Rabbit Death Query

Question
My 6 month mini lop died recently & I am just seeking an opinion on what may have contributed to his death. I got him from a pet store, he'd bonded with his sister but they were split up when she was bought. He was very affectionate, followed me around all the time when I was at home & I left him outside of his hutch with door open during day in backyard when I was at work (no preditors only neighbour's cat which came over once when I was with him). Probably not a good idea in hindsight but I felt bad leaving him in there as always wanted to get out, bit & struggled when I tried to put him in (he'd broken out of his hutch by pushing roof off once, a couple of times I could hear him thumping in the hutch from the house)- he seemed a very relaxed around me but every now and then something would give him a big fright even when I was inside the house with him, things would go flying & he'd tear off to my room. In the backyard I noticed he was eating a climbing ficus plant on the fence and probably some other plants he shouldn't have been nibbling on. Last Thu I came home & he wouldn't come running in when I called. When he finally came in he went straight to his litter tray and then started pulling at his bottom area and would fall over and then jumped out and curled up like a hedgehog on the floor going round & round pulling at himself. I picked him up and noticed his anus was swollen & he'd eaten a chunk out of it, thought initally it was flystrike. His droppings in tray were very unusual, large and long egg shape, dark & dry looking ,crumbled, irregular sizes, shapes ,some softer droppings wouldn't come away from his fur so I had to pick them off and he was slightly urinating on himself while he was tugging at his bottom. I took him to the vet and she said looked like a prolapsed rectum & rabbits can also bite themselves but didn't put him in a collar as I had to work & he'd have to be fed his caecotropes. He was given 3 injections, painkiller, anti imflam, not sure of other one. That was Thu & had an appointment to see her again on Sat morning. I left him in the bathroom when I went to work on Fri but when came home there was urine everywhere and very hard looking small black droppings over the floor, not using his litter tray, and he'd chewed away at himself even more and kept trying to get at himself (had only eaten greens I had left him). Grinding his teeth. I rushed him to the vet but it didn't look good & it would cost hundreds of dollars just to put him under to investigate what was going on so he was put to slept. The following morning I noticed on the lawn some mushy droppings and fur pulled which might have been there since Wed or Thu the day I took him to the vet. I feel very guilty about it. I didn't ask the vet what he suspected it was. A blockage of some sort. Not sure if from perhaps plants he was eating outside,too many greens on top of what he was eating in garden and not enough hay, he had been chewing on the carpet too, anxiety of being left all day on his own outside of hutch & being frightened easily & being a bonded rabbit originally. I haven't found anything about a rabbit chewing madly at itself - he'd have some bloodied tissue sticking to his whiskers, he must have been in a lot of pain - the chewing of himself to bits was extremely upsetting.
Thank you.

Answer
Dear Simone,

Without being able to examine the rabbit, I have no idea of the cause of death.  It could have been any of dozens of things.

The chewing at her rear end really does sound like fly strike, and I have to wonder if something was missed.  A prolapsed rectum must be addressed surgically, and I'm surprised the vet just sent you home if that was really the problem!  Perhaps this was not a vet who is very experienced with rabbits?

The vet was pulling at straws saying it was a "blockage".  The chewing at himself was a red flag that *something* was very wrong at his back end, and I'm afraid the vet didn't do a thorough enough exam to find the cause of your poor bunny's misery.

I am sorry for your loss.

Dana