I began renting a single family house in San Francisco a few years ago, and my landlord has specified "no animals on the premises under any circumstances" in my lease. Meanwhile, my teenaged daughter has found it very difficult to live without her dog (which previously lived only at her dad's house) when she's at my place, so her psychiatrist has written a letter verifying that be made a therapy dog. What are my legal rights around keeping this dog at my house? And if we're legally allowed to keep him for now, can my landlord force us to move out when this year's lease is up?