Neutering is NOT going to stop marking. Treat the marking as you would urinating. Do not allow it. Watch for signs & take him outside. Clean everywhere he has marked with a good enzyme based cleaner & then treat him as a pup. Crate/tether while inside & frequent trips outside.
I have had intact males who never marked indoors & I've had neutered males who would try to mark anything..or anyone.
You could also look into belly bands, but I prefer the training approach over a management approach.
Teach/train for what you want. It is much easier than trying to "untrain" a learned/allowed behaviour.

Wiley answered on 1/18/13. Helpful? / 0