Dogs can be unsanitary which will cause health problems in the workplace. For example if they use the restroom in the office it would be bad, or if they start to lick people. Another reason is if they get in the kitchen they will likely tear it up if not trained properly.
Dogs will also need to be taken outside, fed, given water, and played with throughout the day which will cause the owner to be distracted at work. This could likely leave other co-workers feeling like they are not working as much because they are to busy taking care of their dog.not to mention some people in the workplace are allergic to them.
Lastly dogs can be clumsey and unpredictable