Sweat Glands of Anhidrotic Horses -- Short Circuit Found

Researchers are one step closer to understanding the mystery of anhidrosis (failure to sweat). Results of a study performed by scientists at Glasgow Caledonian University and Michigan State University have revealed that the sweat glands of anhidrotic horses secrete chloride ions differently than normal horses--these chloride ions underpin the formation of sweat in equine sweat glands.

Anhidrosis is a disorder in which the horse gradually loses his ability to sweat. This malfunction can occur in small patches or produce a near-total inability to sweat. Because sweating is key to the horse regulating his body temperature, a lack of sweat can have a severe impact on the horse's well-being and increase the potential for heat stroke.

In this study researchers collected skin samples from clinically normal horses in Scotland and Singapore (to compare any effect of the horses' climate) and three anhidrotic horses from Singapore. The researchers transported the collected samples to Scotland (allowing for assessment of whether long transport affected the samples) and cultured the sweat gland cells over several weeks. Monolayers of the cultured cells were then used in an Ussing chamber (which measures short-circuit current as an indicator of net ion transport across the epithelium, a cellular covering of the internal and external surfaces of the body) to investigate ion movement across the cells.

The researchers found that the transepithelial movement of chloride ions in response to agonists (drugs that stimulate activity at cell receptors) was significantly reduced in anhidrotic animals, while there was no difference in the cells cultured from free-sweating horses in Scotland and Singapore.

The researchers noted that while the sweat glands of anhidrotic horses have a demonstrated short circuit, further studies including more horses are needed to confirm this, and the reason for the fault remains unknown.

Researchers on this study, "A preliminary study of the short circuit current responses of sweat glands from normal and anhidrotic horses to purinergic and andrenergic agonists," included Darius C. S. Wilson, BSc; Alistair D. Corbett, PhD; Cate Steel, BVSc, FACVSc; Roshni Pannirselvam, BVSc, DVSc; and Douglas L. Bovell, PhD.

This study was published in the June issue of Veterinary Dermatology.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care.

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