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VanDierendonck, M. C., de Vries, H., Schilder, M.B.H. (1995). An Analysis of Dominance, Its Behavioural Parameters and Possible Determinants in a Herd of Icelandic horses in captivity. Netherl. J. Zool., 45(3-4), 362–385.
Abstract: Feral horses are social animals, which have to rely on survival strategies centered on the formation of cohesive social bonds within their bands. Many problems in the husbandry of social animals such as horses, are due to the fact that the limits of their adaptive abilities are exceeded. Evidence suggests that the fundamental social characteristics of domestic horses have remained relatively unchanged. The social structure, social strategies and social interactions were investigated (3 non-consecutive years, 24 hr per day for several weeks) in long term established groups of domestic horses (mares and geldings of all ages) and a few small introduced groups, kept in (semi)natural environments. The general aim was to investigate the social needs of domestic horses. The social life of domestic horses was characterised by long lasting bonds with preferred partners which were established and maintained by allogrooming, play, proximity and dominance behaviours. Bonding partners were mainly found within the same sex-age group, but adult geldings also bonded with sub-adult mares and geldings. Adult mares were clustered in a group, while the other animals formed a second group. Among the adult mares, subgroups according to reproductive state were formed. Individuals regulated their social network by interfering with interactions between other members of the herd, which in itself is complex. An intervention is a behavioural action of one animal that actively interferes with an ongoing interaction between a dyad with the apparent aim of altering that interaction. This was verified by post-hoc analyses of disturbed and undisturbed interactions. Interventions in allogrooming or play were performed significantly more often when at least one member of the initial dyad was a preferred partner of, or familiar to (within the small introduced bands) the intervener. The stronger the preferred association in allogrooming between the intervener and member(s) of the initial dyad, the higher the probability the intervener would displace one initial member and continue allogrooming with the other. Just five behaviours were extracted which reliably reflected the dominance relations among horses. Aggression with the hind quarters was used both offensively and defensively and therefore not suitable as a reliable parameter. Individual dominance relationships were related to social experience. The implications of these findings for horse husbandry were assessed. It is argued that the execution of affiliative behaviours may be rewarding in itself, and therefore always will be a highly motivated behaviour. It is shown that social positive physical interactions (allogrooming, play) with other horses is an ethological need and therefore indispensable in modern husbandry systems. Ethological needs are so important for the animal that husbandry systems that lack the possibilities to execute such behaviours will cause chronic stress. It is concluded that all horses need physical social contact, and that horses, which lack appropriate social learning experiences during ontogeny, may be hampered in their social functioning later in life. Solutions for problems, including dominance problems, in individual social housing and group housing are presented.
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VanDierendonck, M. C., de Vries, H., & Schilder, M. B. H. (1995). An Analysis of Dominance, Its Behavioural Parameters and Possible Determinants in a Herd of Icelandic orses in Captivity. Netherl. J. Zool., 45(3-4), 362–385.
Abstract: Th e applicability of the concept of dominance was investigated in a captive herd of  Icelandic
horses and  ponies of diff erent breeds. Eight out of  behaviours possibly related
to dominance occurred frequently enough to be investigated in detail. For these eight agonistic
behaviours the coverage, the unidirectionality in the exchange, and the degree of
transitivity (Landau`s linearity index) were calculated. Four off ensive behaviours, together
with avoidance, were suitable for further analysis with regard to dominance. Th e patterns
of asymmetries with which these behaviours were exchanged were suffi ciently similar as to
justify the application of the dominance concept and to construct a (nearly) linear dominance
hierarchy. Th e rank order of the castrated stallions was completely linear, the hierarchy
of the mares was almost completely linear. Th e results suggest that off ensive and defensive
aggressive behaviours should be treated separately and that the concept of dominance
is applicable. However, ritualized formal dominance signals between adult horses appear to
be (almost) absent. Th e rank positions of the individuals were correlated with age and residency
in the herd but not with height. Middle ranking horses tended to be more frequently
in the close vicinity of another horse than high ranking or low ranking horses. Over and
above this correlation at the individual level, it was found that pairs of horses close in rank
to each other were more often also spatially close to each other. Being in oestrus did not infl
uence the dominance relationships between mares. For castrated stallions the rank positions
were correlated with the age at which they were castrated. Th is suggests that in male
horses experience prior to neutering infl uences the behaviour afterwards.
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McCrory, P., Turner, M., LeMasson, B., Bodere, C., & Allemandou, A. (2006). An analysis of injuries resulting from professional horse racing in France during 1991-2001: a comparison with injuries resulting from professional horse racing in Great Britain during 1992-2001. Br J Sports Med, 40(7), 614–618.
Abstract: BACKGROUND: It has been previously shown that professional jockeys suffer high rates of fatal and non-fatal injuries in the pursuit of their occupation. Little is known, however, about differences in injury rates between countries. AIM: To determine the rate of fatal and non-fatal injuries in flat and jump jockeys in France and to compare the injury rates with those in Great Britain and Ireland Method: Prospectively collected injury data on professional jockeys were used as the basis of the analysis. RESULTS: Limb fractures occur four times more often in both flat and jump racing in France than in Great Britain. Similarly dislocations are diagnosed 20 times more often in flat and three times more often in jump racing. This difference is surprising given that French jockeys have fewer falls per ride than their British counterparts in flat racing, although they do have more falls than the British in jump racing. Similarly concussion rates seem to be higher in French jockeys, although there may be a difference in the diagnostic methods used in the different countries. By contrast, soft tissue injuries account for a far smaller percentage of injuries than in Great Britain. CONCLUSION: There are striking differences in injury rates between countries which may be explained in part by a difference in track conditions-for example, harder tracks in France-or different styles of racing--for example, larger fields of horses per race in France.
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Jansen, W. L., van Alphen, M., Berghout, M., Everts, H., & Beynen, A. C. (2001). An approach to assessment of the efficiency of dietary energy utilization by horses and ponies kept at riding schools. Vet Q, 23(4), 195–198.
Abstract: The ratio of calculated net energy intake (NEi) to calculate net energy requirement (NEr) might serve as an indicator of the efficiency of dietary energy utilization. The ratio was determined for 93 horses and ponies from 10 riding schools. For each animal with an assumed constant body weight, energy intake and energy requirements were assessed. On average, the estimated NEi was 14% greater than NEr. There was a significant, negative association between crude fibre intake and the NEi: NEr ratio. Earlier work indicated that extra fat intake may lead to over estimation of the calculated energy value of the ration due to changes in macronutrient digestibility. Dietary fat concentration was found to range from 32 to 52 g/kg dry matter (5 to 6 g/MJ net energy), but on the basis of digestibility trials this range in fat concentration is too small to significantly influence the NEi: NEr ratio. This study shows that assessment of the efficiency of dietary energy utilization under normal conditions, on the basis of the NEi: NEr ratio is fraught with uncertainty.
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Sinclair, M., Buhrmann, G., & Gummow, B. (2006). An epidemiological investigation of the African horsesickness outbreak in the Western Cape Province of South Africa in 2004 and its relevance to the current equine export protocol. J S Afr Vet Assoc, 77(4), 191–196.
Abstract: African Horsesickness (AHS) is a controlled disease in South Africa. The country is divided into an infected area and a control area. An outbreak of AHS in the control area can result in a ban of exports for at least 2 years. A retrospective epidemiological study was carried out on data collected during the 2004 AHS outbreak in the surveillance zone of the AHS control area in the Western Cape Province. The objective of this study was to describe the 2004 outbreak and compare it with the 1999 AHS outbreak in the same area. As part of the investigation, a questionnaire survey was conducted in the 30 km radius surrounding the index case. Spatial, temporal and population patterns for the outbreak are described. The investigation found that the outbreak occurred before any significant rainfall and that the main AHS vector (Culicoides imicola) was present in abundance during the outbreak. Furthermore, 63% of cases occurred at temperatures < or = 15 degrees C, the Eerste River Valley was a high risk area, only 17% of owners used vector protection as a control measure and 70% of horses in the outbreak area were protected by means of vaccination at the start of the outbreak. The study revealed that the current AHS control measures do not function optimally because of the high percentage of vaccinated horses in the surveillance zone, which results in insufficient sentinel animals and the consequent failure of the early warning system. Alternative options for control that allow continued export are discussed in the paper.
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Sivak, J. G., & Allen, D. B. (1975). An evaluation of the “ramp” retina of the horse eye. Vision Res, 15(12), 1353–1356.
Abstract: Using a rapid freezing and sectioning technique, the distance between the lens and retina of the horse eye was measured. There is no indication of a ramp retina that could serve accommodation. The pupil axis of the eye coincides with the maximum lens to retina distance. The changes in the lens-retina distance are greater below the axis than above it. Calculations were made of refractive power of the horse eye from measurements of curvature and refractive indices of the ocular tissues. These calculations agree both qualitatively and quantitatively with retinoscopic measurements on live horses. Both show that the refractive state shifts in the direction of hyperopia above and below the axis and that this shift is greater below the axis than above it. Some dynamic accommodative ability in the living eye was observed.
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Barrey, E., & Galloux, P. (1997). Analysis of the equine jumping technique by accelerometry. Equine Vet J Suppl, (23), 45–49.
Abstract: The purpose of this study was to demonstrate the relationships between jumping technique and dorsoventral acceleration measured at the sternum. Eight saddle horses of various jumping abilities competed on a selective experimental show jumping course including 14 obstacles. An accelerometric belt fastened onto the thorax continuously measured the dorsoventral acceleration during the course. At each jump, 11 locomotor parameters (acceleration peaks, durations and stride frequency) were obtained from the dorsoventral acceleration-time curves. The type of obstacle significantly influenced the hindlimb acceleration peak at take-off and the landing acceleration peak (P<0.01). The poor jumpers exhibited a higher mean forelimb acceleration peak at take-off, a higher forelimb/hindlimb ratio between peaks of acceleration (F/H), and a lower approach stride frequency than good jumpers. Knocking over an obstacle was significantly associated with a low hindlimb acceleration peak at take-off and a high F/H ratio (P<0.01). In order to observe the continuous changes in the frequency domain of the dorsoventral acceleration during the approach and take-off phase, a Morlet's wavelet analysis was computed for each horse jumping over a series of 3 vertical obstacles. Different patterns of time-frequency images obtained by wavelet analysis were found when the horse either knocked over a vertical obstacle or cleared it. In the latter case, the image pattern showed an instantaneous increase in stride frequency at the end of the approach phase, and a marked energy content in the middle frequency range at take-off.
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Turner, J. W. J., & Kirkpatrick, J. F. (1982). Androgens, behaviour and fertility control in feral stallions. J Reprod Fertil Suppl, 32, 79–87.
Abstract: This field study of feral stallions in Montana and Idaho examines and correlates the seasonal pattern of plasma androgens and specific sociosexual behaviour and reports the effect of a long-acting androgenic steroid on this behaviour and on fertility. Plasma testosterone was measured by competitive protein binding assay in samples obtained by jugular venepuncture from captured animals. In samples taken from 34 sexually mature stallions in 6 different months during the year, a definite seasonal pattern in testosterone was present, with a peak in May (3.04 +/- 0.63 ng/ml) and a nadir in December (1.55 +/- 0.34 ng/ml). Values were less than 2.0 ng/ml in non-breeding months and greater than 2.4 ng/ml in breeding months. Behavioural endpoints measured were (1) stallion scent marking in response to elimination by mares (elimination marking), (2) mounting and (3) copulation. The frequencies of each of these endpoints followed closely the seasonal pattern seen for plasma androgens. In the fertility study microcapsulated testosterone propionate (microTP) was administered i.m. to 10 harem stud stallions 3 months before the 1980 breeding season. In these stallions and in 10 control harem studs, the above behavioural endpoints were examined in the 1980 and 1981 breeding seasons, and foal counts were made in 1981. There were no direct inhibitory or stimulatory effects of microTP treatment on any of the behavioural endpoints in either year. In 1981 foals were produced in 87.5% of the control bands and 28.4% of the microTP-treated bands. These results indicate that microencapsulated testosterone propionate can provide effective fertility control in feral horses without causing significant alterations in sociosexual behaviour.
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Morales, J. L., Manchado, M., Vivo, J., Galisteo, A. M., Aguera, E., & Miro, F. (1998). Angular kinematic patterns of limbs in elite and riding horses at trot. Equine Vet J, 30(6), 528–533.
Abstract: Normal speed videography was used to determine the angular parameters of 28 Spanish Thoroughbreds at trot. Horses were divided into 3 groups: Group UT, comprising 9 animals (provided by the VII National Stud, Cordoba, Spain) which had undergone no specific training programme and which were hand led at the trot; Group T, formed by 19 horses considered to be highly bred and trained, and which were also hand led; and Group RT, comprising the same horses as the latter group but this time trotted by a rider. Each animal was filmed 6 times from the right-hand side, using a Hi8 (25 Hz) video camera. Angular parameters for fore- and hindlimb joints were measured in each stride from computer-grabbed frames and entered into a spreadsheet for calculation; parameters included maximum and minimum angles, range of motion, and angles at landing, lift off and maximum hoof height; the times at which maximum angle, minimum angle, lift off and maximum hoof height occurred were calculated as percentages of total stride duration. Stride velocity (mean [s.d.]) was 4.01 (0.62), 3.60 (0.34) and 3.07 (0.36) m/s for Groups UT, T and RT, respectively. Data were then compared between Groups UT-T and Groups T-RT. Compared with Group UT, horses from Group T featured a shorter stance percentage (P<0.001) in both fore- and hindlimbs. The range of motion in forelimbs was smaller (P<0.05), due to lower retraction (P<0.001); moreover, maximum retraction appeared earlier (P<0.05). Greater scapular inclination was in evidence (P<0.05) and the shoulder joint extended further (P<0.05). Fore- and hind fetlock joints revealed a relatively shorter hyperextension period during the stance phase (P<0.01). Compared with Group T, horses from Group RT had a longer stance percentage, with belated maximum retraction of the fore- and hindlimbs. The range of movement in scapular inclination was greater (P<0.05), due to a smaller minimum angle (P<0.01), and the shoulder joint flexed more (P<0.05). The elbow joint extended more and for longer during the stance phase. Initial extension of the hip joint (P<0.05) and tarsus (P<0.001) lasted longer. The carpal and fore and hind fetlock joints recorded relatively longer hyperextension times, in addition to greater hyperextension during the stance phase. The results from the present study suggest that rider-effect must be taken in consideration when well gaited horses are selected for dressage purposes.
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Houpt, K. A. (1991). Animal behavior and animal welfare. J Am Vet Med Assoc, 198(8), 1355–1360.
Abstract: The value of behavioral techniques in assessing animal welfare, and in particular assessing the psychological well being of animals, is reviewed. Using cats and horses as examples, 3 behavioral methods are presented: (1) comparison of behavior patterns and time budgets; (2) choice tests; and (3) operant conditioning. The behaviors of intact and declawed cats were compared in order to determine if declawing led to behavioral problems or to a change in personality. Apparently it did not. The behavior of free ranging horses was compared with that of stabled horses. Using two-choice preference tests, the preference of horses for visual contact with other horses and the preference for bedding were determined. Horses show no significant preference for locations from which they can make visual contact with other horses, but they do prefer bedding, especially when lying down. Horses will perform an operant response in order to obtain light in a darkened barn or heat in an outside shed. These same techniques can be used to answer a variety of questions about an animal's motivation for a particular attribute of its environment.
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