What Does It Mean If Your Pet Has Crystals In The Urine? — Safari Vet, League City TX

What causes the crystals?

The kidney disposes of waste materials from the body. If certain minerals are present in high quantities they can form crystals. Calcium, phosphate and nitrogen containing minerals commonly form crystals in dog and cat urine. The most common crystals are struvite (magnesium, ammonium and phosphate) oxalate (calcium and carbon compounds) urate (ammonium compounds) and cystine (silica and ammonium compounds).

The exact mechanism of crystal formation is not known, however we do know:

• Uroliths are not produced unless sufficiently high urine concentrations of urolith-forming constituents exist
• Transit time of crystals within the urinary tract is prolonged.
• For selected stones (e.g., struvite, cystine, urate), other favorable conditions (e.g., proper pH) for crystallization must also exist.

These criteria can be affected by urinary tract infection, diet, intestinal absorption, urine volume, frequency of urination, therapeutic agents, and genetics.

Is this the same as bladder stones?

Crystals and microscopic but they can aggregate or clump together, often around bacteria, to form into stones called uroliths or calculi which can cause obstructions and difficulty urinating. Urinary crystals are a precursor to bladder stones.

Characteristic bladder stones

How are they diagnosed?

Routine urinalysis will detect the presence of urinary crystals. The crystals have characteristic shapes when view under a microscope as this example on the right of struvite crystals shows.

Bladder stones are diagnosed with ultrasound or x-rays. Struvite and oxalate stones bigger than 3mm are visible on x-rays as shown below.

Should I be concerned?

Yes, even at low concentrations the presence of crystals in the urine should not be ignored. At Safari Veterinary Care Centers, we may recommend a repeat urinalysis in a month to see if crystals are persistent, diets to dissolve stones, antibiotics to remove infection or ultrasound/radiographs to check for stone formation. If struvite stones are recurring then a urine culture may be required.

What is the treatment?

The treatment recommendations at Veterinary Hospital League City will vary depending on the type and quantity of crystals. In general, diets will aim to reduce the mineral content of the urine and increasing water intake will reduce the concentration of minerals in the urine reducing the likelihood of stone formation.

• Struvite crystals form when there are ureases producing bacteria in the urine and the pH of the urine is high. We will recommend a course of antibiotics and a special diet that dissolves struvite stones.
• Oxalate crystals are most common in middle-aged dogs. There is no diet which will dissolve these stones. Radiographs and ultrasound are required to check for bladder stones and urinary culture will be carried out to check for bacterial infection. Stones are removed surgically and Hills prescription diet u/d can be used for prevention.
• Urate crystals usually indicate liver problems so a bile acids test and abdominal ultrasound will be recommended.
• Cystine crystals are hereditary in English Bulldogs, they require ultrasound and surgery. Contact Veterinary Wellness Center in Texas for more information.