Genetic markers tied to loss of sweating ability in horses identified by researchers

POSTED ON  |  07-09-2021

Anhidrosis test
Sweating is a critical tool to keep horses comfortable and healthy, but chronic idiopathic anhidrosis, a dangerous equine condition, can impede their natural cooling mechanism and cause performance and health issues. For the first time, researchers with the University of Florida’s Institute of Food and Agricultural Sciences have identified genomic markers that cause the potentially fatal condition.

The genomic mapping study gave researchers a discovery-based approach to attacking this disease, pushing aside prior assumptions about the disease’s causes. A team of University of Florida scientists from the Genetics Institute and the College of Veterinary Medicine used genetic markers like signposts, looking for the common genomic markers found in horses that had chronic idiopathic anhidrosis disease. These genetic signposts pointed to a defective potassium transporter that likely hinders sweat function.

“Now that we know which biological pathways cause the condition, we hope to design specificâ?¯strategiesâ?¯toâ?¯intervene,” said Samantha Brooks, associate professor of equine physiology with the institute. “We found that this disease hasâ?¯similaritiesâ?¯to cystic fibrosis whichâ?¯hasâ?¯many drug treatmentsâ?¯available and in development. Knowing this, we can start to consider ways to treatâ?¯these horses that suffer from this condition, helping them sweat more normally over longer periodsâ?¯of time.”

Genetic mutations leading to cystic fibrosis also impact ion channels and gave researchers some clues as to how this particular defective potassium transporter might work. Additional research is needed to fully understand, but researchers found a change in the protein that alters when this ion transporter turns on and off. The stress of the sweat gland attempting to function with this faulty transporter likely destroys the ability to sweat over time.

“Using histology, the study of the structure of the tissues, previous work found that the sweat glands become damaged after horses live with chronic idiopathic anhidrosis over long periods of time,” Brooks said. “That is why we have not been successful in reversing the disease and restoring sweat function. Trying to sweat without a functional ion transporter could be the cause of the damage to the cells in the sweat gland. We may not be able to reverse that.”

Having chronic idiopathic anhidrosis is like driving a car on a flat tire, Brooks explained. Over time, a horse living with this disease experiences impacts to their overall health beyond the inability to sweat. Living with the condition becomes a quality-of-life concern and unlike other kinds of anhidrosis, chronic idiopathic anhidrosis cannot be solved quickly or cured.

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