I just now stumbled on this thread, and I am so sorry for what you went through. I know how devastating it is to try to help a bunny and then not be able to, or feel like we’ve even harmed them. But I certainly wouldn’t worry about the fluids — I have given fluids many, many times and it has ALWAYS made the bunny feel better (as long as the fluids are warm). They know when you are trying to help them.
I think through the month of eating just hay and no greens or pellets (not really enough to recover from a spay), she probably got dehydrated and had some constipation as well as sludge buildup in her bladder, causing her urinary symptoms. Dry, hard fecal pellets and sludge can both keep urine from voiding well. The vet telling you just to increase water intake was the right idea, but wasn’t enough — he should have given subq fluids and showed you how to continue that at home at the very least, especially since he saw the sediment buildup. Then giving you oral amoxicillin very definitely shows he wasn’t rabbit-savvy. So most likely the injectible antibiotic wasn’t the right thing to give and was what sent her downhill. I have had rabbits react very badly to that type of antibiotic and no longer use it.
Your decision to spay her was in her best interest, and you went above and beyond taking her so far away to get it done. I don’t think you should feel at all bad about that! I very much doubt that the spay went wrong, or I think you would have seen worse symptoms much sooner. It is common to feel some adhesions and scar tissue after a spay, without them causing any lasting problems (unless the local vet palpated her so hard that it burst something loose!).
I hope you can try to focus on all the great times you spent together, and the good home you gave her — all those play times in the park sound so wonderful! With a good vet so far away, there’s really nothing more you could have done. I am sure she is very grateful to you for everything, and not at all feeling hurt.
And you CAN tell her you’re sorry, or even write her a letter saying what you are sorry for and how much you miss her. It helps. I took a very dear bunny last year to a vet I didn’t know but who had treated many, many rabbits, and was very recommended. Despite that, it was a very bad experience for my bunny (and for me) and I had to put her to sleep. I tell my bunny almost every day how sorry I am that I took her to him. And I have 30 years experience with bunnies. So be kind and gentle with yourself, give yourself credit for being such a good bunny mom to her, and thank her for all that she has brought and taught you
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