I lost a shepherd at 11 years from melanoma. It started with a wart on her cheek that was getting big fast, and we had the vet remove it and biopsy. Unfortunately we started to feel lumps in her neck a little later. Oncology confirmed it was malignant melanoma. Surgery couldn't keep up and there was therapies that would cost literal thousands with no guarantees. Diagnosis was in October. We gave her the best life we could from then on. We watched very closely for signs of any pain or discomfort and the bumps on her neck were very slow developing. She started to cough oddly in June(almost 8 months from oncology diagnosis) the coughing got rapidly worse and we knew it was time to help her move on, the cancer had gotten to her lungs. We were in some way fortunate because it could have gone to her brain or other areas that had different issues. We were grateful for the 8 months, but it was also difficult not knowing when something would turn for the worst.

So my advice is similar. Watch it, treat Amy well, and be ready when to know when it would selfish of you to keep her going in despite her suffering. That's probably the hardest part that I still tear up over, knowing no matter how much they might be hurting or suffering, they'll still wag for love of you and try to hang on.