Electrolyte problems in the heat are directly proportional to sweat loss, so it makes perfect sense that horses working long periods are at greatest risk. This puts the spotlight on endurance horses.

Equine sweat is a concentrated electrolyte solution. Chloride is the most abundant electrolyte in sweat, followed by sodium, then potassium, with much smaller amounts of calcium and magnesium. The daily requirement for sodium can double with just one hour of low level sweating.

Even at low rates of sweating the horse will lose over a gallon of fluid per hour - and up to 4 gallons per hour with heavy sweating. That's a lot of fluid! The first consequence of this is dehydration. Since sodium lost in the sweat is needed to hold water in the body tissues, drinking water alone is not enough to correct the dehydration. Even mild dehydration has a major impact on the ability to perform.

Electrolyte losses triggered by exercise and sweating can produce a variety of temporary signs which respond to hydration and electrolyte replacement. Normal levels are required for regular heart rhythm, intestinal motility, coordinated movements of involuntary muscles like the diaphragm, skeletal muscle contraction and relaxation and the regulation of nerve firing.

Endurance horses show some typical changes in their blood electrolyte profiles. Low chloride is common. As above, chloride is very high in sweat. They do not have good stores of chloride in the tissues to replace what is lost in sweat. Low potassium is more common than low sodium. This is because horses can pull sodium from the tissues surrounding the body's cells to keep blood levels up. The kidney also conserves sodium by reducing sodium in the urine and replacing it with potassium.

Read more: Electrolyte Problems in Endurance Horses

Animal Wellness Applauds Cohen’s Tireless Work for Horses.

WASHINGTON, D.C. July 2, 2020 – Today, the U.S. House of Representatives passed H.R. 1400, the Horse Transportation Safety Act, authored by Rep. Steve Cohen (D-TN-09), that would ban the transportation of horses across state lines in ‘double decker’ trucks or trailers containing two or more levels stacked on top of one another.

“I applaud Rep. Steve Cohen for his tireless work and dedication to horse protection -- he’s a knight in shining armor to the voiceless we care so deeply about,” said Marty Irby, executive director at Animal Wellness Action, and past president of the Tennessee Walking Horse Breeders’ & Exhibitors’ Association. “The horses that have transported millions of Americans for centuries, themselves deserve to be transported in a humane manner while they continue to bring joy, emotional support, and economic benefits to horsemen and women across the nation.”

“Horses deserve to be transported in as humane a manner as possible. Double-deck trailers do not provide adequate headroom for adult horses, and accidents involving double-deck trailers are a horrendous reminder that the practice is also dangerous to the driving public,” said Congressman Steve Cohen (D-TN-09). “I’m pleased this important measure is included in HR. 2, the Moving Forward Act.”

Double decker trucks and trailers present tremendous transportation risks to both the horses on board, and motorists sharing the state, federal, and local roadways with them. Numerous crashes that have occurred along interstate highways have resulted in not only the deaths of the horses, but innocent travelers as well. Even the U.S. Department of Agriculture has openly declared that these vehicles “do not provide adequate headroom for equines,” and that equines are far more likely to face injury in double decker trailers than in one level trailers that can better transport them.

Read more: U.S. Rep. Steve Cohen Ushers Horse Transportation Safety Act to Passage