The beneficial effects of horse trekking on autonomic nervous activity in experienced rider with no disability

The aim of this study was to determine whether autonomic nervous activity of a rider with no disability was altered by one practical and applicable horse trekking (HT) exercise. Changes in autonomic nervous activity were analyzed by heart rate variability (HRV). Twenty‐three participants with no disability rode horses along a predetermined HT course at trotting and walking for 60 min. HRV was sampled at 60 min before and immediately, following 60 min, and 120 min after HT. As a control, the same measurements were performed for 22 age‐matched participants during their rest. Only in the HT group, the value of normalized unit in high frequency component (HF nu), an index of parasympathetic nervous activity, was higher at 120 min after treatment than before HT (P < 0.05). The low / high frequency ratio (LF / HF), believed to reflect sympathetic nervous activity, was lower in the HT group than those in the control group at 60 min (P < 0.05) and 120 min after treatment (P < 0.01). These findings suggest that a single HT shifted the autonomic nervous balance of a rider toward parasympathetic dominance. The results obtained by the present study could accelerate the use of horses for human health.     

Influence of riders’ skill on plasma cortisol levels of horses walking on forest and field trekking courses

The aim of this study was to evaluate the influence of rider's skill on the plasma cortisol levels of trekking horses on two courses, walking on field and forest courses (about 4.5 to 5.1 km each). Three riders of different skills did horse trekking (HT) in a tandem line under a fixed order: advanced‐leading, beginner‐second and intermediate‐last. A total of six horses were used and they experienced all positions in both courses; a total of 12 experiments were done. Blood samples were obtained before HT, immediately after and 2 h after HT. As a control, additional blood samples were obtained from the same horses on non‐riding days. Irrespective of the course and the rider's skill, the cortisol level before HT was higher than that of control (P < 0.05). In both courses, the cortisol levels immediately after HT ridden by the advanced rider were higher than that of control (P < 0.05). However, in every case, the cortisol level 2 h after HT was closely similar to the level of the control. Thus, we concluded the stress of trekking horse was not sufficient to disturb the circadian rhythm of the cortisol level, irrespective of the course and the rider's skill.     

Behaviour of the heart rate of horses with auricular fibrillation during exercise and after treatment.

Cardioversion through varying quinidine sulphate treatments was achieved in 3 riding horses with auricular fibrillation. The horses were subjected to continual telemetric ECG registration before and after reversion in a uniform exercise-tolerance-test. A comparison of the heart rate curves showed a strong decline of the heart beat frequency during the exercise phase after synchronisation. The decrease in heart rate during exercise was greater than 30% in all 3 patients. Anti-arrhythmic treatment is, therefore, recommended for horses with auricular fibrillation and without concurrent heart disease.     

Plasma cortisol and ACTH concentrations in the warmblood horse in response to a standardized treadmill exercise test as physiological markers for evaluation of training status

Reliable physiological markers for performance evaluation in sport horses are missing. To determine the diagnostic value of plasma ACTH and cortisol measurements in the warmblood horse, 10 initially 3-yr-old geldings of the Hannovarian breed were either exposed to a training schedule or served as controls. During experimental Phase 1, horses were group-housed, and half of the horses were trained for 20 wk on a high-speed treadmill. During Phase 2, groups were switched and one group was trained for 10 wk as during Phase 1, whereas the control group was confined to boxes. During Phase 3 horses were initially schooled for riding. Thereafter, all horses were regularly schooled for dressage and jumping, and half of the horses received an additional endurance training for 24 wk. During all phases horses were exposed at regular intervals to various standardized treadmill exercise tests. During and after the tests frequent blood samples were taken from an indwelling jugular catheter for determination of ACTH and cortisol. Treadmill exercise increased both hormones. Maximum ACTH concentrations were recorded at the end of exercise, and maximum cortisol levels were recorded 20 to 30 min later. Except for one test there were no differences in ACTH levels between trained horses and controls. There was no significant effect of training on the cortisol response (net increase) to treadmill exercise in any of the tests during Phase 1. During Phase 2 higher cortisol responses were recorded in controls than in trained horses (P < .05) after 10 wk of training (controls confined to boxes). During Phase 3 plasma cortisol responses were also higher in controls than in trained horses (P < .05 after 6, 18, and 24, P < or = .07 after 12 wk of training) when the inclination of the treadmill was 5%, but not at 3%. There was no overlap in net cortisol responses at 30 min between trained and untrained horses. An ACTH application after 24 wk of training resulted in higher cortisol responses in controls than in trained horses (P < or = .05), without any overlap between the groups at 30 min after ACTH. Plasma cortisol responses to either treadmill exercise or ACTH injection may be a reliable physiological marker for performance evaluation. Prerequisites are sufficient differences in training status and sufficient intensity of exercise test conditions.     

Preliminary investigations of horses' (Equus caballus) responses to different bridles during foundation training

Throughout equitation history, bitted bridles have been the primary method of controlling the ridden horse. In response to health and behavioral concerns arising from the use of bitted bridles, bitless bridles offer new methods of steering and control. However, the effectiveness of bitless bridles on horses had not been previously examined scientifically. Therefore, the current study measured behavioral and cardiac responses of horses undergoing foundation training (bridling, long reining, and riding) wearing either a bitted or a bitless bridle.The horses wearing the bitted bridle exhibited more chewing, opening of the mouth, pawing the ground, and tail swishing than those in the bitless bridle. The horses wearing the bitless bridle exhibited more head lowering during long reining compared to those in the bitted bridle. The frequency of chewing, opening the mouth, and head raising decreased as training progressed. The number of steps taken after the application of the halt stimulus was greatest for the horses in the bitted bridle during long reining compared with those in the bitless bridle. During long reining, the heart rate and heart rate variability of the horses were higher for those in a bitted bridle compared with those in a bitless bridle.The results of this study suggest that horses wearing bitless bridles performed at least as well as, if not better than, those in bitted bridles. If the use of bitted bridles does cause discomfort to horses, as suggested by some, then the use of bitless bridles could be beneficial and certainly warrants further investigation.     

Emotional Response to Novelty and to Expectation of Novelty in Young Race Horses

The aim of this study was to estimate the emotional response to novelty and to expectation of novelty in young race horses. The novelty in this study was the first training on an automated horse walker at a new training center. To estimate the level of emotionality in horses, the telemetric measurement of heart rate (HR) was used. A hypothesis was developed that expectation of novelty can be as exciting for horses as a novelty test. In this study, 40 horses were studied just before and then during their first walk on an automated horse walker. They were divided into four groups, with 10 horses in each group. These groups were as follows: (1) 1.5-year-old Thoroughbred colts, (2) 1.5-year-old Thoroughbred fillies, (3) 2.5-year-old Purebred Arabian colts, and (4) 2.5-year-old Purebred Arabian fillies. HR was measured at rest before exercise, during handling and moving the horse from the stable, while walking on the automated horse walker for about 20 minutes, while moving the horse from the walker to the stable, and at rest after exercise. HR response to the anticipation of novelty was higher in colts than in fillies, particularly in the group of Thoroughbreds.     

Effects of aqua-treadmill exercise on selected blood parameters and on heart-rate variability of horses

The objectives of the present study were to investigate the effects of Aquatraining of horses (aqua-treadmill exercise; treadmill manufactured by Equitech - L.u.S. Equipment, Warendorf, Germany) on selected blood parameters [lactic acid concentration (mmol/l), haemoglobin content (g/l)] and on heart-rate variability (HRV) [heart rate (beats per min; b.p.m.), standard deviation of all NN-intervals (SDNN; ms), normalized power of the low and high frequency band (LFnorm, Hfnorm; au), % recurrence, % determinism and ratio(corr)]. Seven horses performed six exercise tests with different work loads (walking (x = 1.56 +/- 0.08 m/s) and trotting (x = 2.9 +/- 0.13 m/s): dry, water above the carpus and water above the elbow). The standardized test-protocol was: 5 min warm-up at walk while the water was pumped in, followed by the 20-min exercise period at walk or trot, followed by a 5-min walk while pumping out the water. Blood samples were taken prior to each test at rest in the stable, as well as exactly 5 min after the end of the 20-min exercise period. Electrocardiograms were recorded during rest and the 20-min exercise period. Compared to rest, neither the chosen velocities, the two water levels, nor the dry tests led to a significant increase of the lactic acid concentration in any horse. The haemoglobin content showed a significant increase as a result of exercise. Significant differences could be found between the heart rates at rest and the six exercise tests and between the mean of the levels 'walking' and the mean of the levels 'trotting'. An exercise-induced change of HRV was characterized by a decreasing SDNN, a significantly higher LFnorm (sympathetic influence) combined with a significantly lower HF(norm) power (parasympathetic activity) and a rising degree of order (significantly higher % determinism and nearly unchanged % recurrence) and stability (significantly rising ratio(corr)) of the recurrence plot. In conclusion, the used training-protocol for aqua-treadmill exercises only represents a medium-sized aerobic work load for horses, but the different levels of burden were indicated especially by changes in HRV.     

Training horses: Positive reinforcement,positive punishment,and ridden behavior problems

An Internet survey was used to investigate the relationship between riders’ responses to their horse’s behavior in 8 commonly encountered riding scenarios and the frequency of generic behavior problems displayed by their horse during ridden work. There was a significant negative correlation between the percentage of rewarding rider responses to appropriate behavior scenarios from their horse and ridden behavior problem score (P = 0.007), but there was no association between punishing rider responses toward inappropriate behavior scenarios and their horses’ generic ridden behavior problem score. Consistency of reward for appropriate behavior scenarios and punishment of inappropriate behavior scenarios had no correlation with the horses’ generic ridden behavior problem score. However, riders who used a higher proportion of rewarding responses overall, even toward inappropriate behavior scenarios, had horses with fewer generic ridden behavioral problems (P = 0.011). These respondents reported using reassuring responses to calm their horse and may have had greater success by responding to their horses’ emotional state than by responding to their behavior per se.     

Effect of difference in training skills on stress in horses trained by Kazakh trainers

This study aimed to evaluate the effect of differences in trainer skills on horse training during the early stages of riding habituation by measuring the levels of stress and changes in stress levels. Among nine untrained horses employed, five in Group A were trained by two low-skilled trainers, whereas the remaining four in Group B were trained by two high-skilled trainers using the traditional Kazakh method. Salivary α-amylase concentration was measured as a biomarker of stress immediately before and after each riding session during the training period. In the duration of riding and mooring times to the total riding habituation time for each horse, no significant difference was observed between the two groups. In contrast, the mean total stress and mean final stress were significantly lower in Group B than in Group A, and the mean total change in stress before and after riding habituation was significantly higher in Group B. Differences in trainer skills were evidenced as differences in training methods to suppress the total stress levels through differences in the application of stress burden during the training of individual horses.     

Correlations between the behavior of recreational horses,the physiological parameters and summer atmospheric conditions

The aim of this paper was to select atmospheric factors and their values, which may disrupt the correct behavior and physiological condition of recreational horses. The studies were carried out from 1 July until 1 September on 16 Anglo‐Arabian geldings. Each day, from 09.00 to 10.00 hours, the horses worked under saddle. The riders and the authors gave a qualitative behavioral assessment for each horse. Mood and willingness to work were evaluated. The quantitative assessment was called ‘incorrect behavior of the horse while riding’ (IBHR). The percentage time of duration and the number of occurrences of the features while riding were calculated. Heart rate, body temperature and respiratory rate were taken at 08.00 hours (resting measurement) and at 10.05 hours (post‐exercise measurement). Air temperature, relative air humidity, wind speed and atmospheric pressure were measured at 08.00 and 10.00 hours. The results showed that adverse changes in the behavior of recreational horses can occur if the horse is ridden when the air temperature is above 26°C and when wind speeds exceed 5.5 m/s. Such conditions may cause a reduction in the mood and willingness to work in horses. Physiological parameters like heart rate and body temperature seem to be more sensitive indicators of the horse body reaction to the weather than behavioral reactions.     

Dynamic epiglottic retroversion as a cause of abnormal inspiratory noise in six adult horses

This case report describes the endoscopic findings and outcome in 6 horses diagnosed with dynamic epiglottic retroversion (ER) during exercise. Horses included 2 showjumpers, one eventer, one pleasure riding horse and 2 Thoroughbred racehorses. All were adults (age range: 4–10 years). Dorsal angulation of the epiglottis was identified at rest in one horse. However, resting endoscopy was unremarkable in the remaining 5 horses. Exercising endoscopy was performed during high‐speed treadmill exercise in 3 horses and during ridden exercise in the other 3. Intermittent ER occurred during inspiration in all horses and the frequency increased with increasing speed. In 2 horses the epiglottis retroverted beyond the rima glottidis. All horses made an abnormal respiratory noise described as a ‘grunt’ when retroversion of the epiglottis occurred. Poll flexion was found to be an exacerbating factor in the nonracehorses. Two horses continued in work but abnormal inspiratory noise persisted. Surgical treatment, in the form of subepiglottic resection, was attempted in one horse. However, it never raced again after the procedure. Of the remaining horses, 2 were retired and the third was subjected to euthanasia.     

Competition Horses Housed in Single Stalls (II): Effects of Free Exercise on the Behavior in the Stable, the Behavior during Training, and the Degree of Stress

Although housing horses in single stalls limits their natural behavior to a great extent, this housing system is widespread in Germany, especially for competition horses. To improve the welfare of this system, free exercise on pastures or paddocks is deemed suitable, but it is also feared because of injuries and decreased willingness or motivation to perform. In the present study, three treatments were investigated with regard to their effect on the behavior of six competition horses in the stable, behavior during training, and on their degree of stress: daily training without free exercise (no turnout [NT]), solitary turnout for 2 hours after training, and 2-hour turnout in groups of two after training (group turnout). The horses’ behavior in the stable was continuously analyzed through video recordings (2 pm to 6 am) on 3 days at the end of each treatment. The degree of stress was evaluated daily by heart rate variability at rest. The behavior during training was evaluated by a questionnaire answered by the riders, and the distance covered during training was measured by global positioning system. When NT was allowed, the horses showed less lying in the stable compared with the treatments with turnout. Heart rate variability measurements resulted in great individual differences, but generally, there was a higher degree of stress shown with the treatment NT according to the following parameters: standard deviation of inter-beat-intervals (SDNN), square root of the mean of the sum of the squares of differences between successive inter-beat-intervals (RMSSD), and ratio between low frequency and high frequency (LF/HF). The willingness to perform was evaluated as being slightly better in the treatments with turnout than in the treatment without turnout.     

Influence of subclinical pulmonary findings on cardiac parameters in Icelandic horses

In the present study we examined, if in Icelandic horses an increase in heart and/ or breathing rate is physiological and breed dependend or a sign of a pulmonary or cardiac disease. Therefore we examined 37 Icelandic horses with the prereport of being healthy. During clinical lung examination four horses showed symptoms of a pulmonary disease like increased breathing rate and enforced breathing at rest. These horses were excluded from the study. The other 33 horses were clinically normal. 17 of these horses were unridden (untrained) and 16 horses were regularly worked (trained). After clinical examination in all horses analysis of arterial blood gas, endoscopy with tracheo- bronchial secret analysis and radiographic examination of the lung were carried out. Additionally electro- and echocardiographic examinations and standardised exercise tests with determination of heart and breathing rate as well as plasma lactate values were performed in all horses. During electro- and echocardiographic examination no pathological findings were observed. In total 22 of the 33 horses showed abnormal lung findings. Seven horses had mild signs of RAO and 15 horses had mild signs of interstitial bronchitis. Three horses had additional pulmonary haemorrhage. Eleven out of the 33 horses showed no abnormal lung findings. The breathing rate at rest differed not significantly between horses with (21 +/- 1/min) or without (23 +/- 2/min) pulmonary findings. The heart rate also did not differ significantly between horses with (39 +/- 1/min) or without (42 +/- 1/min) pulmonary findings. In contrast to this the trained Icelandic horses with abnormal pulmonary findings had significantly higher heart rates (p = 0.01) and significantly lower breathing rates (p = 0.009) compared to those without abnormal pulmonary findings. During echocardiography Icelandic horses with abnormal pulmonary findings had significantly larger left atrial diameter (without abnormal pulmonary findings: 82 +/- 7 mm, with abnormal pulmonary findings: 90 +/- 8 mm, p = 0.02). Compared to the untrained Icelandic horses (5.4 +/- 2 mmol/l) the trained horses showed significantly lower plasma lactate values (3.1 +/- 2 mmol/l, p = 0.001) immediately after exercise. After exercise the icelandic horses with abnormal pulmonary findings had significantly higher breathing rates (p < 0.05) and longer recovery periods (30 minutes) than horses without abnormal respiratory findings (15 minutes). Recovery of heart rate after exercise showed no differences between groups.     

Determination and repeatability of maximum oxygen uptake and other cardiorespiratory measurements in the exercising horse

A rapid incremental treadmill exercise test was used to determine the repeatability of the following measurements in exercising horses: maximal oxygen consumption (VO2max), maximal heart rate (HRmax), velocity at a heart rate of 200 beats/min (V-200), oxygen consumption at a heart rate of 200 beats/min (VO2-200), oxygen consumption at HRmax (VO2-HRmax), work rate at a heart rate of 200 beats/min (W-200), work rate at HRmax (W-HRmax) and treadmill velocity at HRmax (V-HRmax). Six Standardbred geldings were exercised on three separate occasions on a treadmill set at an inclination of 6 degrees. The exercise protocol was that each horse was exercised for 2 mins at 3 m/sec, after which the treadmill speed was increased by 1 m/sec every 60 secs, until the horse could no longer maintain its speed. A minimum of 24 h was allowed between repeated tests. No significant differences were found between the three means of any of the eight cardiorespiratory variables with repeated measurement. Variables with high coefficients of variation (greater than 10 per cent) included V-HRmax, W-HRmax and VO2-HRmax. The V-200, W-200 and VO2-200 showed less variation. The VO2max showed good reproducibility, there being coefficients of variation ranging from 1.4 to 9.0 per cent. The individual horse values for VO2max ranged from 104 to 169 ml/kg bodyweight/min. Maximal heart rate was also highly reproducible and the coefficients of variation were less than or equal to 2.7 per cent in all horses. It is concluded that the measurement of VO2max has good reproducibility, but other estimates of maximal aerobic capacity are less precise.     

Effect of different head–neck positions on physical and psychological stress parameters in the ridden horse

Different head–neck positions (HNPs) are used in equestrian sports and are regarded as desirable for training and competition by riders, judges and trainers. Even though some studies have been indicative of hyperflexion having negative effects on horses, this unnatural position is frequently used. In the present study, the influence of different HNPs on physical and psychological stress parameters in the ridden horse was investigated. Heart rate (HR), heart rate variability (HRV) and blood cortisol levels were measured in 18 horses. Low frequency (LF) and high frequency (HF) are power components in the frequency domain measurement of HRV which show the activity of the sympathetic and parasympathetic nervous system. Values were recorded at rest, while riding with a working HNP and while riding with hyperflexion of the horse's head, neck and poll. In addition, rideability and behaviour during the different investigation stages were evaluated by the rider and by an observer. Neither the HR nor the HRV showed a significant difference between working HNP (HR = 105 ± 22/min; LF/HF = 3.89 ± 5.68; LF = 37.28 ± 10.77%) and hyperflexion (HR = 110 ± 18; LF/HF = 1.94 ± 2.21; LF = 38.39 ± 13.01%). Blood cortisol levels revealed a significant increase comparing working HNP (158 ± 60 nm ) and hyperflexion (176 ± 64 nm , p = 0.01). The evaluation of rider and observer resulted in clear changes of rideability and behavioural changes for the worse in all parameters collected between a working HNP and hyperflexion. In conclusion, changes of the cortisol blood level as a physical parameter led to the assumption that hyperflexion of head, neck and poll effects a stress reaction in the horse, and observation of the behaviour illustrates adverse effects on the well‐being of horses during hyperflexion.     

The opioid haemorphin-7 in horses during low-speed and high-speed treadmill exercise to fatigue

The opioid neuropeptide haemorphin-7 was measured, by immunoreactivity, in Standardbred horses during low-speed (7 m/s) and high-speed (10 m/s) endurance exercises, lasting 49-58 and 12-16 min respectively. In parallel, heart rate, muscle temperature and plasma lactate concentrations were measured. The profile of the low-speed exercise showed significantly increased heart rate after 10 min [154 beats per minute (bpm)]. After the exercise, muscle temperature (42.1 degrees C) and plasma lactate (4.8 mmol/l) were significantly increased. The profile of the high-speed exercise was comparatively characterized by a higher increase of heart rate after 5 min (194 bpm) and higher increases of muscle temperature (43.2 degrees C) and lactate levels (15.8 mmol/l) after the exercise. The horses were probably exhausted by glycogen depletion in the low-speed exercise and by muscle pH decrease in the high-speed exercise. Haemorphin-7 increased significantly during the high-speed exercise (274.8 fmol/ml) but not during low speed (108.3 fmol/ml), coincident with the results of lactate. These results suggest that plasma haemorphin-7 is measurable in the horse by immunoreactivity, and that intense exercise stimulates release of this opioid. Such endogenous opioids are most likely involved in regulatory functions associated with pain, physical effort, inflammation, and blood pressure variation in horses, as have been established in other species.     

Effects of different forms of exercise on post inhibitory rebound and unwanted behaviour in stabled horses

Reasons for performing study: It is unknown if different locomotor activities are equally effective at meeting the stabled horse's need for exercise and if they attenuate unwanted behaviour. Hypothesis: Alternative forms of exercise influence the intensity of locomotor activities during a period of turn‐out (the so‐called rebound effect) and the occurrence of unwanted or undesirable activities during standard handling situations. Method: Twenty‐four horses kept in stables were randomly assigned to one of 4 exercise regimes (walker, treadmill, turn‐out and riding) for 4 consecutive days. Because these forms of exercise provide additional environmental stimulation, beyond that provided by exercise, each horse served as its own control in 4 corresponding (no exercise) control treatments presented in a balanced order. Unwanted behaviour was tested by taking horses to weighing scales and loading and unloading them onto a 4‐horse float by an experienced handler and the rebound effect was tested by releasing them into a large arena for a period of 15 min at the end of the exercise and control treatments. Results: Locomotor activities made up a large part of behaviour in the large arena following control treatments and all exercise regimes were sufficient to reduce the intensity of walking (P<0.05), trotting (P<0.01) and cantering (P<0.001) on release into a large arena. Exercise regime reduced the number of bucks (P<0.01) and rolling (P<0.05) during rebound tests suggesting that turn‐out was having a stronger effect than the other 3 exercise regimes. Exercise regimes significantly reduced the amount of unwanted behaviour and the number of commands given by the handler during weighing (P<0.05) but had no effect on these behaviours during loading onto a float. Conclusion: Providing stabled horses with one hour/day of exercise on a walker, treadmill, turn‐out or by being ridden are all effective at allowing expression of locomotor activities in stabled horses. Potential relevance: Providing stabled horses with regular exercise is likely to provide positive effects on horse welfare, training ability and handler safety.     

Workload and stress in horses: comparison in horses ridden deep and round ('rollkur') with a draw rein and horses ridden in a natural frame with only light rein contact

'Rollkur' or 'overbending' is the low and deep riding of a dressage horse during training or warming up. Lately, this technique has been criticized, and not necessarily objectively, on welfare grounds. To be able to evaluate these criticisms, more needs to be known about the workload and stress of horses being ridden 'rollkur'. The aim of the present study was to compare the workload of eight riding-school horses when being ridden deep and round with a draw rein ('rollkur') and when being ridden in a natural frame with only light rein contact ('free'). Workload (as measured by heart rate and blood lactate concentration) was slightly higher when horses were ridden 'rollkur' than when they were ridden 'free'. There were no differences in packed cell volume, or glucose and cortisol concentrations. No signs of uneasiness or stress could be determined when the horses were ridden 'rollkur'. Subjectively, all horses improved their way of moving during 'rollkur' and were more responsive to their rider.     

Object habituation in horses: The effect of voluntary versus negatively reinforced approach to frightening stimuli

Reasons for performing the study: The ability of horses to habituate to novel objects influences safety in the horse–human relationship. However, the effectiveness of different habituation techniques has not been investigated in detail. Objectives: 1) To investigate whether horses show increased stress responses when negatively reinforced to approach novel objects, compared with horses allowed to voluntarily explore the objects and 2) whether a negatively reinforced approach facilitates object habituation. Methods: Twenty‐two 2–3‐year‐old Danish Warmblood geldings were included. Half of the horses (NR group) were negatively reinforced by a familiar human handler to approach a collection of novel objects in a test arena. The other half were individually released in the arena and were free to explore the objects (VOL group). On the next day, the horses were exposed to the objects again without a human handler, to investigate the rate of habituation. Behavioural and heart rate responses were recorded. Results: All VOL horses initially avoided the unknown objects, whereas the handler was able to get all NR horses to approach and stand next to the objects within the first 2 min session. The NR horses had a significantly longer duration of alertness and a higher max heart rate in the first session. On the next day, however, NR horses spent significantly less time investigating the objects and had a shorter latency to approach a feed container, placed next to the objects, indicating increased habituation. Conclusion: A negatively reinforced approach to novel objects increases stress responses during the initial exposure but facilitates habituation in young horses. Potential relevance: Although a negatively reinforced approach appears beneficial for habituation, the procedure should be carefully managed due to increased stress responses in the horse, which may constitute a safety risk. Further experiments should aim to investigate differences in stimulus intensity.     

Temperature regulation in horses during exercise and recovery in a cool environment

Background

Clipping the winter coat in horses is done to improve heat dissipation during exercise and make grooming easier. It is often combined with blanketing to keep the horse warm. The aims of the present study were to investigate how clipping and the use of blankets affect thermoregulation during exercise and recovery in horses.

Methods

One Gotland pony, one New Forest pony, and one warm-blooded horse exercised one after the other on a 6450 m long track. The horses walked, trotted and cantered according to a predetermined scheme, which took about 50 minutes including three stops. The scheme was repeated on five consecutive days when horses were: 1) unclipped 2) unclipped + blanket during recovery, 3) left or right side clipped, 4) clipped, and 5) clipped + riding blanket + blanket during recovery. Heart rate (HR) was measured with telemetry, respiratory rate (RR) by counting flank contractions, skin temperatures by thermistor probes, and rectal temperature with a digital thermometer. Skin wetness (SW) was estimated by ocular inspection (dripping = 5, dry = 0).

Results

Mean outdoor temperature varied from -1.1 to - 8.7°C. HR increased progressively during exercise with no difference between treatments. Maximum RR was 77 ± 30 breaths/min (unclipped) and 49 ± 27 breaths/min (clipped). The lowest skin temperature was 17.5 ± 2.7°C in a hind leg during exercise, which increased to 34.5 ± 0.1°C during recovery. Rectal temperature was elevated during recovery in unclipped, but not in clipped horses and skin temperature at base of tail was elevated during recovery except in unclipped horses without blanket. Moisture after exercise scored 3.2 ± 0.8 in unclipped and zero in clipped horses.

Discussion and conclusion

Leg skin temperature initially dropped at onset of exercise in clipped horses, and then increased after about 30 minutes due to internal heat from the working muscles. These changes were not significant when clipped horses had riding blankets, whereas unclipped horses became overheated as judged from respiratory rate and elevated rectal temperature. Providing clipped horses with blankets dampened the changes in leg skin temperature during exercise.