Horses need six different classes of nutrients—carbohydrates, protein, fat, minerals, vitamins, and water. Adequate water intake is imperative to equine well-being and horses, just like other mammals, must be hydrated to maintain normal bodily functions including digestion and thermoregulation. Monitoring your horse’s water intake and encouraging adequate hydration are key aspects of nutritional support.

How Much Water Should I Give My Horse?

Before you evaluate your horse’s water intake, understanding their basic requirements can be helpful in creating an optimal plan. “Maintenance water intake for a 1,000-pound horse can range from 6-12 gallons (27-54 L) daily or more,” says Stephanie Whalen, DVM, associate equine veterinarian at Troy Equine Services, in Sheffield, Ontario. “Some horses do not readily drink this volume and need some added encouragement.”

Increasing Your Horse’s Water Intake

There are a variety of tactics to encourage horses to drink enough water. “General strategies for encouraging water intake include maximizing their access to water, optimizing the condition of the water, increasing their thirst, and increasing the water content of their food,” says Whalen.

Owners should also consider herd dynamics to maximize their horses’ access to water in a group setting. “It is important to observe if any dominant horses are preventing lower-ranking horses from reaching the water regularly,” says Whalen. Additionally, be sure to maintain the footing near the water source so all horses can safely and easily access their water no matter the season, she adds—for instance, in colder climates winter often means uneven and frozen footing that can hamper accessibility.

Horse owners might consider adding salt to their horses’ feed to increase thirst. “Adding salt to the horse’s diet is necessary for a healthy nervous system and for proper water balance,” says Juliet Getty, PhD, equine nutritionist, owner of Getty Equine Nutrition, in Denton, Texas. “By providing enough salt (sodium), the horse will sense that they are thirsty and will seek water.”

Salt can be provided to horses several ways. “A full-sized horse requires at least 1 ounce (2 tablespoons) of salt per day year-round,” says Getty. Horse owners can provide both loose salt and salt blocks to supplement their animals with sodium; however, both Getty and Whalen note it is challenging for horses to consume their daily sodium requirement from a salt block/lick.

“Salt blocks were originally intended for cattle, (which have) rough tongues,” says Getty. “But the horse’s tongue is smooth and can become irritated with too much licking. A much better way to provide salt is by adding it to your horse’s meal.”

Adding water to your horse’s feed can also help increase their daily water intake. “Feeding soaked hay cubes or other soaked feed increases a horse’s water intake,” says Whalen. (Feeding soaked cubes is also a good way—for horses that find added salt unpalatable—to decrease the salty taste of a meal without adding concentrate.) “The amount and type of soaked feed will depend on your horse’s nutritional needs. Partially soaked hay cubes, with a softened outside but dry core, are a risk for choke (esophageal obstruction) in horses and, therefore, cubes should be soaked thoroughly,” she adds.

Considerations in Cold Weather

Researchers have shown that horses will drink more warm water than cold during winter, so many equine nutritionists recommend owners maintain their horses’ water source above freezing. “Good hydration is important to prevent impaction colic,” says Whalen. “This is especially true since in colder climates, pasture (and its moisture content) is not available in winter, and horses are instead eating dry hay. Horses may also be ingesting increased amounts of hay to maintain their body heat, necessitating good hydration to prevent impaction colic.”

“If your horse’s water trough freezes over during the night and you have to take a hammer to it in the morning, you are taking a large risk with your horse’s water status,” adds Getty. “Therefore, it is absolutely necessary that a heated water source is available. … (These) will heat the water to a mild 50 degrees Fahrenheit (10 degrees Celsius), an optimal temperature for water consumption,” says Getty.

Still, there are some additional considerations you must make when using them to ensure your horse is staying adequately hydrated. “Trough heaters or heated buckets are valuable tools, but they must be checked daily in case of malfunction such as allowing freezing or causing electric shock,” says Whalen. This check can be as simple as using a voltmeter or scheduling an electrician to come out and check. Looking at the water source daily will also give you a good idea of how much the water level typically drops—this will make it easier to recognize a sudden change in water consumption.

Has Your Horse Had Enough to Drink?

Providing adequate access to water is crucial, but you also need to be able to evaluate your horses’ hydration status. “The most reliable external parameter to monitor hydration is checking the mucous membranes for a slippery texture,” says Whalen. “Carefully reach under the upper lip to palpate along the gums and side of the mouth, noting whether the saliva feels slippery or tacky.” It is important to make a habit of performing this check even when your horse is in good health because it will give you a sense of what their normal is.

“Note that the mucous membranes will feel more slippery immediately after taking a drink, even if the horse is dehydrated,” adds Whalen. Another common hydration test is the skin-pinch or skin-tent test, where you pinch a fold of skin on the horse’s neck or shoulder to see if it springs back into place within 2 seconds of release. “A skin tent test can be assessed, although more variation exists between young and old horses as the skin elasticity changes,” says Whalen.

These tests are important because even mild dehydration can be detrimental to your horse’s health: “Muscles get tired and can tie up, and colic risk increases due to decreased intestinal motility,” says Getty. “The best barometer of hydration is to offer the horse a drink of temperature-controlled water. You ‘cannot make them drink,’ as the old saying goes, but if they do drink, then you know they needed it. If their thirst mechanism is out of whack because of not enough salt, feed them something that they enjoy and add some salt to it, while keeping water nearby.”

Take-Home Message

Overall, maximizing access to water and providing a high-quality water source are imperative to your horses’ well-being. Providing heated water in the winter, keeping water sources clean (free of bacterial growth and algae), and checking them regularly can help increase water consumption. Additionally, ensure that the water sources are easily accessible for all horses in the herd.