The Non-Sweating Horse - Anhidrosis
By Eleanor Blazer
       "Hey man, no sweat!"

       This informal reply generally means "don't worry about it".  But when used to describe a non-sweating horse it's reason for worry.

       Horses (and humans) cool their bodies by sweating.  When a horse is exercising or overheated the brain detects the rise in body temperature.  Signals are sent to the sweat glands, which begin to secrete moisture.  The evaporation of this moisture helps the horse feel cooler. 

       Keeping the brain and internal organs from over-heating is the primary function of sweating.  Blood that is becoming hot travels out from the core of the body and toward the skin.  Energy needed to produce sweat is pulled from the blood in the form of heat, which cools the blood and protects the vital organs.

       Horses with anhidrosis cannot sweat, so they risk organ failure, which can lead to death.

       While most anhidrosis cases are concentrated in hot and humid areas (Gulf Coast states), it can occur anywhere. It can be mild to severe.

       Some horses who suffer from anhidrosis many still exhibit small amounts of sweat, but not enough to cool their bodies.

       While a lack of sweat is the most obvious symptom, others include panting and a body temperature greater than 102° F. (38.8 ° C.).  Dry skin and loss of hair may also be noticed.

       No one knows what triggers anhidrosis.  Moving a horse from a cool climate to a hot, humid one may trigger the condtion.  Other horses may stop sweating when the sweat glands are overly stimulated.  A genetic link may also be possible - related horses may exhibit anhidrosis.  Stress can be another contributing factor.

      Horses with anhidrosis must be managed.
      The best thing for them is to move to a cooler climate.  There is no cure. 

      If moving to a cooler climate is not possible, there are steps that can be taken to give the non-sweating horse some relief.

       Providing the horse with fans and misters can help.  If the horse is kept outside, shade must be available and hosing him with cool water during the heat of the day is advised. Exercise and training should be done early in the morning - before the sun rises, or late in the evening.  These horses should not perform during the heat of the day.

       There are nutritional supplements on the market that are advertised for the anhidrotic horse.  No controlled studies have been conducted to prove their effectiveness.  Research at the University of Florida has shown one supplement, One AC, having some benefit. 

      Many owners of anhidrotic horses swear dark beer helps. 

      Other treatments which have been tried are electrolyte supplementation, a treatment with a drug called methy dopa, using thyroid supplementation and acupuncture.  None of these methods have been proven to work consistently and some have side effects.

      Don't take "no sweat" lightly.  A dry horse in hot, humid conditions is a sick horse and immediate care is needed.

       For information about horse care take the online courses " Stable Management " and " Nutrition for Maximum Performance " taught by Eleanor Blazer.  Earn certification or work toward a Bachelor of Science degree in equine studies.

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Eleanor Blazer

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