my guess would be they are talking about a centipede, since millipedes are vegetarians...
i've never tried to feed my centipedes mice, but i have tried to feed lizards before. They did no thrashing or anything with the lizards.. Just bit it, and i have to assume shot venom too, as the lizard was totally immobilized. The pede then just totally ignored it. So i removed the lizard after a few minutes. Then to my surprise a few more minutes later, like 15 or so, the lizard was back up and running around again...so i tossed him in with one of my tarantulas... he wasn't so lucky that time.
And from movies i've seen online of centipedes eating mice the venom has similar effects vs mice, not that it kills them just totally shuts them down in a very small amount of time. so i'd have to wager that this story is a little over the top.
The only real way i see the centipede constantly trampling the little rat pup would be if the little rat pup was retarded enough to constantly poke at the pede. "oooh what's this?" "ACK it attacked me!" "i'm gonna go back and do that again!!" ..