I agree with Chicktwit..mineral oil..I have had to use it on my AmBulldogs..several times, they are very lg dogs, have to give it two times usually to get it moving. It was over a tennis ball, front door mat, my dh high school leather football. (This was on the advise of my vet but you may want to check with yours first)..perforated bowels and becoming impacted are two problems.
