Every publication I have read has stated therethat any color from milky white to reddish orange is considered normal,depending on what the rabbit has eaten and what is being secreted inthe urine.
That said, whenever I notice red urine in the pans of ourrabbits, it has always been due to overly concentrated urine when thereis something wrong. (Such as a rabbit not off it's feed andnot drinking enough). I currently have a couple weanilingsnot eating well, who have orange urine.
A doe we had that exhibited red urine for over 6 months improved after a rigorous de-worming program.
So -- in contradiction with any info on red urine that I have ever seen-- I am concerned when I note red urine in the rabbit's pans due to thefact it often can indicate dehydration or illness. In myexperience, I have never noted red urine in a perfectly healthyrabbit's pan; There has always been a health reason for thehighly concentrated urine which, in advanced stages, is accompanied bya strong odor.
Consider my advice along with a grain of salt, as I do not wish tocause undue concern
(Also keep in mind that excessivecarrots can cause discoloration to the urine).
I would try to increase your rabbit's liquid intake to see if the condition improves.
I agree with Carolyn that you may want to have avet examine a sample.
Pam