That sucks, OP!
Surely, he didn't do it on purpose. If he obviously feels bad about it then I would think that is punishment enough.
Maybe get him to sit with you when you make all the phone calls you have to make and see what is happening because of his mistake? That should be pretty boring and give him some time to think about it.
Depending on your home insurance policy you may be covered for some of that stuff. I know I am but I have a very comprehensive policy due to the fact that I may or may not have done that very thing in the past.....
Maybe also try ringing the kennel and get them to check their driveway and if they are kind they might even go for a walk along the road near their property. I know I would do that for someone if they lost their wallet and lived 100ks away.