Abstract: The first month of training of a young horse is suspected to be stressful, but the endocrine responses to initial training are unknown. Therefore in our study a total of 40 Quarter Horses (QH), all at the age of almost 2 years, were followed during the first 30 days of their training. During this time faecal samples were collected twice daily and faecal cortisol metabolites (FCM) were measured. Baseline values of FCM ranged between 1.3 and 20.1 (median: 6.7) ng/g faeces. No differences in FCM values between days of training were found. Mares showed the highest values. Significant diurnal variations were observed in mares (p=0.035) and stallions (p=0.003), but not in geldings (p=0.282). As in this study adrenocortical activity was not increased during initial training, horses seem to cope very well with this new situation. The results of our large-scale study provide basic physiological data about initial training. This gives additional input in an emotional debate about animal welfare aspects of first time handling and training of horses.
Abbreviations: 11,17-DOA = 11,17-dioxoandrostanes; EIA = Enyzme Immunoassay; FCM = faecal cortisol metabolites; GC = glucocorticoids; HPA-axis = hypothalamic-pituitary-adrenocortical-axis; QH = Quarter Horses
[Das Einreiten eines jungen Pferdes steht unter Verdacht belastend zu sein. Bisher gibt es aber keine Veröffentlichungen über endokrine Vorgänge während dieser Phase. Mit der vorliegenden Studie wurde überprüft, ob Pferde aufgrund physischer und psychischer Belastungen während des Trainings höhere Konzentrationen an Kortisolmetaboliten im Kot (FCM) aufweisen. Es wurden dazu 40 Quarter Horses im Alter von 2 Jahren während der ersten 30 Tage der Grundausbildung des Westernreitens beobachtet und ihre FCM Werte gemessen. Während dieser Zeitspanne wurden täglich morgens und abends Kotproben der Pferde genommen. Die Basalwerte der FCM Konzentration variierten zwischen 1,3 und 20,1 (Median: 6,7) ng/g Kot, wobei Stuten die höchsten Werte hatten. Signifikante Unterschiede während der einzelnen Trainingstage konnten nicht festgestellt werden. In der Tagesrhythmik wurden signifikante Unterschiede bei Stuten (p=0,035) und bei Hengsten (p=0,003), jedoch nicht bei Wallachen (p=0,282) ermittelt. In dieser Studie konnte keine erhöhte Aktivität der Nebennierenrinde im Verlauf der Grundausbildung eines Pferdes im Westernreitstil festgestellt werden. Das legt nahe, dass Pferde mit dieser neuen, zeitlich kurz andauernden Situationen gut zurechtkommen. Unsere Studie wurde an einer großen Anzahl von Tieren unter Feldbedingungen durchgeführt. Sie bietet daher eine gute Datenbasis über Belastungen während des Einreitens. Damit liefert sie einen zusätzlichen Beitrag zu einer mitunter emotional geführten Debatte über tierschutzrelevante Aspekte bei der Grundausbildung von Pferden.]

Abstract: No detailed comparative data are available on the hormonal parameters of horses suffering from a number of diseases. The aim of our study was to measure concentrations of cortisol, adrenocorticotropic hormone (ACTH), serotonin, adrenaline and noradrenaline in horses with various diseases and following surgery, to assess the response of the HPA axis and adrenal medulla. Blood samples were obtained from six groups of horses comprising a total of 119 animals as follows: laminitis, acute abdominal syndrome (AAS), castration surgery, acute diseases, chronic diseases and healthy controls. Serum hormonal concentrations were determined for each group for comparison. Statistically significant differences between all groups and controls were found for cortisol, ACTH (except for castration), serotonin and adrenaline concentrations but only in horses with laminitis and AAS for noradrenaline. No statistically significant differences were found between males and females. The largest changes in the pituitary–adrenal axis activity occurred mainly in acute diseases, laminitis and in the AAS group.

Abstract: The aim of the study was to investigate whether heart rate variability (HRV) could assess alterations of the autonomic nervous system (ANS) at different levels of excitement. The behavioural and physiological responses of 20 warmblood horses to a challenging ground exercise task were studied. Prior to the experiment, the horses were evaluated at rest and during forward walking (FW). The horses were then forced to move backwards continuously during 3 min according to a standardised protocol (BW1). Subsequently, the horses were exposed to two training sessions, after which the backward walking (BW2) was re-evaluated. Heart rate (HR) and HRV-parameters such as the standard deviation of the beat-to-beat intervals (SDRR), the low (LF; sympathetic tone) and high frequency (HF) component of HRV (HF; parasympathetic tone) and their ratio (LF/HF; index representing the sympatho-vagal balance) were sampled at rest, and during FW, BW1 and BW2. Stress-related behaviour during BW1 and BW2 was determined from video recordings. The results of the different evaluations were compared to each other. Compared to rest and FW, the first backward experiment induced a significant rise in HR, LF and LF/HF and a significant decrease of HF. SDRR decreased from both FW and rest with only the latter reaching significance. In BW2 after the training sessions, HR and the parameters of the sympathetic branch of the ANS (LF, LF/HF) were decreased and the vagal tone (HF) increased compared to BW1; all changes were significant. The duration of stress indicating behavioural patterns revealed also a significant decrease of excitement after the training, when backward walking did not differ from forward walking in any parameter. Correlations between HRV-parameters and stress indicating behaviour as well as HR were found. We conclude that the HRV-parameters LF and HF are valuable measures to quantify sympatho-vagal balance, which allows a more precise assessment of the responses of HR and SDRR to mental stress during low intensity exercise.

Abstract: The ability of horses to learn and remember new tasks is fundamentally important for their use by humans. Fearfulness may, however, interfere with learning, because stimuli in the environment can overshadow signals from the rider or handler. In addition, prolonged high levels of stress hormones can affect neurons within the hippocampus; a brain region central to learning and memory. In a series of experiments, we aimed to investigate the link between performance in two learning tests, the baseline level of stress hormones, measured as faecal cortisol metabolites (FCM), fearfulness, and social rank. Twenty-five geldings (2 or 3 years old) pastured in one group were included in the study. The learning tests were performed by professional trainers and included a number of predefined stages during which the horses were gradually trained to perform exercises, using either negative (NR) or positive reinforcement (PR). Each of the learning tests lasted 3 days; 7min/horse/day. The NR test was repeated in a novel environment. Performance, measured as final stage in the training programme, and heart rate (HR) were recorded. Faeces were collected on four separate days where the horses had been undisturbed at pasture for 48h. Social rank was determined through observations of social interactions during feeding. The fear test was a novel object test during which behaviour and HR were recorded. Performance in the NR and PR learning tests did not correlate. In the NR test, there was a significant, negative correlation between performance and HR in the novel environment (rS=-0.66, P<0.001, i.e. nervous horses had reduced performance), whereas there was no such correlation in the home environment (both NR and PR). Behavioural reactions in the fear test correlated significantly with performance in the NR test in the novel environment (e.g. object alertness and final stage: rS=-0.43, P=0.04), suggesting that performance under unfamiliar, stressful conditions may be predicted by behavioural responses in a fear test. There was a negative correlation between social rank and baseline stress hormones (rS=-0.43, P=0.04), i.e. high rank corresponded to low FCM concentrations, whereas neither rank nor FCM correlated with fearfulness or learning performance. We conclude that performance under stressful conditions is affected by activation of the sympathetic nervous system during training and related to behavioural responses in a standardised fear test. Learning performance in the home environment, however, appears unrelated to fearfulness, social rank and baseline FCM levels.

Abstract: Summary The effects of various factors on the inflammatory and stress response in horses during transportation were examined in Experiments 1 and 2, carried out in April and August, respectively. In Experiment 1, three groups (G1-G3) of four Thoroughbreds were used, and in Experiment 2, two groups (G4, G5). G1 animals were loaded into lorries with their heads facing forwards (FF) and given periods of short rest (SR) (30 min for every 4 h driven). G2 horses were loaded facing rearwards (FR) and given SR. G3 horses were FF and given periods of long rest (LR) (2 h rest for every 4 h driven). G4 horses were transported FF with hay suspended in front of them and no cleaning of faeces or urine during rest stops. G5 horses were FF and given pellets instead of hay, and the lorry was cleaned and washed at each rest stop. G4 and G5 horses were rested for 1 h after every 5 h of driving. All groups were driven a distance of 1500 km, and the total journey time was 37 h for G1 and G2, 49 h for G3, and 40 h for G4 and G5. In Experiment 1, indicators of inflammatory and stress responses tended to be highest in G1, intermediate in G2 and lowest in G3. In Experiment 2 they tended to be higher in G4 than in G5. The results suggested that increasing the rest time and cleaning the interior of the vehicle during rest stops reduced transportation stress and respiratory insults, factors that may lead to respiratory disease.