There is so much to learn about cancer. We have a lady friend that was designated as having terminal cancer about 15years back. She got better almost as soon as the doctor's told her to get her life in order. She is still alive and doing well. Something caused her bone cancer to retreat. The doctors have actually done some extensive testing on her to find the cause of her cure. To the best of my knowledge, she is still an unknown quantity to the medical profession. She simply says that her mission wasn't complete and God wasn't ready for her.
Cancer in animals is just as iffy. I had a very good black Angus cow that developed a cancer on her face. The veterinarian told me the cancer would never retreat, and I should sell her for dog food. I did not accept that, and asked for some antibiotic salve to put on her. I kept her in a pen and the cancer cured up in about a month. I told that to the vet, and asked him was he sure it was cancer. He said yes, it was lab tested as a cancer and it would not cure. That was four years back, and that cow still looks amazingly good. Go figure. Medicine is not an exact science, and the doctors do not have all the answers. Having said that, I admire doctors and other medical professionals, and it is not something that I want to do.
I don't believe people dump dogs in the country as much as they did some 20 or so years back.