Humans love their holidays, but can the same be said for horses?
The opportunity of a break in new surroundings, with fresh routines in place of the monotony of everyday working life, sounds idyllic to most people, but the evidence is far from conclusive for competition and working horses.
Researchers in Spain have examined how police horses handled a break from their duties in fresh surroundings by measuring levels of the stress hormone cortisol in their hair.
Jaume Gardela and his colleagues, writing in the journal Animals, note that transporting horses for rest periods is a widespread practice to provide a break from either sport competition or working tasks.
While cortisol can be measured in saliva and other bodily fluids, the study team chose to analyse hair cortisol as it allows reliable monitoring of the accumulation of cortisol during the hair growth cycle.
They did so by shaving a small area, and then reshaving the same area every month to provide hair for analysis. The hair obtained this way is representative of the cortisol accumulation and activity in the hypothalamic-pituitary-adrenal axis for the preceding month.
The study involved eight Pure Spanish stallions who work for the Municipal Police of Barcelona. All of them were assessed as having a healthy body score.
Four of the horses were used as controls. They were kept in the police stables and rostered to work their normal shifts throughout the seven-month study.
The other four were similarly on duty for most of the seven months and housed in the same police stables, but were driven 39.5km away for a 22-day summer break.
When on duty, the eight horses were housed in conventional stalls measuring 2m by 2m with wood-chip bedding. They had free access to water and were fed eight times a day with a combination of forage, pelleted feed, bran and fresh grass.
While at work, horses either trained daily on a treadmill, patrolled areas of the city, or exercised in an outdoor arena.
The spelled horses were housed in 3m by 4m outdoor enclosures with free access to water. They were fed three times a day and had no routine work or training. Their caregivers were not known to them, and they could see and presumably smell unknown male and female horses in the vicinity.
Hair cortisol levels were similar between both groups of horses when fulfilling their normal duties, but a moderate increase was seen in the hair shavings taken partway through the break, with a much more pronounced spike seen in the test about a month after the end of their relocation.
This, the researchers said, suggested a change in their welfare status, probably related to the sudden change that had occurred in their surroundings.
“Our results suggest that an unexpected change in the multiple factors associated with a temporary relocation and resting period such as environment condition, housing system, habitual workload, nutrition, changes in staff and support, and social novelty may result in a wide range of stressors that increase the hypothalamic-pituitary-adrenal axis activity in a long-term manner.”
The authors stress that the results should be interpreted cautiously due to the low sample size used.
The nature of the relationship between hair cortisol concentrations and horse welfare needs to be
further examined, they said.
The study team said the results suggest that hair cortisol concentrations can be used to monitor the adaptation of horses to environmental and management variations, although the accurate nature of the relationship between these levels and welfare needs to be further investigated.
“Results of the present study could be applied to improve the management and environment of horses, which in turn could potentially improve the animals’ welfare.
“However, future studies with a larger sample size are needed to confirm these implications.”
Gardela, J.; Carbajal, A.; Tallo-Parra, O.; Olvera-Maneu, S.; Álvarez-Rodríguez, M.; Jose-Cunilleras, E.; López-Béjar, M. Temporary Relocation during Rest Periods: Relocation Stress and Other Factors Influence Hair Cortisol Concentrations in Horses. Animals 2020, 10, 642.