I'm so sorry to hear about Sequoia. My RB dog Rocky had lymphoma and I remember how difficult it was to accept when the time had come to let him go. His last night I lay beside him holding his head up all night because otherwise he couldn't breathe. I would have willingly done that for ever but realized this was not a life he would want. There'll come a point when you too will realize that Sequoia is no longer enjoying life and the only kind thing to do it to let her go.