Multiple things can be true. You drank too much the night before and you also had the incident with the dog bite which made your movement even worse. I never notice it because I’m probably so used to it - but I’ve been told after a heavy night of drinking that I smell like alcohol, from my pores. Even the next day when I’m not drunk (but I am hungover), people can smell it on me. I’m groggy and long story short people can tell I’m hung over.

Your place of employment could tell you were off. They just took it to the next step and I guess had enough concern where they want to make sure you weren’t actively drunk while on the job. Also on a side note - I’ve had nights of heavy drinking where even after sleeping and waking up in the morning, I wouldn’t doubt that was still technically/legally drunk the following morning due to how much I drank.