Let's not start blaming the kennel. I think keeping strange dogs is very difficult.
My only blame would be for them not using choke chains. A vet not using a choke chain was how the Grand Victor the other year slipped out of the handler's lead/collar and got run over by a car. Another great reason for chokes. A straining dog will not escape unless you let go of the lead.
Especially if you have a dog that's an escape artist.
We don't know ~how~ he got out, only that he did... and that he was smart enough to get home. It's just a shame he did it.
I'm not blaming the kennel, as I have no idea of the circumstances of the dog's departure. I just wondered whether the city might try to hold them financially liable. Depends on the terms of the boarding contract, probably.