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15 September 2014

Hydration, it’s more than a drop in the bucket

by Lucinda Stapleton


Hydration is very easy to balance in humans but is not that easy to balance in horses. Every one of you who has taken your horse out for a long day’s ride or put him/her in your trailer and tried to get them 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 per cent can impact your horse’s health. The difference between a horse with 4 per cent dehydration and one with 10 per cent dehydration (in very serious trouble requiring immediate veterinary attention) is just 30kgs bodyweight loss or 30 litres of fluid --- a difference of 3 hours sweating in an endurance ride.

Even minor dehydration can have a negative impact on performance. For human distance runners, running pace is slowed by 2 per cent for every 1 per cent 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 decrease in running performance is applied to an endurance horse capable of a nine-hour 100-mile ride, then a 4 per cent 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 per cent, so this could increase ride time by over one hour.

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 32-kms ride, or trotting the first loop of a longer ride, your horse will generate enough heat to bring 15 gallons of water to the boil. This is true regardless of weather, it is internal.

Signs that you should 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, a 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, the horse loses water and salt equally but because there is no build-up in salt concentration in his body, the horse’s thirst sensors fail to recognise this loss of water. So, even though your horse is clearly dehydrated, he will not drink. He’s not stubborn – his body is just not giving him an early enough warning signal.

This problem is compounded by the fact that horses are more susceptible to dehydration than other animals because they have significant muscle mass which generates a tremendous amount of heat, making them sweat profusely when worked hard in warm temperatures. This causes the horse to lose body fluids and the salts that they contain. The horse usually

sweats in an attempt to cool himself. When faced with the choice of overheating or dehydrating, your horse chooses to dehydrate, using up water to keep cool. But there is a limit to your horse’s water reserves, and as he begins to run out of body fluid, his temperature climbs. A dehydrated horse without sufficient fluid to stay cool may suffer a three degree increase in temperature per hour of moderate exercise. Your horse can lose up to four gallons of fluid per hour when he works hard in hot weather. If the air is dry, sweat evaporates quickly and cools the horse. But if the air is humid, sweat won’t evaporate.  Your horse stays hot and clammy and sweats even more in an attempt to cool off.

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 your own water, although this isn’t always practical given a horse can drink seven gallons a day! Add to this the excitement of the away day and even home water can be refused. Instead try offering sloppy sugar beet water or putting an apple, carrot or peppermint additive in the water. Senior and Supreme Champion Thay Stephenson used new product Horse Quencher as part of her 2009 campaign. She says: “Bull has always avoided drinking for 25-30kms no matter what concoctions we offered 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.”

Other strategies include offering 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 manger-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 cold days. In general, fussy drinkers tend to be more nervous and highly-strung so try to keep everything as similar as possible to the routine at home. Use the same containers and if you are going to use new additives or products, try them at home first. Electrolytes can also be given but they are only useful when your horse is already hydrated.  Try and get your horse to drink before you leave home and again 30 minutes before the ride so that he can stay hydrated throughout the event. At water stops and crewing areas, try to wait until all horses close to you are finished drinking before leaving the watering place. The herd instinct is so strong that some horses won’t drink if they are distracted by the fear of being left behind. Don’t give your horse dry hay after competition – it will soak up water 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.

Lucinda has very kindly offered to send a free sample to anyone who cares to get in touch. Contact her at or 01842 879161. For more information

There is also a very interesting and useful item on HQ and electrolytes on the FAQs on the website.