Help save Luna

As most of you know, my sister Crystal has recently been shoved between a rock and a hard place. She found out the her beloved 5 year old harlequin great dane has been diagnosed with an aggressive form of bone cancer (Osteosarcoma). You can imagine the hurt she felt hearing that news as Luna was her service dog for a couple of years. Due to size, it got harder to take her places but their bond never grew apart even when her other dog took the place of being her service animal. Luna helped my sister overcome so many obstacles and now my sister is faced with this. She was only given 2 options since this is such an aggressive form. Option 1 was to amputate the leg prolonging her life a little longer and also keep her from being in pain from the cancer. The vet said maybe 6 months at best but there are plenty of people who have reached out with stories about their dog going through the same thing and they lived well past that happy and healthy. Option 2 was palliative care and give pain meds until they stopped working and then put her down. The issue with that is the tumor can burst causing the leg to break and Luna having to immediately put down while suffering a tremendous amount of pain right before. My sister has decided to amputate the leg and spend a little more time with her baby. That comes with a large vet bill as you can imagine. Yes this is common in large breed dogs but she is only 5. She was against doing one of these because as pet owners, it is our responsibility to take care of them. She loves her animals more than herself and always puts them first. But also as pet owners, some things are beyond our means of being able to take care of them. That's why once in a while we must ask for help. So I am asking for help for her. I know she would do the same for me and anyone else that finds their selves in a position like this.