Of the five basic nutrient groups: protein, carbohydrates & fats, water, minerals, and vitamins, water is the most commonly overlooked nutrient group for horses but is often the most critical to ensure the health of your animals. University research has clearly shown that horses with less than their required water amounts for only three days will not consume feed, and even a minor reduction in water intake or an increase in sweat loss can cause serious dehydration. This issue can result in decreased performance, shock, and even possible death of your horse.

Water serves four major functions in a horse’s body: regulating body temperature, transporting nutrients, removing waste, and digesting, absorbing, and using nutrients. Ideally your horses should have free access to clean drinking water comparable in quality to human drinking water. However, the specific amount of water your horse requires will vary greatly from horse to horse, depending on the size of the horse, the dry-matter content of the diet, the environmental temperature, and the production stage or activity of the horse. A good rule of thumb is that a horse will consume about one gallon of water per 100 pounds of body weight. For example, a 1,000-pound horse would need an average of 9-11 gallons per day.

Another consideration is the water content of the feeds in your horse’s diet. Most grains, commercial mixes, and hays contain around 10-12 percent water. Fresh forages in pasture could contain as much as 80 percent water. A horse requires two quarts of water per pound of dry matter consumed. So, our 1,000-pound horse consuming 20 pounds of hay per day would require 36 quarts or 9 gallons of water per day (20 pounds of hay consist of about 18 pounds of dry matter). Diets with extremely high dry matter content would in turn cause your horse to consume more water than under normal conditions. Horses typically reduce water intake during extremely cold weather like we experienced earlier in the year here in Martin County, which can cause an increase in impaction colic especially with high dry matter feeds. As a result, additional water intake should be encouraged prior to an expected dramatic reduction in water intake, like in the case of cold weather.

Water intake, conversely, increases during hot, humid weather – like we have experienced this past week – as your horse compensates for the additional fluid loss due to sweat. Research has shown that increasing the temperatures from 55-70 degrees will significantly increase water requirements of your horse. Meaning the 1,000-pound horse from our example who would typically consume about 10 gallons a day could elevate its intake to as high as 17 gallons.

Horses also have a preference in water temperature. Their preferred drinking range is between 45 and 65 degrees. They will still drink at temperatures above or below this range, but the responsible horseman would take some precautions to make drinking water more temperate. During freezing conditions, ice should be chipped and removed, and during hot weather water tubs or buckets should be kept in shaded areas to minimize direct exposure to sunlight.

Water should be freely available to horses always, exceptafter exercise. Hot horses should be hand walked until their body temperature is reduced before offering them free water access. Ideally, an exercised horse should be walked a minimum of 30-90 minutes before watering. Horses who consume large amounts of cold water before their body temperature reaches an equilibrium run risk of foundering as their digestive tract is largely inactive during exercise. You can monitor your horses body temperature by palpating the pectoral or chest muscle and the area behind the elbow, which are the last areas that the horse will exhibit a cooler body temperature.

For more information on the nutrient requirements of horses or other livestock, or any questions relating to livestock production or horticulture, contact Laura Oliver, Martin County Extension Director, at 789-4370 or laura_oliver@ncsu.edu.

The technical information in this article was sourced from the NC Extension Publication entitled “Horse Feeding Management” prepared by Dr. Robert Mowrey, Extension Horse Specialist, 1997.