Indeed - farmers will tell you stories of sometimes having to chop off the head of a blue-tongue in order for them to let go!
And ye gods, our idiotic mutt is at it again. I mentioned he had a go at one recently which he should not have done if he had any brains, because the first time he tried it on with a blue-tongue a few months ago, it latched onto his paw and managed to tear one of his claws out. By the time we extracated the lizard, there was the dogs claw in the its mouth. Dog was in a fair bit of shock (lot of bleeding too), but interestingly enough his claw has since grown back.
Well just a couple of hours ago he was at it again. One of the biggest blue-tongues we've seen for a while (possibly another pregnant female). My wife had to physically drag him inside before he came to anymore grief. Obviously our hound is too much twittish Beagle and not enough Cavalier.