20/01/2026
🌡️ Anhydrosis in Horses – When Sweating Stops Working 🌡️
Anhydrosis is a condition that disrupts a horse’s ability to sweat efficiently in response to heat and exercise. Because sweating is the horse’s primary way of cooling down, this condition can seriously compromise temperature regulation and place horses at risk of overheating.
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🐎 How Common Is Anhydrosis?
Anhydrosis is relatively common in hot, humid regions such as Northern Australia, with surveys suggesting up to 30% of horses may be affected to some degree.
Humidity is the key trigger — particularly when horses don’t have time to gradually acclimatise during sudden seasonal changes or are transported from cooler climates into tropical conditions.
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💦 Why Sweating Is So Important
Like humans, horses rely heavily on sweating to regulate body temperature. Sweating accounts for around 50–65% of heat loss during exercise, allowing heat to evaporate from the skin and prevent dangerous internal temperature rise.
When sweating is reduced or stops altogether, horses struggle to dissipate heat, increasing the risk of muscle damage, dehydration and heat-related stress — especially during work in hot, humid weather.
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🔬 A Unique Cooling System
Horses (along with humans) are unique among mammals in their ability to cool themselves through skin sweating.
A 500 kg horse has around 5 square metres of skin surface, packed with thousands of sweat glands that work together to regulate body temperature during exercise and heat exposure.
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⚠️ Why Anhydrosis Is a Serious Issue
Anhydrosis develops when horses lose their ability to sweat efficiently under heat stress. Dehydration, prolonged exercise and fluid loss further reduce sweat evaporation, making cooling even more difficult.
In severe cases, affected horses may overheat rapidly and suffer heat colic, muscle damage or collapse.
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❓ What Causes Anhydrosis?
The exact cause is complex and not fully understood, but contributing factors may include:
• Reduced adrenaline response affecting sweat gland stimulation
• Chronic heat stress
• Electrolyte imbalances
• Dehydration
• Thyroid hormone disruption
• Training and competition stress
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👀 Signs to Watch For
Symptoms often develop gradually over weeks to months and may include:
• Reduced or patchy sweating (“shy sweating”)
• Panting or shallow breathing (“the puffs”)
• Loss of performance
• Lethargy and reduced appetite
• Elevated resting heart rate
• Poor exercise tolerance________________________________________
🩺 Diagnosis
Diagnosis is based on clinical signs and history, with confirmation possible through skin testing using adrenaline or salbutamol to assess sweat gland response. In some cases, skin biopsies may be used to evaluate gland function.
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🧊 Management & Prevention
Management focuses on reducing heat load and improving cooling, including:
• Shade, fans and good ventilation
• Misting systems or refrigerated air-conditioning (not evaporative)
• Plenty of cool, clean water
• Cooling strategies after exercise
• Exercising during cooler times of day
• Pre-conditioning horses before hot weather
• Adjusting exercise intensity and duration
Dietary management is also important — high protein diets can increase internal heat production, so careful ration planning helps reduce heat stress.
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🧂 Nutritional Support Can Help
Observations suggest that electrolytes combined with Vitamin E and Vitamin C can assist horses showing signs of reduced or patchy sweating.
Kohnke’s Own Troppo-Salts™ is a targeted electrolyte supplement containing sodium, potassium, chloride and magnesium, along with Vitamin E, Vitamin C, zinc, antioxidants and L-arginine.
Dr John Kohnke has found this formulation to be consistently successful in helping horses maintain their ability to sweat under hot, humid conditions.
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✅ Take-Home Message
Anhydrosis is a serious condition that can significantly impact horse welfare in hot, humid climates. Early recognition, proactive management, environmental control and appropriate nutritional support are key to keeping affected horses comfortable, safe and performing at their best.
If you’re concerned your horse may not be sweating normally, early intervention can make a big difference. 🐎💧
