Hi Friday_Witch,
I was replying to Pops, but I'm glad you posted and I know all too well the feelings you have about your baby and how you feel you failed her. The unfortunate thing with bunnies is that even when we do our best and have the best intentions, they often do end up in pain and die badly, just because nobody really knows all that much about them still, and what is exactly the right thing to do in each case. I just lost a bunny two weekends ago to respiratory failure and am heartbroken and second-guessing all the what-ifs and shoulda-coulda-wouldas. I've had other bunnies die badly too, some after I took advice that was wrong from vets I trusted, even when my own research told me not to listen to them.
The bad thing is that although bunnies are very fragile and can go downhill in a heartbeat, they are also immensely strong and people everywhere have tales of how much their bunnies have fought to stay alive and how much they have been willing to put up with to do so. Your bunny must have shown signs of wanting to live and of being up to radiation for you to have chosen that option. I saw the video online of a bunny with that hind-leg flicking thing after radiation and it scared me, but the people I talked to didn't have that experience with radiation with their bunnies, so I took heart. Most bunnies don't have much trouble with radiation, at least until much later. Who knows if it was a bad radiation session, too much stress, or something else in her system or makeup that gave your bunny side-effects. What is certain, though, is that you couldn't have known in advance what the effects might be. None of us have that much-desired crystal ball.
It sounds like you did have many more months with her, even though her health and behavior were different in some ways. Was she still affectionate and desiring affection from you? Did she have more good days than bad? It sounds like she was still eating pretty well until the following May. That is a long time. Make a list of the ways her life improved or stayed the same after radiation -- yes, there will always be negatives but if you ask a disabled or chronically ill person would they choose to die instead, most would say no. When we make medical decisions for ourselves, we sometimes choose treatments that aren't pleasant just so that we can have more time with loved ones and enjoying this earth.
Also, there are so many things that can affect bunnies -- e. cuniculi, pasteurella, parasites, infections. It could just be that her illness and the stress of it brought some of these up and that they would have happened even without radiation. The frustrating thing is that you will never know what WOULD have happened had you not done the radiation. I think about that with my bunny -- what if I'd just tried prednisolone, as a lot of bunnies do? But because my bunny's mass was so large and solid (not cystic), radiation really was the best option, and it sounds like it appeared that way for your bunny too. My bunny was 6 years old, but I've had a dwarf bunny who lived to 13.5 years, so I considered him young enough to go for it. And I knew his personality. I knew he wouldn't have wanted me to give up on him so soon.
The other thing to focus on is the 7 years you had with your bunny before she became ill. Being willing to spend that much money on your bun shows what a caring and devoted mother you were to her for all those years, and I assume her health was good from how you describe her after the radiation. Most bunnies don't live beyond 3-4 years (sadly) because they are in households that don't research or know much about bunnies, and they die pretty miserable deaths from stasis or an infection that could be easily cured if the people would just take them to a vet. But so many don't. So although her last year may not have been as you wished it, she had many more good ones than that just by being in your care.
I am struggling at the moment with my little dwarf girl who also has breathing difficulties and a possible thymoma, and going through all those decisions again. Do I give her medications that might have side-effects, do I continue to bring her on the table for meds twice a day even though she hates it, or should I just pts? She has lost a lot of weight, but she is still feisty, comes running (while wheezing) for treats, and grooms and is groomed by her husbun. How can I take her life away when I don't know how much she is really suffering, or is willing to suffer just for one more snuggle or salad?
If you search for rabbit and euthanasia or quality of life, you might find some helpful pages. I would highly recommend reading the two I've listed below, since I have used them not only to guide my decisions but to come to terms with decisions I've made in the past. Also, remember that anything you have gone through, even if you do decide you've made bad decisions, will help you in the future with other rabbits, or advising other people about their rabbits. It may even help you advise or make difficult decisions for the humans in your life. Whatever you ultimately decide to do with or learn from the experience, I sympathize, because in the school of life, it's one of the steepest tuitions you'll ever pay.
"Quality of Life"
http://www.rabbit.org/journal/2-8/quality-of-life.html
"When did you put YOUR rabbit down?"
http://www.bunspace.com/forum/thread?tid=16943&posts_tgp_no=1&posts_tgp_limit=10