Temporary Relocation during Rest Periods: Relocation Stress and Other Factors Influence Hair Cortisol Concentrations in Horses

Abstract

Horse transportation for temporary relocation during rest periods is a common and widespread practice among horse owners, either from sport competition or working tasks. This study aimed to determine the effect of a relocation period and the multiple factors associated with a rest period on hair cortisol concentrations (HCCs) in horses. Additionally, this study reports the seasonal effect on HCCs and hair growth over a year. Thirteen police horses, Pure Spanish stallions of various ages (5–13 y), were selected to participate in this study. Hair sample collection was carried out approximately every 30 d for seven months (Study 1) and a year (Study 2). Cortisol determinations were performed by enzyme immunoassay. Interestingly, Study 1 revealed that relocated horses (n = 4) exhibited elevated HCCs compared with control horses (n = 4) after the relocation period (p < 0.05). Study 2 (n = 5) showed higher HCCs during summer compared with autumn and winter, and higher hair growth rates in winter compared with the other seasons (p < 0.05). Relocated horses had higher HCCs, suggesting a change in their welfare status, probably related to the sudden change in their surrounding conditions. However, these results should be interpreted cautiously due to the low sample size used. The nature of the relationship between HCCs and horse welfare needs to be further examined.

Hair Cortisol, Testosterone, Dehydroepiandrosterone Sulfate and Their Ratios in Stallions as a Retrospective Measure of Hypothalamic–Pituitary–Adrenal and Hypothalamic–Pituitary–Gonadal Axes Activity: Exploring the Influence of Seasonality

“…Therefore, six samples ( n = 6) per individual were collected during the study period (samples were chronologically identified as P1 to P6, corresponding, respectively, to late autumn–early winter, winter, spring, late spring–early summer, summer, and autumn). Samples were collected using the “shave-reshave” method, consisting of shaving the selected area at the beginning of the study and re-shaving the regrown hair in the same area after the time of interest has ended [ 27 ]. Specifically, a 7 × 7 cm area was caudally shaved to the sternum using an electric clipper as close as possible to the skin (0.5 ± 0.5 mm).…”

“…The electric clipper was cleaned between individuals with 70% ethanol to avoid cross-contamination. Body location was selected to prevent potential injuries with the mount, to avoid visible aesthetic defects in the horses, and to avoid faecal and urine contamination [ 27 ]. Samples were stored in individually identified paper envelopes at room temperature until sample processing.…”

“…Several studies in domestic and wild mammals have revealed different sources of variation in hair steroids levels [ 13 ], depending on hair specific characteristics (e.g., body region [ 17 ], hair growth phase [ 18 ], or colour [ 19 , 20 ]), intrinsic animal-based characteristics (e.g., age [ 19 , 21 ], sex [ 22 , 23 ] or reproductive status [ 24 , 25 ]) and, finally, external factors (e.g., season [ 26 , 27 ]). All of the previously presented components should be considered when using hair to assess hormonal levels as stress indicators.…”

“…Previous studies have examined hair cortisol concentrations (HCC) as a presumptive measure of stress, and demonstrated their seasonal fluctuations in horses [ 18 , 22 , 27 , 28 ]. Few studies have been performed using T [ 11 , 28 , 29 , 30 ] and, to date, to the best of our knowledge, there is no information published on the seasonal variations in the hair T levels of horses.…”

Genetic Parameters of Effort and Recovery in Sport Horses Assessed with Infrared Thermography

“…Monitoring these physiological changes has been assessed with heart rate (HR) response, blood lactate concentrations, oxygen uptake in relation to exercise intensity [ 4 , 5 ], salivary, hair and blood cortisol [ 3 , 6 , 7 , 8 ], or immune cell proliferation [ 9 , 10 , 11 ]. However, they are all quite difficult measures to be assessed during regular equestrian competitions as riders and owners are unwilling to allow the experimental procedures to impact on the animal and affect their sport results.…”