Maintaining Hydration in Horses: The Roles of Water and Salt By Mary Beth Gordon, PhD
The old adage is accurate: “You can lead a horse to water, but you can’t make him drink.” That’s especially true for severely dehydrated horses in medical crisis. But there are ways to keep your horse well-hydrated from the start and avoid these potentially dangerous scenarios.
First, provide fresh, clean water in clean troughs or buckets at all times. Check frequently for dirt, debris, manure, dead animals, or other contaminants. (These truly are deterrents: I have seen horses dehydrated and colicking in a paddock because they would not drink water from a trough with a dead opossum in it.) Scrubbing dirty troughs and buckets and refilling them is part of the nitty-gritty of horse keeping–don’t overlook this important first step.
In cold weather horses drink less water, especially if the water is cold as ice (or literally is ice). Warm up the water in the wintertime by regularly adding hot water or by using bucket or trough heaters. Studies have shown that horses prefer drinking water that is around 50°F.
On the other hand, horses drink more water in hot and/or humid weather conditions, especially if they have been exercising and sweating. Horses’ water intake can double under these circumstances, so make sure they have enough fresh, clean water; refilling water receptacles frequently or add buckets/troughs as necessary to account for this increase in water intake.
Next, make sure your horse’s diet is meeting his sodium requirements; correct sodium balance in the horse is necessary for proper thirst response and body water equilibrium. There are multiple ways to provide salt to your horse. Salt blocks or salt licks are an affordable and convenient approach. However, researchers have shown that individual intake of salt from these blocks is highly variable, and horses might not consume enough salt from these sources to meet their daily sodium requirements, especially if they are exercising and sweating regularly.
Offering plain, loose table salt free-choice or along with daily concentrate meals is another way to supplement sodium in a ration. This is also relatively convenient and inexpensive, but it’s important to consider these points when choosing this option as well: Top-dressing large quantities of salt can lead to inconsistent intake (some horses can sort salt from the feed with their lips, leaving the supplement uneaten) or palatability problems (top-dressed salt can reduce feed consumption because some horses might not like the taste).
Additionally, researchers at Oklahoma State University showed that feeding repeated daily doses of electrolytes (which are compounds typically used in a similar fashion to salt, usually containing sodium, potassium, and chloride) correlated with an exacerbation of gastric ulcers. If you have a horse prone to ulcers, discuss the type and amount of salt or electrolytes you feed with your veterinarian to help prevent additional damage.
At this point, you might be wondering, “Do I need to supplement at all? Doesn’t my feed and hay cover the sodium requirements for my horse?” And this is a great question, to which the answer is: Maybe. Sodium content varies widely among hays—with most offering low amounts—and horse owners should not rely on hay for meeting horses’ sodium requirements. Commercial concentrate feeds usually contain some sodium, typically as added salt at 0.1 to 1.0%. This might be enough for some horses at rest, in addition to their hay, but once horses begin exercising and sweating, sodium requirements must be met with supplementation. In these cases, provide salt or seek a product that offers sodium in sufficient amounts to meet body hydration requirements and maintain thirst response while, importantly, retaining palatability.
In conclusion, it’s simple to keep your horse hydrated if you follow some simple steps: Provide plenty of clean, fresh water and ensure horses’ diets meet their sodium requirements. If concerns arise about a horse’s hydration or sodium status, contact a veterinarian or equine nutritionist for further advice.
About the Author
Mary Beth Gordon, PhD, is the Director of Equine Research and New Product Development for the horse business group at Purina Animal Nutrition. Her duties include research, analyzing data, scouting for new products, reformulating older products, and working to improve the health of the horse through nutrition.