  A dynamical model based on effective Lagrangians is proposed to describe the
bremsstrahlung reaction $ \pi N \to \pi N \gamma$ at low energies. The
$\Delta(1232)$ degrees of freedom are incorporated in a way consistent with
both, electromagnetic gauge invariance and invariance under contact
transformations. The model also includes the initial and final state
rescattering of hadrons via a T-matrix with off-shell effects. The $\pi N
\gamma$ differential cross sections are calculated using three different
T-matrix models and the results are compared with the soft photon
approximation, and with experimental data. The aim of this analysis is to test
the off-shell behavior of the different T-matrices under consideration.
