The influence of polarization force, trapped degenerate electrons, and nonthermal ions on the propagation characteristics of dust acoustic solitary waves (DASWs) in a magnetized dusty plasma is investigated. The reductive perturbation approach has been adopted to derive the extended Zakharov- Kuznetsov (eZK) equation and the solitary pulse solution is obtained to investigate the characteristics of DASWs. Pulse stability has also been analysed following the method proposed by Allen and Rowlands. Influence of different relevant plasma parameters on the growth rate of DASWs is studied. It is also found that the relevant plasma parameters have significant impact on the instability criteria of DASWs. This investigation is useful in explaining the nonlinear structures in ultra-dense degenerate plasma media which may exist in astrophysical compact objects (e.g., white dwarfs, neutron stars, etc.) and high density plasma experiments in which plasma degeneracy and relativistic effects play an important role.