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Urolith Basics

What are uroliths?
Uroliths (also known as calculi or stones) are solidified aggregates of mineral and non-mineral crystalloids that form in the urinary tract when urine becomes oversaturated with crystallogenic precursors. Most uroliths are composed of biogenic minerals, but also form from drug metabolites, amino acids or over foreign substances such as suture material from a previous surgery.
photo of multiple uroliths and a urolith with a suture nidus

What is the anatomy of a urolith?
diagram of a urolith and description of the layers

 Why submit uroliths for analysis?
radiograph from a canine with a urate urolith
Developing strategies to minimize urolith recurrence requires knowledge of its composition. Urolith composition is a clue to the underlying diseases responsible for their formation.  Submit all or a representative number of uroliths to obtain an accurate analysis. How to submit uroliths


What methods of analysis are recommended?

  1. Quantitative analytical methods are most accurate. The Minnesota UrolithCenter uses optical crystallography, infrared spectroscopy, x-ray diffraction,energy dispersive techniques, and other methods to quantitatively analyze eachlayer in uroliths.
  2. Qualitative analytical methods are less reliable. This method uses chemicaltests to identify chemical radicals and ions. Several components in stonescannot be identified chemically.

How can uroliths be retrieved for analysis?

  1. Voluntary voiding
  2. Catheter retrieval
  3. Voiding urohydropropulsion
  4. Basket retrieval
  5. Laser lithotripsy and basket retrieval
  6. Percutaneous cystolithotomy/nephrolithotomy and basket retrieval
  7. Surgery

For more information about retrieval techniques visit our publication page under urolith retrieval methods.

What steps should be taken to minimize urolith recurrence? The Minnesota Urolith Center provides detailed diagnostic and therapeutic strategies to assist veterinarians and pet parents in caring for dogs and cats with uroliths and other urinary disorders. See our Treatment Recommendations.