  Generalised Fierz-Pauli mass terms allow to describe massive higher-spin
fields on flat background by means of simple quadratic deformations of the
corresponding geometric, massless Lagrangians. In this framework there is no
need for auxiliary fields. We briefly review the construction in the bosonic
case and study the interaction of these massive fields with external sources,
computing the corresponding propagators. In the same fashion as for the massive
graviton, but differently from theories where auxiliary fields are present, the
structure of the current exchange is completely determined by the form of the
mass term itself.
