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Carroll, G. L., Matthews, N. S., Hartsfield, S. M., Slater, M. R., Champney, T. H., & Erickson, S. W. (1997). The effect of detomidine and its antagonism with tolazoline on stress-related hormones, metabolites, physiologic responses, and behavior in awake ponies. Vet Surg, 26(1), 69–77.
Abstract: Six ponies were used to investigate the effect of tolazoline antagonism of detomidine on physiological responses, behavior, epinephrine, norepinephrine, cortisol, glucose, and free fatty acids in awake ponies. Each pony had a catheter inserted into a jugular vein 1 hour before beginning the study. Awake ponies were administered detomidine (0.04 mg/kg intravenously [i.v.]) followed 20 minutes later by either tolazoline (4.0 mg/kg i.v.) or saline. Blood samples were drawn from the catheter 5 minutes before detomidine administration (baseline), 5 minutes after detomidine administration, 20 minutes before detomidine administration which was immediately before the administration of tolazoline or saline (time [T] = 0), and at 5, 30, and 60 minutes after injections of tolazoline or saline (T = 5, 30, and 60 minutes, respectively). Compared with heart rate at T = 0, tolazoline antagonism increased heart rate 45% at 5 minutes. There was no difference in heart rate between treatments at 30 minutes. Blood pressure remained stable after tolazoline, while it decreased over time after saline. Compared with concentrations at T = 0, tolazoline antagonism of detomidine in awake ponies resulted in a 55% increase in cortisol at 30 minutes and a 52% increase in glucose at 5 minutes. The change in free fatty acids was different for tolazoline and saline over time. Free fatty acids decreased after detomidine administration. Free fatty acids did not change after saline administration. After tolazoline administration, free fatty acids increased transiently. Tolazoline tended to decrease sedation and analgesia at 15 and 60 minutes postantagonism. Antagonism of detomidine-induced physiological and behavioral effects with tolazoline in awake ponies that were not experiencing pain appears to precipitate a stress response as measured by cortisol, glucose, and free fatty acids. If antagonism of an alpha-agonist is contemplated, the potential effect on hormones and metabolites should be considered.
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Domjan, M. (1977). Selective suppression of drinking during a limited period following aversive drug treatment in rats. J Exp Psychol Anim Behav Process, 3(1), 66–76.
Abstract: Administration of lithium chloride disrupted the intake of flavored solutions but not water in rats. This intake suppression was directly related to the amount of lithium administered (Experiment 1), occurred with both palatable and unpalatable novel saccharin solutions (Experiment 2), but was only observed if subjects were tested starting less than 75 min. after lithium treatment (Experiment 3). Twenty-five daily exposures to saccharin did not attenuate the effect (Experiment 4). However, in saccharin-reared and vinegar-reared rats, lithium did not disrupt consumption of the solutions these subjects had access to throughout life, even though suppressions of intake were observed when these subjects were tested with novel flavors (Experiment 5). The selective disruption of drinking is interpreted as a novelty-dependent sensitization reaction to the discomfort of aversive drug administration.
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Mejdell, C. M., Buvik, T., Jørgensen, G. H. M., & Bøe, K. E. (2016). Horses can learn to use symbols to communicate their preferences. Appl. Anim. Behav. Sci., 184, 66–73.
Abstract: Abstract This paper describes a method in which horses learn to communicate by touching different neutral visual symbols, in order to tell the handler whether they want to have a blanket on or not. Horses were trained for 10–15 min per day, following a training program comprising ten steps in a strategic order. Reward based operant conditioning was used to teach horses to approach and touch a board, and to understand the meaning of three different symbols. Heat and cold challenges were performed to help learning and to check level of understanding. At certain stages, a learning criterion of correct responses for 8–14 successive trials had to be achieved before proceeding. After introducing the free choice situation, on average at training day 11, the horse could choose between a “no change” symbol and the symbol for either “blanket on” or “blanket off” depending on whether the horse already wore a blanket or not. A cut off point for performance or non-performance was set to day 14, and 23/23 horses successfully learned the task within this limit. Horses of warm-blood type needed fewer training days to reach criterion than cold-bloods (P < 0.05). Horses were then tested under differing weather conditions. Results show that choices made, i.e. the symbol touched, was not random but dependent on weather. Horses chose to stay without a blanket in nice weather, and they chose to have a blanket on when the weather was wet, windy and cold (χ2 = 36.67, P < 0.005). This indicates that horses both had an understanding of the consequence of their choice on own thermal comfort, and that they successfully had learned to communicate their preference by using the symbols. The method represents a novel tool for studying preferences in horses.
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Mejdell, C. M., Buvik, T., Jørgensen, G. H. M., & Bøe, K. E. (2016). Horses can learn to use symbols to communicate their preferences. Appl. Anim. Behav. Sci., 184, 66–73.
Abstract: This paper describes a method in which horses learn to communicate by touching different neutral visual symbols, in order to tell the handler whether they want to have a blanket on or not. Horses were trained for 10-15min per day, following a training program comprising ten steps in a strategic order. Reward based operant conditioning was used to teach horses to approach and touch a board, and to understand the meaning of three different symbols. Heat and cold challenges were performed to help learning and to check level of understanding. At certain stages, a learning criterion of correct responses for 8-14 successive trials had to be achieved before proceeding. After introducing the free choice situation, on average at training day 11, the horse could choose between a “no change” symbol and the symbol for either “blanket on” or “blanket off” depending on whether the horse already wore a blanket or not. A cut off point for performance or non-performance was set to day 14, and 23/23 horses successfully learned the task within this limit. Horses of warm-blood type needed fewer training days to reach criterion than cold-bloods (P<0.05). Horses were then tested under differing weather conditions. Results show that choices made, i.e. the symbol touched, was not random but dependent on weather. Horses chose to stay without a blanket in nice weather, and they chose to have a blanket on when the weather was wet, windy and cold (χ2=36.67, P<0.005). This indicates that horses both had an understanding of the consequence of their choice on own thermal comfort, and that they successfully had learned to communicate their preference by using the symbols. The method represents a novel tool for studying preferences in horses.
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Mejdell, C. M., Buvik, T., Jørgensen, G. H. M., & Bøe, K. E. (2016). Horses can learn to use symbols to communicate their preferences. Appl. Anim. Behav. Sci., 184, 66–73.
Abstract: This paper describes a method in which horses learn to communicate by touching different neutral visual symbols, in order to tell the handler whether they want to have a blanket on or not. Horses were trained for 10-15min per day, following a training program comprising ten steps in a strategic order. Reward based operant conditioning was used to teach horses to approach and touch a board, and to understand the meaning of three different symbols. Heat and cold challenges were performed to help learning and to check level of understanding. At certain stages, a learning criterion of correct responses for 8-14 successive trials had to be achieved before proceeding. After introducing the free choice situation, on average at training day 11, the horse could choose between a “no change” symbol and the symbol for either “blanket on” or “blanket off” depending on whether the horse already wore a blanket or not. A cut off point for performance or non-performance was set to day 14, and 23/23 horses successfully learned the task within this limit. Horses of warm-blood type needed fewer training days to reach criterion than cold-bloods (P<0.05). Horses were then tested under differing weather conditions. Results show that choices made, i.e. the symbol touched, was not random but dependent on weather. Horses chose to stay without a blanket in nice weather, and they chose to have a blanket on when the weather was wet, windy and cold (χ2=36.67, P<0.005). This indicates that horses both had an understanding of the consequence of their choice on own thermal comfort, and that they successfully had learned to communicate their preference by using the symbols. The method represents a novel tool for studying preferences in horses.
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Zehnder, A. M., Ramer, J. C., & Proudfoot, J. S. (2006). The use of altrenogest to control aggression in a male Grant's Zebra (Equus burchelli boehmi). J Zoo Wildl Med, 37(1), 61–63.
Abstract: A male Grant's Zebra (Equus burchelli boehmi) housed with two mares at the Indianapolis Zoo had a 9-yr history of intermittent aggressive behavior toward mares and other animals. Periods of separation allowed the mares time to heal after sustaining superficial bite wounds. On 26 March 2003, the male (890293) was started on altrenogest at a dosage of 19.8 mg orally once daily to allow reintroduction. The dosage was doubled (40 mg once a day) because of a perceived lack of response. Reintroduction to the mares occurred on 17 May 2003 with no signs of aggression noted. Treatment was reduced to 19.8 mg orally once a day and then discontinued. Altrenogest was restarted at 39.5 mg orally once a day because of the planned introduction of a new mare. There have been no major aggressive displays at this dosage of altrenogest and the dosage has recently been reduced following successful introduction of a new mare.
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Spadavecchia, C., Arendt-Nielsen, L., Spadavecchia, L., Mosing, M., Auer, U., & van den Hoven, R. (2007). Effects of butorphanol on the withdrawal reflex using threshold, suprathreshold and repeated subthreshold electrical stimuli in conscious horses. Vet Anaesth Analg, 34(1), 48–58.
Abstract: OBJECTIVE: To assess the effects of a single intravenous dose of butorphanol (0.1 mg kg(-1)) on the nociceptive withdrawal reflex (NWR) using threshold, suprathreshold and repeated subthreshold electrical stimuli in conscious horses. STUDY DESIGN: 'Unblinded', prospective experimental study. ANIMALS: Ten adult horses, five geldings and five mares, mean body mass 517 kg (range 487-569 kg). METHODS: The NWR was elicited using single transcutaneous electrical stimulation of the palmar digital nerve. Repeated stimulations were applied to evoke temporal summation. Surface electromyography was performed to record and quantify the responses of the common digital extensor muscle to stimulation and behavioural reactions were scored. Before butorphanol administration and at fixed time points up to 2 hours after injection, baseline threshold intensities for NWR and temporal summation were defined and single suprathreshold stimulations applied. Friedman repeated-measures analysis of variance on ranks and Wilcoxon signed-rank test were used with the Student-Newman-Keul's method applied post-hoc. The level of significance (alpha) was set at 0.05. RESULTS: Butorphanol did not modify either the thresholds for NWR and temporal summation or the reaction scores, but the difference between suprathreshold and threshold reflex amplitudes was reduced when single stimulation was applied. Upon repeated stimulation after butorphanol administration, a significant decrease in the relative amplitude was calculated for both the 30-80 and the 80-200 millisecond intervals after each stimulus, and for the whole post-stimulation interval in the right thoracic limb. In the left thoracic limb a decrease in the relative amplitude was found only in the 30-80 millisecond epoch. CONCLUSION: Butorphanol at 0.1 mg kg(-1) has no direct action on spinal Adelta nociceptive activity but may have some supraspinal effects that reduce the gain of the nociceptive system. CLINICAL RELEVANCE: Butorphanol has minimal effect on sharp immediate Adelta-mediated pain but may alter spinal processing and decrease the delayed sensations of pain.
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Mitchell, D., Kirschbaum, E. H., & Perry, R. L. (1975). Effects of neophobia and habituation on the poison-induced avoidance of exteroceptive stimuli in the rat. J Exp Psychol Anim Behav Process, 1(1), 47–55.
Abstract: Two experiments on the role of neophobia in poison-induced aversions to exteroceptive stimuli are reported. In Experiment 1, rats were given either 10 or 25 days of habituation to the test situation prior to conditioning. Those animals with the longer habituation period avoided a complex of novel exteroceptive stimuli while those with the shorter habituation period did not. In Experiment 2 rats initially avoided the more novel of two containers, but gradually came to eat equal amounts from both. A single pairing of toxicosis with consumption from either the novel or the familiar container reinstated the avoidance of the novel container in both cases. The results were discussed in terms of an interaction between habituation and conditioning procedures. It was suggested that previously reported differences between interoceptive and exteroceptive conditioning effects may have been influenced by the differential novelty of the two classes of stimuli in the test situation. It was further suggested that non-contingently poisoned control groups should routinely be included in poison avoidance conditioning studies.
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Elhay, M., Newbold, A., Britton, A., Turley, P., Dowsett, K., & Walker, J. (2007). Suppression of behavioural and physiological oestrus in the mare by vaccination against GnRH. Aust Vet J, 85(1-2), 39–45.
Abstract: OBJECTIVE: To examine the immunogenicity of an equine immunocontraceptive vaccine and its efficacy in controlling hormone-related behaviour. DESIGN: A total of 24 mares at two sites in Australia were vaccinated with an immunocontraceptive vaccine comprising gonadotrophin releasing hormone (GnRH) conjugated to a carrier protein in immunostimulating complex as an adjuvant. Twelve animals at each site received a placebo of adjuvant alone and served as controls for seasonal oestrus, hormonal and behaviour patterns. Animals were observed for injection site reactions, ovarian and follicular activity, and serum levels of antibody, 17beta-oestradiol and progesterone in the weeks following vaccination. Mares were also examined for oestrous behaviour by teasing with a stallion. RESULTS: All mares responded to vaccination. Two weeks following the second vaccination there was a peak in antibody response to GnRH that declined gradually over the following weeks. Commensurate with the elevated anti-GnRH antibody there was a marked effect on ovarian activity with a reduction in 17beta-oestradiol and progesterone levels in the 24 vaccinated mares. There was also a reduction of oestrus-related behaviour as determined by a teaser stallion. This effect lasted a minimum of 3 months and correlated with the initial level of antibody response. CONCLUSION: Following a conventional two-dose immunisation regime this commercially available equine immunocontraceptive vaccine was effective at inhibiting oestrous behaviour for at least 3 months. This vaccine has a high level of safety since there were no significant local reactions nor were there any adverse systemic responses to vaccination.
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Alexander, F. (1952). The effects of some humoral agents on the horse ileum. Br J Pharmacol Chemother, 7(1), 25–32.
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