I am so sorry Debra that you received such devastating news about little Gracie. I have no advice to offer about SM as thankfully Bubbles does not suffer from this heartbreaking condition. My heart goes out to everyone on the board who is living with SM. Cavaliers are the most beautiful and loving dogs on the planet and I am deeply saddened that these wonderful pets have to suffer such pain and that the breed is in danger. You will get some valuable advice in the coming days from owners of cavaliers with SM and I'm sure you will make the right decision for Gracie. In the meantime, give her a hug from me.