There are only a few rules governing emotional support animals, and there isn’t any official registry, therefore emotional support animal letter renewal it’s really hard to establish how many there are. Both service and emotional support animals could be excluded from the workplace should they pose either an undue hardship or an immediate threat at work. Registration isn’t required by law and doesn’t make your pet an ESA. Emotional Support Animal letters are usually considered valid for a single year. The animal has to be housebroken. They are different from service animals, because they can be of any breed.