I came to this forum to try and help with what's worked for our paralysed daschund. Pooping on demand is the most difficult achievement when trying to simply 'express' the feces. We discovered by accident that while holding over the toilet of you tickle and or apply pressure around and under the rectum with a COLD and wet wad of toilet paper that a paralysed dog will be stimulated to push and if there's a BM ready it'll come! You'll know it's working when you see right away that they are pushing and sometimes even twitching and lifting their tail!
In the years since owning our girl - we've had two other paralysed daxis in our care for which this worked well and was life changing for their owners.