  We obtain the equations of motion for a ferromagnetic Bose condensate of
arbitrary spin in the long wavelength limit. We find that the magnetization of
the condensate is described by a non-trivial modification of the
Landau-Lifshitz equation, in which the magnetization is advected by the
superfluid velocity. This hydrodynamic description, valid when the condensate
wavefunction varies on scales much longer than either the density or spin
healing lengths, is physically more transparent than the corresponding
time-dependent Gross-Pitaevskii equation. We discuss the conservation laws of
the theory and its application to the analysis of the stability of magnetic
helices and Larmor precession. Precessional instabilities in particular provide
a novel physical signature of dipolar forces. Finally, we discuss the
anisotropic spin wave instability observed in the recent experiment of
Vengalattore et. al. (Phys. Rev. Lett. 100, 170403, (2008)).
