By: Dr Rosie Alcorn BVSc PG Cert VPS Cert AVP MRCVS
As temperatures rise, maintaining adequate hydration in horses becomes a critical aspect of equine welfare. Water is often the most overlooked nutrient, yet it plays a vital role in nearly every physiological process in the horse’s body. As the old adage goes, “You can lead a horse to water, but you can’t make it drink.”
This article explains how horses use water, how much they need daily, and provides practical, science-based strategies to encourage water intake, especially during hot weather, travel, or strenuous activity.
Approximately 70% of an adult horse's body is composed of water. It functions both within and between cells, supporting critical systems such as:
Circulatory health – maintaining blood volume and transporting nutrients
Digestive processes – aiding the breakdown and movement of feed
Waste elimination – enabling proper kidney and gut function
Thermoregulation – allowing sweat-based cooling to regulate body temperature
Joint and muscle function – supporting movement, flexibility, and performance
Even a 2% reduction in body water can impair thermoregulation and performance. Early signs of dehydration in horses include lethargy, reduced appetite, and poor recovery after exercise. If not addressed, dehydration can lead to colic, metabolic disturbances, or even death.
As a general guide, horses require approximately:
50 ml per kg of body weight per day
→ For a 500 kg horse, this equals around 25 litres per day under normal conditions.
However, water requirements increase significantly due to:
Exercise or heavy sweating
Hot or humid weather
Lactation
Long-distance travel
Illness or diarrhoea
This makes constant access to clean, fresh water essential. Buckets, troughs, and automatic drinkers should be cleaned regularly to prevent contamination, algae growth, or stagnation.
While most horses will drink adequately when at home, stress, travel, or unfamiliar surroundings can reduce intake. Here are evidence-based strategies to encourage hydration:
Horses are sensitive to water taste and cleanliness. Clean containers regularly and replace water frequently, especially during hot weather or when travelling.
At shows or in transit, access to water may be limited. Offer small amounts regularly, particularly in warm conditions or after exertion. Always bring fresh water and avoid letting it sit in heat.
Fresh pasture contains 60–80% water and contributes significantly to hydration. Horses on hay or dry forage require more supplemental water.
Adding water to feed-such as soaked hay cubes or beet pulp-can significantly increase fluid intake. Many horses enjoy a wet mash, even if they are reluctant to drink plain water.
Keyflow's Pink Mash is a super product for ensuring your horse stays hydrated. If you are struggling to get your horse to drink, try adding a small amount of Pink Mash to a bucket of water to encourage them to drink.
Electrolytes replace minerals lost in sweat and may stimulate thirst. Plain salt (sodium chloride) can also encourage drinking when added to the feed. Always provide access to clean water alongside.
Note: Electrolyte supplementation will be covered in more detail in a future article.
Flavouring water with a small amount of apple juice, peppermint extract, or molasses can make it more appealing, especially useful when travelling or dealing with unfamiliar water sources.
Some horses are highly sensitive to changes in water taste or mineral content. Bringing water from home or using pre-flavoured water may encourage drinking in unfamiliar settings.
Hydration management involves more than simply offering water. By understanding how much water a horse needs and applying targeted strategies to increase intake, owners can support their horses’ health, recovery, and performance. Prioritising hydration - especially during hot weather, travel, or competition - helps ensure your horse stays healthy, happy, and ready for work.
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