Urinary Stones in Rats

By PetMD Editorial on Oct. 1, 2008


Urolithiasis is a medical condition referring to the presence of uroliths -- stones, crystals or calculi -- in the kidneys, bladder or anywhere in the urinary tract. Rats with this condition suffer from secondary bacterial infections and pain due to the rubbing of the uroliths against the urinary tract. Male rats are more prone to urolithiasis because of their longer urethras.


Symptoms and Types

Uroliths are rough in nature, causing the rat's urethra, urinary bladder or kidneys to become inflamed. Kidneys can also become inflamed due to secondary bacterial infections. Rats suffering from this condition will lick or bite the urinary area. And while some are unable to urinate or at least urinate properly, others frequently urinate but only in small amounts, leaving the fur around the perineum damp. In severe cases, urolithiasis may lead to renal failure. Some other symptoms include:

  • Painful and difficult urination
  • Cloudy urine
  • Bloody urine
  • Foul-smelling urine
  • Loss of appetite
  • Weakness
  • Lethargy
  • Abdominal pain
  • Dehydration

The consistency of uroliths depends on the types of minerals or solutions in the formations. For example, urolithiasis struvite stones consist of magnesium ammonium phosphate and causes the rat's urine to become highly alkaline, and urolithiasis cystine stones consist of calcium oxalate, causing the urine to become highly acidic. Meanwhile, ammonium acid urates and silicate stones cause the urine pH to become either neutral or acidic.


There are several known risk factors for urolithiasis including diseases and conditions such as leukemia, diabetes, paralysis and diverticula (balloon-like growths on the bladder). Some other causes include:

  • Dehydration
  • Abnormally high levels of calcium in the blood
  • Improper diet
  • Parasitic infections in the bladder (e.g., threadworm)
  • Bacterial infections

Heredity can also cause urolithiasis in rabbits.


Other than observing the rat's clinical symptoms, the veterinarian will conduct X-rays and urine examinations to confirm the diagnosis. Culture and sensitivity tests may be required if secondary bacterial infections are present.



Once the type of urolith is diagnosed and located, your veterinarian will devise a treatment plan. The vet may begin the treatment with antibiotics to dissolve the uroliths, however, if the number or size of uroliths is large, surgical intervention will be needed. The type of surgery for your rat will depend on the location of the uroliths, such as a cystotomy when dealing with the bladder, a nephrotomy when dealing with the kidney(s), or a urethotomy when dealing with the urethra.

Surgery is not always an option. In these cases, your veterinarian may advise euthanasia to spare the rat pain and suffering.

Living and Management

Once the stones are removed, your veterinarian will provide a specific diet and certain living conditions for the rat.


Providing a well-balanced, healthy diet for your rat may help prevent uroliths from forming in your rat, but because there are various causes for the condition, there is no surefire way to prevent it.


Featured Image: iStock.com/alkir


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