Proper electrolyte levels are crucial to a number of essential functions in the horse’s body, including regulating the smooth muscles of the digestive tract and maintaining normal hydration levels. The concentration of sodium within and between cells determines the movement of fluid in the body. Additionally, high concentrations of sodium in the blood trigger thirst. The number one cause of colic during winter months is dehydration.
An idle, 1,100-pound horse in a cool environment should drink 6 to 10 gallons of water per day to maintain sufficient hydration. That amount may increase to 15 gallons per day in a hot environment. Horses in moderate to heavy work require 10-18 gallons of water per day on average but could require much more in hot weather. Nursing mares drink more water because of fluid loss and increased feed intake to support lactation- up to 20 gallons of water per day. Foals also have higher water requirements and will drink 6 to 8 gallons of water per day even in relatively cool weather. When a horse is chronically dehydrated the risk of impaction colic increases.
In times of heavy work or hot weather, horses can lose an impressive amount of electrolytes in a very short period of time through sweat loss. However, even when the horse is at rest and the weather is cool, they still lose approximately 10g of sodium, 25g of potassium, and 40g of chloride per day. Thus, electrolyte levels need continuous daily replacement.
Adequate daily forage is a good source of potassium and typically meets a horse’s daily needs. However, forage is low in sodium and chloride and typically only provides 50% of the required daily sodium. This explains why all horses need year-round daily sodium supplementation. The simplest way to ensure adequate daily sodium intake is to provide a supplemental source.
Some commercial feeds and supplements contain added sodium, but it is often not in sufficient levels and can vary greatly from product to product, so be sure to check the label. Luckily, an inexpensive and readily available source of sodium chloride exists- SALT! Regular table salt or sodium chloride is approximately 61 percent chloride and 39 percent sodium. 2 tablespoons (1 ounce) of table salt will provide 10g of sodium and meet your horse’s daily sodium requirement.
There are many different types and forms of salt on the market today, including many creatively marketed products for horses. If your horse strongly prefers a particular brand/type of salt, it may be a good choice but be sure to check the label. Regardless of the product you chose, salt in loose form is best. Studies have shown that horses will not adequately lick sufficient daily levels of salt on a long-term basis from salt blocks, particularly in cold weather. Most horses find salt very palatable and will readily consume salt top-dressed over their feed.
While there are many other factors to consider in reducing colic risk, by providing adequate year-round daily salt supplementation, you can ensure your horses’ sodium requirements are met, which may help lower the risk of dehydration-related colic.
References:
Cold Weather Colic. Dr. Scott Leibsle, DVM. AAEP. 2016.
Understanding Electrolytes. Dr. Clair Thunes. Summit Equine Nutrition. 2010
