Sorry to here about Hailey.
From experience, with a similar protocol, I can tell you ..
My Bullet (Black Lab Female 4yrs old) was diagnosed locally, Biopsy immediately sent to UW Madison to confirm. Large Cell Lymphoma.
She seemed ok during the early diagnosis stage. I first noticed her neck lymphs were swollen, geez I died when I felt that. 2 - 3 days before her Vet and I decided to try chemo she was going downhill really quickly, lethargic, and appetite loss.
Now .. my experience .. After the 1st Round of Chemo was administered, Bullet had bounced back to just about 100% within 2 days ! I remember I rejoiced, that a miracle had taken place Hail Vincristine ! It was awesome. A couple days before I thought I was losing her and then 2 days later after the 1st treatment, if you didn't know she had cancer you could not even tell anything was wrong.
Prior to that, during the diagnosis period .. Prednisone did a pretty good job, and then it didn't.
We enjoyed the Remission period we were given as a gift. The quality of life that was restored for that period was definitely worth it in her case.
I struggled with the decision to treat or not to treat given the expense, and time, but She was My Girl ... I owed it to her. My Vet who is a Saint, loved Bullet and helped me with the decision, and treated her for only the cost of the medication.
If I am ever faced with that decision to treat or not and am financially able, I would Absolutely Do it again ! The Benefit by far outweighed the risk. The remission period, even though there were some bad days ... the majority in Bullets case were good to very good. Priceless.
Dogs are Mans Best Friend. What a Freakin' Understatment.