Heat Stress in Horses

Les Rees

Hot weather can have some devastating effects on our horses and can cause life threatening consequences, particularly during hot and humid conditions.

For equines, sweating accounts for two thirds of heat dissipation and therefore plays an important role in thermoregulation. However, high temperatures and humid conditions can have devastating effects on sweat evaporation. The high moisture content of a humid environment slows down the evaporation process as increased sweat forms an insulating layer on the body reducing heat dissipation. As a consequence, sweat glands release more water to speed up the process which ultimately causes dehydration, electrolyte imbalance and failure to reduce core body heat.

Symptoms of heat stress include debility and fatigue, a rise in body temperature, increased pulse rate and respiration, laboured breathing, muscle spasms and tremors, stumbling, dark urine and general debility in overall function and behaviour. This can result in death if left undiagnosed.

Prevention Strategies

  • The provision of adequate shade. When temperatures rose to over 30 degrees I noticed a number of horses were out in the sun without access to adequate shade. Having one tree in a paddock doesn't necessarily mean that it'll provide adequate shade throughout the day. It depends on the sun's position in the sky and when only small areas of shade are available, it's the dominant horses that get the best spots whilst the others hang around the margins either getting partial shade or none.

  • Horses kept in stables during the day should be provided with a place where there is adequate movement of air flow and water supply.
  • Provision of fresh clean drinking water. Ensure that troughs are cleaned regularly and there is a continual supply.

  • Provision of salt licks. Himalayan salt licks and/or mineral licks should be supplied in an easily accessible place.

  • Add electrolytes to diet. Sodium, potassium, calcium and chlorine are lost in urine and sweat; if they're not replaced it will cause metabolic problems, and subsequent lack of interest in eating and drinking. It's not uncommon to find salty layers over their backs, a clear demonstration of the amount of electrolyte loss.

  • Wash horses in the evenings to remove the salt and reduce the risk of attracting flies. Use a sweat scraper to remove the excess salty water.

  • Never over-work horses above their level of fitness conditioning. Have a conditioning program and adhere to it. On hot days it's better to ride early in the morning or later in the evening when the heat has dissipated.

  • Be aware of your horse's needs when travelling. Horse floats should have adequate ventilation whilst travelling on hot days. Arrange travel to avoid overly hot conditions and have frequent stops to check on your horse.

  • Acclimatisation. If travelling horses that are not used to the climatic conditions you need to be extra cautious. When moving horses to warmer areas, give the horse plenty of time to acclimatise before riding and ensure that it receives adequate nutrition to maintain good health.
We add sea salt, seaweed granules, apple cider vinegar and herbs to add valuable nutrients & natural electrolytes to our horses feed, and provide Himalayan rock salt licks. I also make sure that the horses are hosed down in the evenings, rugged and sprayed with our herbal Zap-itch blend of essential oils.

If, like me, you keep an eye on the weather forecast, it's worth reminding ourselves that a 40 degree temperature is measured in the shade NOT in full sun. So add a few more degrees and ask yourself if you'd like to be stuck in a paddock without shade for the day!!!!!!

Happy Xmas

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