06/20/2026
Water Consumption in Horses
Brian S. Burks, DVM
Diplomate of the American Board of Veterinary Practitioners®
394 Fox Road
Apollo, PA 15613
(724) 727-3481
www.foxrunequine.com
There is an old adage that says “You can lead a horse to water but you can’t make him drink.” Veterinarians have ways around this for dehydrated and impacted horses, but the idea is to prevent dehydration in the first place. It sounds simple, does it not? Unfortunately, getting horses to drink is not always that simple. Water consumption changes with a multitude of factors: age, body condition, fitness level, workload, reproductive status, environmental conditions, diet, and disease processes. Additionally, water temperature, freshness, purity, and palatability also play a role.
Adult horses are about 60% water, and water is the most important nutrient for life. Horses require water for almost every body function, including vision, breathing, joint lubrication, protection of the CNS, digestion, waste excretion, and thermoregulation. Provision of fresh, clean water is paramount as it is incorporated into every cell of the trillions in the equine body.
Daily, horses have a minimum need for water to survive at rest, which is about 5-10 gallons per day for an average horse, with an ambient temperature of 68 degrees. If the horse is working, the temperature is high, lactating, or the horse has a medical issue, this can more than double or triple. Water comsumption will range between 11 and 15 gallons for the same horse at 86 degrees F, and 19-24 gallons when exercising moderately in 95-degree heat. Water is excreted through urine, f***s, respiration, skin losses and sweat, as well as in milk during lactation.
Hormones regulate water balance and hydration in mammals. Antidiuretic hormone (ADH) from the pituitary gland regulates sodium and water levels in blood, so that if not enough water is consumed, ADH signals the kidneys to retain water in order to dilute blood. Urination will be less and urine will be more concentrated. If there is inadequate sodium intake, the hormone aldosterone signals the kidneys to retain sodium and excrete potassium. Monitoring fluid balance is a function of electrolytes, which are either positive or negative ions, which can create shifts of body fluids and electrolytes to adjust for hydration and health.
It is important to monitor water intake and your horse’s hydration status by monitoring for an elevated heart or pulse rate (28-40 beats per minute is normal for an adult horse). Watch the manure for moistness and for mucus. Heavy mucus indicates that f***s have been sitting in the GIT for too long. The horse should be examined by a veterinarian. You can also check the gums for color and moistness; when the gums are blanched by pushing on them with your thumb, the pink color should return in under two seconds. Longer than that is an indication of dehydration. Pinching the skin on the upper eyelid will indicate dehydration if it does not quickly return to its normal state.
Changes to those vital signs will occur when the horse is 4-6% dehydrated. Visual signs such as a sunken eyes and a tucked up appearance to the abdomen are also indicators, but they are typically seen with increased levels of dehydration approaching 8-10% dehydrated. Unfortunately, the horse’s performance (work, competition, or reproduction) will become adversely affected when the horse becomes 2% dehydrated, before visual signs become evident. Get to know what is normal for your horse, which will make abnormal more easily recognized.
Water intake may decrease if on lush pasture, as fresh green grass is about 60-80% water. Maintaining a horse in a dry lot on hay with 12-15% moisture increases water consumption. The amount of protein in the diet also influences water intake. Horses fed alfalfa hay with 21% protein will consume more water than one on 9% protein grass hay.
Water consumption has been studied and researchers have found that water consumption is best when the water temperature is between 45° to 65° F, with more consumption occurring at the warmer temperatures. Natural water sources may not be these temperatures, weather dependent. When water freezes, consumption dramatically decreases, and impaction colic may occur when the ingesta no longer has enough water to progress. Adding a few tablespoons of table salt to the forage or grain several times per day can help keep horses drinking. Salt blocks vary widely in actual salt content, and mineral blocks do not have enough minerals to make sure the horse receives enough. With plenty of fresh water available, salt overages are not a problem; however, some horses will leave salt on the bottom of the feed trough, eating all the grain. (Do not go too crazy on the salt- it can cause problems).
Water palatability and cleanliness also influences how much water the horse consumes. Horses will consume creek water that is fresh and not stagnant, low in contaminants such as fertilizers or herbicides, and has acceptable salinity. Horses are overly sensitive to changes in taste or smell of water, making water a problem when traveling. For instance, if the horse drinks un-chlorinated well water normally and is taken to a show where chlorinated city water is available, consumption often decreases. Horses can be conditioned to drink chlorinated water or that with a different mineral content by using something to mask the taste. These include Gatorade®, Kool-Aid®, cherry Jell-O® or even Coca-Cola®. The masking can be started ahead of anticipated changes, and the amount of additive can be gradually decreased as the horse begins to consume the new water source.
Horses that have never had access to natural water sources, drinking from troughs and buckets or automatic water sources, may not initially drink from a creek or spring. Having other horses around that are used to this, they will learn by example. Close observation is critical to make sure that the horse does not become dehydrated. Some horses may have to be offered a bucket if they are not drinking from the natural water source. Most horses have no problem with the transitions.
When horses do not consume enough water, they become dehydrated. Mild dehydration can be corrected by offering fresh, clean water in most cases. As dehydration worsens, more than 5% dehydration, a veterinarian will need to be consulted for appropriate fluid and electrolyte therapy, along with treating any underlying medical condition causing the dehydration. It is imperative that owners and caretakers recognize signs of dehydration before there is a serious problem. Make sure that horses are offered clean, fresh, palatable water as this can adversely affect performance.
It may seem simple to put water out and lead the horse to it, but there are many factors involved in getting a horse to drink. Water is the most important nutrient in the diet.
Hydration Tips and Tricks
• Fresh, clean water should always be available. Hot, humid weather conditions will increase water consumption.
• Salt should be available free choice or administered daily to satisfy maintenance requirements of sodium. Electrolyte supplementation is specifically to replace minerals (especially salt) lost through sweat.
• Plain white salt should be made available as a block or as loose salt, even while traveling at horse shows. Avoid mineralized (red) blocks as some horses will not consume them because of the bitter taste. Or, if they are sweetened with sugar or molasses, equines may consume too much. Horses do not self-regulate mineral consumption (with the exception of edible salt). Such blocks often do not contain enough salt.
• A 5-pound salt block (white) should be consumed within two months. If a horse is not consuming at this approximate rate, try offering loose salt instead. Salt blocks and bricks were created for cattle with rougher tongues, and some horses do not like to use that form. Loose salt may be useful to try especially in cold weather when the blocks can freeze and are less inviting to use.
• For maintenance purposes, an ounce of salt (about 2 tablespoons) is an appropriate amount to add to a horse’s daily diet in cool weather and can be doubled in hot and humid conditions.
• Supplementary electrolytes may be necessary to replace those minerals lost in sweat from hot temperatures, humidity or heavy work.
• Horses need access to fresh water after receiving electrolytes. If electrolytes are offered in the water, provide an additional fresh water source as well.
• To prevent ulcers, give electrolytes with feed, or wait until after the horse has eaten to administer. For orally syringed electrolytes, use a liquid antacid or small amount of vegetable oil as the carrier for electrolyte powder.
• Administer electrolytes immediately after the horse has had a drink, preferably after a few gallons.
• Electrolytes are minerals with a very long shelf life. Keep some on hand at the barn for when needed.
• Check the label. Electrolyte supplements should not contain sugar. Salt should be the first and primary ingredient and at least 75% of the total.
Fox Run Equine Center
www.foxrunequine.com
(724) 727-3481
