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 out for an endurance ride or put him in your trailer or lorry and tried to get him to drink away from home, knows the problem all to well! We’ve all been there – horses can be difficult.

Some horses are like pigs: they drink up anything. Others seem to have a more delicate palate and little interest in drink altogether. Some horses are too wound-up during and after hard exercise to drink water in unfamiliar surroundings, their attention is elsewhere. Some might be fussy about the taste of the venue’s water or they might be stressed from the journey. In these situations your horse may not think he is thirsty and therefore it does not occur to him to drink. But in situations such as these it is very important to get your horse to drink.

If your horse won’t drink water when he needs to, you can run into serious health problems with dehydration, loss of performance, fatigue, tying up – and even colic.

Dehydration prevention is especially important during the warmer weather of spring and summer. Serious cases of dehydration have killed horses in as few as two days, and dehydration losses of as little as 4% can impact your horse’s health. The difference between a horse with 4% dehydration and one with 10% (in very serious trouble requiring immediate veterinary attention) is just 30kgs loss of bodyweight or 30 litres loss of fluid --- roughly 3 hours sweating during an endurance ride.

Even minor dehydration can have a negative impact on performance. For human distance runners, running pace is slowed by 2% for every 1% loss of body weight due to dehydration. A runner capable of running 10,000 metres in 35 minutes may be slowed by 2 minutes and 48 seconds. That’s well out of the top ten! If this decrement in running performance is applied to an endurance horse capable of a nine-hour 100-mile ride, then a 4% loss of body mass (an average loss seen on most rides) could increase ride time by about 45 minutes. Many horses are dehydrated by 5-8%, so this could increase ride time by over one hour, and maybe out of the top ten!

Fluid losses tend to occur early in the ride, even though your horse might look normal. Research conducted at endurance rides has demonstrated that many horses experience the greatest loss of fluids and electrolytes within the first 20 miles of exercise. During a 32kms ride, or trotting the first loop of a longer ride, your horse will produce enough heat to bring 15 gallons of water to the boil! This is true regardless of weather, it is internal.

Signs that you might want to look out for are dry mucous membranes, sunken eyes, fatigue, high heart rate and respiratory rate that doesn’t come down with proper cooling-out measures, or colic. It may not be that obvious there is a problem especially as dehydrated horses have been shown to sweat less than normal animals.

While a person might shed two litres of sweat in an hour, an endurance horse has the potential to sweat 15 litres in an hour. Add to this the potential for your horse to not drink well on the journey to the ride, or when corralled or stabled, then his water intake might be considerably reduced and dehydration started prior to the first drop he sweats.

In no instance is the adage “you can take a horse to water but you can’t make him drink” more appropriate than with horses in a state of dehydration. This is because a horse’s thirst response hinges on the salt concentration in his blood. In instances of heavy or prolonged sweating, your horse will lose water and salt equally but because there is no build-up in salt concentration in his body, his thirst sensors fail to recognise this loss of water. So, even though your horse is clearly dehydrated, he will not drink. He is not stubborn – his body is just not giving him an early enough warning signal.

This problem is compounded by the fact that horses have significant muscle mass and can generate a tremendous amount of muscle heat and will sweat profusely when worked hard in warm temperatures. As a result, horses are more susceptible to dehydration than most other animals. They will lose more body fluids and the ionized minerals (electrolytes) that they contain. When muscles contract, ionised potassium passes through cell walls into body fluids. These fluids, which contain concentrations of sodium and chloride ions, absorb the potassium. Sodium and chloride ions from body fluids are absorbed by the muscle cells. As the ion composition in the muscle cells and body fluids become similar due to the exchanges taking place during exercise, muscle fatigue occurs which can lead to cramps and tying up. The dehydrated horse has lost body fluids and the electrolytes found in them. He will exhibit muscle fatigue, a lack of will to win, poor recovery from exercise and/or skin which when pinched is slow to return to normal.

Whether your horse turns his nose up and won’t drink water or acts like an eight-year old child refusing to take his medicine, the good news is there are water-enticing strategies that you can use to try and encourage your horse to drink, enabling you to relax and enjoy your ride instead of spending the entire day stressed out and worrying about dehydration.

One way is to bring supermarket water or water from home, although this isn’t always practical given your horse can drink a minimum of 10 gallons a day! Add to this the excitement of the away day and even this can be refused. Try offering sloppy sugar beet water or putting an apple, carrot or peppermint additive into water. Endurance GB Supreme Champion Thay Stephenson uses new product Horse Quencher. “Horse Quencher is simply a brilliant addition to any endurance rider's equipment and undoubtedly was a huge benefit in my and Bull’s success in 2009. Bull has always avoided drinking for 25-30km no matter what concoctions we offered him but since using Horse Quencher, he simply cannot resist and will drink whenever it is offered. I believe this has effectively kept everything so much more in balance, he has finished even strenuous events looking fresh and without any loss of condition, and therefore it has been so much easier to go on to the next competition with confidence and conviction,” she explained.

Offer your horse water in a quiet area, where he will not be disturbed by all the action around him. Always wait for your horse to drink – give him a minute or two to relax. Hold the bucket waist-high. Horses in strange environments don’t want to hide their head in a bucket, they want to keep a watch out for danger. 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 keep everything as similar as possible to your routine at home. Use the same containers and if you are going to use new additives or products, introduce them at home first.

Try and get your horse to drink before you leave home and again 30 minutes before the start of your ride. At water stops and crewing areas, if possible wait until all horses closest to you are done drinking before leaving. The herd instinct is so strong that some horses won’t drink if they are distracted by the fear of being left behind.

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. And if your horse is stiff after a day of severe exertion, hold his water up to him.

Water is the most important nutrient that horses need to consume daily and regardless of your level of endurance, keeping your horse hydrated throughout the season is an important consideration. He will run faster and for longer and he will have fewer health problems with all the fresh water he can drink. Even the slightest dehydration affects your horse adversely and prevention is the best medicine.