Any illness that is life threatening breaks all our hearts. Our lab had Auto Immune Hemolytic Anemia, a life threatening illness. How she got it, we don't know, but she spent many days at the vet on an IV and meds. Her blood levels got low to warrant a transfusion, but our vet held on and she bounced back. She is on what they consider chemotherapy, oral medication that she will be on for a year. It has been reduced to a therapeutic level, but she still goes to the vet monthly for blood work. If she rebounds it most likely will be fatal, so we live each day to the fullest with her and she is happy which is what counts the most. She is 11 1/2 and acts like a much younger dog, so we are very grateful. I'm so sorry, for your friend's dog and basically a relative of yours since it's your dog's littermate. It's a tough decision and heartbreaking. Anytime you have to euthanize a beloved pet it's not easy. We've had to do it four times and it never gets easier.