Many people have probably seen red urine in the bottom of the cage, and thought that the rabbit was bleeding or had some kind of internal injury. Well red urine is perfectly normal. Some rabbits get it often, and some never have it. Red urine is basically when the urine contains large amounts of calcuim oxalate, and forms on the cage floor. Certain types of feed often cause this, such as alfalfa and Leucaena. So if you're worried about this, stop worrying. The rabbit is just getting rid of all that excess calcium from. It is often seen in the cooler months of the year. One thing to worry about, is if the rabbit is constantly showing red urine, he may have a kidney stone, or a tumor in the bladder. There is no treatment for this and it could be very painful. Take them to a vet if the red urine persists over a long period of time, just to be safe.