I've had dogs all my life, but have never seen this before. We have an 8 month old wire hair fox terrier. We're doing pretty well on the house training, but still have accidents. We're really observant of his behaviors trying to figure out his signs that he wants to go out to potty, but have noticed this one weird things since we got him at 4 months old. Sometimes we notice that (trying to put this delicately!) his anus is visably pulsing at about the same rate as the curser on my computer! This can last from 15 - 45 seconds and then stops. When we notice it, we take him out and sometimes he poops and sometimes he doesn't. What the heck??? Has anyone else noticed this type of thing? I'd never seen it EVER with any of my other dogs. It doesn't seem to bother him in the least, and there is no scooting, licking or anything. Any input would be welcome!