I had finished my next blog but decided to put it on the shelf at the last minute because of a story that has been getting a lot of play in the news the last week or so – how freely consuming water during exercise could kill you.
The story is actually talking about hyponatremia, a dangerously low level of sodium in the blood. According to the articles, upwards of 30% of people participating in sports are overhydrated and some 14 individuals have been identified as suspected to have died from forcing too much water and diluting their blood sodium to a dangerous level – i.e., hyponatremia.
My concern is that people will see these articles and start to wonder if they should be restricting how much water they let their horses drink during and after exercise, especially when seeing how much a horse will drink under those conditions. There is no reason for this concern.
For one thing, the people in the human studies were forcing themselves to drink extra water even if not thirsty and with no regard to how much water they might actually need. Far more people were overhydrated than actually got into trouble with hyponatremia, leading researchers to postulate there is a hormonal malfunction also operating in the people who develop hyponatremia.
As anyone who knows that sweat is salty might predict, low blood sodium risk can also be reduced by replacing sweat electrolyte losses during exercise and starting exercise with optimal levels.
Exercise and overhydration hyponatremia has never been seen in a horse. You can’t force a horse to drink more than they need. In fact, research has found that horses getting electrolytes in their feed that had increased water consumption showed improved speed in endurance horses. As an aside, horses with more water used to cool them during endurance races had better performance and finishing positions.
The bottom line is pay attention to salt intake in working horses, at least 2 oz/day in warm water and more with prolonged exercise. Don’t hold back on water for drinking and cooling. In fact, the more the better.