The Weird Truth About How Horses Cool Down
People often joke that you learn something new every day, and for many, today’s “lesson” is one they wish they could unlearn. It involves horses - creatures that already intimidate plenty of people thanks to their size, strength, and surprising moods - and yet this new discovery has managed to unsettle the internet even more.
If this is your first time hearing it, consider yourself warned. Many online users have joked that if they had to find out, then everyone else should share in the experience, too.
Nature is packed with odd biological surprises: hippos secrete a pinkish fluid that acts like sunscreen, pigs release sweat only from their snouts, and dogs cool themselves through their paws. So unusual traits are nothing new.
Still, one particular detail about horses has left people genuinely creeped out - their approach to cooling down looks a lot stranger than anyone expects. An X user recently went viral after admitting they were “petrified” by a fact they stumbled across: horses don’t just sweat. Their sweat foams.
Yes, foamy sweat. Not a metaphor, not a rare mutation.
Regular, everyday horse sweat can turn into white lather, especially when the animal is working hard. And naturally, the question on everyone’s mind is: why?
Humans gained an edge because we cool down far better than panting animals.
Author and academic Vybarr Cregan-Reid explained the science behind this in an article for The Conversation. Most four-legged animals, including horses, do sweat, but not primarily to cool down.
Instead, their sweat plays roles in scent communication and skin maintenance. When it comes to lowering body temperature, most quadrupeds rely on panting - forcing air through their bodies to shed heat.
The problem is that panting is energy-intensive, so if these animals were chased on a hot day, they’d slow down long before a human would.
Humans, on the other hand, cool down by sweating across the entire body, which is far more efficient over long distances. According to Cregan-Reid, this gave early humans an unexpected advantage as hunters: our cooling system didn’t “overheat” as quickly as that of our prey.
But horses are different from other quadrupeds in one significant way: they’re incredibly hairy. Their thick coat traps heat and slows evaporation. Sweating alone wouldn’t be enough to cool them efficiently - unless their bodies evolved a workaround.
And they did.
Horses cool down with lather-rich sweat that spreads fast and turns into foam.
Researchers studying equine biology discovered that horses produce a special protein in their sweat called latherin. While human sweat is salty and low in protein, horse sweat is rich in this unusual substance.
Latherin behaves almost like a natural detergent. It reduces water's surface tension, allowing sweat to spread quickly through the animal’s dense coat. This helps moisture travel from the skin to the outer hair, where it can evaporate much more easily.
The side effect? Foam.
So when you see a hard-working horse with white froth along its neck or flanks, that’s simply latherin doing its job. The protein creates a bubbly, soapy appearance, especially in areas where the saddle or reins rub.
Kentucky Equine Research further explains that this foamy look is entirely normal. Because horses generate an enormous amount of heat during exercise, they rely on latherin to cool themselves fast enough to stay safe. Without it, their thick coats would trap sweat, slowing the entire process.
It may not be the most glamorous biological feature, but it’s incredibly effective.
Now you’re in on the secret: horses may look elegant and powerful, but their bodies rely on a cooling system that turns sweat into foam. It can catch people off guard the first time they see it, yet it’s simply nature doing its job efficiently.
It may seem unusual or even a bit unsettling, but this bubbly sweat helps these animals stay comfortable while they run, work, and exercise.
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