Veterinary advice should be sought before applying any treatment or vaccine.


Dry Coat Syndrome, Non-sweating Syndrome

Anhidrosis, more commonly known as non-sweating syndrome, is a condition in which horses are unable to sweat properly. Horses that are unable to sweat will overheat much faster than a normal horse, due to the inability of the body to cool itself through sweating the heat produced during muscular activity. It can have a big impact on the horse's performance, as without the ability to regulate their body temperature during exercise, they are prone to overheating which limits their performance. In addition, it can put affected horses at increased risk of developing hyperthermia or heat stroke.

The disease usually happens in horses living in very hot, humid climates. It is usually easy to spot because affected horses will maintain a dry coat even after strenuous exercise in the heat. It is a problem for horses that are transported from Northern states to Southern states in the United States for a portion of the year. Some horses with equine pituitary pars intermedia dysfunction (PPID) that are living in tropical climates develop anhidrosis and heat stress with secondary exercise intolerance. Once treated for PPID the condition will generally resolve. Onset of anhidrosis might be abrupt or gradual. Horses most frequently develop incomplete or partial anhidrosis, however chronic cases also occur. The more a horse is worked until they develop signs of heat stress, the more likely they will eventually develop anhidrosis.

Latest Research
Latest research studies conducted in Florida found that horses that come from sires and dams with a history of anhidrosis are more likely to develop anhidrosis. It has also been shown that the earlier anhidrotic horses can be treated, there is less chance of permanent structural damage to the sweat glands.


Decreased to no sweat production
Labored breathing during and long after exercise
Loss of appetite
Thinning, patchy hair coat
Facial hair loss
Reduced water intake
Lethargy and exhaustion


  • History
  • Clinical signs
  • Physical exam
  • Injections of dilutions of terbutaline
  • Blood test
  • Skin biopsy



Exercise reduction
Environmental/management changestrain or ride the horse during the cooler times of the day, provide constant access to shade and water, install stall cooling fans, turnout horse at night or cooler portions of the day, instead of during the day
Chinese herbal medicineNew Xiang Ru San
Vitamins, minerals and amino acidsOne AC, True Sweat, Platinum Refresh, and electrolytes may be helpful
BeerProvide a can of beer a day, beneficial for the yeast extract and B vitamins to aid in sweat gland function.
ClenbuterolAdministered by your veterinarian
Relocate the horse to a cooler climate.


  • Limit working horses during hot conditions
  • Give horses enough time acclimatize to new climates.

Scientific Research

General Overviews

Risk Factors

  • High protein or energy diet
  • Living in warm or humid climates where the minimal daily temperature is above 23°C (73°F)
  • Vitamin/mineral deficiencies (sodium chloride, potassium, electrolytes)
  • Concurrent systemic infection
  • Intensive training in warm climates
  • Decreased thyroid function
  • Genetic predisposition
  • Darker colored horse