Urinary Tract Stones (Struvite) in Cats

Urolithiasis is a medical term referring to the presence of stones in the urinary tract. Struvite is a material that is comprised of magnesium, ammonium and phosphate. These type of stones can be found in the urinary bladder, the urethra or in the kidneys. While some forms of the stones can be flushed out or dissolved, others must be removed surgically.


Symptoms and Types

Many animals do not display any signs or symptoms of the disease. However, some will have:

  • Abnormal urine patterns
  • Difficulty urinating (dysuria)
  • Frequent urination
  • Bloody urine (hematuria)
  • Cloudy urine
  • Increased thirst
  • Enlarged belly 

The most common urinary tract stones (uroliths) are struvite and oxalate. Struvite stones are crystal-like formations that are small in size and primarily made up of magnesium, ammonium and phosphate. When cats have struvite plugs in their urethra (the tube that extends from the bladder to the outside of the body to discharge urine), they are typically comprised of larger stones and are often mixed with crystals.


The median age for urolithiasis is around seven years old and it is more common in female animals than in males. Animals that have small urethral outlets are also more prone to develop these type of obstructions. It is thought that the stones are developed following urinary tract infections, as well as when large quantities of minerals are bound to other foreign materials such as tissue, blood and other inflammatory reactants.


Sometimes a thicker bladder wall will be felt by the veterinarian; difficulty urinating and an abnormal outflow may also be diagnosed. Urine samples will be obtained by the veterinarian to examine for abnormalities. Ultrasounds are used to determine the size, shape and location of the stones for treatment options; other imaging tests may also be performed to determine if there are any other underlying medical conditions.

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