I'm sorry to hear about your guys injuries. I'm not sure about the negligence, I think that it would depend on the laws of your state but it probably falls under some type of protection law for a boarding facility.
There is hope.
I really don't know what to think regarding the negligence. Seems to me, if I owned the business, I would do everything possible to secure the health and welfare of the animals and to especially reduce my liabilities. Accidents happen but this one could have been avoided.