Ongoing research into how best to rehydrate horses after exercise is destroying some common myths and preconceptions, while generating some useful information:
• A University of Michigan study found no ill effects when horses were allowed unlimited access to water immediately after completing a 45-km exercise test.
However, they also found that restricting the amount of water the horse was permitted to receive during the first five to 20 minutes after work didn’t have a negative influence on the total amount of water the horse would consume during the first hour.
Take home message: Letting your horse drink all he wants after work won’t hurt him, but if you still don’t feel comfortable doing it at least make sure he has free access after the initial 20 minutes cool down. He’ll make up the difference himself.
• Another Michigan State study looked at the influence of water temperature on how much the horse would drink. They found a significantly higher intake when water was 20?° C (68?° F) compared to 10?° or 30?° C. Take home message: Horses prefer lukewarm water.
• Horses that are sodium-depleted from heavy sweating that wasn’t replaced by enough salt/electrolyte supplement are hard to rehydrate. Several studies drive that point home and show that plain water is not necessarily the best thing to give your horse after exercise. Horses not only often prefer salted water, they rehydrate much quicker when it’s provided.
Take home message: The most rapid rehydration occurs when horses are given a 0.9% saline solution to drink. This is the same concentration of sodium as is normally present in the blood stream. You can make your own 0.9% saline solution simply by adding eight teaspoons of plain white table salt to each gallon of water you need.