  We show that the interplay between the structure anisotropy and the energy
splitting between the TE and TM modes of a microcavity leads to the appearance
of a gauge field for a propagating polariton condensate. This field is analog
with a spin-orbit coupling and the field texture can be tuned by rotating the
sample and ranges continuously from a Rashba to a monopolar field. In the
linear regime, the monopolar field leads to a remarkable focusing effect. In
the interacting regime, the effective spin-orbit coupling induces a breakdown
of superfluidity. The spatially homogeneous flows become unstable and
dynamically evolve into textured ground states such as stripes and domain
walls.

Quantum Gases