An index of the environmental thermal load imposed on exercising horses and riders by hot weather conditions.
Abstract: There is a need to determine objectively the environmental heat load imposed on horses competing to an international standard in 3-day-events in environments where there is likely to be a high level of radiation added to high ambient temperatures and relative humidity; the presently used FEI 'Comfort Index' is severely limited in its applicability. It is proposed that the Wet Bulb Globe Temperature (WBGT) Index be used. This index was originally established for man exercising strenuously under harsh climatic conditions with high solar radiation levels. It may be defined as: WBGT = 0.7Twb + 0.3Tg where Twb is the wet bulb temperature of the ambient air, measured in the shade and Tg is the black globe temperature. Climatic conditions should be monitored continuously at a site representative of the detailed topography and nature of the terrain of the competition course. The upper limit for the index for competitions involving fit, fully acclimatised horses, running on ground of optimal going, is recommended to be 32.5 degrees C. This limit should be reduced, by an as yet undetermined amount, for unacclimatised and unfit horses or when the going is less good.
Publication Date: 1995-11-01 PubMed ID: 8933080DOI: 10.1111/j.2042-3306.1995.tb05003.xGoogle Scholar: Lookup
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Summary
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The study suggests adopting the Wet Bulb Globe Temperature (WBGT) Index to objectively measure the effect of heat on horses and riders participating in three-day international events. The research recommends the upper limit for the WBGT index should be 32.5 degrees Celsius for fully adapted fit horses, albeit the limit should be lower for horses not acclimatised or unfit.
Background
- The research is born out of the need for an objective determination of the environmental heat load on horses competing to international standard in 3-day-events.
- These conditions often contain high radiation levels in addition to elevated ambient temperatures and relative humidity.
- The currently used Federation Equestre Internationale (FEI) ‘Comfort Index’ doesn’t cover all conditions, limiting its usefulness.
The Wet Bulb Globe Temperature (WBGT) Index
- The study proposes the use of the WBGT Index, originally designed for humans working under harsh climatic conditions with high solar radiation levels.
- WBGT is defined as: WBGT = 0.7Twb + 0.3Tg, where Twb is the wet bulb temperature of the ambient air, measured in the shade and Tg is the black globe temperature.
- This index gives a better representation of the heat stress under differing environmental conditions.
Suggestions for implementation
- Climatic conditions for competitions should be continuously monitored at a site that is representative of the specific topography and nature of the competition course
- The upper limit for the WBGT index for competitions involving fit, fully acclimatised horses, running on optimal ground conditions, is recommended to be 32.5 degrees Celsius.
- This critical WBGT index limit should be reduced for unacclimatised and unfit horses or when the ground conditions are less favourable.
- However, the specific lower limit for such conditions has not yet been determined.
Implications
- The research promises a more objective measurement of the heat stress on horses and riders during competition in hot weather conditions.
- Further studies are needed to determine the reduced WBGT index limit for less-acclimatised or unfit horses or less favourable ground conditions.
Cite This Article
APA
Schroter RC, Marlin DJ.
(1995).
An index of the environmental thermal load imposed on exercising horses and riders by hot weather conditions.
Equine Vet J Suppl(20), 16-22.
https://doi.org/10.1111/j.2042-3306.1995.tb05003.x Publication
Researcher Affiliations
- Centre for Biological and Medical Systems, Imperial College of Science, Technology and Medicine, London, UK.
MeSH Terms
- Animals
- Body Temperature Regulation
- Climate
- Horses / metabolism
- Hot Temperature
- Humans
- Mathematics
- Weather
Citations
This article has been cited 4 times.- Trigg LE, Lyons S, Mullan S. Risk factors for, and prediction of, exertional heat illness in Thoroughbred racehorses at British racecourses. Sci Rep 2023 Mar 14;13(1):3063.
- 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.
- Hall EJ, Carter AJ, Chico G, Bradbury J, Gentle LK, Barfield D, O'Neill DG. Risk Factors for Severe and Fatal Heat-Related Illness in UK Dogs-A VetCompass Study. Vet Sci 2022 May 11;9(5).
- Verdegaal EJMM, Howarth GS, McWhorter TJ, Boshuizen B, Franklin SH, Vidal Moreno de Vega C, Jonas SE, Folwell LE, Delesalle CJG. Continuous Monitoring of the Thermoregulatory Response in Endurance Horses and Trotter Horses During Field Exercise: Baselining for Future Hot Weather Studies. Front Physiol 2021;12:708737.
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