Strenuous exercise can push the limits of a horse’s recovery mechanisms. More often than not these mechanisms function properly and the horse is able to perform the requested work and recover appropriately. Sometimes the recovery is inadequate and the horse goes into a shock-like state. This means that several organs (muscles, kidneys, central nervous system, clotting system) may shut down. Severe exhaustion and overheating can become a grave and life threatening situation. Today we will be talking about risk factors, signs of exhaustion and overheating, prevention, and treatment.

Risks: The likelihood of exhaustion and overheating increases when any of the following conditions exist:

  • Poor fitness
  • Heat and humidity
  • Horse’s inability to sweat
  • Rough or steep terrain
  • High altitude
  • Presence of disease or lameness
  • Rider inexperience

Signs: Horses suffering from exhaustion or overheating can show behavior ranging from distressed and anxious to lethargic and unstable. The following are common findings on physical exam of a horse suffering from exhaustion or overheating:

  • Persistent high heart rate
  • Persistent high respiratory rate
  • Persistent high temperature
  • Hot and dry skin
  • Pale and dry mucous membranes
  • Weak irregular pulse
  • No gut sounds
  • Severe stiffness and muscle pain

Horses severely affected may have long term effects such as laminitis, kidney or other organ failure, and diarrhea. Some horses are so critically affected that the body shuts down, the blood pressure can become extremely low, and the horse can collapse and die.

Prevention:

  • Horses should be thoroughly prepared for the conditions of the event.
  • Includes fitness, temperature and humidity, type of terrain
  • Horses should be carefully monitored when exercising in extreme conditions

The average healthy horse without underlying conditions or forced exercise can adequately cope with the heat if he has access to the following:

  • Clean water
  • Electrolytes (salt blocks, salt supplements, or electrolyte water)
  • Shade
  • Air Circulation

Older horses, younger horses, and horses with a medical condition or infection are more sensitive to heat and have a decreased ability to thermoregulate. These horses should be monitored more closely and extra precautions should be taken:

  • Horses with heavy coats (uncontrolled Cushings disease) should be clipped.
  • Foals should have access to water at the level they can reach, even if they are still nursing.
  • Horses with infections or fevers should have their temperature taken frequently and kept as cool as possible.

Treatment:

Performed by rider/owner:

  • Whole body ice water rinses or repeating rinsing/scraping cycles.
  • ** Research has shown that ice water rinses are a quick and safe method to reduce the horse’s core temperature, protecting from organ shut down**
  • Place in front of fans.
  • Move out of sun into shade.
  • Offer clean water.
  • Do not limit to several gulps, offer ½ bucket increments.

If the listed treatment is provided by the owner/trainer for 1 hour without the horse improving in mental status/behavior, temperature (>103°F), respiratory rate or heart rate call HEHC.

Performed by Veterinarian:

  • Intravenous fluids
  • Medications to relieve pain and improve proper metabolism
  • Oral fluids
  • Bloodwork to evaluate organ function and hydration status

“Extensive research conducted during 1995 at the University of Illinois and University of Guelph and at the 1996 Olympic Summer Games in Atlanta proved conclusively that horses working under hot and humid conditions were better able to maintain core body temperature within an acceptable range or even reduce it during rest periods after intense phases when ice water baths were used. Liberal application of icy cold water to overheated horses helps to dissipate heat not only by providing more water to evaporate from the skin, but also by direct conduction of the horse’s body heat into the water which runs off the horse, carrying away excess heat in the process. According to University of Illinois researcher Dr. Jonathan Foreman, “In our treadmill simulations of C Halt (a rest period during a phase of the equestrian competitions at the Olympic games), cold water baths were used with significant decreases in core temperatures and heart rates. No adverse clinical effects were apparent during the remainder of Phase C trotting or after exercise. Horses actually trotted more freely after bathing stops.” Kevin Kline PhD University of Illinois