A Preliminary Investigation into the Relationship Between Under-Rug Temperatures and Sleep-Related Behavior in Stabled Horses Using Non-Invasive Temperature Measures

Isobel Bullement; Lorna Cameron; Linda Greening

doi:10.64292/ijes.196

Authors

Isobel Bullement Hartpury University, Gloucester, Hartpury, GL19 3BE, United Kingdom https://orcid.org/0009-0007-9737-8016
Lorna Cameron Hartpury University, Gloucester, Hartpury, GL19 3BE, United Kingdom https://orcid.org/0009-0007-3377-2698
Linda Greening Hartpury University, Gloucester, Hartpury, GL19 3BE, United Kingdom https://orcid.org/0000-0001-8955-0305

DOI:

https://doi.org/10.64292/ijes.196

Keywords:

Body temperature, equine, rugging, thermoregulation, under-rug microclimate

Abstract

Stabled horses are managed within a domestic environment, where the effects of artificial lighting and bedding on sleep have been reported. Beyond the environment, equine husbandry practices such as rugging or clipping are influential on equine thermoregulation. However, the influence of these practices on sleep and related behaviors is unknown, despite the link between core body temperature and the occurrence of sleep. The aim of this pilot study was to investigate the viability of using novel temperature recording equipment to determine whether a relationship between under-rug temperature and sleep-related behavior could be detected. Under-rug temperatures were measured using Thermachron iButtons© at 10-minute intervals across five nights, while closed-circuit television camera equipment enabled continuous focal observations of sleep-related behavior. Duration of behavioral states according to a pre-determined ethogram was recorded between the hours of 00:00 and 07:00 for four stabled horses. Overnight environmental temperatures were reported between -6 °C and 4 °C. Mean under-rug temperature from all horses across five nights was 22.91 ± 0.12 °C (minimum 14.0 °C, maximum 34.0 °C) and was different between nights and between individual horses. No significant relationships were identified between under-rug temperatures and total duration of behavioral states. While the iButtons demonstrated the capacity to measure temperatures, several recommendations are made for future studies based on this foundational work. The relationship between under-rug temperature and sleep behavior warrants further investigation, which in the future could include data on sleep onset or sleep quality.

References

Carskadon MA, Dement WC. Normal human sleep: an overview. In: Kryger MH, Roth T, editors. Principles and Practice of Sleep Medicine, Elsevier/Saunders; 2005, p. 13–23.

Cirelli C, Tononi G. Is sleep essential? PLoS Biology 2008;6:e216. https://doi.org/10.1371/journal.pbio.0060216.

Toth LA, Bhargava P. Animal models of sleep disorders. Comp Med 2013;63:91–104.

Borbély A, Tobler I. The two-process model: origin of its concepts and their implications. Clinical and Translational Neuroscience 2023;8:5. https://doi.org/10.3390/ctn8010005.

Dallaire A. Rest behavior. Veterinary Clinics of North America: Equine Practice 1986;2:591–607. https://doi.org/10.1016/s0749-0739(17)30708-3.

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.

Boyd LE, Carbonaro DA, Houpt KA. The 24-hour time budget of Przewalski horses. Applied Animal Behaviour Science 1988;21:5–17. https://doi.org/10.1016/0168-1591(88)90098-6.

Raspa F, Tarantola M, Bergero D, Nery J, Visconti A, Mastrazzo CM, et al. Time-budget of horses reared for meat production: influence of stocking density on behavioural activities and subsequent welfare. Animals 2020;10:1334. https://doi.org/10.3390/ani10081334.

Auer U, Kelemen Z, Engl V, Jenner F. Activity time budgets—a potential tool to monitor equine welfare? Animals 2021;11:850. https://doi.org/10.3390/ani11030850.

Fisk AS, Tam SKE, Brown LA, Vyazovskiy VV, Bannerman DM, Peirson SN. Light and cognition: Roles for circadian rhythms, sleep, and arousal. Frontiers in Neurology 2018;9:56. https://doi.org/10.3389/fneur.2018.00056.

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.

Collery A, Browne JA, O'Brien C, Sheridan JT, Murphy BA. Optimised stable lighting strengthens circadian clock gene rhythmicity in equine hair follicles. Animals 2023;13:2335. https://doi.org/10.3390/ani13142335.

Harding EC, Franks NP, Wisden W. The temperature dependence of sleep. Frontiers in Neuroscience 2019;13:336. https://doi.org/10.3389/fnins.2019.00336.

Fan Y, Wang Y, Gu P, Han J, Tian Y. How temperature influences sleep. International Journal of Molecular Sciences 2022;23:12191. https://doi.org/10.3390/ijms232012191.

Togo F, Aizawa S, Arai J, Yoshikawa S, Ishiwata T, Shephard RJ, et al. Influence on human sleep patterns of lowering and delaying the minimum core body temperature by slow changes in the thermal environment. Sleep 2007;30:797–802. https://doi.org/10.1093/sleep/30.6.797.

Harding EC, Yu X, Miao A, Andrews N, Ma Y, Ye Z, et al. A neuronal hub binding sleep initiation and body cooling in response to a warm external stimulus. Current Biology 2018;28:2263-2273.e4. https://doi.org/10.1016/j.cub.2018.05.054.

Bigler P, Janzen B. Too hot to sleep. Journal of Environmental Economics and Management 2024;128:103063. https://doi.org/10.1016/j.jeem.2024.103063.

Kräuchi K, Cajochen C, Wirz-Justice A. A relationship between heat loss and sleepiness: effects of postural change and melatonin administration. Journal of Applied Physiology 1997;83:134–9. https://doi.org/10.1152/jappl.1997.83.1.134.

Piccione G, Caola G, Refinetti R. The circadian rhythm of body temperature of the horse. Biological Rhythm Research 2002;33:113–9. https://doi.org/10.1076/brhm.33.1.113.1322.

Giannetto C, Fazio F, Vazzana I, Panzera M, Piccione G. Comparison of cortisol and rectal temperature circadian rhythms in horses: the role of light/dark cycle and constant darkness. Biological Rhythm Research 2012;43:681–7. https://doi.org/10.1080/09291016.2011.632231.

Padalino B, Loy J, Hawson L, Randle H. Effects of a light-colored cotton rug use on horse thermoregulation and behavior indicators of stress. Journal of Veterinary Behavior 2019;29:134–9. https://doi.org/10.1016/j.jveb.2019.02.001.

Troynikov O, Watson CG, Nawaz N. Sleep environments and sleep physiology: A review. Journal of Thermal Biology 2018;78:192–203. https://doi.org/10.1016/j.jtherbio.2018.09.012.

Green AR, Gates RS, Lawrence LM. Measurement of horse core body temperature. Journal of Thermal Biology 2005;30:370–7. https://doi.org/10.1016/j.jtherbio.2005.03.003.

Verdegaal E-LJMM, Howarth GS, McWhorter TJ, Delesalle CJG. Is continuous monitoring of skin surface temperature a reliable proxy to assess the thermoregulatory response in endurance horses during field exercise? Frontiers in Veterinary Science 2022;9:894146. https://doi.org/10.3389/fvets.2022.894146.

Brown AE, Twigg-Flesner A. Are we over-rugging? A preliminary research article into how rugging affects clipped, stabled horses using the Orscana© rug-monitoring device, Gloucester, United Kingdom: University Centre Hartpury; 2018.

Hartman N, Greening LM. A preliminary study investigating the influence of auditory stimulation on the occurrence of nocturnal equine sleep-related behavior in stabled horses. Journal of Equine Veterinary Science 2019;82:102782. https://doi.org/10.1016/j.jevs.2019.07.003.

Kelemen Z, Grimm H, Vogl C, Long M, Cavalleri JMV, Auer U, et al. Equine activity time budgets: the effect of housing and management conditions on geriatric horses and horses with chronic orthopaedic disease. Animals 2021;11:1867. https://doi.org/10.3390/ani11071867.

Hasselberg M. Peripheral skin temperature and sleep/wake state in individuals with Alzheimer's disease. Doctoral Dissertation. University of Rochester, 2013.

Long M, Greening L. A pilot study investigating under-rug temperature and the nocturnal behavioural profile of the stabled horse, Loughborough University: 2024.

Kräuchi K. The thermophysiological cascade leading to sleep initiation in relation to phase of entrainment. Sleep Medicine Reviews 2007;11:439–51. https://doi.org/10.1016/j.smrv.2007.07.001.

Eggenberger P, MacRae BA, Kemp S, Bürgisser M, Rossi RM, Annaheim S. Prediction of core body temperature based on skin temperature, heat flux, and heart rate under different exercise and clothing conditions in the heat in young adult males. Frontiers in Physiology 2018;9:1780. https://doi.org/10.3389/fphys.2018.01780.

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.

Kang H, Zsoldos RR, Sole-Guitart A, Narayan E, Cawdell-Smith AJ, Gaughan JB. Heat stress in horses: a literature review. International Journal of Biometeorology 2023;67:957–73. https://doi.org/10.1007/s00484-023-02467-7.

Phillipson EA, Murphy E, Kozar LF. Regulation of respiration in sleeping dogs. Journal of Applied Physiology 1976;40:688–93. https://doi.org/10.1152/jappl.1976.40.5.688.

Amici R, Jones CA, Perez E, Zamboni G. A physiological view of rem sleep structure. The Physiologic Nature of Sleep, Published by Imperial College Press and Distributed by World Scientific Publishing Co.; 2005, p. 161–85. https://doi.org/10.1142/9781860947186_0008.

Mejdell CM, Bøe KE, Jørgensen GHM. Caring for the horse in a cold climate—reviewing principles for thermoregulation and horse preferences. Applied Animal Behaviour Science 2020;231:105071. https://doi.org/10.1016/j.applanim.2020.105071.

Masebo NT, Benedetti B, Mountricha M, Lee L, Padalino B. A literature review on equine bedding: impacts on horse and human welfare, health, and the environment. Animals 2025;15:751. https://doi.org/10.3390/ani15050751.

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.

Daw F, Burn C, Chang Y-M, Nicol C. Effect of turnout rugs on the behaviour of horses under mild autumn conditions in the United Kingdom. Applied Animal Behaviour Science 2025;288:106661. https://doi.org/10.1016/j.applanim.2025.106661.

Gilbert SS, van den Heuvel CJ, Ferguson SA, Dawson D. Thermoregulation as a sleep signalling system. Sleep Medicine Reviews 2004;8:81–93. https://doi.org/10.1016/s1087-0792(03)00023-6.

Chung ELT, Khairuddin NH, Azizan TRPT, Adamu L. Sleeping patterns of horses in selected local horse stables in Malaysia. Journal of Veterinary Behavior 2018;26:1–4. https://doi.org/10.1016/j.jveb.2018.03.014.

Zisapel N. Melatonin and sleep. The Open Neuroendocrinology Journal 2010;3:85–95. https://doi.org/10.2174/1876528901003010085.

Murphy BA, Elliott JA, Sessions DR, Vick MM, Kennedy EL, Fitzgerald BP. Rapid phase adjustment of melatonin and core body temperature rhythms following a 6-h advance of the light/dark cycle in the horse. Journal of Circadian Rhythms 2007;5:5. https://doi.org/10.1186/1740-3391-5-5.

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. https://doi.org/10.1242/bio.059964.

Lushington K, Dawson D, Lack L. Core body temperature is elevated during constant wakefulness in elderly poor sleepers. Sleep 2000;23:1–7. https://doi.org/10.1093/sleep/23.4.1d.