Effect of ambient temperature and humidity on pulmonary artery temperature of exercising horses.
Abstract: Six healthy Thoroughbred mares were trained to run on a high-speed treadmill and were conditioned for approximately 5 weeks. Each horse performed 6 identical standardised exercise tests (SET) 5 to 7 days apart. Each SET was performed under different ambient laboratory conditions: low temperature/low humidity (LL) 20.2 degrees +/- 0.6 degree C, 53.6 +/- 4.1%; low temperature/high humidity (LH) 19.7 +/- 0.6 degrees C, 86.7 +/- 4.2%; medium temperature/low humidity (ML) 24.6 +/- 0.2 degrees C, 58.7 +/- 3.7%; medium temperature/high humidity (MH) 24.7 +/- 0.3 degrees C, 87.5 +/- 1.4%; high temperature/low humidity (HL) 31.1 +/- 0.6 degrees C, 41.6 +/- 3.5%; and high temperature/high humidity (HH) 30.6 +/- 0.2 degrees C, 84.4 +/- 3.6%. Horses completed the 46 min SET, became fatigued or exercise was terminated when a pulmonary artery temperature (PAT) of 41.5 degrees C was reached. During a 30 min recovery period, horses stood quietly on the treadmill. Only one trial was terminated due to fatigue; in all other trials horses completed the 46 min SET or the trial was terminated when PAT = 41.5 degrees C. The relationships among run time (min) or PAT (degree C), ambient temperature and % relative humidity were defined by multiple linear regression analysis. Run time (min) = 90.9 - (1.39 x ambient temperature degree C) - (0.236 x relative humidity %). Approximately 54% of the variation in run times was explained by variation in environmental conditions, indicating that ambient temperature and humidity contribute substantially to the rate of rise in PAT. Run times to a PAT of 41.5 degrees C were significantly shorter (P < 0.000001) in HH than in other groups during the SET. Approximately 63% of the variation in PAT at the end of exercise was due to ambient temperature and humidity. In general, the longer the exercise time, the better the correlation among PAT, ambient temperature and relative humidity. Rectal temperature increased significantly (P < 0.0001) during the recovery period only in horses in the HH group, indicating that heat dissipation during recovery may have been impaired by environmental conditions. This study demonstrates that hot humid conditions result in more rapid rate of rise in PAT for horses undertaking identical exercise tests.
Publication Date: 2000-02-05 PubMed ID: 10659290DOI: 10.1111/j.2042-3306.1999.tb05256.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates how different ambient temperature and humidity conditions impact the pulmonary artery temperature of exercising horses. The research indicates that hot and humid conditions cause a more rapid increase in the horses’ pulmonary artery temperature.
About the Study
- The study involved six healthy Thoroughbred mares who were trained and conditioned for approximately five weeks to run on a high-speed treadmill.
- Each horse performed six identical standardized exercise tests (SETs) under different ambient laboratory conditions: low temperature/low humidity, low temperature/high humidity, medium temperature/low humidity, medium temperature/high humidity, high temperature/low humidity, and high temperature/high humidity.
- The exercise was completed after 46 minutes, if the horse became tired, or if the pulmonary artery temperature (PAT) reached 41.5 degrees Celsius. After the exercise, the horses rested for 30 minutes on the treadmill.
The Findings
- Environmental conditions significantly affected run times with approximately 54% variation in run times resulting from changes in temperature and humidity.
- Hot and humid conditions produced shorter run times before the PAT reached 41.5 degrees Celsius. This indicates that these conditions lead to a quicker rise in PAT.
- About 63% of the variation in PAT at the end of exercise was also due to changes in the ambient temperature and humidity.
- Increased correlation was noticed between PAT, ambient temperature, and relative humidity the longer the exercise lasted.
- Rectal temperature only increased significantly during the recovery period for horses in the high temperature/high humidity group. This suggests that heat dissipation during recovery might be hindered by environmental conditions.
Conclusion
- The findings demonstrate that higher ambient temperature and humidity levels significantly increase the pulmonary artery temperature of horses during exercise. Thus, hot and humid conditions cause a faster rise in PAT for horses, affecting their exercise performance.
Cite This Article
APA
Kohn CW, Hinchcliff KW, McKeever KH.
(2000).
Effect of ambient temperature and humidity on pulmonary artery temperature of exercising horses.
Equine Vet J Suppl(30), 404-411.
https://doi.org/10.1111/j.2042-3306.1999.tb05256.x Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, Ohio State University, Columbus 43210, USA.
MeSH Terms
- Animals
- Body Temperature
- Body Weight
- Exercise Test / veterinary
- Female
- Heart Rate
- Horses / physiology
- Humidity
- Physical Conditioning, Animal
- Pulmonary Artery
- Temperature
Citations
This article has been cited 4 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.
- 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.
- 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.
- Tapper S, Nocera JJ, Burness G. Experimental evidence that hyperthermia limits offspring provisioning in a temperate-breeding bird. R Soc Open Sci 2020 Oct;7(10):201589.
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