Effects of a urolith prevention diet on urine compositions of glycosaminoglycans, Tamm-Horsfall glycoprotein, and nephrocalcin in cats with calcium oxalate urolithiasis.

OBJECTIVE: To evaluate urine concentrations of glycosaminoglycans, Tamm-Horsfall glycoprotein, and nephrocalcin in cats fed a diet formulated to prevent calcium oxalate uroliths. ANIMALS: 10 cats with calcium oxalate urolithiasis. PROCEDURES: In a previous study conducted in accordance with a balanced crossover design, cats were sequentially fed 2 diets (the diet each cat was consuming prior to urolith detection and a diet formulated to prevent calcium oxalate uroliths). Each diet was fed for 8 weeks. At the end of each 8-week period, a 72-hour urine sample was collected. Concentrations of glycosaminoglycans, Tamm-Horsfall glycoprotein, and the 4 isoforms of nephrocalcin in urine samples collected during that previous study were measured in the study reported here. RESULTS; Diet had no effect on the quantity of Tamm-Horsfall glycoprotein and nephrocalcin in urine. However, the urine concentration of glycosaminoglycans was significantly higher during consumption of the urolith prevention diet. CONCLUSIONS AND CLINICAL RELEVANCE: Feeding a urolith prevention diet increased the urine concentration of glycosaminoglycans, which are glycoprotein inhibitors of growth and aggregation of calcium oxalate crystals.