This is used to detect excessive urate excretion in breeds, such as Dalmatians, and to monitor response to therapy with allopurinol. Dalmatians excrete up to 400 to 600 mg uric acid per day in their urine, compared to non-Dalmation dogs, which excrete less than 100 mg uric acid per day in urine.
The best method for measuring urinary urate excretion is from a 24-hour urine collection, as recent studies have shown that a single urine uric acid to creatinine ratio does not correlate well to 24-hour urinary uric acid excretion. In addition, the amount of uric acid excreted in urine is dependent on diet (higher on meat-based diets). However, measurement of 24-hour excretion of uric acid in the urine is cumbersome and impractical and most people use urine uric acid to creatinine ratios for monitoring therapy. Guidelines in the literature for uric acid/creatinine ratios in urine are shown below:
|non-Dalmation||0.2 to 0.4|
|Dalmation||0.6 to 1.5|
|Dalmation on allopurinol therapy||50% reduction (i.e. 0.25 to 0.3 in most dogs)|
Care must be taken when submitting urine samples for measurement of uric acid. Uric acid precipitates rapidly when urine is cooled, so the sample must be resuspended and a well-mixed aliquot provided to the laboratory, to prevent falsely decreased values due to precipitation (ideally, the urine should be submitted in the original container it was collected into).