Wow, I am so sorry to hear that about Pup, they are just like kids. I had to give my poodle away when I got cancer and I really miss her. But I know she is being taken care of real good.
I have to agree that if she is going to be in pain I would have her put down too. And it will be real hard on you and your mom. Please let us know how Pup is doing. Odie
