Just the angle and deepness of the cut it does not look like the crate could have done that. I and my parents have used a large variety of crates in our lives and none of them have wires that have loose ends on the inside of the crate. I would visit without the pup and ask to see the types of crates the dogs are kept in. You should be able to tell if there is anything that could have caused it in the crate. I don't want to make assumptions or jump to conclusions so that's the first step I would take. I just really don't understand how that could have happened and no one has any idea how or when. Please let us know what you find out and keep the pup safe from infection by following up with your vet.
Hail Gunther 7-2-2013
If at first you don't succeed, destroy all evidence that you ever tried.
"Some people never end up going crazy...what a truly terrible life they must lead." - Unknown