Hi @RPSeal. Thanks for your insights!
I'll use AAV8 in the future for DH neurons. I've used AAV9 for intrathecal injections, and it's the best serotype for DRG transduction, in my hands. It did transduce the DH robustly too, but mostly in the deep DH, as I mentioned. It probably also infected DRGs through their terminals in the DH, but for my purposes in this experiment, this wasn't a prime concern.
I wasn't using a Cre line. I agree I may have gone too deep, but strangely, I saw lamina I neurons transduced, but in several animals, lamina II was distinctly lacking expression. It could be a serotype issue or a transgene issue. I'll figure that out when/if I try AAV8.