregulation, in accordance with data from human athletes, resulted significantly different in trained and untrained horses, while other parameters didn't vary significantly between the two groups. Thermoregulatory responses to exercise-generated heat load in a standardised test, studied by simple parameters, can thus offer useful information about fitness and training state of endurance horses.
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De Boyer Des Roches, A., Richard-Yris, M. - A., Henry, S., Ezzaouia, M., & Hausberger, M. (2008). Laterality and emotions: visual laterality in the domestic horse (Equus caballus) differs with objects' emotional value. Physiol. Behav., 94(3), 487–490.
Abstract: Lateralization of emotions has received great attention in the last decades, both in humans and animals, but little interest has been given to side bias in perceptual processing. Here, we investigated the influence of the emotional valence of stimuli on visual and olfactory explorations by horses, a large mammalian species with two large monocular visual fields and almost complete decussation of optic fibres. We confronted 38 Arab mares to three objects with either a positive, negative or neutral emotional valence (novel object). The results revealed a gradient of exploration of the 3 objects according to their emotional value and a clear asymmetry in visual exploration. When exploring the novel object, mares used preferentially their right eyes, while they showed a slight tendency to use their left eyes for the negative object. No asymmetry was evidenced for the object with the positive valence. A trend for an asymmetry in olfactory investigation was also observed. Our data confirm the role of the left hemisphere in assessing novelty in horses like in many vertebrate species and the possible role of the right hemisphere in processing negative emotional responses. Our findings also suggest the importance of both hemispheres in the processing positive emotions. This study is, to our knowledge, the first to demonstrate clearly that the emotional valence of a stimulus induces a specific visual lateralization pattern.
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VanDierendonck, M. C., de Vries, H., Schilder, M. B. H., Colenbrander, B., & Þorhallsdóttir, A. G. and S., H. (2009). Interventions in social behaviour in a herd of mares and geldings. Appl. Anim. Behav. Sci., 116(1), 67–73.
Abstract: Social dynamics and maintenance of social cohesion were studied by analysing social interventions in two groups of horses consisting of adult mares, their offspring, adult geldings and sub-adults. The animals were observed for a total of 1316 h. All relevant dyadic and triadic social interactions, including initial behaviour, possible intervention and outcome, were recorded. The main question was: do horses use interventions in affiliative interactions to safeguard their social network? Horses were significantly more likely to intervene in allogrooming or play interactions that involved a preferred partner. The stronger the preferred association in allogrooming, the higher the likelihood the intervener took over allogrooming with an initial dyad member. Interveners originating from two newly introduced groups (n = 3 and 5), intervened significantly more often when a member of their own group allogroomed with an unfamiliar horse. In play, no correlation with unfamiliarity was found. Overall, the intervening horses stopped more than half of the initial allogrooming interactions, and a third of all interactions. Therefore, social facilitation cannot sufficiently explain interference behaviour. This study shows that maintaining relationships with preferred partners is important to horses and has implications for equine husbandry and management.
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Anderson, M. K., Friend, T. H., Evans, J. W., & Bushong, D. M. (1999). Behavioral assessment of horses in therapeutic riding programs. Appl. Anim. Behav. Sci., 63(1), 11–24.
Abstract: A behavioral assessment of horses who were being used and not used in therapeutic riding programs was conducted to help determine useful methods of selecting horses for use in therapeutic riding programs. A total of 103 horses (76 horses from five therapeutic riding centers and 27 non-therapeutic riding horses from four sites) were used. Temperament survey for each horse were completed by three riding instructors at each therapeutic riding center or by the individual most knowledgeable about the horse at the other sites. Twenty personality traits from the survey were used to quantify temperament. Concentrations of plasma cortisol, norepinephrine and epinephrine were also measured in each horse. A reactivity test was then conducted which involved introducing three novel stimuli: a walking and vocalizing toy pig placed on a cardboard surface in front of the horse for 20 s; popping a balloon near the horse's flank area; and suddenly opening an umbrella and holding it open in front of the horse for 20 s. Reactions (expressions, vocalizations and movement) to each of the stimuli were scored and used to calculate an average reactivity score for each horse. The therapeutic riding instructors did not often agree on the temperament of their center's horses. The personality trait ratings made by the therapeutic riding instructors at each center were on average significantly correlated (P<0.01, r>0.52) for only 37.8% of the horses for any two instructors and 7.8% for three instructors. No significant correlations were found between temperament, reactivity, and the hormone concentrations (r<0.19), but regression analysis indicated a possibility of predicting temperament from the reactivity score and hormone concentrations (P<0.08). There was also a tendency for relationships between extremes in temperament (desirable vs. undesirable) and the hormone concentrations (P<0.09), and between extremes in reactivity (low vs. high) and the hormone concentrations (P=0.08). The difference in ratings among riding instructors indicates a need for more collaboration between instructors when evaluating horse temperament. This study also indicates that it was very difficult to objectively determine the suitability of horses for therapeutic riding programs regarding their temperament and reactivity, probably because other traits (e.g., smoothness of gait) are also considered very important.
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Uller, C., & Lewis, J. (2009). Horses (Equus caballus) select the greater of two quantities in small numerical contrasts. Anim. Cogn., 12(5), 733–738.
Abstract: Abstract The ability to select the greater numerosity over another in small sets seems to stem from the calculation of which set contains more, and has been taken as evidence of a primordial representation at the roots of the primate numerical system. We tested 56 horses (Equus caballus) in a paradigm previously used with human infants and nonhuman primates. Horses saw two quantities paired in contrasts—2 versus 1, 3 versus 2, 6 versus 4 and a control for volume, 2 versus 1 big—and had to make a choice by snout touching the container holding the numerosity selected. The horses spontaneously selected the greater of the two quantities when the numerosities were small. These results add to evidence showing spontaneous quantity assessment in a variety of species.
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Wallner, B., Brem, G., Muller, M., & Achmann, R. (2003). Fixed nucleotide differences on the Y chromosome indicate clear divergence between Equus przewalskii and Equus caballus. Anim Genet, 34(6), 453–456.
Abstract: The phylogenetic relationship between Equus przewalskii and E. caballus is often a matter of debate. Although these taxa have different chromosome numbers, they do not form monophyletic clades in a phylogenetic tree based on mtDNA sequences. Here we report sequence variation from five newly identified Y chromosome regions of the horse. Two fixed nucleotide differences on the Y chromosome clearly display Przewalski's horse and domestic horse as sister taxa. At both positions the Przewalski's horse haplotype shows the ancestral state, in common with the members of the zebra/ass lineage. We discuss the factors that may have led to the differences in mtDNA and Y-chromosomal observations.
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Oakenfull, E. A., & Ryder, O. A. (1998). Mitochondrial control region and 12S rRNA variation in Przewalski's horse (Equus przewalskii). Anim Genet, 29(6), 456–459.
Abstract: Variation in the control region and the 12S rRNA gene of all surviving mitochondrial lineages of Przewalski's horse was investigated. Variation is low despite the present day population being descended from 13 individuals probably representing animals from three different regions of its range. Phylogenetic comparison of these sequences, with sequences for the domestic horse, does not resolve the ancestral status of either horse.
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Ishida, N., Oyunsuren, T., Mashima, S., Mukoyama, H., & Saitou, N. (1995). Mitochondrial DNA sequences of various species of the genus Equus with special reference to the phylogenetic relationship between Przewalskii's wild horse and domestic horse. J Mol Evol, 41(2), 180–188.
Abstract: The noncoding region between tRNAPro and the large conserved sequence block is the most variable region in the mammalian mitochondrial DNA D-loop region. This variable region (ca. 270 bp) of four species of Equus, including Mongolian and Japanese native domestic horses as well as Przewalskii's (or Mongolian) wild horse, were sequenced. These data were compared with our recently published Thoroughbred horse mitochondrial DNA sequences. The evolutionary rate of this region among the four species of Equus was estimated to be 2-4 x 10(-8) per site per year. Phylogenetic trees of Equus species demonstrate that Przewalskii's wild horse is within the genetic variation among the domestic horse. This suggests that the chromosome number change (probably increase) of the Przewalskii's wild horse occurred rather recently.
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Momozawa, Y., Kusunose, R., Kikusui, T., Takeuchi, Y., & Mori, Y. (2005). Assessment of equine temperament questionnaire by comparing factor structure between two separate surveys. Appl. Anim. Behav. Sci., 92(1-2), 77–84.
Abstract: To establish a method for assessing equine temperament by use of a questionnaire, we carried out two surveys. The subject animals were all thoroughbreds maintained at the same farm. Respondents were the primary caretaker and two colleagues working with each horse. Factor analysis was performed on the responses to each survey. In both surveys, five factors were extracted and four of them were common between the two surveys. The common factors were [`]Anxiety', [`]Trainability', [`]Affability', and [`]Gate entrance'. There were sufficient internal consistencies in responses about [`]Anxiety', [`]Trainability', and [`]Affability' in the two surveys to indicate the validity of this questionnaire in evaluating these factors in equine temperament.
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Jezierski, T., Jaworski, Z., & Górecka, A. (1999). Effects of handling on behaviour and heart rate in Konik horses: comparison of stable and forest reared youngstock. Appl. Anim. Behav. Sci., 62(1), 1–11.
Abstract: Thirty foals and young Konik horses born in 3 consecutive years and reared up to weaning either in a forest reserve (R) or conventional stable (S) were compared with respect to behavioural reactions and heart rate (HR) during handling manipulations. The foals were randomly allocated within sex and rearing group to one of two handling treatments. Intensively handled (IH) foals received a 10-min handling, 5 days/week, beginning at the age of 2 weeks (S foals) or 10 months (R foals), and lasting up to the age of 24 months. During handling IH foals were haltered, touched, rubbed and their feet were picked up; non-handled (NH) foals were not handled except for routine or emergency veterinary care. The horses were tested at the age of approximately 6 months (S only) and 12, 18 and 24 months of age. In a test comprising catching the horse on a paddock, leading away from and towards the stable, picking up feet and being approached by an unfamiliar person, the horses' behaviour was scored and the HR was recorded telemetrically. The IH horses scored better as far as manageability behaviour is concerned (P<0.001) and demonstrated lower HR than the NH ones and the S horses scored better than R ones (P<0.001). Fillies demonstrated higher HR than colts (P=0.007). Youngstock of all groups tended to be less manageable at the age of 24 months than at 18 months. Differences between youngstock stemming from particular harems from the reserve seem to be related to differences in accidental contact with people visiting the forest reserve.
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