Are Water Softener Salt Blocks Safe for Horses?

Is every salt block created equal?

Updated August 10, 2023

In general, you must be very careful about any kind of mineral block that you offer your horse, as they may contain other ingredients that can be harmful.

For example, horses are very susceptible to a common ingredient in livestock blocks called monensin, or Rumensin. It is a growth-promoting agent in cattle that works in the rumen of the digestive tract. The equine GI tract does not have a rumen, so monensin is toxic to horses. There are also high protein livestock blocks, deer licks, and sweetened or flavored horse blocks, all of which we recommend you avoid.

Regarding whether water softener salt may be harmful to animals, the Cargill website states:

“As with food considerations, water softening salts are not intended for human or animal feeding. The particle size is inappropriate for small animals. In addition, water softening salt may have additives that are inappropriate for animal feed.”

One of these additives is sodium hexametaphosphate, a surfactant, which is not something you want your horse eating. In addition, there are at least three different kinds of salt that can be used to soften water. One of them, rock salt, is only 95% sodium chloride. The remaining 5% is made up of the questionable and mysterious “insoluble matter.” Finally, some water softeners are made with potassium, not sodium, which could be deadly to a horse with HYPP (hyperkalemic periodic paralysis).

For these reasons, we recommend you stick with salt and trace mineralized salt that is specifically designed for horses and stay away from water softener salt, deicing salt, and blocks for other species.

In fact, you may want to stay away from blocks altogether. Horses may not be able to get the proper daily serving of salt and other minerals they need from a block, especially if they are sweating a lot from hard work or high temperatures. Small cuts, abrasions, or ulcers in the mouth may dissuade a horse from licking a salt block because it could be painful. Also, your horse might not spend enough time licking it, and therefore miss out on the nutrients. Providing your horse with a loose salt supplement during feedings is a smart, simple way to meet his daily needs.