Why Are There Crystals In My Dog Or Cat's Urine ?















Ron Hines DVM PhD

To see what normal blood and urine values are, go here

For an explanation of causes of most abnormal blood and urine tests, go here

To see how tests are grouped, go here

Crystals Observed Microscopically In Your Pet's Urine

Crystals observed in your pet’s urine always mean that the urine is quite concentrated (supersaturated = high specific gravity). In concentrated urine, various dissolved constituents of your pet’s urine will form crystals. When those crystals are associated with urinary tract symptoms, they might be significant. Most of the crystals can be identified by their shape and by the pH of the urine in which they were found. Common crystals that can be associated with urinary tract disease are struvite (magnesium ammonium phosphate, triple phosphate) - associated with FUS and oxalate (Calcium oxalate mono or dihydrate). Some metabolic defects present from birth can also cause crystals to be present (cystine crystals in male dogs or uric acid crystals in dalmatians).



Certain sulfa antibiotics that your pet is receiving can also account for crystals in its urine.

Please remember that crystals found in stale urine or previously refrigerated urine may contain crystals that did not form in your pet. Very concentrated urine-of-the-morning or samples from dehydrated pets may not be a sign of disease nor of crystal formation throughout the day. The presence of other urine abnormalities and the pet's symptoms will be the decision makers.

Complementary tests :

urine pH, Blood calcium levels, crystal specimens submitted to lab for identification.