Stress Response In Horses Research Articles

Stress Responses in Horses Housed in Different Stable Designs during Summer in a Tropical Savanna Climate.

Single-confinement housing can pose welfare risks to domestic horses. This study investigated horses' stress responses when confined to single stalls in different stable designs in a tropical savanna region to address a gap in the literature. In total, 23 horses were assigned to a stable with a central corridor and solid external walls (A) (N = 8), a stable with one side corridor and solid external walls (B) (N = 6), or a stable with a central corridor and no solid external walls (C) (N = 9). Air velocity, relative humidity, air temperature, and noxious gases were measured inside the stables, and the heart rate and HRV of the horses were also determined. The relative humidity was lower in stable C than in stable A (p < 0.05), while the air temperature was higher in stable C than in stable B (p < 0.05) during the day. The airflow and ammonia levels were higher in stable C than in stables B and A (p < 0.01-0.0001). Overall, horses' HRV in stable A was lower than in those in stables B and C (p < 0.05-0.01). Horses in stable A tended to experience more stress than those in other stables.

Physiological stress responses in horses participating in novice endurance rides

Horses participating in endurance events encounter enormous physical challenges. Heart rate (HR) and heart rate variability (HRV) have been reported before and after endurance rides, but these have not been determined during the rides. Moreover, the modulation in HRV and haematology in horses with different ride results (completed a course or disqualified due to irregular gait) have not been elucidated. Therefore, this study aimed to investigate changes in HR, HRV, and haematological parameters during novice endurance rides and to compare these parameters between horses that successfully completed the course (SC) or were disqualified for irregular gait (FTQ-GA). Beat-to-beat (RR) intervals of 16 healthy horses (aged 6–14 years) were recorded before and throughout the approximately 40 km endurance event. Blood samples were taken at the pre-ride inspection and after passing each veterinary inspection. HRV and haematology measures were determined from nine SC and seven FTQ-GA horses. Horses with different ride results demonstrated distinctive physiological stress responses. Increases in PCV, RBC, WBC and neutrophils after completing the ride were found only in SC horses, implying that they were ridden with greater effort than FTQ-GA horses. A reduction in HRV during warm-up, followed by a significant reduction during the first and second riding phases, was observed. HRV returned to baseline at the compulsory rest period of both phases. FTQ-GA horses experienced lower RR intervals, RR triangular index, modified deceleration capacity, very-low-frequency band, and parasympathetic nervous system index, coinciding with higher HR and sympathetic nervous system and stress indices than SC horses. These results indicated that endurance horses revealed a shift toward sympathetic activity during the ride. Lower parasympathetic activity in FTQ-GA horses suggests they were under more stress or discomfort than SC horses in novice endurance rides. These results have welfare implications, indicating the need for additional rest breaks in FTQ-GA horses.

Effects of the Chinese herbal medicine prescription Suanzaoren decoction on stress response of horses in transportation

Effects of the Chinese herbal medicine prescription Suanzaoren decoction on stress response of horses in transportation

PSVII-14 Reduction in Heart Rate Variability Parameters in Horses Treated with a Mixture of Lavender and Eucalyptus Essential Oil

Abstract Routine medical examinations can produce stress which can negatively impact the health and well-being of horses. Heart rate variability (HRV) is a non-invasive and inexpensive method to measure the balance between sympathetic and parasympathetic nervous system activity, which can help identify stress in horses. This study examined the effect of a combination of lavender and eucalyptus essential oil on stress responses in horses undergoing a routine medical exam. After a five-minute stall rest (baseline reading) data were collected in three, five-minute intervals (walk to and enter stock, medical exam, and recovery in stall). This study utilized a switch-back design where each horse (n = 10) received both treatments on different dates. The treatment groups received lavender (20%) and eucalyptus essential oil (5%) dissolved in petroleum jelly and virgin sunflower oil applied to inner nostrils. The control treatment consisted of only petroleum jelly and virgin sunflower oil applied to inner nostrils. The root mean square of the successive differences of heartbeats (RMSSD) was significantly reduced (P &amp;lt; 0.05) when horses were treated with essential oils while walking to stocks (51.7 ± 3.7), during the medical exam (50.5 ± 4.9), and during the recovery period (64.1.9 ± 5.7) compared with control treatment, to stocks (36.1 ± 4.4), the medical exam (39.0 .± 4.5), and during the recovery period (49.7 ± 5.5). The measured SD1 (parasympathetic) was significantly greater (P &amp;lt; 0.008) at walk to stocks in horses treated with essential oils (37.2 ± 1.9) compared with control treated (30.3 ± 3.1). The measured SD2 (sympathetic) was significantly less (P &amp;lt; 0.008) at walk to stocks in horses treated with essential oils (62.8 ± 1.9) compared with control treated (69.7 ± 6.8). The ratio of SD1/SD2 was significantly less (P &amp;lt; 0.008) at walk to stocks in horses treated with essential oils (1.7 ± 0.17) compared with control treated (2.4 ± 0.26). The high frequency percent (HF%) was also greater (P &amp;lt; 0.04) at walk to stocks in horses treated with essential oils (39.6 ± 4.9) compared with control treated (26.0 ± 4.1). The standard deviation of RR Interval (SDNN) values were increased (P &amp;lt; 0.03) in horses treated with essential oils during walking to stalks (50.8 ± 1.9), the medical exam (56.7 ± 5.0), and the recovery period (72.4 ± 12.9) compared with the control treatment, to stalks (44.5 ± 5.2), medical exam (44.0 ± 4.5), and during the recovery period (54.6 ± 6.2). The results of this study indicate that lavender and eucalyptus oil could be an effective means of reducing short-term stress in horses. The findings of this study can help develop more effective and humane management strategies for horses.

Inflammatory-like status and acute stress response in horses after road transport

This study aimed to evaluate the change of white blood cell count, serum concentration of cortisol, C-reactive protein, albumin and globulin fractions in horse after road transport, and to assess the linkage among hypothalamic–pituitary–adrenal axis (HPA) and inflammatory reaction. From 10 horses blood samples were collected at rest, before road transport (218 km) (BT); after unloaded (AT), 30 and 60 min after unloaded (AT30 and AT60) in order to assess white blood cell count (WBC), serum cortisol, C-reactive protein (CRP), total proteins, albumin, α1-, α-2, β1-, β2- and γ-globulins. WBC, cortisol, CRP, α1-, α-2 and β2-globulins values increased after road transport than rest condition (p < 0.001). Albumin and A/G ratio showed lower values after road transport than rest (p < 0.001). Pearson’s test showed a negative correlation between cortisol and the values of WBC, CRP, α1-, α2-, β1-, β2- globulins, and a positive correlation between WBC and serum concentration of CRP, α1- and α2-, β1-, β2-globulins at AT and AT30. The results showed that road transport evokes an inflammatory like-status in horses. Moreover, the activation of HPA and the onset of acute phase reaction in response to road transport seem to be interconnected with effects on horse’s immune status.

7 Validation of a commercial ELISA kit for non-invasive measurement of equine cortisol concentration

The measurement of fecal corticosteroid metabolites (FCM) is a method for quantifying potential stress. The sampling method is relatively non-invasive, especially when compared with blood cortisol. Fecal collection reduces concern for a rise in cortisol from the sampling method itself and has been shown to be a more consistent measure of cortisol in horses without the daily diurnal rhythm observed in blood cortisol. Commercial ELISA kits offer many benefits over previously validated RIA methods but lack validation. Further, time point of fecal collection has not been established. The objective of this study was to provide both analytical and biologic validation of fecal and plasma samples from horses using a commercial cortisol ELISA Kit (Arbor Assays DetectX Cortisol ELISA kit, K003-H1). In October, horses (4 M, 4 F, 8 ± 7 yr) were transported in pairs for a 15-min transportation session using a livestock trailer that included a divider to prevent physical contact and limit visual contact. Blood samples were collected via jugular venipuncture before, immediately after, and 60 min post-transportation. Fecal samples were collected via drop or grab sampling before transportation and 20, 24, and 28 h post-transportation. Data were analyzed using PROC MIXED in SAS. Inter-assay and intra-assay coefficients of variation for FCM were 9.0 and 10.8%, respectively and for plasma cortisol 11.0 and 7.2%, respectively. Dilutionalparallelism was observed between dilutions 1:20 and 1:40 for fecal samples and 1:100 and 1:250 for plasma samples. The recovery of a known spike for plasma cortisol and FCM were 98.2 and 100.0%, respectively. Plasma cortisol concentrations increased in response to trailering (73.4 ± 7.6 ng/ml, 0 min post-transportation, P = 0.02) compared with pre-transportation (41.2 ± 7.6 ng/ml) and began to decline 60 min post-transportation (51.0 ± 7.6 ng/ml) when compared with immediately post-trailering (P = 0.09). Plasma cortisol concentrations pre-trailering were not different from 60 min post-trailering. FCM concentrations increased 24 h post-trailering (10.8 ± 1.7 ng/g, P = 0.04) when compared with pre-transportation (7.4 ± 1.7 ng/g). FCM concentrations pre-trailering were not different from 20 h (8.68 ± 1.7 ng/g, P = 0.64) or 28 h post-trailering (10.0 ± 1.7 ng/g, P = 0.11). These data support that 15 min of transport with limited visual/physical contact between conspecifics is adequate to elicit a stress response in horses and that changes in FCM are observed 24 h post-stressor. In conclusion, the Arbor Assay Cortisol ELISA kit is a reliable, economic option for the measurement of cortisol in equine plasma and fecal samples.

Evaluation of Substance P as a New Stress Parameter in Horses in a Stress Model Involving Four Different Stress Levels.

Stress has a significant impact on equine welfare. There are some studies on the stress response in horses ridden with tight nosebands, but little is known about other stress parameters than cortisol, which potentially could address an emotional component. In this study, blood samples of a total of 74 warmblood horses were used to establish reference values for plasma substance P (SP) concentrations. Moreover, 16 of these warmblood horses were included in a stress model. Four different stress levels (level 1: horses ridden with loose noseband, level 2: tight noseband, level 3: loose noseband and overground endoscope, level 4: tight noseband and overground endoscope) were applied to evaluate SP as a potential stress parameter in horses. Blood samples were taken at rest (t0) and directly after inducing stress (noseband tightening, insertion of endoscope; t1), as well as after 20 min of riding at all gaits (t2). A ridden horse ethogram was applied and showed that horses in the tight noseband group resorted to other stress-related behavioral issues than horses with loose nosebands. Serum cortisol showed a linear increase concurrent with the increase in stress levels with a significant difference between level 1 and level 4 (p = 0.043), proving that stress factors were adequate to evaluate the stress response, whereas SP did not show a correlation with the stress levels. Furthermore, concentrations of SP differed widely between horses but stayed within more narrow limits in the individual horse. As a conclusion, SP might not be a reliable stress parameter in horses in the applied minor stress model.

Cortisol Variations to Estimate the Physiological Stress Response in Horses at a Traditional Equestrian Event.

In many countries, horses remain involved in traditional equestrian events such as those celebrated in Menorca (Balearic Islands, Spain) every year since at least the 14th century. The present study aimed to evaluate the variations in salivary cortisol concentrations to estimate the physiological stress response in horses at the Menorca patronal festivals. Two different editions (years 2016 and 2018) of the festivals in honor of the Virgin of Grace in Maó (Menorca, Spain) were studied. Nineteen and seventeen Pure Breed Menorca stallions were included in the study, respectively. The stallions were aged between seven and twelve years. During celebrations, samples were collected before the start of the festivals between 8-9 a.m. and during the festivals at 8-9 p.m. On the second day of celebrations, the samples were collected at 8-9 a.m. and 3-4 p.m. Finally, on the day after the festivals, one sample was collected at 8-9 p.m. Additionally, a control group was sampled at 8-9 a.m., 3-4 p.m., and 8-9 p.m. Salivary cortisol concentrations were assessed by using a commercial enzyme immunoassay kit specially validated to quantify salivary cortisol in horses. Salivary cortisol concentrations did not show significant differences between sampling hours in the control group (p > 0.05). All the samples collected during festivals were significantly higher than samples of the control group (p < 0.05). Within the twenty-four hours after the end of the celebrations, cortisol concentrations returned to baseline levels and did not differ significantly from the control group (p > 0.05). Hence, the present study describes that the participation of the horses in these particular acts generate an acute and transitory stress response. Overall, the current work provides a reasonable basis for future research on the stress physiology and well-being of horses participating in traditional celebrations or similar events.

The impact of strategic ventilation adjustments on stress responses in horses housed full-time in a vector-protected barn during the African horse sickness outbreak in Thailand.

The severe outbreak of African horse sickness (AHS) in Thailand has forced horses to reside full-time inside barns that are covered by a small mesh net to prevent minuscule AHS insect vectors from gaining access. However, housing in the net-covered barn induces stress in horses, which compromises their welfare. Implementing strategic airflow adjustment while retaining the vector-protection characteristics has been proposed to help alleviate this problem. The present study aimed to investigate the effect of strategic ventilation adjustment on blood cortisol levels, heart rate and behaviour in horses in a vector-protected barn. Nine horses underwent two sequential stabling conditions: vector-protected barn housing and housing in a barn in which the air ventilation was explicitly adjusted. Heart rate was higher in the afternoon in horses housed in the barn without ventilation adjustment, whereas no change was observed in the barn with ventilation adjustment. The vector-protected housing increased the horses' behavioural scores. Blood cortisol level declined over time, and an earlier decrease was detected at 1400h in the barn with ventilation adjustment. Although airflow adjustment did not appear to statistically alter the stress response in horses during housing in the vector-protected barn, an earlier decline in cortisol level alongside an unchanged heart rate in horses during the day may indicate the positive impact of ventilation adjustment within the vector-protected barn. With limited options to reduce stress or discomfort in horses, this strategic protocol could, at least in part, be applied to managing horses' welfare during the AHS outbreak.

Stress response as a contributing factor in horses with laminitis.

Laminitis is a complex and debilitating disease of horses. Numerous predisposing factors contribute to laminitis development, however the exact pathogenesis remains undetermined. Serum T4, cortisol, and histamine are components of the innate stress response and could play a causative or contributory role. Stress hormone concentrations in laminitis are largely unknown. To evaluate parameters associated with stress response in horses with laminitis, and compare these to healthy horses and horses with gastrointestinal (GI) disease. Thirty-eight adult horses presenting for non-medical conditions, GI abnormalities, or clinical laminitis were prospectively enrolled. Horses were assigned to the appropriate disease group (healthy, GI disease, and laminitis) and had blood drawn on presentation to the hospital. Samples were analyzed for plasma endogenous adrenocorticotrophic hormone (eACTH), serum cortisol, serum thyroid hormone, and plasma histamine. Stress hormone concentrations were significantly different between horses in the laminitis and GI disease groups. Plasma histamine levels were highest in horses with laminitis, compared with GI disease and controls. Both horses with laminitis and GI disease had increased plasma eACTH when compared to healthy horses. Horses with GI disease had higher serum cortisol concentrations than horses with laminitis or controls. Serum T4 was lower in horses with GI disease than in horses with laminitis and controls. Horses with laminitis had relative increases in both plasma histamine and eACTH concentrations. Serum T4 and cortisol concentrations of horses with laminitis did not differ significantly when compared to healthy horses. The role of stress hormones in equine disease warrants further investigation.

Stress, Metabolic and Serum Muscle-Derived Enzymes Response of Horses Employed in Wooded Area and Field Trekking Courses

Horse trekking is a non-competitive sport that, as other kinds of exercise, involves skeletal muscle effort and may implicate significant energy expenditure leading to stress. The aim of the current study was to assess the effect of trekking on metabolic and stress response as well as muscle damage markers in clinically healthy horses. Thirty horses were equally divided in 3 groups according to trekking course: Group A (trekking course 15 km long), Group B (trekking course 35 km long starting;), Group C (three trekking courses for three consecutive days; during the first day the trekking course was 25 km long, Group C1; during the second day the trekking course was 40 km long, Group C2; during the third day the trekking course was 25 km long, Group C3). Blood samples were collected from each horse before trekking (TPRE), after 5 min (TPOST) and 1 h from the trekking end to assess lactate, glucose, total proteins, non-esterified fatty acids (NEFAs), creatinine, aspartate aminotransferase (AST), creatine phosphokinase (CPK), lactate dehydrogenase (LDH) and cortisol concentration. Higher cortisol, lactate, glucose, NEFAs, creatinine, CPK, LDH and AST values were found after trekking than rest (P < .001). Horses of Groups C2 and C3 showed higher values of the investigated haematochemical parameters and muscle enzymes than Groups A and B. The findings suggest that trekking induces a metabolic reaction accompanied by an acute stress response in horses and underline that this recreational exercise, if not associated with the adequate recovery period, can increase the probability of muscle damage.

Equine-Assisted Interventions (EAIs) for Children with Autism Spectrum Disorders (ASD): Behavioural and Physiological Indices of Stress in Domestic Horses (Equus caballus) during Riding Sessions.

Simple SummaryEquine-assisted interventions (EAIs) are gaining increasing attention as complementary practices in autism spectrum disorders (ASD) as they can provide physical and psychological enrichment to children. However, ASD children could manifest inappropriate behaviours, potentially affecting the welfare of horses. This multicentre study aimed to investigate behavioural and physiological indices of stress in horses involved in EAI standardised sessions with children with ASD compared to sessions involving typically developing (TD) children. It followed a controlled within-subject design with repeated measurements involving 19 horses and 38 children. We compared behavioural and physiological responses of horses between sessions and among session phases. Results indicate a lower sympathetic tone in horses involved in ASD sessions, while in the mounting and dismounting phases, the horses displayed behavioural signs of stress, independently from children’s behaviour. Results from this study indicate that professionals should increase their awareness of horse’s welfare and refine methodologies used in EAIs.Equine-assisted interventions (EAIs) are well-known complementary practices combining physical activity with emotional/cognitive stimulation. They are especially suited for children with autism spectrum disorders (ASD) who need a high degree of physical and psychological enrichment. Even though EAIs have become a common practice, stress responses in horses interacting with individuals that can manifest inappropriate behaviours, such as ASD children, have not been thoroughly investigated. Our multicentre study aimed to investigate behavioural and physiological indices of stress in horses involved in EAI standardised sessions with children with ASD compared to typically developing (TD) children. A controlled within-subject design with repeated measurements involving 19 horses and 38 children was adopted. Stress-related behaviours, heart rate, heart rate variability, and eye temperature were recorded during the riding sessions. Moreover, blood samples were collected from horses before and after each session to monitor changes in blood adrenocorticotropic hormone (ACTH), cortisol, and catecholamines. Results indicate that, in general, stress responses in horses involved in EAIs did not differ as a function of the horse being ridden by children with ASD or TD. A lower sympathetic tone in horses involved in ASD sessions was found, while in the mounting and dismounting phases, horses displayed behavioural signs of stress, independently from children’s behaviour. We conclude that professionals working in EAI should increase their awareness of animal welfare and refine riding practices, taking into account horse’s needs.

A Delphi study to determine expert consensus on the behavioural indicators of stress in horses undergoing veterinary care

Horses undergoing veterinary care may perceive the experience to be stressful and their behavioural responses can result in injuries to people involved in their care. Being able to accurately measure the stress response in horses undergoing veterinary care would have potential benefits. Firstly, it may highlight common behavioural indicators that the horse is stressed, which could be used as warning signs that the risk of an aversive reaction is more likely. Secondly, it would inform the development of low stress handling techniques for veterinary procedures. To determine if there was expert consensus on the most appropriate measures to identify stress in horses undergoing veterinary care a two round Delphi analysis was undertaken; involving experts in the fields of equitation science (n = 16), equine veterinarians (n = 10), and animal and behaviour welfare scientists who do not normally work with horses (n = 7). Each round was completed as an online anonymous survey. In the first round (R1) participants viewed 11 scenarios of horses undergoing veterinary care and were asked to assign the degree of stress they perceived the horses were experiencing on a numerical rating scale (from 1 to 10) and describe any behavioural indicators of stress (BI). In the second round (R2) they were asked to rate the usefulness of a list of BI that had been compiled from results in R1. Analysis of participants’ responses and merging of similar terms identified 41 BI in R1. There was poor agreement between participants (kappa = 0.08) on the degree of stress they perceived the horse was experiencing in each scenario (R1), with a wide range of scores used for most scenarios. In R2 participants reached agreement that 34/41 (83 %) BI were useful indicators of stress. BI considered indicative of severe acute stress were most likely to be identified as very useful in assessing horse stress. The results highlighted a variation in the ability of experts to identify when horses were stressed in the veterinary clinic, particularly when horses were not showing very overt behavioural responses. Although a number of BI were identified as useful, it is likely that development of a structured ethogram and training would be required to allow assessment of BIs to be used successfully in the veterinary clinic to reduce the likelihood of human injuries.

PSIV-17 Muscular Tension as a Marker of Stress in Horses

Abstract Effects of social isolation, sham clipping, and novel object exposure on muscular and behavioral responses were investigated in horses. Humans increase muscular tension under psychologically or physically demanding situations and thus, similar conditions were expected to alter stress responses in horses. Eight mature Standardbreds (4 mares, 4 geldings) were exposed to 3 min of social isolation (ISO), sham clipping (CLIP), novel object (NOV), and control (CON) conditions in a replicated 4×4 Latin Square experimental design with 10 min washout periods. Surface electromyography (EMG) and stress-related behaviors were recorded continuously. Median frequency (MF) and average rectified value (ARV) of the EMG signal were calculated for the first, middle, and final 10 sec of each period. EMG data were log transformed prior to analysis with a mixed model, repeated measures ANOVA. Behavior data were analyzed using a negative binomial distribution mixed model ANOVA. Significantly different means were separated using Tukey’s method. More stress-related behaviors (P &amp;lt; 0.05) were observed during ISO (3.25 ± 0.26, LSM ± SE) than CON (1.46 ± 0.29) or CLIP (1.50 ± 0.36). ISO tended (P = 0.054) to produce more stress-related behaviors than NOV (2.31 ± 0.28). CLIP and ISO produced higher (P &amp;lt; 0.05) ARV than CON or NOV in the left and right masseter. CLIP elicited the highest (P &amp;lt; 0.05) MF in the left and right masseter with ISO resulting in lower (P &amp;lt; 0.05) MF than CON. ARV was higher (P &amp;lt; 0.05) in the left cervical trapezius during ISO as compared to all other conditions and in the right as compared to CON and CLIP. In the right cervical trapezius, ISO elicited higher (P &amp;lt; 0.05) MF than CON. Increased stress-related behaviors indicate a stress response was induced. Elevated muscular activity suggests muscular tension can be used in assessing stress.

The Effects of the Quantum and Finesse Bridles on Equine M. Brachiocephalicus and M. Splenius Function at Three Different Speeds

Badly designed and fitted tack induces physiological stress responses in horses, and may compromise animal welfare. Moreover, horses, just like humans, comprise a series of interconnected myofascial lines. However, to date there are no measurements of the effects of horse tack, such as bridles on muscle parameters. This study used acoustic myography to test whether two commercial anatomically designed and fitted bridles, have a measurable and positive effect on both equine muscle-function and performance. A Quantum bridle was tested on 12 Icelandic horses, whilst a Finesse bridle was tested on 8 Icelandic horses, and results compared with data from a standard bridle (n = 12) tested at the same time and under identical conditions. Sensors were placed on M. Brachiocephalicus and M. Splenius, and the horses exercised following a set protocol at three speeds. The results revealed statistically significant improvements in muscle performance as assessed by both the regularity of the recording at each speed, and the number of transient powerful contractions (spikes) for the anatomically designed and fitted bridles, compared with the standard bridle. It is concluded that the effect of anatomically designed bridles can not only be measured in the neck muscles of exercising horses, but that they appear to have a positive effect on muscle performance.

Drylot size influences cortisol and stress responses in horses during group turnout

Drylot size influences cortisol and stress responses in horses during group turnout

Efeito da acupuntura nas respostas de estresse em equinos atletas submetidos a reprise de adestramento

Horses have a natural predisposition for sport, however, their use in competitions can result in stress-related problems that impair their sporting performance and especially their health. Thus, the use of strategies that can prevent or minimize the deleterious effects of stress is essential. In this sense, acupuncture is an ancient technique of Traditional Chinese Medicine that has been used in the treatment and prevention of stress-related diseases. Therefore, we evaluated whether acupuncture can alter stress responses in horses submitted to a dressage test. Six Brasileiro de Hipismo horses, aged between 6-8 years old, used for dressage training, from Army Riding School, Rio de Janeiro, Brazil were used. The effect of acupuncture at points GV1, HT7, GV20, and B52 immediately before to the dressage was evaluated through analysis of test performance, serum cortisol and heart rate variability (HRV). Polar Equine ™ heart rate monitor was used for HRV analysis and blood samples were collected before and 30 minutes after the end of the dressage. The performance was judged by official judges and by the riders. Acupuncture significantly reduced the LF / HF ratio (p < 0,0001), an index that indicates the sympathovagal balance suggesting that acupuncture can reduce the cardiac autonomic response in stressful situations. However, acupuncture had no effect on heart rate, cortisol levels and performance assessed by judges and riders. Our results suggest that acupuncture may reduce some stress responses in horse athletes submitted to dressage and that this effect can be related to its potentiating action of vagal activity

0796 Stress responses in horses tied with overchecks

0796 Stress responses in horses tied with overchecks

Changes of the hindgut microbiota due to high-starch diet can be associated with behavioral stress response in horses

The digestive system of horses is adapted to a high-fiber diet consumed in small amounts over a long time. However, during training, high-starch and low-fiber diets are usually fed which may induce hindgut microbial disturbances and intestinal pain. These diets can be described as alimentary stress. The aim of the present study was to investigate to what extent changes in behavior are associated with alimentary stress and microbial composition changes of the cecal or colonic ecosystem. Six fistulated horses were used. The alimentary stress was a modification of diet from a high-fiber diet (100% hay) to a progressive low-fiber and high-starch diet (from 90% hay and 10% barley to 57% hay and 43% barley in 5days). Cecal and colonic total anaerobic, cellulolytic, amylolytic and lactate-utilizing bacteria were enumerated three times (twice on high-fiber diet and once on 57% hay and 43% barley diet). The behavior of horses was assessed from continuous video recording over an 18-h time period. In addition two personality traits were measured: neophobia (assessed from the reaction to the presence of a novel object placed near a feeder in a test arena) and sociability (assessed from the reaction to an unfamiliar horse in a stall). Video recordings were analyzed by scan sampling every 10min using the following behavioral categories: lying, resting, feeding and being vigilant. In addition, we recorded time spent feeding and time spent in vigilance during the neophobia test, and time spent in vigilance and time spent in interactions with the unfamiliar horse during the sociability test. The alimentary stress induced significant increases of colonic total anaerobic bacteria, lactate-utilizing bacteria and amylolytic bacteria concentrations. When horses were fed the 57% hay–43% barley diet, time spent in vigilance tended to be positively correlated with cecal and colonic amylolytic bacteria concentrations during the sociability test and with cecal lactate-utilizing and colonic amylolytic bacteria concentrations during the neophobia test. These correlations suggested that dietary-induced modulation of the microbiota may affect horse behavior and that behavioral cues may be used as non-invasive indicators of alimentary stress. It might prove useful to prevent intestinal pain of horses on farms.

No increased stress response in horses on small and electrically fenced paddocks

Regular free movement is an important factor for the wellbeing of horses, reducing the risk of behavioural disorders as well as maintaining bodily functions healthy. Currently animal welfare legislations in several countries require minimal stay times in outdoor enclosures. However, clear legal recommendations for the fence type enclosing or surrounding this area do not exist. With regard to electric fencing systems, some concerns exist that the latter could affect the behaviour of horses, cause chronic stress and reduce the accessible space. The aim of this study was to quantify stress responses in horses kept in small and big paddocks with wooden fencing compared to paddocks with electric fencing, focusing on possible differences concerning the utilisation of the paddock area between the two types of fencing and size. Twenty horses aged between 6 and 18 years were tested comparing two paddock sizes (12.25m2/36m2) either with wooden or electric fencing in order to evaluate physical and behavioural parameters. Each horse was tested in a randomised sequence in all four paddock types during 90min per type. During the experiments the horses were continuously recorded on video for later analyses of behavioural patterns and the utilisation of the available paddock area. Additionally, periodic measurements of heart rate (HR), heart rate variability (HRV) as well as standardised salivary samplings for later cortisol determination were carried out. Horses used the available area significantly less both in electrically fenced and small paddocks (p<0.001). The border area (50cm) was used less both in electrically fenced and small paddocks (p<0.001). The total amount of stress-indicating behaviour did not differ between the two fence types. Horses moved less in small (p<0.001) and electrically fenced (p<0.005) paddocks than in big and wooden fenced ones. Horses rolled less in small paddocks (p<0.001). Fence contact was significantly less with electric fencing (p<0.001). Stress-indicating behaviour tended to be more prominent in small paddocks. Salivary cortisol and HRV parameters did not differ between the paddocks but a slight tendency of alteration of the low frequency/high frequency ratio indicating stress reactions was observed with electric fencing. Based on the measured physiological parameters there is no indication for stress in electrically fenced paddocks. However horses use less of the available paddock area both in electrically fenced paddocks and small paddocks, especially by avoiding the area near the fence.