Complex sentence: The World Organisation for Animal Health is the intergovernmental organisation responsible for improving animal health worldwide and was created by an international agreement as the International Office of Epizootics (still known by its French acronym "Office International des Epizooties"-OIE) on 25 January 1924.
Split into simpler sentences: The World Organisation for Animal Health is the intergovernmental organisation responsible for improving animal health worldwide. It was created by an international agreement as the International Office of Epizootics (still known by its French acronym "Office International des Epizooties"-OIE) on 25 January 1924.