Preliminary Insights into Resting Patterns of Young Thoroughbred Racehorses During Initial Training

Eric D. P.  Sotelo; Meire S.  Paulista; Tiago M.  Oliveira; Raquel Y. A.  Baccarin; Ruan R.  Daros; Pedro V.  Michelotto

doi:10.64292/ijes.206

Authors

Eric D. P. Sotelo Graduate Program in Animal Science, Pontifícia Universidade Católica do Paraná, Rua Imaculada Conceição 1155, Prado Velho, 80215-901, Curitiba, PR, Brazil https://orcid.org/0000-0002-1938-4521
Meire S. Paulista Veterinary Medicine, Pontifícia Universidade Católica do Paraná, Rua Imaculada Conceição 1155, Prado Velho, 80215-901, Curitiba, PR, Brazil https://orcid.org/0009-0002-0174-2332
Tiago M. Oliveira School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87, São Paulo 05508270, Brazil https://orcid.org/0000-0002-3246-901X
Raquel Y. A. Baccarin School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87, São Paulo 05508270, Brazil https://orcid.org/0000-0001-9730-0840
Ruan R. Daros Graduate Program in Animal Science, Pontifícia Universidade Católica do Paraná, Rua Imaculada Conceição 1155, Prado Velho, 80215-901, Curitiba, PR, Brazil; EthoLab – Animal Welfare and Applied Ethology Lab, Pontifícia Universidade Católica do Paraná, Rua Imaculada Conceição 1155, Prado Velho, 80215-901, Curitiba, PR, Brazil https://orcid.org/0000-0003-2331-1648
Pedro V. Michelotto Graduate Program in Animal Science, Pontifícia Universidade Católica do Paraná, Rua Imaculada Conceição 1155, Prado Velho, 80215-901, Curitiba, PR, Brazil; EthoLab – Animal Welfare and Applied Ethology Lab, Pontifícia Universidade Católica do Paraná, Rua Imaculada Conceição 1155, Prado Velho, 80215-901, Curitiba, PR, Brazil https://orcid.org/0000-0003-0893-1654

DOI:

https://doi.org/10.64292/ijes.206

Keywords:

Equine, horse, rest, sleep, welfare

Abstract

Rest and sleep are key components of equine welfare and athletic performance, particularly in young racehorses adapting to the demands of early training. This preliminary study evaluated resting behavior in five two-year-old Thoroughbreds during their initial adaptation to stabling and after their first high-intensity gallop. Horses were monitored using continuous 24-hour infrared video recordings at two time points: immediately following arrival at the racetrack (M0) and approximately 3–4 months later, during advanced training (M1). The total time spent standing, in sternal recumbency, and in lateral recumbency, as well as the frequency of recumbent events, were quantified. No day-to-day differences were detected within either moment. When comparing moments, horses spent significantly more time standing (P = 0.003) and less time in both sternal (P = 0.017) and lateral (P = 0.049) recumbency at M1. Lateral recumbency frequency was reduced following intense exercise (P = 0.003) when compared to M0, whereas no other exercise-related effects were identified. In conclusion, despite the progressive increase in workload, the horses did not exhibit major disturbances; however, further research is needed to clarify whether these behavioral changes represent adaptation, vigilance, or early indicators of sleep restriction.

References

Chennaoui M, Sauvet F, Drogou C, Van Beers P, Langrume C, Guillard M, et al. Effect of one night of sleep loss on changes in tumor necrosis factor alpha (TNF-α) levels in healthy men. Cytokine 2011;56:318–24. https://doi.org/10.1016/j.cyto.2011.06.002.

Kelemen Z, Grimm H, Long M, Auer U, Jenner F. Recumbency as an equine welfare indicator in geriatric horses and horses with chronic orthopaedic disease. Animals 2021;11:3189. https://doi.org/10.3390/ani11113189.

Greening L, Downing J, Amiouny D, Lekang L, McBride S. The effect of altering routine husbandry factors on sleep duration and memory consolidation in the horse. Applied Animal Behaviour Science 2021;236:105229. https://doi.org/10.1016/j.applanim.2021.105229.

Oliveira T, Santos A, Silva J, Trindade P, Yamada A, Jaramillo F, et al. Hospitalisation and disease severity alter the resting pattern of horses. Journal of Equine Veterinary Science 2022;110:103832. https://doi.org/10.1016/j.jevs.2021.103832.

Rumpel AS, Alievi MM, Jardim Filho JO, Rozo CAC, Schuster LAH, da Silva AV, et al. Can the training regimen influence night time physical activity in racehorses? Veterinary and Animal Science 2021;14:100208. https://doi.org/10.1016/j.vas.2021.100208.

Patrick Y, Lee A, Raha O, Pillai K, Gupta S, Sethi S, et al. Effects of sleep deprivation on cognitive and physical performance in university students. Sleep and Biological Rhythms 2017;15:217–25. https://doi.org/10.1007/s41105-017-0099-5.

Dąbrowski J, Ziemba A, Tomczak A, Mikulski T. Physical performance of healthy men exposed to long exercise and sleep deprivation. Medicina Sportiva 2012;16:6–11.

Fullagar HHK, Skorski S, Duffield R, Hammes D, Coutts AJ, Meyer T. Sleep and athletic performance: the effects of sleep loss on exercise performance, and physiological and cognitive responses to exercise. Sports Medicine 2015;45:161–86. https://doi.org/10.1007/s40279-014-0260-0.

Barbosa ÂP, Oliveira TM, Trindade PHE, Seidel SRT, Tokawa PKA, Jaramilo FM, et al. Sleep pattern interference in the cognitive performance of Lusitano horses. Animals 2024;14:334. https://doi.org/10.3390/ani14020334.

Barbosa ÂP, Oliveira TM, Seidel SRT, Tokawa PKA, Jaramillo FM, Roncati NV, et al. Could restricting horses' REM sleep improve dressage performance? Applied Animal Behaviour Science 2025;291:106740. https://doi.org/10.1016/j.applanim.2025.106740.

Bertone JJ. Excessive drowsiness secondary to recumbent sleep deprivation in two horses. Veterinary Clinics of North America: Equine Practice 2006;22:157–62. https://doi.org/10.1016/j.cveq.2005.12.020.

Aleman M, Williams DC, Holliday T. Sleep and sleep disorders in horses. AAEP Proceedings 2008;54:180–5.

Fuchs C, Kiefner C, Reese S, Erhard M, Wöhr A. Narcolepsy: Do adult horses really suffer from a neurological disorder or rather from a recumbent sleep deprivation/rapid eye movement (REM)-sleep deficiency? Equine Veterinary Journal 2016;48:9. https://doi.org/10.1111/evj.09_12612.

Greening L, McBride S. A review of equine sleep: implications for equine welfare. Frontiers in Veterinary Science 2022;9:916737. https://doi.org/10.3389/fvets.2022.916737.

Oliveira TM, Zanotto GM, Trindade PHE, Baccarin RYA. Environment change causes a transient adverse impact on horse behavioral resting patterns. Applied Animal Behaviour Science 2025;282:106482. https://doi.org/10.1016/j.applanim.2024.106482.

Wöhr A, Kalus M, Reese S, Fuchs C, Erhard M. Equine sleep behaviour and physiology based on Polysomnographic examinations. Equine Veterinary Journal 2016;48:9–9. https://doi.org/10.1111/evj.08_12612.

Greening L, Allen S, McBride S. Towards an objective measurement of sleep quality in non-human animals: using the horse as a model species for the creation of sleep quality indices. Biology Open 2023;12:bio059964. https://doi.org/10.1242/bio.059964.

Nınomıya S, Aoyama M, Ujiie Y, Kusunose R, Kuwano A. Effects of bedding material on the lying behavior in stabled horses. Journal of Equine Science 2008;19:53–6. https://doi.org/10.1294/jes.19.53.

Hodgson DR, McGowan CM, McKeever KH. The athletic horse: Principles and practice of equine sports medicine. Elsevier Health Sciences; 2013.

Zanker A, Wöhr A-C, Reese S, Erhard M. Qualitative and quantitative analyses of polysomnographic measurements in foals. Scientific Reports 2021;11:16288. https://doi.org/10.1038/s41598-021-95770-5.