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Christensen, J. W., & Rundgren, M. (2008). Predator odour per se does not frighten domestic horses. Appl. Anim. Behav. Sci., 112(1-2), 136–145.
Abstract: Horses frequently react nervously when passing animal production farms and other places with distinctive smells, leading riders to believe that horses are innately frightened by certain odours. In three experiments, we investigated how horses respond to (1) urine from wolves and lions, (2) blood from slaughtered conspecifics and fur-derived wolf odour, and (3) a sudden auditory stimulus in either presence or absence of fur-derived wolf odour. The experiments were carried out under standardised conditions using a total of 45 naive, 2-year-old horses. In the first two experiments we found that horses showed significant changes in behaviour (Experiments 1 and 2: increased sniffing; Experiment 2 only: increased vigilance, decreased eating, and more behavioural shifts), but no increase in heart rate compared to controls when exposed to predator odours and conspecific blood in a known test environment. However, the third experiment showed that exposure to a combination of wolf odour and a sudden stimulus (sound of a moving plastic bag) caused significantly increased heart rate responses and a tendency to a longer latency to resume feeding, compared to control horses exposed to the sudden stimulus without the wolf odour. The results indicate that predator odour per se does not frighten horses but it may cause an increased level of vigilance. The presence of predator odour may, however, cause an increased heart rate response if horses are presented to an additional fear-eliciting stimulus. This strategy may be adaptive in the wild where equids share habitats with their predators, and have to trade-off time and energy spent on anti-predation responses against time allocated to essential non-defensive activities.
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Waiblinger, S., Menke, C., Korff, J., & Bucher, A. (2004). Previous handling and gentle interactions affect behaviour and heart rate of dairy cows during a veterinary procedure. Appl. Anim. Behav. Sci., 85(1-2), 31–42.
Abstract: Veterinary and management procedures often are aversive to the animals, resulting in physiological and behavioural stress reactions, which increase the risk of accidents and might lower performance. We investigated the effects of previous positive handling and of gentle interactions during the procedure on behaviour and heart rate in dairy cows during rectal palpation with sham insemination. Twenty cows were allocated randomly into two groups of 10 animals: handling, received additional positive handling over a period of four weeks by one person (handler); control, only routine handling by different caretakers. The week after the handling period, tests lasting 9 min, including 4 min rectal palpation, were carried out with each animal on four successive days in four situations in a balanced order: cow is alone during the test, with the handler, with an usual caretaker, or with an unknown person. Behaviour and heart rate were recorded. Previously handled animals had lower heart rate during tests (P<=0.05, n=19), kicked less when alone (P<=0.05, n=19) and tended to show less restless behaviour (P<=0.1, n=19). Cows were further calmed by gentle interactions during the test, but people differed remarkably. Cows showed less restless behaviour when gentled by the handler, both in the 4 min of rectal palpation and in the 9 min test period (each: P<=0.001, n=19). No significant stress reducing effect was found for the other two persons. In conclusion, stress reactions of cows during rectal palpation/insemination can be reduced by previous positive handling as well as by a person providing positive, gentle interactions during the procedure. The results underline the importance of positive, gentle interactions with the animals to enhance animal welfare and reduce the risk of accidents. They also show that people differ in the success to calm down the animals in aversive situations and indicate the need to investigate the characteristics responsible for the differences and identify the preconditions for a stress reducing effect in future research.
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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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Hillidge, C. J., & Lees, P. (1975). Cardiac output in the conscious and anaesthetised horse. Equine Vet J, 7(1), 16–21.
Abstract: Cardiac output in the horse was measured before and at predetermined times during 2-hour periods of thiopentone-halothane and thiopentone-diethyl ether anaesthesia. Left ventricular stroke volume was decreased to a similar extent during anaesthesia with each volatile agent, but a greater reduction in cardiac output occurred during halothane anaesthesia. This finding reflected the differing effects of halothane and ether on heart rate, a slight bradycardia occurring with the former agent while ether produced a small degree of tachycardia. The latter effect was attributed to enhanced sympathoadrenal activity. Changes in cardiac output and stroke volume were considered in relation to other factors, including arterial blood pH and tensions of oxygen and carbon dioxide. Positive correlations between some of these variables and cardiac function were established. With both volatile agents the reductions in stroke volume and cardiac output were related to the duration of anaesthesia, being greatest during the early stages. Possible reasons for the tendency of stroke volume and cardiac output to return towards control levels are discussed.
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Lees, P., & Tavernor, W. D. (1970). Influence of halothane and catecholamines on heart rate and rhythm in the horse. Br J Pharmacol, 39(1), 149–159.
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Aureli, F., Preston, S. D., & de Waal, F. B. (1999). Heart rate responses to social interactions in free-moving rhesus macaques (Macaca mulatta): a pilot study. J Comp Psychol, 113(1), 59–65.
Abstract: Heart rate telemetry was explored as a means to access animal emotion during social interactions under naturalistic conditions. Heart rates of 2 middle-ranking adult females living in a large group of rhesus macaques (Macaca mulatta) were recorded along with their behavior. Heart rate changes during 2 types of interactions were investigated, while controlling for the effects of posture and activity. The risk of aggression associated with the approach of a dominant individual was expected to provoke anxiety in the approachee. This prediction was supported by the heart rate increase after such an approach. No increase was found when the approacher was a kin or a subordinate individual. The tension-reduction function of allogrooming was also supported. Heart rate decelerated faster during the receipt of grooming than in matched control periods.
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Waran, N. K., Robertson, V., Cuddeford, D., Kokoszko, A., & Marlin, D. J. (1996). Effects of transporting horses facing either forwards or backwards on their behaviour and heart rate. Vet. Rec., 139(1), 7–11.
Abstract: The effects of transporting horses facing either forwards or backwards were compared by transporting six thoroughbred horses in pairs in a lorry on one journey facing in the direction of travel, and on another journey facing away from the direction of travel, over a standard one-hour route. Heart rate monitors were used to record their heart rate before, during and after the journey and the horses' behaviour was recorded by scan sampling each horse every other minute. The average heart rate was significantly lower (P < 0.05) when the horses were transported facing backwards, and they also tended to rest on their rumps more (P = 0.059). In the forward-facing position, the horses moved more frequently (P < 0.05) and tended to hold their necks in a higher than normal position and to vocalise more frequently (P = 0.059). During loading the average peak heart rate was 38 bpm lower (P < 0.05) when the horses were backed into the horse box for rear-facing transport than when they were loaded facing forwards. However, there was no difference between transport facing forwards or backwards in terms of the peak unloading heart rate, or the average heart rate during loading or unloading. The horses seemed to find being transported less physically stressful when they were facing backwards than when they were facing forwards.
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Gutierrez Rincon, J. A., Vives Turco, J., Muro Martinez, I., & Casas Vaque, I. (1992). A comparative study of the metabolic effort expended by horse riders during a jumping competition. Br J Sports Med, 26(1), 33–35.
Abstract: The three main Olympic horse riding disciplines are dressage, jumping, and three-day eventing (including dressage, cross country and jumping). In the jumping discipline (obstacle race), the 'team' (horse rider) is judged under the different conditions that might take place in a varied run. The horse is expected to show power and ability; the rider must show riding skill and good physical condition. However, the different conditions encountered by the rider during competition (duration of event, continuous isometric working level, especially in the inferior trunk, lead us to consider the need for a rider to develop different metabolic pathways to meet the high energy requirements of the competition.
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Cattell, R. B., & Korth, B. (1973). The isolation of temperament dimensions in dogs. Behav Biol, 9(1), 15–30.
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Aerts, J. - M., Gebruers, F., Van Camp, E., & Berckmans, D. (2008). Controlling horse heart rate as a basis for training improvement. Computers and Electronics in Agriculture, 64(1), 78–84.
Abstract: Equine training methods, and consequently, performance times have improved little since the last decades. With advances in measuring signals on-line by means of several new technologies and analytical procedures, and processing these signals immediately with strong and compact processors, it may be possible to develop new training methods. In this research, the objective was to explore the possibilities of using modern model-based algorithms to control the heart rate of horses (bpm) on-line by means of the control input running speed (km/h). Forty-five experiments with five horses and four riders were carried out to generate measurements of physiological status during running. The dynamical characteristics of each horse were quantified using linear discrete transfer function models. The dynamic response of heart rate to step changes in running speed were accurately described. In 90% of the cases, a first-order model gave the best fit. For 69% of the models, the r2 was higher than 0.90 and for 34% of the models, the r2 was even higher than 0.95. In a next step, the model-based algorithm was evaluated by controlling cardiac responses of two horses (horses 2 and 4) to a pre-defined trajectory. The model parameters were kept constant. On average, the error between the defined target trajectory in heart rate and the actual controlled heart rate ranged between 0.2 and 1.4 bpm for the whole target heart rate trajectory. During the steady-state part of the trajectory the average error was maximum 1.1 bpm. In the transient from one steady-state heart rate to another level, the error could increase on average up to 5 bpm. In the future, the combination of on-line measured bioresponses with real-time analysis can be used for adjusting the work load of the horse, during training, directly to the immediate needs of horse (welfare) and trainer (performance).
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