Mini Lops ( Death )

Question
Hi.  We have 2 mini lops, sisters about 2 1/2 years old in a hutch with a large run outside, plenty of food and water.
Both looked fit, bright eyed, ran around, inquisitive, bit of weight on them but its coming up to winter.

The largest and most bossy of the two was found dead this morning in the sleeping area, no problems previously, dropping all okay.
We are at a loss to why this may have happened, any ideas? second lop is understandably stressed.  

Answer
Hello Nigel!
I am sorry to here about your loss.
Unfortunatly I do not have enough Info. about you rabbit
Questions  are :
1-Age may have been a factor some  rabbits live past 5-6 yrs ols but outside rabbits that may be overweight may only live 2-3 yrs.
Now with that said the other sister may live to 6 I don`t know.
2-something may have scared them.

You may want to have a vet examine her  and determine the cause of her death have him check the lungs for infection, the liver , the large intestine which may have burst.
Good luck
Dan