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  • Partial or complete loss of sweating ability
  • Hyperthermia (overheating)
  • Tachypnea (breath difficulty)
  • Reduced appetite
  • Decreased water intake
  • Alopecia (loss of hair)
  • Dull hair coat
  • Depression

Brooks Equine Genetics


Ongoing study at the University of Florida

How to Participate

About Anhidrosis

Please contact the Brooks Equine Genetics Lab for more information.  You can reach us by phone at (352) 273-8080 or email,
References Cited

Evans, C. (1957). Physiological factors in the condition of “dry coat” in horses. Vet Rec, 1-9.
Evans, C. (1966). Physiological Mechanisms that Underlie Sweating in the Horse. Br Vet J, 117-173.
Hubert, J. D. (2002). Equine Anhidrosis. Vet Clin Equine , 355-369.
Johnson, E. B. (2010). An Epidemiologic Study of Anhidrosis in Horses in Florida. Journal of the Epidemiologic Study of Anhidrosis in Horses in Florida, 1091-1097.
MacKay, R. (2008). Quantitative Intradermal Terbutaline Sweat Test in Horses. Equine Vet Journal, 518-520.

We need DNA samples from horses who have been previously diagnosed with Anhidrosis, as well as horses who have had an offspring with Anhidrosis. If you would like to submit a sample, please click the button below and fill the survey. At the end of the survey, you’ll be able to download the sample submission forms or request that we mail you a sample collection kit. All studies are confidential, so be assured both you and your horse’s identity will not be released at any point should you decide to participate.  
  • Work horses in cooler parts of the day such as the evenings or early mornings
  • Observe your horse closely for signs of overheating, rapid heart rate, and high body temperature.
  • When introducing a new horse to a hot and humid climate, allow time to readjust with turnout and light work.
  • Start your horses spring/summer workout regime earlier, so that they weigh less at the hottest parts of the season.
  • Always make sure shade is available. Misters and fans can be used for added caution with an anhidrotic horse.
  • Hosing off your horse during the hottest parts of the day will help keep his internal body temperature down.

A quantitative intradermal sweat test (with terbutaline) can be used for identification of freely sweating horses (MacKay, 2008).  Currently there is no treatment for Anhidrosis that passes even the lowest standard for evidence-based medicine. Current, only good management can help prevent the anhidrotic horse from overheating.

Tips for keeping an Anhidrotic horse cool include:

Brooks Equine Genetics Lab is working to identify genetic components contributing to Anhidrosis, a frustrating condition of particular concern in the southern US.

Our Study

The odds of anhidrosis have been reported to be 21.67 times higher in horses with a family history of anhidrosis, highlighting the strong genetic component to this disease (Johnson, 2010).Here at Brooks Equine Genetics Lab our study will be focused on looking into some of the sweat genes of the horse and their genetic association to anhidrosis. If you own a horse that is diagnosed with anhidrosis, we would like you to contact us for involvement in this study. Enrollment in this study is strictly confidential, so rest assured you and your horse’s information are secure. Veterinarians are encouraged to pass on study information to clients who may be interested in participating. 

Dr. Laura Patterson-Rosa, a PhD student in the Brooks Lab and a veterinarian, is working to find genes responsible for anhidrosis in the horse

Anhidrosis, also know as “non-sweaters” or “dry coat”, is a disease in horses that is characterized by the inability to sweat in response to appropriate stimuli (Hubert, 2002). Prevalence of the disorder favors hotter and more humid climates, although cases of anhidrosis have been reported in many different regions (Johnson, 2010).  Any horse can become afflicted as it is not limited to any particular sex, breed, or age (Johnson, 2010). The severity of Anhidrosis can vary, however anhidrotic horses require careful observation and management as well as reduced workload or removal from physical activity. Anhidrotic horses forced to perform can suffer severe consequences, including multiple organ failure in response to hyperthermia and, in some instances, death (Evans, 1966).

Clinical Symptoms might include: