Hypercalciuria and Urolithiasis in Rabbits

Kidney stones form in the urinary tract due to the deposition of complex compounds containing calcium in the urine. In rabbits, all the calcium that is consumed is absorbed, and urine usually contains 45-60 percent calcium (other mammals’ urine contains only two percent calcium). Rabbits between three and five years of age are at higher risk.

Symptoms and Types

Symptoms will ultimately depend on the location, size, and amount of material in the bladder. Some of the more common symptoms associated with kidney stones include:

• Blood in urine (hematuria)
• Urine staining in the perineum
• Straining/pain during urination
• Thick, pasty, cloudy, or beige- to brown-colored urine
• Hunched posture, tremors, and difficulty walking (when neurologic or orthopedic disorders lead to urine retention)
• Loss of appetite
• Weight loss
• Lethargy
• Tooth grinding
• Swollen urinary bladder (may be palpable)
• Swollen kidney (may be palpable)

Causes

Commercial rabbit foods, such as pellets, typically contain very high content of calcium, much higher than the daily dietary requirements. This combined with factors such as inadequate water intake, lack of exercise, obesity, and incomplete emptying of the bladder can cause precipitation of calcium in the urine, ultimately leading to the formation of stones.

Diagnosis

You will need to give a thorough history of your rabbit's health and onset of symptoms. Your veterinarian will then perform a thorough physical exam on your rabbit. The first step will be to differentiate between stones and other causes of abnormal urine output. Blood and urine analyses will be conducted to check blood and urine calcium levels, and an analysis will be done of any stone (uroliths) that are removed form the bladder. X-ray and ultrasound imaging can be used to reveal the presence, size, and location of the stones.