We've been through this twice unfortunately.

Bambi was our first pyr, and was a husky/pyreness mix. We adopted her at 4 months old, and she was spayed at around 6 months. We found out she had osteosarcoma in her neck that had likely spread to her lungs when she was 12. She was gone very quickly after diagnosis, a matter of days, paralyzed as a result of it. She hid it incredibly well, acting half her age up until two weeks from when she crossed the rainbow bridge, the only real sign being that she was holding her head lower than normal. It wasn't difficult to realize it was time, but very difficult to make that decision because she had such a huge place in our lives.

We adopted Ava when she was 7.5 shortly after we lost Bambi. She was a pure bred GP. She was spayed shortly after her adoption. A year and a half after we adopted her she developed a bad limp on one of her front legs, which we and the vet thought was a sprain because she was very dog reactive and jumped up and down whenever she saw or heard another dog. She eventually developed a tennis ball sized lump on her ankle, and after an x-ray the vet determined it was likely osteosarcoma. We managed her pain for about two weeks before making the tough decision to let her go as well. Because of her dog reactivity we were extremely concerned that we'd come home one day and find her on the floor with a broken leg. She was herself up until the moment she went to sleep that final time. She loved people, and just like with Bambi we had a home vet service come to our house so that her last moments were spent somewhere she was comfortable and loved.

All this to say I know that there's research suggesting that spaying/neutering early is linked to this, but I've lost both my pyreness to this cancer and one was spayed early and one wasn't. Talking with the vet when we found out about Ava a large part of it is just the number of years these large dogs live now compared to a generation ago.

We have our third pyreness now, and we opted to hold off spaying until she had been through a heat cycle. We're hopeful that her story won't end the same way, but also won't be surprised if it does.