To begin, I understand that some people may find it easier to work around thier dogs, but not everyone does. It would be very possible for workers who have had bad experiences with dogs in the past to obtain anxiety from being around them. That kind of psychological distress could cause decreased work productivity. Some workers may even feel obligated to quit thier jobs.
Also, an unhealthy work enviroment is no place for workers to be. Not everyone gives thier dogs the care needed to be completely healthy, which could spread disease to