High temperatures and high humidity in much of the U.S. have created higher stress conditions for people and for horses. I have been judging some horse shows recently in outdoor arenas with temperatures well in the 90’s with heat index values 100+ and I can see the impact on the horses as the show progresses.
Horses do require about 1-2 ounces of salt per day to provide help meet their requirement for sodium and chloride under normal temperature conditions. This requirement can increase to 4-6 ounces of salt per day in hot climates or under exercise where losses in sweat increase greatly. Inadequate salt in the diet can result in abnormal eating behavior such as licking or chewing objects which have salt on them (fork handles etc.) or licking/eating dirt. Water intake may also decrease, increasing the risk of impaction colic. In more extreme cases, horses will stop eating and may experience muscle incoordination.
A good option to maintain year around salt intake is to offer loose salt available free choice, either in stalls or in a covered mineral feeder. Salt intake from loose salt has been observed to be higher than from salt blocks due to the ease of consumption. It is a challenge for a horse to lick enough salt off a salt block to consume the higher levels required during high heat and humidity.
If horses are salt starved, it may be a good idea to limit the amount of salt put out for them initially until they have adjusted their intake. It is absolutely essential that fresh water at an appropriate temperature be available at all times as well. Horses tend to consume less water if the water temperature is too high, even if they should be drinking more water in the warm, humid conditions.
Commercial feeds normally contain 0.5-1.0% salt, so horses on this type of feed will typically consume less free choice salt than horses not receiving salt in their feed. They may still benefit from having loose salt available free choice. A salt block is better than not having any salt available free choice, but may not be as effective in maintaining salt intake when high intakes are required in hot, humid weather.
Providing salt free choice is a good management tool that can help your horse eat and drink well all year long!