  We discuss complete theory of point-like particles in fully polarized BECs
describing difference in behaviour of electrically- and magnetically polarized
BECs. Next we present generalization of this theory on finite size particles to
include contribution of size of real molecules on dynamical properties of
dipolar BECs. As an application of obtained equation we calculate spectrum of
linear collective excitations getting generalization of the Bogoliubov's
spectrum. We show absence of roton instability due to positivity of
polarization contribution in the excitation spectrum. We found that new type of
instabilities appears in small wave length limit due to finite size of
molecules.
