  We study the renormalization and conservation at the quantum level of
higher-spin currents in affine Toda theories with particular emphasis on the
nonsimply-laced cases. For specific examples, namely the spin-3 current for the
$a_3^{(2)}$ and $c_2^{(1)}$ theories, we prove conservation to all-loop order,
thus establishing the existence of factorized S-matrices. For these theories,
as well as the simply-laced $a_2^{(1)}$ theory, we compute one-loop corrections
to the corresponding higher-spin charges and study charge conservation for the
three-particle vertex function. For the $a_3^{(2)}$ theory we show that
although the current is conserved, anomalous threshold singularities spoil the
conservation of the corresponding charge for the on-shell vertex function,
implying a breakdown of some of the bootstrap procedures commonly used in
determining the exact S-matrix.
