Page 94 - May 2022

EQUINE HEALTH
GENETIC STUDIES
A team of University of Florida scientists from the Genetics Institute and the College
of Veterinary Medicine used genetic markers to find the common genomic markers in horses that had chronic anhidrosis disease. These genetic signposts pointed to a defective potassium transporter that likely hinders sweat function. Their report was published in 2021.
Now we know which biological pathways cause the condition. Samantha Brooks, University of Florida’s Institute of Food and Agricultural Sciences (UF/IFAS) associate professor of
equine physiology, says this disease is similar to cystic fibrosis. Genetic mutations leading to
cystic fibrosis also impact ion channels and gave researchers some clues as to how this defective potassium transporter might work in horses that don’t sweat. Additional research is needed, but this study discovered 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.
The sweat glands become damaged after horses live with chronic anhidrosis over long periods. Trying to sweat without a functional ion transporter could be the cause of the damage to the cells in the sweat gland.
92 SPEEDHORSE May 2022
“For treatment of an anhidrotic horse through summer we generally try One AC and potassium chloride. That helps a fair number, and if that doesn’t work, I’ve used a product called Cholodin and it seems to help some of them—though it’s very expensive. It’s always trial and error trying to find something that helps a certain horse,” he says.
“In the late spring and early summer, if a horse stops sweating, we generally start them on the One AC and potassium chloride along with acupuncture a couple of times. If we start soon enough, a lot of those horses will be okay for the rest of the summer, though there are some we don’t seem to be able to help,” Randall says.
Prolonged inability to sweat puts the horse at risk for heat stroke and other problems, but if discovered early, this condition can often be reversed by giving his cooling system a break. The best way is to remove the horse from the stressful environment, taking him to a cooler climate or trying to change the conditions he’s living in. This may mean using deep shade, misting fans, and other ways to cool the horse.
“Management changes are what we recommend,” says Mallicote. If the horse is overheated, he should be cooled with water or sprayed with a fine mist (fans with misters on them work well), to bring his temperature down to normal, and then his temperature should be
out of the sun, but not in a hot stall. A portable fan may help keep him cool until his sweating reflex recovers. If corrected as soon as it occurs, anhidrosis may resolve within a few days. If a problem is longstanding, however, the horse may need help for several weeks. The horse should only be exercised during the coolest times of the day.
“If the horse is at pasture, you could use a sprinkler that’s on a timer so it will turn on every so often,” says Mallicote. The horse will take advantage of the spray of water, which will cool him with subsequent evaporation, like the effects of sweat. She also suggests putting him in a pasture with a pond so he can go in the water.
“Some people with valuable performance horses build air-conditioned stalls. That’s a
big investment but it can really help. With some severely affected horses, the owners send the horse to a cooler climate. For some horses anhidrosis can be life-threatening, and they have no quality of life in a hot climate. Change of environment may be necessary, just as with a horse that has really bad heaves,” she says.
Treatment options include:
Acupuncture. Fans in stalls.
Cooling with water or spraying with mist.
kept low, so he doesn’t have to sweat. Keep him