rabbit died, and i have no idea how

Question
My pet rabbit, fuzzles was a lionhead. A friend of mine had rescued her from the reptile expo at the prince William county fairgrounds. she was only a couple of months old and just the past thanksgiving, 11/26/09 had died. the night before my daughter came running down the stairs with her and she had seemed like she was having trouble swallowing her pellets and looked like she was going to throw them up or regurgitate them. nothing had come out of her mouth but her nose was running so much. she was making little grunting/choking noises. after awhile she stopped making the noises but she wasn't breathing normally. my daughter had fed her a carrot and she ate it all.my daughter kept an eye on her for the night but everything was fine except her breathing. the next morning(thanksgiving) we had been planning a trip to Pittsburgh, Pennsylvania and we were bringing the rabbit too. that morning she had seemed fine except she seemed a little less energetic than usual. the whole way up, my daughter was holding her in her lap. for the first hour she seemed like herself but after awhile she really wouldn't hop around the front seat and would stay still. when we stopped to take a rest we had tried to feed her pellets again. she would take one bite but wouldn't chew. finally my daughter got worried and had got the rabbit to open its mouth and the pellets rolled out. so we could tell she wasn't eating normally. the rest of the trip up my daughter, who loves her pets to death, kept saying " Mom something is wrong, she doesn't act like this." and i said that it was probably the car ride but she said that no it couldn't be because our other rabbits acted normally on long car rides. when we arrived at the house, she had set the cage down and we had all gotten settled.my daughter all of a sudden had started crying and yelling my name.my daughter said that the rabbit had been trying to get into its litter box but had ended up not being able to move its back legs. she had opened up the cage and had put the rabbit on the floor to show me, its back legs seemed like they didn't work because she just fell to her side.my daughter had tried to set her upright again but all of a sudden the rabbit had had something almost like a muscle spasm in her legs. my daughter had then gotten hysterical and i took her away from her till she got calm because i knew that the rabbit wasn't going to make it and that it wanted to be loved in its last minutes. so as soon as i had given her to my daughter my daughter looked at me and said
"mommy shes not going to make it." and so that day the rabbit had died in my daughters arms. this event has saddened our household especially my daughter and i just wanted to try and figure out what went wrong. thank you

Answer
Hi Sarah....First, my condolences to your family and especially your daughter.  It's always difficult to lose one but this one sounds tough.  Short of a necropsy, I can only give you an educated guess...so part of my response may be a little uncomfortable but the information is critical in helping get an idea of what happened.

My first thought based on the information is a GI issue.  The loss of appetite, breathing difficulty and loss of limb control all lends itself to a bacterial toxin in the GI.  If you would, please let me know everything you have fed your rabbit recently and how much.....pellets (including brand name and amount per day), type and brand of hay you feed and any other veggies or treats.

The usual signs of GI toxins are the rabbit will lose it's appetite and become lethargic.  As the toxins progress, you will usually see the rabbit start to sway from side to side and eventually fall over.  Sometimes they can right themselves for a short time.  Then their back legs usually will stretch out in an extended fashion and they will appear to be gasping for air.  In the last moments, you may see something like a seizure and they usually paw rapidly with their from feet.  Many will scream.  I am very sorry to be so graphic but in hopes of giving you good information, I need to know if these events occurred.