Personally I would call the authorities.

This is their BUSINESS, if they do not "know" it is because they do not care. In this day and age there is NO reason for a business owner operating in the US to remain so ignorant, there is too much information out there and if they wanted to, they WOULD know better.

You yourself have mentioned numerous incidents, yet apparently that didn't help. If this was a daycare operation treating children badly I doubt if people would say "well just give them more time and try to educate them, there is no urgency".

Besides it will probably take the authorities ages to even look into the matter. Honestly I doubt if it will make a difference, but it is important to try when sick animals are not being cared for properly.