I probably wouldn't use it all the time because they are ingesting it. But here and there is probably ok... although I just put the soft dog toys in the washer and the rubbery ones you can put in soap and water...?
Kennels and play pens etc..hard surfaces are ok because they are not ingesting it all the time.
Also although it says it is safe, 10 times less than vinegar..what about if you used it constantly at lets say 200 times in a course of 1 yr or less and then every yr there after..does it build up like chemicals can it the body or is it flushed out? We never really know..? Better to be safe.