The Newtonian superfluid hydrodynamic equations describing the outer-core regions of neutron stars are generalized to include dissipation. The effects of viscosity, thermal conductivity, and mutual friction (due to the scattering of electrons off the neutron and proton vortices) are included. The low-frequency-long-wavelength limit is taken to obtain a set of equations suitable for studies of p-modes in rapidly rotating neutron stars. An energy functional is constructed which determines the damping times due to the various forms of dissipation. The most important result is that mutual friction will be the dominant damping mechanism for the large-scale oscillations of rapidly rotating neutron stars for the temperature range 10(7) K less-than-or-equal-to T < T(c), where T(c) approximately 10(9) K is the superfluid transition temperature.