Abstract: Even though the term “stress” is widely used, a precise definition is notoriously difficult. Notwithstanding this difficulty, stress continues to be an important concept in biology because it attempts to describe how animals cope with environmental change under emergency conditions. Without a precise definition, however, it becomes nearly impossible to make testable a priori predictions about how physiological and hormonal systems will respond to emergency conditions and what the ultimate impact on the animal will be. The reactive scope model is a recent attempt to formulate testable predictions. This model provides a physiological basis to explain why corticosterone negative feedback, but not baseline corticosterone concentrations, corticosterone responses to acute stress, or the interrenal capacity to secrete corticosterone, is correlated with survival during famine conditions in Galápagos marine iguanas. Reactive scope thus provides a foundation for interpreting and predicting physiological stress responses.

Abstract: Rescued equids are often exposed to rehabilitation and training (or retraining) programmes to improve their physical and psychological well-being as well as to facilitate the re-homing process. Training uses either positive or negative reinforcement learning procedures and it is considered here that, there may be welfare implications associated with using the latter technique as it has the potential to overlay acute stress on animals with a chronic stress life history. The aim of this study, therefore, was to compare these training strategies (negative versus positive reinforcement) on equine behaviour and physiology as the first step in establishing an optimal rehabilitation approach (from a welfare perspective) for equids that have been subjected to chronic stress in the form of long-term neglect/cruelty. Over a 7-week period, 16 ponies (aged 6–18 months) were trained using either positive (‘positive’) (n = 8) or negative reinforcement (‘negative’) (n = 8) techniques to lead in hand, stand to be groomed, traverse an obstacle course and load into a trailer. Heart rate was measured (5 s intervals) on days 1 and 4 of each training week, ‘Pre’- (1 h), ‘During’ (0.5 h) and ‘Post’- (1 h) training session. Ethograms (10.00–20.00 h) outside of the training period were also compiled twice weekly. In addition, weekly arena tests (as a measure of reactivity) were also performed 1 week before and during the 7 weeks of training. Results showed significant differences between the two training schedules for some measures during the latter stages of the trial and suggested that animals trained under a positive reinforcement schedule were more motivated to participate in the training sessions and exhibited more exploratory or ‘trial and error’ type behaviours in novel situations/environments. In this context, the incorporation of positive reinforcement schedules within a rehabilitation programme may be of benefit to the animal from a welfare perspective.

Abstract: Social relationships significantly influence physiology and behavior, including the hypothalamo–pituitary–adrenal axis, anxiety, and mental
health. Disruption of social bonds through separation or death often results in profound grieving, depression, and physical illness. As the
monogamous prairie vole forms enduring, selective pair bonds with the mating partner, they provide an animal model to study the
physiological consequences of pair bonding and, thus, the loss of the bonded partner. Male prairie voles were paired with a novel female
or male sibling. After 5 days, half of the males of each group were separated from the partner. Elevated plus-maze, forced swim, and tail
suspension tests were used to assess anxiety-like and passive stress-coping behaviors indicative of depressive-like behavior. Following 4
days of separation from the female but not the male partner, experimental males displayed increased passive stress-coping. This effect
was abolished by long-term intracerebroventricular infusion of a nonselective corticotropin-releasing factor (CRF) receptor antagonist
without disrupting the bond itself. Both CRF type 1 and 2 receptors were involved in the emergence of passive stress-coping behavior.
Furthermore, pairing with a female was associated with elevated CRF mRNA in the bed nucleus of the stria terminalis, and partner loss
elicited a pronounced increase in circulating corticosteroid and adrenal weight. We speculate that the CRF system may mediate an
aversive affect following separation from the female partner, which may facilitate proximity seeking between the pair-bonded individuals.
Hence, the prairie vole model may provide insights into brain mechanisms involved in the psychopathological consequences of partner
loss.

Abstract: A multitude of endocrine mechanisms are involved in coping with challenges. Glucocorticoids, secreted by the adrenal glands, are in the front line of the battle to overcome stressful situations. They are usually measured in plasma samples as parameters of adrenal activity and thus of disturbance. Unfortunately, collecting blood samples itself can disturb an animal. Thus, non-invasive methods for the determination of glucocorticoids or their metabolites have become increasingly popular. The pros and cons of various non-invasive sample materials (saliva, excreta, milk, hair/feathers and eggs) for glucocorticoid determination are given. Above all, faecal samples offer the
advantage that they can be collected easily. In faecal samples, circulating hormone levels are integrated over a certain period of time and represent the cumulative secretion of hormones. Thus, the levels are less affected by short fluctuations or the pulse-like nature of hormone secretion. However, using this technique to assess an animal’s adrenocortical activity is not especially simple. Whether frequent sampling is necessary or single samples will suffice depends upon the study’s aim (whether one is examining the impact of acute or chronic stressors). Background knowledge of the metabolism and excretion of cortisol/corticosterone metabolites is required and a careful validation for each species and sex investigated is obligatory. The present review also addresses analytical issues regarding sample storage, extraction procedures and immunoassays and includes a comprehensive list of published studies (up to 2011) describing the use of such methods in farmed animals. Applied properly, non-invasive techniques to monitor glucocorticoid metabolites in faecal samples of various species are a useful tool for welfare assessment, especially as they are easily applied at farm or group level.

Abstract: In dieser Untersuchung sollte überprüft werden, ob die für die Stressmessung beim Menschen angewandte „Chronopsychobiologische Regulationsdiagnostik“ (CRD) mithilfe des smardwatch®-Messsystems auch beim Pferd psychische Belastungssituationen aussagekräftig widerspiegelt. Menschen können anhand variierender physiologischer und ethologischer Reaktionen auf Stressoren aus der Umwelt in Stresstypen eingeteilt werden. Auch Pferde reagieren in identischen Situationen ganz unterschiedlich. Es stellte sich daher die Frage, ob Pferde ebenfalls bestimmten Stresstypen zugeordnet werden können.
Mit 26 dreijährigen Hengsten des Landgestüts Celle wurde ein Verhaltenstest durchgeführt. Auf der Grundlage wissenschaftlich dokumentierter und modifizierter Testsituationen (Open-Field-Test, Novel-Object-Test, Startling-Test Objekt/Geräusch, Mensch-Pferd-Interaktion, Ressourcenkontrolle) wurde das Erkundungs- und Fluchtverhalten untersucht (Goslar 2011). Während dieser Belastungssituationen wurden mit dem smardwatch®-Messgerät die elektrophysiologischen Parameter Hautwiderstand, Hautpotential und Muskelaktivität erfasst. Durch eine Zeitreihenmessung dieser physiologischen Parameter konnten die Reaktionen des übergeordneten Reglers (vegetatives Nervensystem) dargestellt werden. Der Hautwiderstand spiegelt die vegetativ-emotionalen Reaktionen wider, das Hautpotential die vegetativ-nervalen und somit laut Balzer (2009) die kognitiven Verarbeitungsweisen, und durch das Elektromyogramm werden die typischen muskulär-motorischen Reaktionen aufgezeichnet. Die vorliegenden Datenzeitreihen wurden mit Hilfe einer biorhythmometrischen Zeitreihenanalyse nach Balzer und Hecht (Hecht 2001, Balzer 2009) ausgewertet. Als Ergebnis wurden chronobiologische Regulationszustände definiert, die dann gemäß dem „Periodischen System der Regulationszustände“ (PSR) (Balzer 2000) eine Beurteilung der psychischen Belastungssituation erlauben. Zur Bestimmung von Stresstypen wurde die Untersuchung nach dem Reiz-Reaktions-Prinzip in drei Phasen unterteilt: Ruhephase, Stressreizphase und Stressverarbeitungsphase. Der Verhaltenstest wurde nach einer Woche zur gleichen Tageszeit mit jedem Hengst einmal wiederholt. Als physiologische Vergleichsparameter wurden vor, während und nach der Belastung insgesamt zehn Speichelproben zur Cortisolbestimmung entnommen.
Die smardwatch®-Messtechnik ist prinzipiell geeignet die physiologischen Parameter Hautwiderstand, Hautpotential und Muskelaktivität auf der Haut des Pferdes aufzunehmen. Durch die biorhythmometrische Zeitreihenanalyse konnten chronobiologische Regulationszustände definiert werden.
Der Verhaltenstest führte bei allen Pferden zu einem signifikanten Anstieg der Cortisolwerte. Ein ebenfalls statistisch gesicherter Unterschied der aktivierten Cortisolwerte zwischen der ersten und zweiten Testwoche zeigt eine geringere Stressreaktion und weist auf einen Lerneffekt der Pferde hin:
Entsprechend der relativen Instabilitäten der Regulation der Körperfunktionen in Messphase 2 und 3 konnten die Pferde in vier Stressregulationstypen (nach Balzer u. Hecht 1996) eingeteilt werden: Stressbeherrscher, -bewältiger und kompensierer sowie Stressnichtbewältiger.
Anhand der Aktivierung von Sympathikus und Parasympathikus konnten zusätzlich vier verschiedene Vegetative Stresstypen unterschieden werden: Sympathikotoniker, Amphotoniker, Indifferenter Typ und Vagotoniker.
Die Cortisolreaktion der Hengste war individuell sehr unterschiedlich. Um die maximalen Anstiege vergleichen zu können, wurde der Trend der jeweiligen Cortisolverlaufskurve bestimmt. Anhand der Trend-korrigierten Cortisolkurven konnten einerseits die relativen Maxima der Cortisolreaktion besser verglichen werden, anderseits konnten die Pferde mittels des unterschiedlichen Trendes in drei Cortisolverlaufsgruppen eingeteilt werden: Tendenz fallend, gleichbleibend oder steigend.
Ein statistischer Nachweis für eine Abhängigkeit zwischen den verschiedenen Stresstypenklassifizierungen konnte anhand der geringen Stichprobenzahl nicht erbracht werden. Jedoch lassen sich Pferde, wie Menschen, unterschiedlichen Stresstypen zuordnen. Schwierig bleibt aber die objektive Beurteilung von Befindlichkeiten, da Empfindungen und Gefühle nur subjektiv wahrnehmbare Qualitäten sind, die von einer Reihe innerer und äußerer Faktoren abhängen. Die Verhaltenszuordnung emotionaler Zustände durch die „Chronopsychobiologische Regulationsdiagnostik“ (CRD) kann nicht ohne die Basis weiterer vergleichender Studien vom Mensch auf das Pferd übertragen werden.
Die CRD-Methode könnte allerdings einen interdisziplinären Ansatz ermöglichen und zukünftig neben den klassischen deskriptiven Verhaltensbeobachtungen bei der Beurteilung von Haltungs- und Umgangssituationen von Tieren wertvolle Aufschlüsse über die Fähigkeit zur Stressbewältigung und deren Konsequenzen für das Wohlbefinden der Tiere geben.
In this study we examined, whether the “Chronopsychobiological regulation diagnosis” (CRD) with the smardwatch®-system which is used to assess specific strain in humans, is also able to reflect convincingly specific strain in horses. Humans can be categorized into so-called stress types, because they react differently in physiology and behaviour to environmental stimuli. Concerning horses, it is also known that individuals react differently in identical situations. The question to be answered is, if it is possible to categorize horses into certain stress types as well.
We carried out a behavioural test with 26 three-year-old stallions of the State Stud of Celle, involving different test situations. On the basis of test situations, well known in scientific literature including slight modifications (open-field-test, novel-object-test, startling-test object/sound, human-horse-interaction, resource control) the explorative and flight behaviour of horses were examined (Goslar 2011). During these situations of strain the system smardwatch® measured the electro-physiological parameters skin resistance, skin potential and muscle activity. With time series analyses of these physiological parameters the reactions of the vegetative nervous system as superior control could be shown. The skin resistance reflects the vegetative-emotional, the skin potential the vegetative-nervous hence according to Balzer (2009) cognitive reactions and the electromyogram shows the motorized reactions. The time series of measured data was analyzed using the biorhythmometrical time series analysis of Balzer and Hecht (Hecht 2001, Balzer 2009). As a result of this, typical states of chronobiological regulation were defined. With the help of the “periodic system of regulatory states” (PSR) (Balzer 2000) these led to a classification of mental stress situations. To categorize horses into stress types the study was devided into three phases according to the stimulus-response principle: phase 1 (relaxing), phase 2 (situation of strain) and phase 3 (stimulus processing phase). The behavioural test was repeated once with each stallion exactly one week later. In addition ten samples of saliva were taken before, during and after the situations of strain from which we determined the cortisol concentration to be compared with the chronopsychobiological parameters.
The smardwatch®-measurement technology is fundamentally suitable to measure the physiological parameters skin resistance, skin potential and electrical muscle activity of horses. Using the biorhythmometrical time series analysis, chronobiological regulatory states could be defined for horses as well.
For each horse the cortisol value increased significantly during the behavioural test. A remarkable difference of the cortisol values assessed in the first and second test, indicates a learning effect: The behavioural test led to a significantly lower stress reaction in the second week.
Depending on the proportions of unstable regulation processes during and after the situations of strain, four types of regulation (Balzer u. Hecht 1996) can be defined: the Control-, Cope-, Compensate- and Non-cope-type.
Using the activation of the sympathetic and parasympathetic nervous system four vegetative stress types could be determined: Sympathicotonic, Amphotonic, Indifferent Type and Vagotonic.
The stress reaction of the stallions in terms of cortisol level was quite individual. To compare the maximum increase the trend of each cortisol trajectory was analyzed. On the one hand correcting for the trend allowed a comparison of relative maxima, on the other hand the horses could be categorized into groups, according to the evolution of their cortisol level (cortisol progression groups): Tendency falling, stable or rising.
The number of samples was not considered to be sufficient in order to statistically assess some dependence among the different classifications of stress types. But to our point of view horses can be assigned to different stress types like humans. But it’s still difficult to judge the emotions of animals, because emotions are subjectively perceptible qualities dependent on many internal and external factors. The assignment of emotional behaviour to the chronopsychobiological regulation diagnosis (CRD) can’t be transferred from human to horse without further studies.
However, the CRD method could enable an interdisciplinary approach. Besides classic descriptive observations of behavior, the CRD could give further information about the coping capacity and the consequences for animal welfare in the assessment of stressful situations.