Please help...please: 3 mo. old dwarf rabbit dies suddenly

Question
I need help in understanding or determining what went wrong and why, seemingly, suddenly my 3 month old rescued dwarf, male rabbit died today.

Environment:  completely indoor at all times.  4x4 cage and let out to scamper and spaz out whenever he wanted - liked to snooze during the day and have a blast at night.

Today:  observed what I thought was less activity than normal, but he liked to sleep during the day and I thought I was over observing.  Gave alfalfa hay around 8:30a - didn't seem interested...seemed strange.  Later, offered parsley around 1p to see if any interest and there was some...ate it.  Not all sprawled out like usual - hunched in a ball more than normal, but nothing startling or abnormal...just my intuition.  Noticed not drinking water - seemed unusual as he drinks a lot everyday.  Observing closely - didn't leave house as planned, stayed and wondering if I was overreacting...

I was in the bedroom on the phone and heard an unusual sound - like something hit the cage.  Puff (cat) ran out ahead of me and we found RabbI on the floor of the cage in distress...on his side...convulsing...all a matter of seconds.  I rushed him to the vet (within 10 minutes) and they told me he was 'gone.'  I am devastated and paralyzed with confusion.

Hindsight:  Last couple of days...things I can think of...1)  he jumped in latent gas fireplace last night with gas logs (there is ash in there from maybe insulation or whatever would be in there...definitely synthetic...I've never burnt anything in there and rarely use it).  I pulled him right out, wiped his face and put him in cage.  Could this residue have been poisonous to him?  2)  Also, about 3-5 days ago, he started being able to reach my freddy begonia plant (he's growing and his reach is expanding) - before I could catch him, he had nibbled a small amt of the leaf.  I observed for the next 24 hours and he was fine...would it have taken longer for the reaction?  I just read that there can be a delayed reaction and that I should have taken him to the vet immediately...what are the symptoms of poisoning?  3)  neighbors cat (new neighbor) came for unexpected visit - walked away for a minute (literally!) and he had jumped in cage with rabbit.  Cat was lying on one side and rabbit lying on other and both were seemingly nonplussed.  I checked rabbit immediately - for attitude (agitated, etc.) and for punctures, scratches, etc. and found nothing  Is there something I don't know about or haven't thought about that the cat could have done that wouldn't be obvious?  4)  I was very distraught tonight and climbed in his cage because I was sad.  I lifted up one of his nesting areas and a spider came out (i live in Southern California).  It is brown, medium size, white spots on back...I can't find what it is on the internet...could a spider bite have caused this tragedy?  5)  Kitty grass from Ralph's - is there anything that might have been in the kitty grass that would have cause this?  I have been buying it for both cat and rabbit and have gone through 4 different batches - no problems in past at all.  It is pre-grown in a small container (bacteria, fungus, etc.???). I notice that the roots are a bit moldy and there were 'gnats' all over it today (I just bought it 2 days ago) - RabbI ate it last night. 6)  Alfalfa hay - got hay from local feedstore - have been giving to him for past week and a half.  Made sure it's all pestiside free, etc.  Could there have been a build up from something in the hay?

History:  My teenage neighbor bought him from the LA garment district for $20.  I rescued the 3 week old, unweaned baby.  It was starving, had flea anemia and some type of 'uti' per the vet (who also told me it was a female and today I found out he was a male).  Fit in the palm of my hand (no fingers - just the palm).  I made my bathtub his world, took to vet immediately next day, they put on baytril for 10 days - uti cleared up, gained weight, seemed very healthy and happy and lovin' life.  Overall, a very active bunny who integrate well with my kity Puff - they played and slept together (supervised always) and overall loved each other about as much I did.  Bunny was eating primarily hay then pellets then I had recently integrated parsley, basil, mustard greens, watercress - thinking that I was supposed per some research...well, I was about to stop this process as I realized it was too early for his digestive system.  There had been NO SIGNS whatsoever until this morning...the listlessness that I thought I was imagining and the lack of water consumption.  Up until that point, lots of running and jumping and loving and EATING!  Oh yeah, and sleeping like there was nothing to fear in the world - all sprawled out and comfy.

I am very attentive - very dedicated and when I take something on, well, it's with all that I am.

I read and read and read and researched only to realize how much there was still to know.

What am I missing?  What did I do wrong?  I must have missed something - this little guy trusted me...I raised it and I finally fell in love with him a few weeks ago - I CARED for him with devotion before that, but my heart finally gave in and I let myself be consumed...

So much has happened in my life in the last four years - I've watched so much death - lost my cat Sylvester to cancer in February...I was finally thinking about another pet for Puff and RabbI came along.  I keep thinking this didn't really happen.

I want you to please, please be as frank, bold and, if necessary, reprimanding as you like with respect to what I'm telling you.

Veterinarian:  The doctor said 'he's gone' within moments of my arrival...oh my god!  He had a temp of 104 (normal 101 to 103?), she said she saw no indications externally of any trauma.  She did an autopsy (breaking my heart) and saw food in the stomach (he did eat the couple of small pieces of parsley I gave him and from what I can tell, within an hour of his episode, he ate a part of his alfalfa treat), normally formed stool and nothing looked suspicious.  She sent biopsies off to the lab (I can't write from where right now - I'm sorry).

What did I do wrong?  Please, help me - educate me - I don't ever want to make the same mistake again.

Thank you and I hope this email is received well - it's sent with all due respect for your time.

Jenni

Answer
Dear Jenni,

I am so sorry about the loss of your treasured friend.  

I hope the necropsy and histopathology (especially the latter) provide some answers, because that's really the only way one can confidently establish a cause of death in a case like this.  Rabbits are *very* subtle about signs of illness, and when one is lethargic or acts the least bit unusual, it's time to check to see if it's an emergency.  Instructions can be found here:

www.bio.miami.edu/hare/sickbun.html

I don't think it was the begonia.  Don't know about the fireplace.  But cats can be extremely dangerous to rabbits, with even the slightest, not-noticeable scratch or bite enough to inoculate with deadly bacteria (Pasteurella and/or Bartonella etc.) and cause fatal systemic infection that can develop anywhere from 12-48 hours later.  The elevated temperature suggests this might have been a possibility, though a rabbit's temperature can elevate just due to stress, too. There's just no way to know.

I am so sorry.  I hope the results of the tests will give you some closure.  He will always live in your heart.

Dana