So I just got news today that my malamute of 14.5 years (female) has bone cancer in her right rear leg. Vet says my choices are amputate the leg or let nature take it's course and prescribe pain pills to ease things. She isn't in immediate pain right now, the area is tender, but if she is resting/lying down she is OK. Walking is another matter, she already has mild hip displasia/arthritis and for the last year she has been getting slower standing up and uneasy on her feet. For the last week she has been favoring her right rear leg after hurting it going down the steps off the porch. (which led to the vet visit)
My gut instinct says to go with pain meds as necessary and let things play out as-is, but always open to other thoughts on the matter. She's had a good life. If she was younger, or if it was a front leg, I would lean towards the surgery, but at her age, and with her hips, I have reservations that she would be mobile with only the one back leg.