I think the anxiety I lately see in dogs is a behavioral issue and most likely in my experience, these dogs suffer from anxiety at home as well. New environment of the sitter's home just adds to that and may exacerbate the anxious behavior. There is little you could do about anxious dog except to leave him or her alone. Some of them calm down if you don't fuss over them. Pacing is their own way to calm themselves. I began to think that anxious dogs are a new normal.

I am an experienced dog handler and sitter. lately, I am getting more and more young dogs with similar issues: pacing, whining, refusal to eat or even drink, pee and poop for a couple of days in extreme cases. The vet i consulted thinks it's behavioral issues mostly of wrong breeding.