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Hot Weather Considerations



While you may enjoy the sunshine, your horse may not be feeling too hot! Here are some things to consider when trying to keep your horse feeling their best in hot weather.


How hot is too hot?


When considering temperature stress, we must consider the thermoneutral zone.

  • The thermoneutral zone: the range of temperatures where the horse can easily regulate their body temperature, and ranges from 5 to 25°C for mature horses.

Outside of this range, the body has to work harder to maintain a normal core body temperature.


It is important to note that this range also depends on factors such as the horse’s body condition, humidity, and acclimation to the climate. Overweight horses, horses exposed to humid climates, and those who are not used to hot temperatures may be more sensitive to temperature stress.


Signs of Temperature Stress: Heat Stress vs Heat Stroke


Heat Stress: The body is heating up faster than it can cool down, losing thermoregulatory control of core body temperature.

  • Increased TPR, temperature > 103 F.

  • Profuse sweating and dehydration.

  • Droopy ears and tiredness.

  • Reduced feed intake.

  • Slow skin pinch.

Heat Stroke: The body can no longer control its temperature. Heat stroke is an emergent situation that requires veterinary attention.

  • Temperature > 106 F, rapid heart and breathing rates that don’t recover within 20 mins post-exercise.

  • Distress, whinnying, dehydration.

  • Muscle weakness, incoordination and collapse.

  • Dry mucous membranes and prolonged skin tent.


Management Strategies

  • Allow time for acclimation during hot weather, which can take 2-3 weeks.

  • Exercise them during the cooler parts of the day, and monitor them throughout the exercise to ensure they are recovering well.

  • Ensure shade access to allow the opportunity to get out of the sun and spraying cold water on their body can help support a normal core body temperature.

  • Access to plenty of fresh & clean water: your horse's water requirement can increase by over 3 times with hot weather or exercise!


Nutritional Strategies

  • Promote hydration with electrolytes and fiber in the diet.

    • Fiber has high water-holding properties in the gut.

    • Dehydration can contribute to colic, especially impaction colic.

  • Giving horses electrolytes 15-30 minutes after exercise can improve their recovery.

  • Avoid excess protein: thermogenic metabolism of protein is believed to impact normal thermoregulatory processes.

  • Antioxidant supplementation (Vitamin E & Vitamin C) has been found to be helpful in reducing heat stress in other livestock species, and are helpful additions to electrolytes.

Monitoring your horse during hot weather, while using strategies to minimize heat stress & dehydration, can help reduce risk of temperature stress, and keep them comfortable!


 

REFERENCES


Falaschini, A., Marangoni, G., Rizzi, S., Tombetta, MF. 2005. Effects of the Daily Administration of a Rehydrating Supplement to Trotter Horses. J. Equine Sci 16(1): 1-9


Green, BL., Wahrmund, JL. 2016. Impact of Hydration Supplements on Blood Electrolyte Concentrations of Exercised Horses During the Summer. Journal of Animal Science 94(1): 69-70.


Martinson, A., Hathway, M., Ward, C., Johnson, R. 2020. Caring for Horses During Hot Weather. University of Minnesota. Accessed online from: https://extension.umn.edu/horse-care-and-management/caring-horses-during-hot-weather#treatment-1301562


Morgan, K. 1997. Thermoneutral zone and critical temperatures of horses. Journal of Thermal Biology 21(1): 59-61.


Rhoads, RP., Baumgard, LH., Suagee, JK., Sanders, SR. 2013. Nutritional Interventions to Alleviate the Negative Consequences of Heat Stress. Advances in Nutrition 4(3): 267-276.


Schott, HC., Hinchcliff, KW. 1998. Treatments Affecting Fluid and Electrolyte Status During Exercise. Veterinary Clinics of North America: Equine Practice 14(1): 175-205.


Waller, AP., Heigenhauser, GJF., Geor, RJ., Spriet, LL., Lindinger, MI. 2009. Fluid and Electrolyte Supplementation After Prolonged Moderate-Intensity Exercise enhances muscle glycogen resynthesis in Standardbred horses. J Appl Physiol 106(2009): 91-100.


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