  The topological susceptibility of the vacuum in quantum chromodynamics has
been simulated numerically using the Asqtad improved staggered fermion
formalism. At nonzero lattice spacing the residual fermion doublers (fermion
``tastes'') in the staggered fermion formalism give contributions to the
susceptibility that deviate from conventional continuum chiral perturbation
theory. In this brief report we estimate the taste-breaking artifact and
compare it with results of recent simulations, finding that it accounts for
roughly half of the scaling violation.
