Why is rabbit urine red in colour?

Rabbits secrete porphyrin, a red pigment, in their urine which is responsible for giving the urine its red colour. It is currently unknown why rabbits secrete porphyrin.

Urinary tract infections, bladder stones and uterine diseases can result in bloody urine. There are strips that can be dipped in urine to determine whether or not there is any blood present.