I've lost dogs to DM, hemangiosarcoma, polymyositis, cauda equina, complete system failure caused by multi-year use of pred, possible bleedout from Deramaxx, and "old age".
The worst I personally experienced was when Niki died from osteosarcoma. It's always so hard to lose a fur kid, but I've always said I NEVER EVER want to go thru that ordeal again as long as I live. The pain could not be controlled by any medication including Duragesic patches and methadone - only amputation of the limb gave him relief.
Kelly's been limping from what I assumed was arthritis (he's been taking Tramadol for problems with arthritis and spondylosis). I took him to the vet today and they took a boat load of x-rays and his doctor is almost 100% sure he has osteosarcoma (it doesn't appear to have spread to his lungs yet). The radiologist will review the x-rays tomorrow, the surgeon will look at them Monday, and he's scheduled for the biopsy Tuesday.
He celebrated his 12th birthday Saturday. He's weakish in the rear and has an elevated ALT problem. Something is causing him to have eye goobers, and is making him chew very gingerly (he had a tooth pulled and complete dental within the past few months). The amoxicillin he's taking for the eye goober/chewing problem has dropped his ALT values to the mid-200's which is still high but not nearly as bad as what it's been before the antibiotic. He's in remission from SIBO.
There's some type of radiation therapy given by a vet group down in Tampa that may help reduce the pain from the osteosarcoma. I haven't done any research yet so can't comment on this option.
IMHO amputation is out of the question given his over all health problems. I know that the pain from osteosarcoma is impossible to control. The radiation may/may not be a short-term solution for keeping him comfortable.
Right now I'm leaning toward allowing him to make the trip to the Bridge when I can no longer offer him a quality life - when the pain can no longer be controlled. I don't know how long this will be. His vet increased his Tramadol from 2 a day to 4-1/2 a day and she's having me add Metacam.