My lab (mentioned earlier in the thread) was running round the garden like a loony one day, when he spied what he thought was his punctured football, so he charged up to it, and there was a crack, and a yelp as he tried to pick up a piece of granite that didn't look anything like a punctured football.

Thankfully the only damage was a broken canine tooth, which, on learning that the dog was insured, the vet offered to put a crown on.
I said I'd think about it.
It was 6 years ago, I've thought about it. The tooth is fine.