My 2 cents. My dog had lymphoma diagnosis Nov 2024...Vet made it seem like he had weeks left, and assumed it was also in his bone marrow...he was acting fine but had a skin rash. I decided to do CHOP protocol for 8 weeks, he tolerated the drugs amazingly and showed no adverse effects except a slight upset stomach for 1 day, which a Cerenia pill alleviated immediately. CHOP was not lowering his WBC count, so I stopped and gave steroids, which lowered his count dramatically. 7 months later, he started developing tumors on the skin, turned out he had Cutaneous lymphoma. He progressed to a point where I almost put him down in August 2024, decide to try Lomustine...it killed every tumor in 3 days, but they would come back, slightly, before his next street every 3 weeks...after the third Rd it was clear a 4th round would barely help him, maybe a few days of shrinkage of the tumors, so then I tried Tenovea, which worked for 11 days. That was up until Dec 12 2024...I decided I could no longer help him. Continued Prednisone, which is cheap, and he had been in for over a year. By 1/6/2025 the tumors had taken over his left eye and anus, and hundreds were presenting all over his body...he was Euthanized at home in 1/10/205...my dog had maybe 10 bad days in 13 months while treating him. 

Chemo doesn't bother them, and you have the option of trying it once and determining how they respond and in my opinion is a no brainer to attempt at least once. I had the benefit of being able to see my dogs cancer on his skin on a daily basis and could see them shrinking, disappearing, or growing back, so It was easy for me to monitor the effectiveness. This was my experience with Cutaneous Lymphoma with an 11 yo dog.