Epsom salts, also known as magnesium sulphate, when mixed with water is a saline purgative that can be given orally to cattle, sheep, horses, pigs, poultry etc. It is mainly used by farmers  to feed dairy cows to treat or prevent grass tetany. It also has other uses on the farm such helping with bites, cuts and grazes when applied to the skin of affected animals and has benefits in treating swollen muscles and ligaments. It also can work as a laxative and as an electrolyte replacer for calves.