Vet Tips 2025: Anhidrosis in Horses—Why Some Horses Stop Sweating 🐴💦

By Dr Duncan Houston BVSc

It’s hot, it’s humid, and your horse just finished a workout—but he’s dry. That’s not a good sign. Horses, like people, sweat to cool off. When they can’t, the result is a dangerous condition called anhidrosis—and it’s more common than you might think. 🌡️🐎

What Is Anhidrosis? 🧠💧

Anhidrosis means a horse cannot sweat properly. Sweating is essential for thermoregulation in horses, and without it, they rely on inefficient methods like panting, which can’t sufficiently cool such a large body. 🫁🔥

Where It Happens:

• ☀️ Most common in hot, humid climates like the southern U.S.
• 📊 Affects up to 20% of horses in these regions

Who It Affects:

• 🐴 Both imported and native horses
• 🧒 More common in younger horses

So, contrary to popular belief, even horses born and raised in Texas can become non-sweaters. 🧠

What Causes Anhidrosis? 🧬🤔

The exact cause is unknown, but current theories include:

• 📉 Down-regulation of sweat gland receptors due to chronic over-stimulation in hot weather
• 🧠 Hormonal or nervous system dysfunction

Over time, the horse’s body “burns out” the sweat system, especially if repeatedly exposed to extreme heat. 🔥

Signs Your Horse May Have Anhidrosis 👀⚠️

Symptoms can be mild or severe. Watch for:

• 💦 Lack of sweat during or after exercise—even in hot weather
• 🐎 Poor performance or early fatigue
• 🌡️ Increased body temperature
• 💨 Rapid breathing at rest or after mild work
• 🥱 Dull coat and depressed behavior in summer

These horses are often hot to the touch and may appear weak or sluggish after exercise. ⛔

Diagnosing Anhidrosis 🔍🩺

Your veterinarian may perform a sweat test using a dilute solution of terbutaline or epinephrine injected into the skin. This causes localized sweating and helps determine if the glands are responsive. 🧪

Other steps include:

• 📋 Full clinical exam and history
• 📈 Monitoring rectal temperature post-exercise
• 🔍 Observing sweating patterns compared to other horses

Managing a Horse With Anhidrosis ❄️🧠

While there’s no cure, many horses can be managed with environmental and nutritional changes:

Cooling Techniques 🧊☀️

• 🌬️ Use large fans and misters in the barn
• ⏰ Exercise only during early morning or late evening
• 🧊 Hose the horse with cold water after work
• 🏠 Provide shaded or air-conditioned turnout (if possible)

Feeding Tips and Supplements 🥣💊

• 🧂 Provide electrolytes daily—salt blocks may not be enough
• 🌿 Some owners report improvement with nutraceuticals like One AC, though results vary
• 🧪 New research continues on thyroid support and metabolic function

Hydration Is Essential 💧

Encourage drinking with:

• 🥕 Soaked hay cubes or beet pulp
• 🍲 Electrolyte water buckets
• 🚿 Lightly flavored water (like carrot juice or apple) in moderation

Can Horses With Anhidrosis Still Compete? 🐎🏅

Some mildly affected horses can continue working with careful temperature monitoring and rest. But others will need to reduce activity during hot months—or may be retired from heavy exercise altogether. ⚠️

When to Call Your Vet 📞🩺

Seek veterinary help if your horse shows:

• 🔥 Persistent elevated body temperature after rest
• 💨 Labored breathing or respiratory distress
• 🥵 Refusal to move or collapse
• 💦 Complete lack of sweat after hard work in heat

Anhidrosis can turn into a life-threatening condition without fast intervention. 🧠

Need Help With a Suspected Non-Sweater? Ask A Vet 📱🐴

Not sure if your horse is sweating normally? Worried about overheating or summer performance? Connect with an equine health expert at Ask A Vet.

Download the Ask A Vet app for 24/7 help with thermoregulation, hydration plans, and customized anhidrosis management strategies. 🐎💧

Final Thoughts: Stay Cool and Aware 🧠❄️

Anhidrosis isn’t just inconvenient—it’s a serious health risk. With early detection, smart cooling strategies, and the help of your vet, many horses can stay healthy through summer’s worst. 🌞

Need help evaluating sweating patterns or finding a safe supplement plan? Visit Ask A Vet and get trusted support today. 🐴💙