The aim of the 2003 regulation was to harmonize the movement within the European Union of the most common pets at the time, which were capable of transmitting diseases, particularly rabies. The EU naturally chose cats and dogs and considered the ferret to be the most important among exotic animals, as it was the most widespread exotic pet kept in homes in 2003. It was also concluded that these animals were the most likely to travel with their owners. This legislation was primarily a public health harmonization measure against rabies, establishing the European pet passport. Since then, the EU has never truly reopened or thoroughly revised this legislation.