What may have caused death?

Question
Hi.  My rabbit, Lily, died yesterday.  She was only three years old.  When we first bought her from a petstore (which later I found out worse place to purchase a bunny), she became ill, runy noise, sneezing.  Treated by antibiotics, fine.  THis was on and off for a year, chronic sneezing.  Then she had to be admitted to the vet overnight for treatment.  After that she was fine.  It was just the first two years.  This last year she was great.  Playful interactive with us and with her fellow bunnies (we have 2 other bunnies).  then all of a sudden yesterday, she would not eat and she just sat in one place making gurgling noises and breathing heavy and finally starting to fall over, she couldn't keep herself up.  I was on the phone with the vet but in the meantime she died.  It was that quick.  HEalthy, playful and eating the day before and then suddenly dead.  Her and the other rabbits had a huge cage, got time to run the house and outside.  The other 2 healthy as can be.  Could it have been a heart attack just from the years of chronically being ill?  Any advise would be appreciated.  I loved her so much, and I just don't know what happened.  Thank you.

Answer
It sounds rather like she either had pneumonia (which comes on quickly) or she had chronic lung issues and finally her lungs couldn't deal with it any more.  They could have been scarred.

I doubt it was a heart attack because of the way she sounded.

If you have her in the frig rather than burying her or putting her in a freezer, you could ask your vet to do a necropsy to determine the cause of death.

It would be a good idea if you could just to make sure the other 2 can't catch anything.

Pneumonia in rabbits is a very fast killer, by the time you notice they have it it is generally too late to treat them.

Kim