For parabolic linear operators $L$ of second order in divergence form, we prove that the solvability of initial ${{L}^{p}}$ Dirichlet problems for the whole range $1\,<\,p\,<\,\infty $ is preserved under appropriate small perturbations of the coefficients of the operators involved. We also prove that if the coefficients of $L$ satisfy a suitable controlled oscillation in the form of Carleson measure conditions, then for certain values of $p\,>\,1$, the initial ${{L}^{p}}$ Dirichlet problem associated with $Lu\,=\,0$ over non-cylindrical domains is solvable. The results are adequate adaptations of the corresponding results for elliptic equations.