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McCall, C. A., Hall, S., McElhenney, W. H., & Cummins, K. A. (2006). Evaluation and comparison of four methods of ranking horses based on reactivity. Appl. Anim. Behav. Sci., 96(1-2), 115–127.
Abstract: Four methods of ranking horses on reactivity were evaluated and compared: isolation from conspecifics, presentation of a static novel stimulus, traversing a novel stimulus in a runway (isolation, novel stimulus and runway tests, respectively) and assigning subjective emotionality scores. In all tests, horses' heart rates were recorded and behaviour was videotaped. To be considered a valid test of reactivity, at least one heart rate and one behavioural measurement in the test had to change significantly between treatments (tranquilizer administation versus sham tranquilizer administration), and behavioural measures had to be displayed in at least 75% of the trials. Forty horses performed each of the three tests daily on three different days in a switchback design. Horses were assigned randomly to a daily test sequence, which was maintained throughout the study. In the runway test, no significant difference in heart rate values in tranquilized and non-tranquilized horses was found, and no behavioural attribute was displayed in more than 52% of the trials; therefore it was rejected as a valid test of reactivity. Both isolation and novel stimulus tests produced valid measurements. Mean heart rate was the most precise physiological measure for these tests, and walking and defecation frequency were the most precise behavioural measures for novel stimulus and isolation tests, respectively. Mean heart rates on the novel stimulus and isolation tests were correlated (rs = 0.79, P < 0.01) indicating that these tests produced similar rankings based on physiological responses. However, behavioural measures ranked horses differently (rs = 0.27, P < 0.10) on the tests. Rank correlations between mean heart rates and behavioural measures were higher in the novel stimulus (rs = 0.66, P < 0.01) than the isolation test (rs = 0.55, P < 0.01), indicating that the novel stimulus test ranked horses based on either physiological or behavioural responses more similarly than did the isolation test. Therefore, the novel stimulus test was considered the more accurate evaluation of reactivity. Subjective emotionality scores were correlated moderately with mean heart rates (rs > 0.33, P < 0.01) from the novel stimulus and isolation tests and with walking scores (rs = 0.47, P < 0.01) from the novel stimulus test. Assignment of subjective emotionality scores was not as accurate as the novel stimulus or isolation tests in ranking horses for reactivity. Using physiological data alone, combining physiological and behavioural measurements or using more than one behavioural measurement in reactivity tests may reflect the reactivity of the horse better than a single behavioural measurement.
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Williams, J. L., Friend, T. H., Nevill, C. H., & Archer, G. (2004). The efficacy of a secondary reinforcer (clicker) during acquisition and extinction of an operant task in horses. Appl. Anim. Behav. Sci., 88(3-4), 331–341.
Abstract: “Clicker training” is a popularly promoted training method based on operant conditioning with the use of a secondary reinforcer (the clicker). While this method draws from theories of learning and is used widely, there has been little scientific investigation of its efficacy. We used 60 horses, Equus callabus, and assigned each horse to one of six reinforcement protocols. The reinforcement protocols involved combinations of reinforcers administered (primary versus secondary plus primary), schedule of reinforcement (continuous versus variable ratio), and reinforcers applied during extinction (none or secondary). There were no differences (P>=0.11) between horses which received a secondary reinforcer (click) followed by the primary reinforcer (food) and those which received only the primary reinforcer (food) in the number of trials required to train the horses to touch their noses to a plastic cone (operant response). There also were no differences (P>=0.12) between horses which received the secondary reinforcer plus primary reinforcer and those which received only the primary reinforcer in regards to the number of trials to extinction. We conclude that there is no difference in the amount of training required to learn the operant task or in the task's resistance to extinction between horses that received a secondary reinforcer followed by a primary reinforcer versus horses which received only a primary reinforcer.
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Langbein, J., Siebert, K., Nuernberg, G., & Manteuffel, G. (2007). The impact of acoustical secondary reinforcement during shape discrimination learning of dwarf goats (Capra hircus). Appl. Anim. Behav. Sci., 103(1-2), 35–44.
Abstract: The use of secondary reinforcement is widely accepted to support operant learning in animals. In farm animals, however, the efficacy of secondary reinforcement has up to now been studied systematically only in horses (“clicker training”), and the results are controversial. We investigated the impact of acoustical secondary reinforcement on voluntary, self-controlled visual discrimination learning of two-dimensional shapes in group-housed dwarf goats (Capra hircus). Learning tests were conducted applying a computer-controlled learning device that was integrated in the animals' home pen. Shapes were presented on a TFT-screen using a four-choice design. Drinking water was used as primary reinforcement. In the control group (Gcontrol, n = 5) animals received only primary reinforcement, whereas in the sound group (Gsound, n = 6) animals got additional acoustical secondary reinforcement. Testing recall of shapes which had been successfully learned by the goats 6 weeks earlier (T1), we found a weak impact of secondary reinforcement on daily learning success (P = 0.07), but not on the number of trials the animals needed to reach the learning criterion (trials to criterion, n.s.). Results in T1 indicated that dwarf goats did not instantly recall previously learned shapes, but, re-learned within 250-450 trials. When learning a set of new shapes (T2), there was a strong influence of secondary reinforcement on daily learning success and on trials to criterion. Animals in Gsound reached the learning criterion earlier (P < 0.05) and needed fewer trials (1320 versus 3700; P < 0.01), compared to animals in Gcontrol. Results suggest that acoustical secondary reinforcement supports visual discrimination learning of dwarf goats, especially when the task is new and the salience of S+ is low.
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McCall, C. A., Salters, M. A., Johnson, K. B., Silverman, S. J., McElhenney, W. H., & Lishak, R. S. (2003). Equine utilization of a previously learned visual stimulus to solve a novel task. Appl. Anim. Behav. Sci., 82(3), 163–172.
Abstract: Forty-four horses were used to determine if a learned stimulus could be used to increase acquisition of a response unrelated to the original learned task. Horses were paired by age, breed and sex. One randomly chosen horse from each pair served as the control while the remaining horse was trained to respond to a visual stimulus by pushing a lever to obtain a food reward. In Experiment I (n=28), the food reward was delivered in a feed box located equidistant between two levers located 2.7 m apart on one wall of the test stall. Trained horses were given 30 training trials daily until they achieved at least 85% correct responses in three nonconsecutive days. After each trained horse reached criterion, both horses in the pair were tested in 30 trials daily for five consecutive days in a modified Y maze. The stimulus that indicated the correct lever in the initial training task was used to signify the correct arm of the maze for both the control and trained horses. The correct arm of the maze was changed randomly during each daily session, and correct choices resulted in a food reward. In Experiment II (n=16), levers were located on opposite walls (11 m apart) of the test stall, and the stimulus and modified Y maze were simplified. Trained horses received 15 training trials daily until they reached at least 85% correct responses on three consecutive days. As each trained horse achieved this criterion, both horses in the pair were tested in a maze for 15 trials daily for 7 days. Again, the stimulus from initial lever-pressing task was used to signify the rewarded arm of the maze. Correct choices of trained and control horses in both experiments were compared using a paired t-test. In Experiment I, no differences (P>0.34) in mean correct responses were detected between trained and control horses on the first day in the maze (15.3 and 16.8, respectively) or after 5 days in the maze (84.0 and 82.1, respectively). Similarly, in Experiment II, trained and control horses did not differ (P>0.50) in mean correct responses on the first day (6.9 and 7.4, respectively) or after 7 days in the maze (63.6 and 61.6, respectively). These results indicate that the stimuli used to solve the lever-pressing task were not utilized by horses in the maze task, and that horses may have difficulty transferring learned visual stimuli to new tasks.
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Heird, J. C., Whitaker, D. D., Bell, R. W., Ramsey, C. B., & Lokey, C. E. (1986). The effects of handling at different ages on the subsequent learning ability of 2-year-old horses. Appl. Anim. Behav. Sci., 15(1), 15–25.
Abstract: Forty weanling Quarter Horses, from the Pitchfork Ranch, Dickens, Texas, were randomly assigned to one of five groups based on the amount of handling they would receive. The five groups were: (1) limited handling; (2) 1 week of handling; (3) 2 weeks of handling; (4) 3 weeks of handling; (5) continuous handling for 18 months. As 2-year-olds, the horses were tested in a simple place-learning T-maze after being preconditioned. A maximum of 30 daily trials were conducted for 20 consecutive days, with feed location alternating between sides on successive days. If a horse met the criterion of 11 out of 12 correct responses with 8 correct responses being consecutive, it was retired without completing the 30 trials. Group 1 made fewer correct responses during the 20 days than any other group except Group 3. All groups achieved learning by Day 10, but the most-handled group reached a consistently higher percentage of correct responses earlier than the less-handled groups. Group 5, the group receiving the most handling, was the least emotional, as determined by the animals' reactivity to a novel stimulus, and received the highest scores for trainability after being ridden. Preconditioning trainability scores, or estimates of the horses' ability to learn prior to conditioning and testing, tended to predict maze-learning ability. These scores were also significantly correlated with post-maze training scores.
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Bachmann, I., Bernasconi, P., Herrmann, R., Weishaupt, M. A., & Stauffacher, M. (2003). Behavioural and physiological responses to an acute stressor in crib-biting and control horses. Appl. Anim. Behav. Sci., 82(4), 297–311.
Abstract: The responses of eleven pairs of crib-biting and non-crib-biting horses (controls) to an arousal-inducing stimulus were studied. Video-observation of the horses revealed that crib-biting horses spent between 10.4 and 64.7% of their stabling time performing the stereotypy. During the first 2 days of an experimental period, the horses were conditioned to receive food from a special bucket. On the third day the food bucket was presented, but the horses were not allowed to feed. Arousal behaviour and crib-biting intensity as well as plasma cortisol concentration, heart rate (HR) and heart rate variability (HRV) were recorded at rest, and during and after presentation of the food stimulus. The stimulus induced a significant increase of HR and arousal behaviour in crib-biters and in controls, whereas the crib-biting frequency decreased. Power spectral analysis of the HRV revealed significant differences between crib-biters and controls at rest: crib-biters had a lower vagal tone (high frequency component, HF) and a higher sympathetic tone (low frequency component, LF) than controls. The lower basal parasympathetic activity might be an indication why crib-biting horses, in contrast to the controls, showed neither a significant decrease of the HF component during presentation of the food stimulus nor an increase of the HF component after presentation. Thus, there might be differences in the tuning of the autonomous nervous system and of the stress reactivity in crib-biting and in control horses. The results suggest that the crib-biting horses are more stress sensitive and physiologically and psychologically less flexible than the control horses.
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McBride, S. D., Hemmings, A., & Robinson, K. (2004). A preliminary study on the effect of massage to reduce stress in the horse. Journal of Equine Veterinary Science, 24(2), 76–81.
Abstract: The use of massage (as a potential form of acupressure) has long been documented as a human relaxation aid. However, little scientific research has been carried out into its potential use as a form of stress reduction in the horse. This preliminary study investigated the effect of massage at six different sites (thoracic trapezius [withers], mid-brachiocephalicus, cervical ventral serrate and cervical trapezius [mid-neck], proximal gluteal fascia and proximal superficial gluteal [croup], proximal and mid-semitendinosus [second thigh], lateral triceps, proximal extensor carpi radialis and proximal common digital extensor [forearm], proximal brachiocephalicus, proximal splenius and ear [poll and ears) on stress-related behavioral and physiological (heart rate [HR]) measures in the horse. Ten riding school ponies/horses were massaged at each of the six sites (three preferred and three nonpreferred sites of allogrooming (mutual grooming between conspecifics) and changes in HR and behavior were recorded. The results indicated that during massage, all sites except the forearm resulted in a significant reduction in HR (P < .05) with massage at the withers, mid-neck, and croup having the greatest effect (preferred sites of allogrooming). Massage at preferred sites of allogrooming also elicited significantly more (P < .05) positive behavioral responses compared with the three nonpreferred sites. The practical implications of this study are discussed.
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Simpson, B. S. (2002). Neonatal foal handling. Appl. Anim. Behav. Sci., 78(2-4), 303–317.
Abstract: Recent interest has focused on the advantage of intensively handling young foals as a means of producing more tractable horses, accustomed to humans and receptive to training. To date, the effect of this intensive handling, dubbed “imprint training” in the popular literature, has not been tested. The present study compares seven foals handled intensively as neonates with eight untreated controls. The handling protocol started from 2-8 h after birth and continued daily for a total of 5 days. The protocol consisted of a series of stimuli and experiences that were each repeated until the foal no longer resisted or reacted negatively. Subsequently, foals were tested before weaning, at 4 months of age. Results indicated that handled foals (HF) ranked higher than control foals (CF) in subjective ratings of calmness (*P<0.0117) and friendliness (*P<0.0001) and in several specific handling tasks (venipuncture *P<0.0220; placing in stock *P<0.0128). Although, in approach tests all foals but one allowed approach of a person to 4 m, significantly more HF approached the person than CF (P<0.0080). In stimulus tests, foals were presented specific stimuli to which they had been tested as neonates. Two of eight CF were too unruly and dangerous to test. Of foals that could be tested, CF required significantly more time to hook-up a heart rate monitor (**P<0.0055). Split-plot analysis indicated that HF had lower heart rates to initial left-sided stimuli, presented first, than CF (*P<0.0421). In response to right-sided stimuli, heart rate scores of CF were not significantly different from HF (P<0.2259), suggesting reduced reactivity over time due to a learning effect. Behavioral responses to specific stimuli did not differ between CF and HF, suggesting that neonatal handling has a general rather than specific effect on subsequent behavior. Cortisol concentrations were measured before and after testing and the difference calculated. All foals had higher post-testing levels than pre-testing levels. There was a significant difference between HF and CF, indicating greater reactivity among the CF (*P<0.050). In general, the results indicated that foals handled as neonates were more tractable and less reactive. Specific neonatal handling tasks, such as sticking a finger up the foal's nose or patting the bottom of the foot, seemed to have no beneficial effect on related tasks such as passing a nasogastric tube or tapping with a farrier's hammer at 4 months of age. Mechanisms for the observed effect of neonatal handling require further investigation.
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Houpt, K. A. (2002). Formation and dissolution of the mare-foal bond. Appl. Anim. Behav. Sci., 78(2-4), 319–328.
Abstract: The behavior of mares at foaling and their behavior during subsequent weekly brief separations from their foals was quantified. Thirteen multiparous pony mares were observed for the first 30 min after foaling. Activities directed toward the foal and toward the fetal membranes were recorded. There were 16+/-8 contacts with the fetal membranes, most in the first 10 min post-partum. There were 81+/-12 activities directed toward the foal. There was a downward trend in foal contacts over the first 30 min. Eight of the 13 mares were observed for the 30-60 min post-partum during which licking and touching the foal continued. Only one of the foals suckled in the first 30 min, but half had suckled by 60 min. Ten mares and foals were separated for 5 min each week for 9 weeks. Although mare responses (neighs and steps) decreased with age of the foal, the foals' responses increased from weeks 1 to 2 and then decreased with foal age. This indicates that foal attachment to the mare is not complete until it is 2 weeks old.
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i Rios, J. F., & Houpt, K. (1995). Sexual behavior in geldings. Appl. Anim. Behav. Sci., 46(1-2), 133–135.
Abstract: Abstract
In response to a request published in Equus, a magazine for those interested in horses, 85 owners of older geldings exhibiting sexual behavior completed history forms. The mean age of geldings was 16 f 5 years. Only 39 of the owners had had the gelding for at least a year before the behavior was noted. These cases could be used to determine the true age of onset of the problem. When log survivorship was used to determine whether there were one or two different populations, a break or change in the slope at age 16 indicated that there are two populations. One population shows the behavior from the time of castration and the other first exhibits the behavior in old age, possibly in response to an ACTH secreting pituitary adenoma. A total of 40% of the horses were Quarterhorses, the most numerous breed in the US; 78% of the horses were purebreds. Fewer than half the owners knew the age at which their horse had been castrated because they did not own the horse at the time.
The mean age at castration, when known, was 3.3 f 2.5 years. The reason for contacting us was sexual behavior (70%), aggression (24%). or some other problem ( 1 o/o). Whether or not aggression was the presenting problem, most of the horses showed aggression (95%), particularly towards other geldings (88%)) but also towards people (3 1%). Copulatory behavior (mounting) was shown by 69% of the geldings and half of those were able to intromit. These findings indicate that the sexual behavior of geldings is a problem for owners and that aggression usually accompanies sexual behavior.
The owners were encouraged to send serum samples taken before and after human chorionic gonadotropin (HCG) administration for testosterone and estrone sulfate analysis to determine whether residual testicular tissue was responsible for the horse’s behavior. Of the 14 horses tested, only one had elevated levels of testosterone indicating that there was residual testicular tissue. A total of six of the owners agreed to treat their horses with cyproheptadine at a dose of 8 mg day- ’ gradually increased to 88 mg day- ’ per horse. A total of three of the horses showed a decline in sexual and aggressive behavior, one got worse and two had side effects and treatment was withdrawn.
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