iO Yellow Sulphur is a very important macro mineral to your horse's health due to the fact that it is present in so many places in his body. iO Yellow Sulphur is necessary for amino acids, B vitamins, insulin, and chondroitin sulfate in your horse. With iO Yellow Sulphur, you can be sure your horse will be given the proper nutrients to keep it happy inside and out. Can also be used as a insect repellent in horses. iO Yellow Sulphur is known to relieve equine cold symptoms.