I see dogs as working animals, and the stress you think they would feel by this is elevated to human standards. A well adjusted dog taken care of by well adjusted people is going to do just fine. I'm sure they tell the renters about the commands they use for the dog and also give them a toy or blanket and the dog's normal food to help them adjust.

My concern was with the contract having a lower limit to how often they have to rent. I would never force somebody to rent a dog twice a month to stay in the program. They should be in on each care session 100%.