[en] From a regulatory perspective foot-and-mouth disease (FMD) vaccines represent a special case due to the number and antigenic diversity of strains that might be used alone or in combination within the context of an authorisation. New guidelines have been developed proposing that an FMD vaccine should be defined as a formulation of ingredients including defined amounts of one or more antigens that vary only in the number and types of antigen present. These new guidelines are in line with those previously proposed for equine influenza vaccines. Slaughter policies being less and less popular in the European Union, there is a tendency to use so-called marker vaccines associated with a companion diagnostic test. Such methodology has already been used for vaccination against pseudo-rabies and infectious bovine rhinotracheitis. Sub-unit marker vaccines against classical swine fever have also been developed; such vaccines are also envisaged against foot-and-mouth disease; it would permit, if satisfying defined criteria, to distinguish vaccinated from infected animals.