Plasma cortisol and faecal cortisol metabolites concentrations in stereotypic and non-stereotypic horses: do stereotypic horses cope better with poor environmental conditions?

Do cows with stereotypic tongue-rolling behaviour cope better with their environment?

Introduction

Stereotypic behaviours, especially oral stereotypic behaviours, are frequently expressed in farm animals. Tongue-rolling is the most common oral stereotypic behaviour in dairy cows (Bos taurus). If animals frequently display stereotypic behaviours, this is an indication of poor welfare. It has been suggested that animals express stereotypic behaviours as a way of coping with stress. As a result, animals with stereotypic behaviours may have lower levels of stress hormones than animals without stereotypic behaviours.

Methods

In this study, 916 Holstein cows in the first lactation were subjected to scan sampling behavioural observations 200 times for 10 days. All cows were assigned to either a stereotypic behaviours group (SB) or a control group (CON). The SB group was further subdivided into a tongue-rolling group (TR) and an other-stereotypic behaviours group (OS). The TR group was also split into an only tongue-rolling group (OTR) and a mixed tongue-rolling and other stereotypic behaviours group (TROS). Some cows in the TR group belonged to an extreme tongue-rolling group (ETR). Hair and saliva samples were collected from 601 cows to test cortisol concentrations and dairy herd improvement (DHI) data were collected from a total of 762 cows.

Results

There were no differences in hair or saliva cortisol concentrations between the groups (p>0.05), and the frequencies of tongue-rolling were not associated with cortisol concentrations (p>0.05). For DHI in cows, the milk protein percentage (p = 0.028), milk true protein percentage (p = 0.021) and milk crude protein percentage (p = 0.023) of cows in the ETR group were significantly lower than those in the CON group. For cows in ETR group, as the frequencies of tongue-rolling increased, the milk protein percentage (p = 0.034, r = 0.365), milk true protein percentage (p = 0.022, r = 0.393) and milk crude protein percentage (p = 0.035, r = 0.363) increased.

Discussion

We investigated the relationship between stereotypic behaviours and stress by using a non-invasive sampling method to minimise harm to the cows. We suggest that tongue-rolling may not be a way for cows to cope with stress, at least in terms of cortisol concentrations.

Investigating the gastrointestinal physiology of mature horses with and without a history of cribbing behavior in response to feeding a digestive support supplement

Cribbing, a stereotypic oral behavior observed in horses, involves placing incisors on a fixed object, arching the neck, pulling against the object, and emitting an audible grunt. This behavior has been associated with gastrointestinal (GI) dysfunction and gastric ulceration. In this randomized crossover study, we investigated the impact of a GI support supplement (SPL) on the GI environment and physiology of four cribbing (CB) and four non-cribbing horses (NCB). Mature Quarter Horses, acclimated to individual stalls for 16 hours daily with paddock turnout in pairs for 8 hours per day, were randomly assigned to receive either the SPL or placebo for 21 days, followed by a 2-week washout period. Fecal and gastric samples were collected for pH determination and blood samples were analyzed for serum cortisol and gastrin levels. Endoscopic examinations assessed gastric ulcer severity, and cribbing frequency and bouts were recorded via video surveillance. Data were analyzed using a mixed-model ANOVA. Results showed no differences in fecal and gastric pH between cribbing statuses. However, an interaction between supplementation and cribbing status was observed for squamous mucosa ulcer scores (P=0.003). There were no differences in glandular mucosa ulcer scores, serum cortisol, serum gastrin, and crib-bite count between CB and NCB horses or between supplementation groups. Crib-bout duration did not differ with supplementation, but differences were found between periods (P<0.05) and hour ranges (P<0.001). Our findings suggest that the GI support supplement may not effectively address cribbing behavior or alter the GI environment in NCB or CB horses.

Selected Acoustic Frequencies Have a Positive Impact on Behavioural and Physiological Welfare Indicators in Thoroughbred Racehorses

(1) Background: Since antiquity, it is considered that sounds influence human emotional states and health. Acoustic enrichment has also been proposed for domestic animals. However, in both humans and animals, effects vary according to the type of sound. Human studies suggest that frequencies, more than melodies, play a key role. Low and high frequencies, music tuning frequency and even EEG slow waves used for 'neurofeedback' produce effects. (2) Methods: We tested the possible impact of such pure frequencies on racehorses' behavior and physiology. A commercial non-audible acoustic stimulus, composed of an array of the above-mentioned frequencies, was broadcasted twice daily and for three weeks to 12 thoroughbred horses in their home stall. (3) Results: The results show a decrease in stereotypic behaviors and other indicators such as yawning or vacuum chewing, an increase in the time spent in recumbent resting and foraging, and better hematological measures during and after the playback phase for 4 of the 10 physiological parameters measured. (4) Conclusions: These results open new lines of research on possible ways of alleviating the stress related to housing and training conditions in racehorses and of improving physical recovery.

Blood profile, hormones, and telomere responses: potential biomarkers in horses exhibiting abnormal oral behaviour

The high prevalence of abnormal oral behaviour (AOB) in working horses has been linked to management issues and the pathophysiology of this behaviour remains unclear. Therefore, this study aims to elucidate the blood profile, hormones, and telomere length responses between low and high levels of AOB among different horse working groups. A total of 207 healthy horses from various breeds were initially selected from four working groups (leisure riding, equestrian, endurance, and patrolling) and observed for the time spent on AOB. Then, six horses each with higher and lower AOB than the population means were randomly selected from each of the working groups and categorized as high and low AOB horses, respectively. Blood samples were collected for haematology, biochemistry, cortisol, ghrelin, leptin, and relative telomere length analyses. High AOB horses notably had higher values of glucose, alanine aminotransferase (ALT), alkaline phosphatase (ALP), and creatine kinase (CK) compared to low AOB horses. High AOB horses also recorded higher plasma cortisol and ghrelin, but lower leptin concentrations. Among working groups, both endurance and patrolling horses presented the highest values in sodium, potassium, chloride, phosphate, ALT, and CK. While patrolling horses had the lowest levels of urea, ALP, and albumin levels, equestrian and leisure horses recorded the highest and lowest plasma cortisol and leptin concentrations, respectively. Finally, the telomere length of endurance and patrolling horses were significantly greater than leisure and equestrian horses. The present findings suggest that AOB horses had distinctive physiological characteristics that could be linked to improper diet and a demanding workload, while ghrelin and leptin hormones could be potential biomarkers for this behaviour.

Biological correlates of altered circadian rhythms, autonomic functions and sleep problems in autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by a complex and multifaceted neurobehavioral syndrome. In the last decades, several studies highlighted an increased prevalence of sleep problems in ASD, which would be associated with autonomic system and circadian rhythm disruption. The present review aimed to summarize the available literature about sleep problems in ASD subjects and about the possible biological factors implicated in circadian rhythm and autonomic system deregulation in this population, as well as possible therapeutic approaches. Shared biological underpinnings between ASD symptoms and altered circadian rhythms/autonomic functions are also discussed. Studies on sleep showed how ASD subjects typically report more problems regarding insufficient sleep time, bedtime resistance and reduced sleep pressure. A link between sleep difficulties and irritability, deficits in social skills and behavioral problems was also highlighted. Among the mechanisms implicated, alteration in genes related to circadian rhythms, such as CLOCK genes, and in melatonin levels were reported. ASD subjects also showed altered hypothalamic pituitary adrenal (HPA) axis and autonomic functions, generally with a tendency towards hyperarousal and hyper sympathetic state. Intriguingly, some of these biological alterations in ASD individuals were not associated only with sleep problems but also with more autism-specific clusters of symptoms, such as communication impairment or repetitive behaviors Although among the available treatments melatonin showed promising results, pharmacological studies for sleep problems in ASD need to follow more standardized protocols to reach more repeatable and reliable results. Further research should investigate the issue of sleep problems in ASD in a broader perspective, taking into account shared pathophysiological mechanisms for core and associated symptoms of ASD.

Heritability of Locomotor Stereotypies in Chilean Horses

The Chilean horse is a breed of closed registry. Stall-walking and weaving are locomotor stereotypies that affect this breed, and genetic predisposition has been suggested for both conditions. The objective of the present study was to estimate heritability of stall-walking and weaving in Chilean horses. Owners of 2,098 horses registered in the Chilean horse Stud Book, which were or had been stabled for at least 1 year, were asked to provide for identification data of the animal and presence or absence of stall-walking and/or weaving. The Chilean Horse Stud Book was accessed online, to collect information on name and registration number of the sire and dam of each horse. The prevalence of stall-walking and weaving was calculated from the sample (n = 2,098). The database to estimate the heritability (h²) included all the sample horses (n = 2,098) and their sires and dams. Additionally, all the ancestors available in the Chilean Horse Stud Book were included in the database for 297 sampled horses including those with locomotor stereotypies. The genealogical database consisted of 7,187 individuals. The prevalence of stall-walking was 2.05% and prevalence of weaving was 1.43%, being more frequent in males (P < .05) for stall-walking. Heritability of stall-walking was low (h² = 0.213 ± 0.08) and moderate for weaving (h² = 0.435 ± 0.06). Heritability and prevalence of locomotor stereotypies found in the Chilean horse suggest that they are hereditary disorders, highly influenced by environmental factors.

Stress hormone level and the welfare of captive European bison (Bison bonasus): the effects of visitor pressure and the social structure of herds

Background

Captive European bison (Bison bonasus) play an active role in conservation measures for this species; this includes education, which may conflict with these animals’ welfare. The effect of the presence of visitors on the welfare of captive animals can be negative, positive or neutral. However, the response of a given species to visitors is difficult to predict, since even closely related species display varying levels of tolerance to captivity. The aim of the study was to compare immunoreactive fecal cortisol levels (regarded as an indicator of the level of physiological stress) in groups of captive European bison that differed in terms of their social structure and the level of visitor pressure. The second aim was to determine if there was a correlation between intestinal parasitic burden and immunoreactive fecal cortisol levels.

Results

Immunoreactive fecal cortisol levels were not influenced by sex or age. However, study site and the interaction between study site and visitor pressure were statistically significant. European bison in one enclosure presented higher levels of immunoreactive fecal cortisol on weekdays than at weekends. In the other two study sites, the levels did not differ between weekdays and weekends. No correlation was found between parasitological infestation and immunoreactive fecal cortisol levels.

Conclusions

Measurement of fecal cortisol metabolites could be a valuable method for further research into the welfare of European bison in captivity. More subtle factors such as individual animal characteristics, feeding systems, and the arrangement of enclosures can be of great importance in terms of the effect of visitors on animals. The results of this study can be used in guidelines for the management of European bison populations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13028-021-00589-9.

Seasonal Variations of Faecal Cortisol Metabolites in Koalas in South East Queensland

The Koala (Phascolarctos cinereus) is an endemic marsupial inhabiting four states of Australia. Urbanisation, declining habitat, drought and fires are threatening the survival of this flagship species. These threats may cause acute and chronic stress in koalas, which might also be associated with occurrence of infectious diseases in koala populations. Stress may induce an increase in cortisol reflected in increased faecal cortisol metabolite (FCM) values. To be able to use faecal cortisol metabolites to measure stress levels in this species, our aim was to determine baseline values for males and females during breeding and non-breeding season. A total of 351 defecations were collected fortnightly, twice a day, for 12 months from koalas at a wildlife facility in South East Queensland. Samples were analysed with three different enzyme immunoassays (EIAs): a cortisol, 5α-pregnane-3β,11β,21-triol-20-one (37e) and tetrahydrocorticosterone (50c) EIA. The latter, which also reacts with tetrahydrocortisol, the main metabolite in koala faeces, was found to have the highest biological sensitivity and, therefore, is the most suitable EIA to measure stress levels in koalas. Utilising this EIA, we found significant differences (p < 0.05) in FCM values between males and females, breeding and non-breeding season, and between morning and evening samples. Values of faecal cortisol metabolites established in stress-free koalas in this study can serve as a reference for future studies in koalas.

On-Farm Welfare Assessment of Horses: The Risks of Putting the Cart before the Horse

Although the question of animal welfare has been an important source of concern in the scientific community for several decades, many aspects are still under debate. On-farm assessments have to be rapid, acceptable to farmers and safe for both the assessors and animals. They are thus very demanding, with multiple decisions to make, such as the choice of appropriate indicators, sampling methods and scoring. Research has moved from resource-based to animal-based criteria, which reflects the subjective welfare state of an animal rather than relying upon external indices. In the present review, we describe two major (i.e., the most frequently/recently tested or disseminated) protocols: one in low-/middle-income countries, and the other in high-income countries, for on-farm assessments of horses, using animal-based resources; we evaluate their strengths and limitations, and then we compare their results with those obtained by various other studies. We propose lines of improvement, particularly in view of public dissemination, and offer suggestions for further refinement or new protocols. We emphasize the high risks of putting the cart before the horse, i.e., proposing protocols that rely upon indicators and sampling methods that need to be refined, as this could lead to under-evaluation (or less likely over-evaluation) of current welfare problems. Because welfare is a subjective experience, the true representation of an individual's actual welfare status has to be evaluated by using objective assessment tools (that are validated and have a scientific basis) used by well-trained observers.

Indicators of Horse Welfare: State-of-the-Art

Animal welfare is defined as a chronic state reflecting an individual's subjective perception of its situation. Because it is possible to be in a good welfare state and nevertheless experience acute fear or pain, and conversely, short-term positive emotions can be experienced during impaired welfare states, welfare as a chronic state has to be clearly distinguished from temporary states related to emotions, pain or stress. The evaluation of non-verbal individuals' welfare state, particularly in interspecific situations, is a real challenge that necessarily implies animal-based measures and requires multidisciplinary scientifically validated measures. In the last decade, studies investigating horses' welfare flourished together with new measures that were not always scientifically tested before being used. At a time were legal decisions are made on animal welfare, it is crucial to rely on reliable welfare indicators in order to prevent false evaluation. The aim of this review is to identify the scientifically tested and reliable indicators of horses' welfare (e.g., body lesions, apathy, aggressiveness, stereotypic behaviours) from signals of temporary states related to acute pain emotions or stress and from popular beliefs, in order to give the scientific community and the horse industry accurate evaluation tools.

Free and bound cortisol in plasma and saliva during ACTH challenge in dairy cows and horses

Cortisol levels reflect hypothalamic-pituitary-adrenocortical (HPA) axis activity. While most plasma cortisol is supposed to be bound to the soluble corticosteroid-binding globulin (CBG), only free cortisol (FC) actively regulates metabolic and immunological processes. We aimed to establish a multispecies suitable method to assess FC in cows and horses which in combination with total cortisol (TC) allows interpreting proportional changes of cortisol in saliva as well as in blood in response to a standardized HPA axis activation via ACTH. We further investigated if the ratios of cortisol fractions as obtained at basal levels in healthy horses (herbivorous and monogastric) and dairy cows (herbivorous and ruminant) change during HPA axis activation, and to which extent saliva cortisol (SC) is representative for alterations in plasma FC and adrenal cortex reactivity. However, it was not the objective of the present study to directly compare the two species. Dosages of ACTH applied in cows and horses were based on published data. Synthetic ACTH was intravenously administered to eight dairy cows (0.16 µg/kg BW) and five horses (1 µg/kg BW). Blood and saliva were collected every 30 min for 3 h from a jugular vein catheter, and analyzed for TC and SC, the ratio of free cortisol (rFC), and the concentration of FC (cFC) in plasma. During the entire sampling period of the ACTH test, plasma TC was paralleled by blood cFC, rFC, and SC in both cows and horses. All cortisol fractions increased within 30 min of ACTH administration compared to basal values (0 min, P < 0.05). Peak TC concentration reached 63.2 ± 9.6 ng/mL and 73.2 ± 11.8 ng/mL in bovine and equine plasma, respectively. Peak values of rFC averaged 17.9 ± 4.5% in cows and 19.2 ± 7.8% in horses. The ratio of SC to cFC in horses remained similar during the ACTH challenge suggesting that SC is recruited from plasma FC. However, SC increased less compared to plasma TC and FC during HPA axis activation in cows. In conclusion, the short-term activation of the HPA axis caused not only an elevation of TC, but also a similar increase of rFC in both species. SC closely reflected changes of FC in horses, but less accurately in cows. The concomitant evaluation of changes among cortisol fractions might give further indications on adaptation mechanisms in glucocorticoid regulation as well as differentiate cortisol-related health disorders.

Low plasma cortisol and fecal cortisol metabolite measures as indicators of compromised welfare in domestic horses (Equus caballus)

The hypothalamic-pituitary-adrenal (HPA) axis response to chronic stress is far from straight forward, particularly with regards to animal welfare. There are reports of no effect as well as both decreases and increases in cortisol after chronic stressors. Therefore, the first aim of the present study was to determine how measures of compromised welfare, such as chronic pain and haematological anomalies, related to cortisol levels in domestic horses (Equus caballus). Domestic horses are an informative model to investigate the impact of chronic stress (due to environment, pain, work, housing conditions…) on the HPA axis. The second aim was to determine whether levels of fecal cortisol metabolites (FCM) may be used as an indicator of welfare measures. The present study used fifty-nine horses (44 geldings and 15 mares), from three riding centres in Brittany, France. The primary findings show that horses whose welfare was clearly compromised (as indicated by an unusual ears backward position, presence of vertebral problems or haematological anomalies, e.g. anaemia) also had lower levels of both FCM and plasma cortisol. This work extends our previous findings showing that withdrawn postures, indicators of depressive-like behavior in horses, are associated with lower plasma cortisol levels. We also found that evening plasma cortisol levels positively correlated with FCM levels in horses. Future research aims to determine the extent to which factors of influence on welfare, such as living conditions (e.g. single stalls versus group housing in pasture or paddocks), early life factors, and human interaction, act as mediators of cortisol levels in horses.

Use of fecal glucocorticoid and salivary cortisol concentrations as a measure of well-being of New York City carriage horses

OBJECTIVE To use noninvasive approaches to assess stress in New York City (NYC) carriage horses during the course of their daily routine to determine whether use of these horses affected their well-being. DESIGN Prospective case control study. ANIMALS 13 (5 mares and 8 geldings) stabled working NYC carriage horses and 5 pastured (nonworking) NYC carriage horses (1 mare and 4 geldings). PROCEDURES Samples for determination of fecal glucocorticoid and salivary cortisol concentrations were collected on 3 successive days from 10, 8, and 9 working carriage horses during rest (time 1), preparation for work (time 2), and return to the stable (time 3) and at 1 hour after work (time 4). Infrared thermography (IRT) measurements were made to determine maximum temperature of the medial canthus at each time point. Fecal samples were also collected from 5 pastured carriage horses for determination of glucocorticoid concentrations. RESULTS No difference was found in mean ± SE fecal glucocorticoid concentrations between pastured (22.1 ± 9.8 ng/g) and working (19.5 ± 4.2 ng/g) carriage horses. A significant difference was found in salivary cortisol concentrations of working carriage horses between time 3 (0.96 ± 0.06 ng/mL) and time 4 (0.77 ± 0.07 ng/mL). The IRT measurement at time 2 (35.5 ± 0.64°C [95.9 ± 1.2°F]) was significantly lower than that at time 3 (36.2 ± 0.64°C [97.1 ± 1.2°F]). No other differences in IRT measurements were found. CONCLUSIONS AND CLINICAL RELEVANCE These working NYC carriage horses did not have physiologic responses indicative of a negative welfare status.

Autism as a disorder of biological and behavioral rhythms: toward new therapeutic perspectives

There is a growing interest in the role of biological and behavioral rhythms in typical and atypical development. Recent studies in cognitive and developmental psychology have highlighted the importance of rhythmicity and synchrony of motor, emotional, and interpersonal rhythms in early development of social communication. The synchronization of rhythms allows tuning and adaptation to the external environment. The role of melatonin in the ontogenetic establishment of circadian rhythms and the synchronization of the circadian clocks network suggests that this hormone might be also involved in the synchrony of motor, emotional, and interpersonal rhythms. Autism provides a challenging model of physiological and behavioral rhythm disturbances and their possible effects on the development of social communication impairments and repetitive behaviors and interests. This article situates autism as a disorder of biological and behavioral rhythms and reviews the recent literature on the role of rhythmicity and synchrony of rhythms in child development. Finally, the hypothesis is developed that an integrated approach focusing on biological, motor, emotional, and interpersonal rhythms may open interesting therapeutic perspectives for children with autism. More specifically, promising avenues are discussed for potential therapeutic benefits in autism spectrum disorder of melatonin combined with developmental behavioral interventions that emphasize synchrony, such as the Early Start Denver Model.