But now I’m concerned. Is it okay for him to drink that much water with electrolytes? Why would he drink so much? I’ve read about adding things like apple cider vinegar to water. Would that be better than using the electrolytes?

A.It’s great you’ve found a convenient way to encourage your horse to drink more water when he’s stalled. This is something a lot of owners struggle with.

There could be many reasons why your horse typically doesn’t drink much when he’s in a stall. First, it’s possible that he doesn’t drink much water when he’s outside, either. But because he likely must drink from a large trough or an automatic waterer, it might not be easy to tell how much he consumes when he’s turned out.

He also might not have much desire to drink when stalled because he’s used to eating fresh pasture grass with a high water content and, therefore, typically does not need to consume as much water. However, when stall-bound and fed dry hay he should be replacing the water he was consuming as moisture in the grass by drinking water. If he doesn’t, his colic risk is increased, so it is important that he drinks when stalled.

If you are not currently adding salt source to your horse’s daily feed ration and are unsure as to how much water he is drinking when out on pasture, you should consider adding more sodium to his diet to stimulate thirst. You can achieve this by the electrolyte that you added to the water. Sodium is very common in electrolytes and helps trigger a desire to drink. However, not all electrolytes contain very much sodium, so you should check the concentration and make sure that the electrolyte you are using lists salt or chloride as the first ingredient.

A cheaper, and sometimes better, option is to just give your horse an ounce of table salt each day; this is equivalent to about 2 tablespoons of salt. An easy rule of thumb is a tablespoon of salt per 500 pounds of body weight.

The electrolyte flavoring might offer another clue. If your horse is not drinking much water even when turned out, it’s possible your water has a strong odor or taste. Horses can be quite sensitive to the concentration of dissolved solids in water and, if this is the case, something like apple cider vinegar or apple juice could have the same effects. However, this will not give your horse the sodium component.

Remember that a 1,100-pound (500-kilogram) horse consuming 1.5% of body weight of hay per day should be drinking approximately 21 to 29 liters (5 to 7.5 gallons) of water per day when not working. Horses in work should consume as much as 36 to 92 liters per day (9.5 to 24 gallons), depending on work level and ambient temperature. Therefore, the consumption of 5 gallons in a 12-hour period is quite reasonable.

There’s no harm in adding one serving of an electrolyte to a 5-gallon bucket of water. This amount of electrolyte likely will only just provide enough sodium and chloride to meet maintenance requirements. If he doesn’t need minerals from the electrolyte, he’ll pass them in his urine. You were wise to offer an untreated bucket as well just in case your horse didn’t like the treated water.

Finally, make sure your horse has access to a plain salt block at all times so that he can consume more salt as he feels the need.