that webpage is the site of one of my vets, the first one i took zack to when i first got him and took my cat to for years. that website is a great resource.
i had a dog when i was a kid in the 60s, and another one in the 70s, and they both occasionally scooted, one was a cocker spaniel (or maybe cavalier?)mix and the other was a small sheltie mix. I never gave it any thought. then last year my daughter got a cavalier and she told me that they need to have their anal glands expressed, this particular breed, if the glands get full, and that a sign of the glands being full is scooting. then i got zack. He scooted. He had chronic diarrhea for a month when i first got him so i thought he was just wiping off his butt. Ttrying to be a responsible dog owner, when i had him to the vet for the second time, a couple of weeks after i got him (it was the same vet that made the website) I asked the technician if the anal glands needed expressing. She didn't bring it up, i did. She said she didn't know, she didn't seem experienced, but she said she would express them, and when she did, nothing happened, i don't think anything came out, she really didn't seem to know how to do it, i thought.
months later, zack got sick and i took him to one of my other vets, and she asked if he had been scooted, and i hesitated but i said yes, i hadn't been concerned about it. she suggested expressing his anal glands. They took him in to another room, away from me. He was given subcutaneous fluids, had blood drawn, and had his toenails clipped, and had the anal gland expression. i don't know what happened because i wasn't there.
After that day, he was scooting more than before. He wasn't scooting very much before this, and i have regretted letting them do it, i don't think he needed it, she later said the glands had not been very full, when i asked. I told her he had been scooting more. She said it was common for there to be more scooting after anal gland expression.
He continued to scoot more often for several weeks but it finally went back to how it was before.