Rabbit urine can range in colour from clear to yellow to red to rust to orange. Colour variation is normal, and not a cause for concern unless it is accompanied by other, troublesome signs such as straining to urinate, fever, sudden changes in water consumption, excessive or lack of urination, or loss of litterbox habits. These signs may be indicative of such problems as urinary tract infection, sludge (hypercalcinuria) or stones (calculi).

Note that red urine does not necessarily mean that presence of blood in the urine. Many bunny owners mistake porphyrinuria (pigment in the urine that results from plants that the rabbit may have eaten) for blood in the urine. Often, the amount of blood in the urine is so small that it can only be detected by using a urine dipstick or by checking it under a microscope. Blood in the urine can indicate a urinary tract infection, sludge or, in unspayed females, uterine cancer/disease.

Sludge and stones are comprised primarily of calcium, which rabbits metabolize differently than other animals.

In very basic terms, most animals absorb only as much calcium from their diet as they need. The excess is excreted through the feces. Rabbits, on the other hand, absorb calcium in direct proportion to their calcium intake, regardless of how much calcium their bodies need at the time. Excess calcium is excreted through the urine in the form of calcium carbonate. This excess calcium is what causes a rabbit’s urine to sometimes turn dry white and chalky. Generally, white chalky urine residue is not a problem, and does not indicate sludge. True sludge causes darker, grayish, thick and gritty residue. It is not clear why some rabbits develop sludge while others do not. For rabbits prone to sludge and stones, it may be beneficial to reduce dietary calcium, although dietary calcium is just one factor that might lead to sludge and stones. Genetics, water intake and infrequent urination, among other things, also can lead to this condition.


Always consult with your vet if you suspect that your rabbit has a urinary tract infection (UTI), sludge or stones. Some treatment options may include the following:

UTI: To accurately diagnose a urinary tract infection, a urinalysis (to detect abnormal cells, as well as the chemical composition of the urine) should be performed. Depending upon the results of the urinalysis, the veterinarian should also perform a culture and sensitivity test to identify any bacteria present in the urine as well as determine which antibiotic(s) the bacteria is sensitive to. Urine can be collected in several ways:

Free catch: You can collect urine at home by allowing your rabbit to urinate into a clean, empty litterbox. The urine can be syringed up, and stored in a covered container in the refrigerator for up to 8 hours. Keep in mind that this method of collection is not sterile, and that contamination by feces may occur.

Manual expression: Your veterinarian or veterinary technician may be able to gently massage or squeeze the bladder until the rabbit urinates. Again, this method of obtaining a urine sample is not sterile.

Cystocentesis: Cystocentesis is the process by which a veterinarian inserts a needle into the bladder through the abdomen wall to withdraw urine. This procedure can be performed without anesthetic with only minimal discomfort to the rabbit, and produces a sterile sample.

Catheterization: A small rubber catheter is placed in the rabbit, and the urine is withdrawn with a syringe. This procedure requires that the rabbit be anesthetized, and produces a sterile sample.

Sludge: Sometimes you will be able to see gritty puddles of sludge in your rabbit’s litter box after urination. Other times, sludge can only be diagnosed by an x-ray. Sludge is usually treated by administering sub-q fluids or by a bladder flush. Because sludge crystals are sharp and can scratch the urethra, pain medication is sometimes prescribed. As well, sludge is sometimes accompanied by an infection, for which an antibiotic should be prescribed (as determined by the result of a culture and sensitivity test). If the rabbit cannot urinate sufficiently on its own, the bladder may have to be manually expressed by a veterinarian during treatment.

Stones: Very small stones may be passed during urination, but larger stones require surgical removal. Stones are diagnosed by x-ray or ultrasound.



Red Urine: Blood or Plant Pigment?-by Sandi Ackerman in consultation with Barbara Deeb, DVM, MS

Bladder Disease and Bladder Stones in the Rabbit- by Dr Sue A. Kestenman, DVM

Bladder Stones and Bladder Sludge in Rabbits- by Dr Susan Brown, DVM


Lowering Blood Calcium compiled by Kathleen Wilsbach, PhD

Kidney Failure:

For various articles on Kidney Failure, see: Kidney Disease and Failure