Dehydration in horses occurs when there is an insufficient amount of fluid in the body, often combined with a lack of essential electrolytes such as sodium, potassium, and chloride. Even a small fluid loss, just 1% of body weight can reduce performance, while a 5% loss indicates clinical dehydration. This can result from heavy sweating, acute diarrhoea, inadequate water intake, or excessive electrolyte loss.
Why Water Is Vital for Horse Health
Water is the most critical nutrient for horses, making up around 68–72% of a horse’s body weight (on a fat-free basis). Horses need water for every major body function, including:
- Digesting and absorbing feed
- Maintaining blood volume
- Regulating body temperature through sweating
- Supporting cellular activity and waste elimination
A resting horse in a mild climate typically needs about 5 litres of clean water per 100 kg of body weight per day. Access to clean, fresh water should always be available so the horse can regulate its intake naturally. Water is lost daily through sweat, urine, faeces, respiration, and in milk for lactating mares.
The Role of Electrolytes in Preventing Dehydration
Electrolytes, specifically sodium, potassium, and chloride are vital for normal cellular and muscular function. Because they are not stored in the body, horses must receive these minerals daily through feed or supplements. If a horse loses electrolytes and does not replace them, serious health problems can occur.
Heat-Related Dehydration in Horses
Sweating is the horse’s main method of cooling down, but it comes at a cost. Horse sweat is rich in electrolytes, and during intense exercise or hot weather, a horse can lose up to 20 litres of sweat in just one hour. This loss of fluid and electrolytes puts the horse at serious risk of heat stress and dehydration.
Horses also have a high muscle-to-bodyweight ratio and relatively low skin surface area, making it harder for them to dissipate heat compared to humans. This makes electrolyte support even more important during hot weather or intense physical activity.
Dehydration in Cold Weather
Dehydration isn't just a summer issue. In colder temperatures, horses may drink less water due to a suppressed thirst response. If a horse drinks large amounts of water without getting enough electrolytes, this can dilute the electrolytes in its body, leading the kidneys to excrete more water further worsening the imbalance.
Without sufficient electrolyte intake, horses can suffer from severe imbalances that may result in illness or even death.
Signs of Dehydration in Horses
Early signs of dehydration include:
- Reduced feed intake
- Weight loss
- Colic or constipation
- Poor performance
- Muscle cramps (thumps)
- Tying up
- Exhausted horse syndrome
While the skin pinch test can give a basic idea of hydration status, blood tests are the most accurate way to assess dehydration and electrolyte levels.
Management of Dehydration
Management of dehydration should always be carried out under veterinary supervision and may involve administering fluids and electrolytes intravenously or via nasogastric tube.
To manage dehydration:
- Ensure constant access to clean, fresh water
- Offer daily electrolyte supplementation such as Osmoplex or Equilibrium Mineral Mix, especially during hot weather, hard work, travel, or illness
- Feed a balanced diet that includes adequate mineral levels
Stance Suggestions - Choosing the Right Electrolyte Supplement
- Electrolyte supplements like Equilibrium Mineral Mix and Osmoplex are designed to meet the daily needs of horses and ponies.
- These supplements provide a balanced blend of macro and trace minerals, electrolytes, and vitamins essential for hydration, performance, and overall health.
- Use TruGuide your Trutsed Guide to supplement selection
- Dosage should be tailored to the horse’s size, workload, and reproductive status (pregnant or lactating mares require more).
- Regular use of a high-quality electrolyte supplement is one of the most effective ways to safeguard your horse against dehydration year-round
