I'm sorry to hear your dog has lymphoma
. The one positive here is that of all the cancers, Lymphoma is the most responsive to chemotherapy. Typically we'll stage the cancer with the bloodwork, chest films and abdominal ultrasound. You'll usually find enlarged lymph nodes in the abdomen, but we're trying to rule out lung/ spleen/ liver masses.
We'll then start chemotherapy. We typically use the University of Wisconsin-Madison Protocol. It's a 25 week protocol where there is an injection of a chemo drug given each week. Dogs will usually go into remission (lymph nodes go down, acting normal, eating/ drinking) within days of the first injection.
The goal of chemo is to return Milo to his pre-cancer quality of life and then maintain there. We shoot for 12 months survival with chemo. Without chemo or with just Prednisone (steroid), we only have a 2-3 month survival. With that said, I would highly recommend chemo if financially feasible. We're giving Milo another 10% of his life span back, so in my opinion it's worth it.
Once they come out of remission (lymph nodes back up, not doing well) then we have the option of rescue protocols or euthanasia. I think I would euthanize at that point as your chances of chemo success go down from there.
I hope this helps, let me know if you have any other questions.