[Evaluation of a test strip for the determination of urine specific gravity in the dog]

The specific gravity of 80 randomly chosen urine samples from healthy dogs without polyuria/polydipsia and from a few dogs with polyuria/polydipsia was measured by refractometry and by test strip method (sg test strip). Urine osmolality and pH were also measured and the urine samples were examined for the presence of glucose. In accordance with earlier observations, there was an excellent correlation between the specific gravity determined by refractory and the osmolality (r = 0.98). The results obtained with the sg test strip correlated poorly with those obtained by refractometry (r = 0.39) and poorly with the osmolality (r = 0.36). In 77.5% of the samples the specific gravity determined with the sg test strip differed by more than 0.005 from that determined by refractometry. After correction of the sg test strip results by +0.005 for urine pH > or = 6.5, this percentage decreased to 60%. The results for the refractometer and sg test strip were significantly different (P < 0.001). These results indicate that the sg test strip investigated is unsuitable for use to determination of the specific gravity of canine urine.