I would not recommend trying to keep it secret. The entire purpose of the ESA letter is to document to your landlord that you are in compliance with your lease. As you cannot be charged the pet fee if you are honest with your landlord, and cannot be evicted for having an emotional support animal, it makes sense to be honest rather than creating a context in which your landlord may view you as a liar and a schemer, particularly if you intend to keep living in the unit after your current lease expires.

