sudden death of lop rabbit - poisoning?

Question
I found my two and a half year old dwarf lop rabbit (female) dead unexpectedly a few days ago. I had seen her in the morning and she was acting as normal, hopping around lively  as usual, attempting to mate with her partner, nothing out of the ordinary i thought for this time of year. But 8 hours later i  found her dead. I could see no signs of anything being wrong with her externally and am pretty certain she has not died of any virus or rabbit disease. The only thing i noticed was that she had one eye shut, which when i looked was a normal appearance, and the other open, which was clouded slightly and the white/pink areas had yellowed. (i dont know if this clouding/yellowing is normal in death or a sign of illness?)
The only thing i realised in hind sight is that she had been drinking a lot lately. (eating normally)(I have 4 other rabbits and so could tell in comparison to what they drink.)
The only possible explanations i can think of are that about two months ago while i was holding her she tried to jump out of my arms twice and i caught her round the middle. Tho i would not say that i squeezed her too tightly. Is it possible that i caused some internal injury? Shortly after this incident i noticed that one of my rabbits urine was a red colour. I thought it was from her. I was going to take her to the vet to get this checked but then it went back to normal after 2/3 days. Then since her urine had suddenly gone back to normal, somebody else suggested that the red could have been from wood on the hutch that is painted that colour and that she continuously ate. Is it possible that she could have been poisoned from the stain on the hutch since she used to chew it all the time? These incidents were all about two months ago and she has shown no signs at all that she was ill,in pain etc since then.
Also, since my rabbit has died the other 4, especially her partner, have become more withdrawn.When i go out to the hutch/run they hide from me. Whereas before they would follow the female lops lead, who was the most friendly and sociable of them.I am concerned that since they all share the same hutches and run and the female rabbit was dead in there, that they are now frightened of me. Is there anything i can about this or is it just a matter of time?
I would really appreciate any help you can give me. lynn

Answer
Dear Lynn,

I am sorry about your loss.

Unfortunately, the only way to determine the cause of death would be with a necropsy.  There are just so many possible reasons for a rabbit to die (apparently) without warning, that anything I might say would be just a guess.

Excessive drinking and excessive urination can be a sign of renal disease.  But a rabbit in kidney failure usually is not bright and active near the end.  I doubt it was the injury she suffered earlier, since a couple of months had passed.  But if a kidney was severely injured (enough to bleed), I suppose that cannot be ruled out.

It's normal for your other bunnies to mourn their friend.  If they had a chance to say goodbye to her body, they know what happened, and they will gradually recover.  At least they have each other for comfort, which is much better than if only one rabbit was left.

Keep a close eye on their behavior, appetite, etc. for any signs of trouble:

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

But I have my doubts that what took your alpha bunny was anything contagious to the others.

I am sorry for your loss.

Dana