Horses always need electrolytes, it is an important part of their health to maintain a correct balance of electrolytic salts. Horses in work need to be supplemented as sweat is a direct loss of these salts. The amount can vary, for example in winter a lower dose may be given (but a horse that hasn’t been clipped will sweat more and so need full levels).
In summer, even no or light work the horse will benefit from a daily dose and horses in full work they are an absolute necessity. It is important to understand the need for a fully balanced formula that replaces all the salts lost in sweat in the right ratios. For horses in hard work such as racing or competing in hot conditions a more direct top up like Quicklyte will provide an instant replenishment and help recovery. Tye-up can often occur in horses just from dehydration.