Well...I can't really elaborate more on the fact that when he would get stopped up, I'd make an appointment to see his DVM...who also practiced Chiro. She was well known in agility and was able to get him from moving sideways, like a crab, to straight. (I"m a former horse trainer, so gait is REALLY important to me..) BUT, she didn't understand the anal glad issue, either. She initially said "Feed him more fiber." Which I tried... but then found fiber wasn't the issue. He was nearly fiber free for the last 5 years of his diet as I believe Ketogenic diets are more healthy and fiber is difficult to eat without carbs. He had no more than 1 c of sweet potatoes a week, on the same days when we'd feed green tripe, which was just to decrease the squirts...and a high fat/low proten diet the rest of the time.
It was something that I just figured out... when he would start being out of balance, aka ... moving like a crab... it was time for an adjustment.
I DO think he had spinal issues for a very long time, as his conformation wasn't great, and he was always sensitive about is "back end". I ended up doing the anal gland expression every 3-6 months, then having a chiro treatment every 9 mos, which seemed to be what he needed.
And, he was moving freely and happily until about the last week of his life... and, given he was probably a boxer/pit, reaching ~15 y/o was pretty remarkable, especially given the condition in which he arrived... Lordy, those gums where a sign of long term issues!!! (PS his DVM was shocked to learn how old he was ... she thought he was 9...)