Physiological, behavioral, and serological responses of horses to shaded or unshaded pens in a hot, sunny environment.
Abstract: Housing recommendations for horses invariably include providing access to shade on hot, sunny days, but the potential benefits have not been scientifically studied. This experiment measured physiological, behavioral, and serological responses of horses confined individually to completely shaded (SH) or completely unshaded (SUN) drylot pens during the summer in Davis, CA. Twelve healthy adult horses in a crossover design experienced both treatments for 5 d each. Rectal temperature, respiration rate, skin temperature, and sweat scores were recorded hourly from 1230 to 1730 h daily. Observations were recorded from 1200 to 1800 h for proximity to water, foraging, locomotion, and insect avoidance behaviors. Daily blood samples were obtained to measure cortisol, hematocrit, and neutrophil-to-lymphocyte ratio. Automated and handheld sensors were used to record environmental conditions. The mean ambient temperature from 1200 to 1800 h during the study was 30.6 °C. Rectal temperature was greater for horses in SUN than for SH (mean 37.8 °C and 37.5 °C, respectively, SE = 0.06, P = 0.002) as was respiration rate (25.5 and 20.5 breaths/min, SE = 1.3, P = 0.008), and skin temperature (35.6 °C and 34.6 °C, SE = 0.1, P 0.05). Cortisol concentrations were greater in SUN than SH (3.4 and 2.6 μg/dL, respectively, P 0.05). Horses exhibited treatment differences in the physiological measures first, most notably in rectal temperature at 1230 h, corresponding to peak solar radiation. Behavioral responses followed these physiological changes, with treatment differences in time standing near water becoming apparent at 1400 h as ambient and black globe temperature increased. Our results indicate that both the SH and SUN treatment groups exhibited thermoregulatory responses to these summer conditions and horses benefited from shade, as it mitigated these physiological and behavioral changes. These results are applicable in developing best management practices for the care of domestic horses.
Publication Date: 2013-10-14 PubMed ID: 24126269DOI: 10.2527/jas.2013-6497Google Scholar: Lookup
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- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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The research paper explores the impact of providing shade to horses in hot and sunny climates. It discusses the physiological, behavioral, and serological responses of horses when kept in shaded versus unshaded pens. The experiment indicates that horses can benefit from shades as it reduces physiological and behavioral changes due to heat.
Methods Used
- The experiment was conducted on twelve healthy adult horses placed in either fully shaded (SH) or unshaded (SUN) pens during summer days in Davis, California.
- The horses were observed over a 5-day period with both groups having a chance to experience both conditions.
- Physiological parameters such as rectal temperature, respiration rate, skin temperature, and sweat scores were recorded hourly from 1230 to 1730 hours each day. Behavioral observations were also recorded during this time for parameters like proximity to water, foraging behaviour, locomotion, and insect avoidance behaviors.
- Daily blood samples were collected from the horses and cortisol, hematocrit, and the neutrophil-to-lymphocyte ratio were measured to monitor stress levels.
- Environmental conditions were recorded using automated and handheld sensors.
Key Findings
- The experiment found that the rectal and skin temperature along with the respiration rate were higher in horses kept under unshaded conditions (SUN), suggesting they were experiencing more heat stress.
- Moreover, horses in the unshaded pens exhibited more sweat (51.4%) compared to those in the shaded pens (1.1%).
- It was observed that horses in the sun spent more time standing near their water sources, indicating an increased need for cooling and hydration.
- The cortisol levels were also found to be higher in horses kept in the sun, indicating some level of heat-related stress, but they were still within the normal range for resting horses.
- No significant changes were observed in foraging, locomotion, or insect avoidance behavior between the two groups. There was also no significant difference in terms of hematocrit or the neutrophil-to-lymphocyte ratio between the two groups.
Conclusion
- The study concludes that provision of shade seems to reduce physiological and behavioral stress in horses, thus mitigating the effects of a hot and sunny environment.
- The findings of this study can be applied to develop best management practices for the care of domestic horses in hot, sunny environments.
Cite This Article
APA
Holcomb KE, Tucker CB, Stull CL.
(2013).
Physiological, behavioral, and serological responses of horses to shaded or unshaded pens in a hot, sunny environment.
J Anim Sci, 91(12), 5926-5936.
https://doi.org/10.2527/jas.2013-6497 Publication
Researcher Affiliations
- Population Health and Reproduction, School of Veterinary Medicine.
MeSH Terms
- Animals
- Behavior, Animal / physiology
- Cross-Over Studies
- Environment
- Female
- Horses / blood
- Horses / physiology
- Hospitals, Animal
- Hot Temperature
- Male
- Weather
Citations
This article has been cited 7 times.- Kang H, Zsoldos RR, Sole-Guitart A, Narayan E, Cawdell-Smith AJ, Gaughan JB. Heat stress in horses: a literature review.. Int J Biometeorol 2023 Jun;67(6):957-973.
- Ojima Y, Torii S, Maeda Y, Matsuura A. Effect of Cooling Blanket on the Heat Stress of Horses in Hot and Humid Environments.. Animals (Basel) 2022 Sep 20;12(19).
- Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Canali E, Drewe JA, Garin-Bastuji B, Gonzales Rojas JL, Gortázar Schmidt C, Michel V, Miranda Chueca MÁ, Padalino B, Pasquali P, Roberts HC, Spoolder H, Stahl K, Velarde A, Viltrop A, Winckler C, Earley B, Edwards S, Faucitano L, Marti S, Miranda de La Lama GC, Costa LN, Thomsen PT, Ashe S, Mur L, Van der Stede Y, Herskin M. Welfare of equidae during transport.. EFSA J 2022 Sep;20(9):e07444.
- Verdegaal EJMM, 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?. Front Vet Sci 2022;9:894146.
- Janczarek I, Stachurska A, Wilk I, Wiśniewska A, Różańska-Boczula M, Kaczmarek B, Łuszczyński J, Kędzierski W. Horse Preferences for Insolation, Shade or Mist Curtain in the Paddock under Heat Conditions: Cardiac and Behavioural Response Analysis.. Animals (Basel) 2021 Mar 25;11(4).
- Zakari FO, Ayo JO, Rekwot PI, Kawu MU, Minka NS. Daily rhythms of rectal and body surface temperatures in donkeys during the cold-dry (harmattan) and hot-dry seasons in a tropical savannah.. Int J Biometeorol 2018 Dec;62(12):2231-2243.
- Hartmann E, Hopkins RJ, von Brömssen C, Dahlborn K. 24-h sheltering behaviour of individually kept horses during Swedish summer weather.. Acta Vet Scand 2015 Aug 20;57(1):45.
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