“but the few months of low-quality life are not worth it”
I agree with you, Nln, and hope they put the dog down mercifully.
Dogs do NOT understand why they are being injected, feel crummy, are in pain. . . a human being (usually) knows and understands, can be happy and so forth.
All the dog knows is that is feels terrible. Chemo, radiation, etc. are horrible. Why subject the dog to that? It is not, actually, merciful, particularly when he is almost certain to die within months.
If your dog gets run over and needs a splint, well, that pain really is temporary and the prognosis really is good. But cancer? I think the most merciful thing is to let him go.
I had friends with a diabetic cat. Twice a day they’d give him his shot. That cat was miserable. Lived in the closet.
Well put. It is simply hard for owners to let go. But the canine patient only wishes to find relief.