I have a 3.5 yo female rat named Ginger. Recently, she developed a tumor and has quickly grown to be about the size of a lime (I've attached pictures). She's skinny and her back legs are starting to drag. I took her to the vet, and my options are either euthanasia ($70) or surgery ($400). Ginger's sister Rosemary (from the same litter) on the other hand is perfectly active and healthy. With Ginger gone, Rosemary would be left alone, and given her good health, would probably live alone for a while (I'd prefer not to get another rat, but I don't want to give her up either). I can't help but feel that without her tumor (which from what I can tell is most likely benign) Ginger would be just as healthy as her sister. Should I do the surgery? Or should I put her to sleep. I have to decide soon, and I'd like some outside opinions.