Keeping your horse hydrated

Summer is here at last and nothing's nicer than a long hack on a summer's day, but it's important to make sure that both you and your horse stay well hydrated in hot weather.

The body contains 60-70% water and this water plays an essential role in transporting blood cells and nutrients around the body. The water in the body is also important for thermoregulation - during exercise sweat is produced, which then evaporates from the skins surface helping us to keep cool. Sweat also contains electrolytes including sodium, chloride, potassium, calcium and magnesium. These electrolytes play an important role in both nerve and muscle function.

The Effects of Dehydration

Bodyweight loss

Result of water loss on the body.
Clinics in Sports Medicine 13, 235-246 (1994)


Normal heat regulation and performance


Thirst is stimulated, performance begins to decline


Decrease in heat regulation, worsening performance


Continuing decrease in performance, muscular endurance decreases


20-30% decrease in performance, dizziness occurs


Headache, irritability, nausea, fatigue


Weakness, severe loss of thermoregulation, heart races



Dehydration occurs when you or your horse lose excessive amounts of water and electrolytes. If you become dehydrated you might notice that you feel dizzy, cannot concentrate or even feel sick. In your horse signs of dehydration can include decreased appetite, increased risk of impaction colic and reduced athletic performance. It's amazing how much sweat your horse can produce; for example after a cross country phase horses can lose 15-20 litres of sweat and an endurance horse could lose double this during a race!

It can be difficult to monitor how much your horse is sweating and the skin-pinch test is very inaccurate. However, a good way of estimating fluid losses is to use a weigh-tape. It is generally accepted that 90% of a horse's weight loss after exercise is due to sweating and 1kg of bodyweight equates to approximately 1 litre of fluids. Following initial research on 100 horses at Warwickshire College our scientifically validated weigh-tape has been used to measure post-exercise body weight losses at Burghley Horse Trials.

Fluid and electrolyte losses must be replaced to avoid dehydration. Simply drinking a bottle of water or offering your horse water after exercise will not be enough to re-hydrate properly as the body cannot hold onto water without the presence of electrolytes. Drinking a sports drink that contains electrolytes will help you re-hydrate and replenish any losses. Similarly if your horse is losing more than 10kg of body weight after work you will need to feed an electrolyte supplement such as Dodson & Horrell Electrolytes.

For more information on keeping your horse hydrated this summer call our Nutritional Helpline on 0845 345 2627