Rabbit died.. want to know cause..

Question
It had to have been something contagious, both rabbits are buried as of now. Food has been checked there is no mold. And from what I've heard, no pesticides on the lawn... Any other ideas?
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Followup To
Question -
I gave my rabbit away a couple of days ago my friend brought him into her back yard with her bunny. The two were from the same pet shop, both males, one was albino and the other had a gray coat. Anyway, three days after moving into my friends house the gray one (I called him Silver) died, I had seen him earlier in the day (at her house) and he was really quiet, just sitting in his cage, I looked more closely, I could tell something was wrong, his eyes looked liquidy. Usually he is chewing on the bars and running around, eating, just being a Netherland Dwarf. We took him out and he hopped behind the cage into a slipper and sat there looking at us. Later that night (what my friend and her mom told me) he started thrashing around the cage and suddenly fell over, dead with his eyes wide open. My friend's bunny died yesterday, my bunny died Friday night, early Saturday morning, her bunny, the albino died the same exact way. What was going on? Before I brought Silver over to my friend's house he was a bit quiet, but I didn't take that seriously... because a few hours later he was back to chewing on his bars as usual.. I used to let Silver out into my yard, on a harness, with about 26 feet worth of rope to hop about, we have dollar weeds back there but I dont think that is poisonous.. I really want to know what happened. HELP!
Answer -
Did you get them from the pet store recently?  If so, go back there, tell them both rabbits died, and insist they give you a refund.  Then check any rabbits they may have there to see if they are ill.

It's likely that they got something at the pet store.  It's also possible they got into something poisonous, if there were pesticides used on the lawn.  OR, the food they ate could have been moldy and killed them.

Unless you refrigerated the rabbits and then took them to a vet for a necropsy, it's not likely you are going to know what happened to them.  

The only sure way to know would have been a necropsy (the animal version of an autopsy).  There's just too many things that COULD be the cause to be able to tell you WHAT the cause actually was.

Kim

Answer
Well, you wouldn't necessarily see the mold if it were mycotoxins (too small to be seen by humans).

How long since you got them from the pet store?  If it was within 2 weeks could have been something they got there.

Anything they ate or got into?  Vegetables that a grocery store had treated with something?  Veggies that were just a bit "off?"

Had you asked within 24 hours of death, and had refrigerated them, a necropsy could have been done, but at this point we are just guessing what it could have been.

Kim