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Hardy, J. L. (1987). The ecology of western equine encephalomyelitis virus in the Central Valley of California, 1945-1985. Am J Trop Med Hyg, 37(3 Suppl), 18s–32s.
Abstract: Reeves' concept of the summer transmission cycle of western equine encephalomyelitis virus in 1945 was that the virus was amplified in a silent transmission cycle involving mosquitoes, domestic chickens, and possibly wild birds, from which it could be transmitted tangentially to and cause disease in human and equine populations. Extensive field and laboratory studies done since 1945 in the Central Valley of California have more clearly defined the specific invertebrate and vertebrate hosts involved in the basic virus transmission cycle, but the overall concept remains unchanged. The basic transmission cycle involves Culex tarsalis as the primary vector mosquito species and house finches and house sparrows as the primary amplifying hosts. Secondary amplifying hosts, upon which Cx. tarsalis frequently feeds, include other passerine species, chickens, and possibly pheasants in areas where they are abundant. Another transmission cycle that most likely is initiated from the Cx. tarsalis-wild bird cycle involves Aedes melanimon and the blacktail jackrabbit. Like humans and horses, California ground squirrels, western tree squirrels, and a few other wild mammal species become infected tangentially with the virus but do not contribute significantly to virus amplification.
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Hartmann, E. (2010). Managing horses in groups to improve horse welfare and human safety. Ph.D. thesis, , .
Abstract: Managing horses in groups to improve horse welfare and human safety
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reactions to mixing and separation
Hartmann, Elke (2010) Managing horses in groups to improve horse welfare and human safety . Doctoral diss. Dept. of Animal Environment and Health, SLU. Acta Universitatis agriculturae Sueciae vol. 2010:87.
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Abstract
The aim of this thesis was to investigate whether specific anecdotal concerns related to keeping horses in groups are supported by science and, if so, provide scientifically based recommendations that could be implemented in practice.
The aim of studies I and II was to identify methods for mixing unfamiliar horses that could minimise aggressive interactions and associated risk of injury. Results of study I revealed that pre-exposure of young horses in neighbouring boxes tended to lower contact-aggression (e.g. kicks, strikes) and biting behaviour in particular was reduced when the same pair of horses subsequently met in a paddock. This was not found when older horses were mixed (study II). Aggressive behaviour received by a new horse was not significantly different in meetings when it met one other horse compared to meeting two unfamiliar horses at the same time.
Removing a horse from a group of four in study III was generally unproblematic. Most horses approached the handler when she was catching the horse and while standing with it in the middle of the paddock. Thus, potential risk may be higher in situations when the handler remains relatively stationary, as other horses of the group have time to approach. Rank did not influence the number of horses following to the paddock gate and interactions between horses were rare.
Since horses naïve to social separation may be more difficult to handle away from the group, the objective in study IV was to investigate whether the initial presence of a companion horse would modify responses to separation. Results revealed no significant differences in heart rates and the number of training sessions required when the horses were subsequently trained in the absence of the partner compared to horses trained alone from the start.
In summary, results give little support for the original areas of concerns about mixing and separating horses. Risk of injury to both horses and humans should not be overestimated when handling horses in groups, but being aware of potential risk situations and being able to react accordingly is likely to increase horse welfare and human safety.
Faculty: Faculty of Veterinary Medicine and Animal Science
Keywords:
equine, behaviour, welfare, housing, mixing, aggression, injury, separation, habituation, learning
Agrovoc terms:
horses, behaviour, bites, injurious factors, animal learning, animal welfare, sweden
ISBN: 978-91-576-7532-3
Series.: Acta Universitatis agriculturae Sueciae
ISSN: 1652-6880
Volume: 2010:87
Papers/manuscripts:
I. Hartmann, E., Winther Christensen, J., Keeling, L.J. (2009). Social interactions of unfamiliar horses during paired encounters: Effect of pre-exposure on aggression level and so risk of injury. Applied Animal Behaviour Science 121, 214-221.
II. Hartmann, E., Rundgren, M., Keeling, L.J. (in press). Comparison of 3 methods for mixing unfamiliar horses (Equus caballus). Journal of Equine Veterinary Behavior: Clinical Applications and Research.
III. Hartmann, E., Søndergaard, E., Keeling, L.J. Identifying potential risk situations for humans when removing horses from groups. Manuscript.
IV. Hartmann, E., Christensen, J.W., Keeling, L.J. (in press). Training young horses to social separation: Effect of a companion horse on training efficiency. Equine Veterinary Journal.
Number of pages: 75
Year of publication: 2010
Language: eng
ID Code: 2396
Deposited By: Hartmann, Elke
Deposited On: 08 November 2010
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Hartmann, E., Christensen, J. W., & Keeling, L. J. (2009). Social interactions of unfamiliar horses during paired encounters: Effect of pre-exposure on aggression level and so risk of injury. Appl. Anim. Behav. Sci., 121(3-4), 214–221.
Abstract: Group housing of horses is not widely applied in practice despite the welfare advantages of keeping animals socially rather than individually. In particular, concerns have been raised about the possible increased risk of injury and how to introduce a new horse into an established group. This study investigated two hypotheses: (1) pre-exposure of young horses in neighbouring boxes reduces the frequency of aggressive interactions when the same horses are subsequently put together in a paddock compared to horses without this previous box experience, (2) the occurrence of aggressive behaviour, in particular contact aggression in the paddock can be predicted after observing the horses' social interactions in neighbouring boxes. Danish Warmblood mares (n = 20), 2 years old, were kept in two groups of 10 horses. In total, 60 encounters were arranged whereby each horse was confronted pair-wise with six horses from the other group, three according to each treatment: treatment I--box (B) and subsequent paddock meeting (BP), and treatment II--only paddock meeting (P). Horses met in neighbouring boxes for 5 min and together in the same paddock for 10 min. The frequencies of aggressive and non-aggressive interactions were analysed from video recordings. Total aggression levels between BP and P did not differ, but [`]contact aggression', i.e. bite, kick, strike, push, tended to be lower in BP compared to P (median BP = 1, P = 2; p = 0.083) and there were less bites in BP than P (median BP = 0, P = 1; p = 0.050). Frequencies of [`]non-aggressive' interactions, e.g. friendly approach, nasal sniff, were lower in BP than P (median BP = 2.5, P = 10; p < 0.01). Results further revealed that [`]bite threat' performed in boxes correlated with [`]contact aggression' in the paddock (r = 0.46, p = 0.011). In conclusion, pre-exposure of young horses in neighbouring boxes may reduce [`]contact aggression', especially biting, in the paddock and [`]bite threat' shown in boxes may help to predict contact aggression when horses are later turned out together. The reduced non-aggressive interactions in the paddock in the BP test were probably a consequence of horses having exchanged these behaviours in the preceding B test. Exposing young horses in boxes next to each other may be a helpful tool before mixing them because horses meet in a safe environment that could assist in reducing the type of aggression where horses are most at risk of being injured.
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Hartmann, E., Keeling, L. J., & Rundgren, M. (2011). Comparison of 3 methods for mixing unfamiliar horses (Equus caballus). J Vet Behav Clin Appl Res, 6(1), 39–49.
Abstract: Horses are likely to exhibit aggression when meeting for the first time. Therefore, this study compared 3 methods for mixing horses to evaluate their effectiveness in reducing aggressive interactions: (1) mixing pairs of horses in a paddock (P, 10 minutes, 15 tests), (2) introducing 1 unfamiliar horse to a pair of familiar, resident horses in a paddock (PP, 10 minutes, 15 tests), (3) allowing limited physical contact between pairs of horses for a short period of pre-exposure in neighboring boxes (B, 5 minutes, 16 tests) before mixing them in a paddock (BP, 10 minutes 16 tests). A total of 16 Swedish Standardbred mares, aged 6-18 years (mean age ± SD: 11 ± 4.4), were included in the study. Half of the horses were familiar with each other (resident horses, n = 8), whereas the other half were bought in from a variety of sources (unfamiliar horses, n = 8). Social interactions, consisting of behaviors from the sender, the receiver, and the subsequent sender's response, were recorded continuously as frequencies. There were no differences in the frequencies of aggressive behaviors between the 3 mixing methods, including those aggressive behaviors in which physical contact had been attempted (kick, strike). Although resident horses were overall more aggressive (median number of aggressive behaviors per horse, 62; Q1, 36; Q3, 68.5) than unfamiliar horses (median per horse, 4; Q1, 2; Q3, 12.5) during all tests (U = 97, P = 0.003), none of the 62 tests needed to be terminated. Unfamiliar horses did not receive more aggression from resident horses in PP (mean per test ± SD: 5.1 ± 3.1) than in P (mean per test ± SD: 6.4 ± 4.9) (t = 0.63, P = 0.544). However, the behavior “attack” was more frequent in PP (median per test, 2; Q1, 0; Q3, 5) than in P (median per test, 0; Q1, 0; Q3, 1) (U = 282, P = 0.042), and “flee” was more frequent in PP (median per test, 6; Q1, 4; Q3, 8) than in P (median per test, 1; Q1, 0; Q3, 6) (U = 290, P = 0.018). Pre-exposure in boxes did not reduce aggression in BP (median per test, 7; Q1, 4.3; Q3, 11.8) as compared with P (median per test, 6; Q1, 2; Q3, 16) (U = 264, P = 0.767), but during pre-exposure in B tests, horses exchanged more nonaggressive (median per test, 2; Q1, 0.3; Q3, 4) than aggressive (median frequency of aggressive behavior, 0; Q1, 0; Q3, 1) (W = 71, P = 0.013) and mixed interactions (median per test, 0; Q1, 0; Q3, 1) (W = 92, P = 0.016) through the opening. Results suggest mixing an unfamiliar horse with 2 resident horses at the same time instead of one by one may be preferable. In this way, the total aggression received by the unfamiliar horse will potentially be less, even though aggressive interactions may be more intense.
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Hartmann, E., Søndergaard, E., & Keeling, L. J. Keeping horses in groups: A review. Appl. Anim. Behav. Sci., .
Abstract: Although husbandry conditions for horses have improved over the last decades, many horses are still kept singly with limited or no physical contact to other horses. This is surprising, given the fact that keeping horses in groups is recognised best to fulfil their physical and behavioural needs, especially their need for social contact with conspecifics, as well as to have a beneficial effect on horse–human interactions during training. Group housing of farm animals is widely applied in practice. As a consequence, scientists have investigated numerous aspects of group housing to help further improve animal welfare and human–animal interactions under these conditions. However, compared to this literature available in farm animals, and the plentiful studies conducted of feral horse populations, there is much less done when it comes to the management of horses kept in groups in the domestic environment. In particular, limited scientific information is available into the effect of group size and group composition on behaviour and methods of introducing new horses into established groups, even though problems related to social integration are repeatedly taken as arguments against keeping horses in groups. This review, therefore, aims to provide an overview of the current scientific knowledge regarding keeping horses in groups. Furthermore, it aims to give insight into whether or not some of the concerns related to keeping horses in groups are justified and to review scientifically based solutions that could be useful in practice to improve horse welfare and human safety.
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Hartmann, E., Søndergaard, E., & Keeling, L. J. (2012). Identifying potential risk situations for humans when removing horses from groups. Appl. Anim. Behav. Sci., 136(1), 37–43.
Abstract: Removing a horse from its social group may be considered risky, both for the handler and the horse, because other horses can interfere in the catching process. The main aim of this study was to identify where and when these risk situations occur while removing a horse from its group. A potential risk situation was defined by the closeness of loose horses in the group or by any physical contact with them. Whether the number of horses following would be influenced by the social rank of the horse being led out, and whether more horses would follow to the gate when a larger proportion of the group was removed compared to when a single horse was taken out were also investigated. Thirty-two mares (1–2 years) were kept in groups of four. All horses were taken out of their home paddock twice alone (64 tests) and twice with a companion (32 tests). One handler (or two handlers when two horses were removed) was asked to approach (phase 1) and catch the target horse (phase 2), walk it to the centre of the paddock and remain stationary at a post for 30 s (phase 3), walk to the paddock entrance (phase 4) and through the gate (phase 5). The number of horses following, and the number of loose horses in proximity (<2 m, 2–5 m) to the target horse and handler was estimated, and horse–horse and horse–human interactions were recorded continuously for the five scoring phases. Significantly more loose horses were within 2 m of a single target horse during the phases approach (mean ± SD: 1.5 ± 0.8), catch (1.6 ± 0.9) and post (1.7 ± 0.7) than during walk (1.0 ± 0.5) and gate (1.1 ± 0.6). Rank did not influence the number of horses following to the gate (high rank: 2.4 ± 0.7; lower rank: 2.0 ± 1.0; P = 0.396) and interactions between horses were rare. A greater proportion of the loose horses followed when two horses (0.9 ± 0.2) were removed compared to when a single horse (0.7 ± 0.3) was taken out (P = 0.011). In conclusion, maintaining a distance to other horses in the group by reducing the time being relatively stationary, so giving loose horses fewer chances to approach, is likely to contribute to improved handler's safety. Removing a small proportion of the group may also decrease the probability of the other horses following.
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Hockenhull, J., & Creighton, E. (2010). Unwanted oral investigative behaviour in horses: A note on the relationship between mugging behaviour, hand-feeding titbits and clicker training. Appl. Anim. Behav. Sci., 127(3-4), 104–107.
Abstract: Unwanted oral investigative in horses has been anecdotally attributed to the practice of hand-feeding. Fears over such behaviour developing as a consequence of using food rewards, for example in clicker training, have been implicated as a common reason for not employing food-based positive reinforcement training techniques. This study used data generated as part of a larger research project, and explored associations between five common oral investigative behaviours and the practices of hand-feeding and clicker training. Data were from a convenience sample of UK leisure horse owners using two self-administered Internet surveys. Ninety-one percent of respondents reported giving their horse food by hand and this practice was significantly associated with three of the five oral investigative behaviours, licking hands (P = 0.006), gently searching clothing (P < 0.001) and roughly searching clothing (P = 0.003). Nipping hands and biting clothes were not associated with hand-feeding, suggesting that risk factors for these behaviours originate outside of this practice. Clicker training techniques were employed by 14% of respondents and their use was not associated with the incidence of any of the five oral investigative behaviours. These findings suggest that horse owners should not be deterred from using food-based positive reinforcement techniques with their horses, as fears that this practice will result in unwanted oral investigative behaviours from their horses appear unfounded.
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Hothersall, B., & Nicol, C. (2009). Role of Diet and Feeding in Normal and Stereotypic Behaviors in Horses. Clinical Nutrition, 25(1), 167–181.
Abstract: This article reviews the effects of diet on equine feeding behavior and feeding patterns, before considering the evidence that diet affects reactivity in horses. A growing body of work suggests that fat- and fiber-based diets may result in calmer patterns of behavior, and possible mechanisms that may underpin these effects are discussed. In contrast, there is little evidence that herbal- or tryptophan-containing supplements influence equine behavior in any measurable way. The role of diet in the development of abnormal oral behaviors, particularly the oral stereotypy crib-biting, is also reviewed, and suggestions for future work are presented.
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Hutchinson, G. W., Abba, S. A., & Mfitilodze, M. W. (1989). Seasonal translation of equine strongyle infective larvae to herbage in tropical Australia. Vet Parasitol, 33(3-4), 251–263.
Abstract: Longevity in faeces, migration to and survival on herbage of mixed strongyle infective larvae (approximately 70% cyathostomes: 30% large strongyles) from experimentally deposited horse faeces was studied in the dry tropical region of North Queensland for up to 2 years. Larvae were recovered from faeces deposited during hot dry weather for a maximum of 12 weeks, up to 32 weeks in cool conditions, but less than 8 weeks in hot wet summer. Translation to herbage was mainly limited to the hot wet season (December-March), except when unseasonal winter rainfall of 40-50 mm per month in July and August allowed some additional migration. Survival on pasture was estimated at 2-4 weeks in the summer wet season and 8-12 weeks in the autumn-winter dry season (April-August). Hot dry spring weather (pre-wet season) was the most unfavourable for larval development, migration and survival. Peak counts of up to 60,000 larvae kg-1 dry herbage were recorded. The seasonal nature of pasture contamination allowed the development of rational anthelmintic control programs based on larval ecology.
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Joubert, L., Oudar, J., Hannoun, C., Beytout, D., Corniou, B., Guillon, J. C., et al. (1970). [Epidemiology of the West Nile virus: study of a focus in Camargue. IV. Meningo-encephalomyelitis of the horse]. Ann Inst Pasteur (Paris), 118(2), 239–247.
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