Water will always be vital to any equine diet. It makes up to 68% of a horse’s body!

Water is also a critical component for aiding digestion and ensuring proper digestive health, among many other critical bodily functions. Therefore, it is always recommended that horses have 24/7, free-choice access to clean, fresh water. It is also a key management task to ensure your horses’ water sources are checked daily - even automatic waterers need to be checked daily to ensure they are functioning properly. 

Studies have shown horses prefer water at temperatures of 68°F (20°C) and will reduce their water consumption with cold or near frozen water. On average, a horse will drink 8 to 12 gallons of water per day, though intake can be over 20 gallons a day under certain conditions. There are many factors that will influence a horse’s water intake, including:

  • Exercise
  • Pregnancy and lactation
  • Weather
  • Age (older horses drink less)
  • Transport
  • Dry matter intake

After exercise, some owners do not allow their horse access to water out of fear of overdrinking or other health-related issues, such as colic or founder. Yet, research has shown that allowing a horse to drink as much water as they wish after heavy exercise is not detrimental to their health in any way. Horses will only drink enough water to fill their stomachs. Therefore, it is recommended to let horses drink as much as they wish, even after heavy bouts of exercise. The water should be at an ambient temperature. Salted water is also recommended as it helps encourage the horse to drink and helps replenish electrolytes lost during exercise.

The amount of dry matter a horse consumes will influence how much water they will drink. Horses kept on pasture will generally drink less, which is due to the moisture content in the forage they are eating. For other sources of feed, such as dry hay and concentrate, this will lead to a higher daily consumption of water.

Horses lose water primarily through sweating and respiration. For example, after one bout of light exercise, a horse will produce about 1 gallon of sweat. With heavy exercise, a horse may sweat up to 5 gallons. This is a substantial loss of water from the body that could lead to dehydration.

When horses do not drink enough water or are denied water for long stretches of time, they can become dehydrated. Dehydration is a dangerous condition for any horse. While a horse can survive for many days (if not weeks) without food, they can die within days without water. If your horse stops drinking for more than a day, you should consult a veterinarian immediately.

A combination of signs will be noticeable if a horse is dehydrated, which includes:

  • Abnormal behavior, such as lethargy and depression
  • Loss of appetite
  • Sunken eyes and flank, abdomen tucked up
  • Gums (mucous membranes) are dry and red
  • Dark urine
  • Skin tenting

A skin pinch test is often used as a test of dehydration in horses. This is simply done by picking up the skin, or gently pinching the horse’s skin around their neck or shoulder and letting it go. A hydrated horse’s skin should bounce back immediately. If a “tent” is seen, it would indicate the animal is dehydrated.

  

If you suspect your horse is dehydrated, there are steps you can take to encourage them to rehydrate. First, provide water to your horse and allow them to drink at 10-minute intervals until they have had their fill. In general, you can encourage horses to drink an acceptable amount of water daily by providing a salt block. A more reliable method is to top dress the horse’s daily ration. Up to 6 ounces (150 grams) of salt (divided between two meals) can be fed each day during the hot summer months or when under heavy exercise. As mentioned above, you can also add salt to water in a bucket, which will assist in encouraging them to drink.

While not covered in this article, it is also essential to replace a horse’s electrolytes after bouts of exercise or activities that cause them to sweat. Salt replaces some electrolytes but does not address others like potassium or magnesium. There are commercial products available to help a horse replace their electrolytes and you can reach out to us if you have any questions or concerns.
 

Chris J. Mortensen, Ph.D.