Regular transportation is a common part of the endurance horse’s life and can cause water and salts to be lost through sweat.

Standing in a trailer or lorry is not at all the same as standing in a box. One research study showed that horses' energy expenditure during travelling was equivalent to that needed for walking. Rough and winding roads (or poor driving!) will require continuous adjustments by the horse in order to maintain his balance. This burns energy and can result in a very tired horse at the end of a long trip.

Horses with a nervous disposition or those with little travel experience generally stop drinking. These horses will expend more energy and be more fatigued after a trip than the old campaigner.

Research has shown that horses can lose 0.5% of their bodyweight every hour they travel, which is 2.5 litres of fluid for a 500kg horse. Much of this loss is due to sweating, and when compounded with the physical tension of constantly balancing themselves, can lead to severe dehydration. Lack of fluid in the gut can lead to impaction, and low fluid levels in the body may cause a horse to tie up or suffer from other muscle problems.

In hotter conditions your horse’s losses through sweat will be even greater. If your horse does not drink on the lorry or does not like the new water at the venue, then its water intake will be considerably reduced and dehydration started before it even begins on the ride. If not corrected, these may develop into serious complications for your horse with the added stress of continuing the performance.

The problem is compounded two-fold.

Firstly, horses are more susceptible to dehydration than other animals. They have significant muscle mass and generate a tremendous amount of muscle heat and will sweat profusely, especially when travelling in warm temperatures.

Secondly, horses that become dehydrated when travelling may not drink despite a drop in body fluids because water and salts are lost equally in sweat. Because there is no build-up in concentration of salts in their bodies, your horse’s thirst sensors fail to recognise this loss of water. Even though your horse is clearly dehydrated, he will not drink.

Dealing with a poor drinker takes some originality and resourcefulness but it can be done. If your budget stretches to it, try bottled supermarket water or water brought from home, although this isn’t always practical if you are travelling several horses, given one horse can drink up to 10 gallons a day! Try offering sloppy sugar beet water although again this can be messy, especially on a long and winding journey! Other water-enticing strategies include putting a carrot or apple cordial into the water, or new product Horse Quencher. Gina Miles, American event rider and Olympic Silver Medallist, used the product in Beijing. “Whenever I travel with my horses, I worry they won't drink enough; with Horse Quencher, my top horse McKinlaigh drank like a champ on the long flights to the Olympics.” Denis O’Brien, Assistant Manager Shadwell Stud, is also an advocate of the product. “The hydration of horses when travelling can be overlooked and Horse Quencher will assist those who reduce their fluid intake while being transported nationally and internationally.” If horses are introduced to these additives at home, they should drink them readily at competitions.

When you stop en route, always wait a while for your horse to drink – give him a minute or two to relax. Your horse will usually drink more in the trailer/lorry when his bucket is held up to him – then he does not have to lower his head to the ground, when he may feel vulnerable because his vision is restricted. If it’s a cold day, bring a thermos and add some warm water to his bucket. Recent research has shown a 40 per cent increase in water intake when horses are offered warm water on cooler days. In general, fussy drinkers tend to be more nervous and highly-strung so try to use the same buckets as those used at home.

Electrolytes can also be given to replace important body salts lost through sweat but they are only useful when your horse is already hydrated. If your horse drinks just electrolyte water, that may in the long run contribute to him becoming dehydrated because it increases urination. Don’t give your horse dry hay or a dried-out net of haylage after a ride or on the way home as this will make him more dehydrated, both draw water into the hindgut that the horse needs elsewhere in the body.

Hydration is very easy to balance in humans but is not that easy to balance on a horse. Every one of you who has taken your horse in a trailer or lorry and tried to get them to drink, knows the problem all to well! We’ve all been there – horses can be difficult. We tend to take water for granted but horses need water above all else to survive. Dehydration is one of the more serious problems that can occur when horses are travelling. Even the slightest dehydration can affect your horse adversely and prevention is the best medicine.