Availability of a digital refractometer for measuring urine specific gravity in dogs

Objective: Urine-specific gravity (USG) is used clinically to evaluate urine concentration and is routinely assessed by refractometry. A few studies compare optical and digital refractometers in evaluating USG in dogs. However, these studies have shown conflicting results. Therefore, this study aimed to evaluate the clinical usability of a hand - held digital refractometer (EDR) (Atago Pal-Usg Dog) in the measurement of USG. Material and Methods: Urine samples were taken from 100 dogs presented to Aydın Adnan Menderes University Veterinary Faculty Animal Hospital for different reasons between June 2022 - May 2023. EDR and the reference method optical handheld refractometer (OER) (Atago URC-NE) results were evaluated with dependent t-test, Pearson correlation analysis, Passing Bablok regression and Bland-Altman test. In addition, the coefficient of variation (CV) and total analytical error (TAE) rates for EDR were determined. Results: A positive excellent (r = 0.996) correlation was found between the two refractometers, although a statistically significant difference (p = 000) was detected between the mean USG measured by OER and EDR. According to the Passing Bablok regression analysis results, no systematic and proportional bias was observed between the results of the two refractometers. In the Bland-Altman test, the mean value of the difference in the measurement values obtained with OER and EDR was calculated as -0.9, and it was revealed that EDR results could be found 1.3 units higher or 3 units less than the value measured with OER. When CV was evaluated, it was observed that the repeatability of EDR was quite good, and when TAE was considered, this value was within the desired limits for USG. Conclusion: This study showed that USG can be measured safely, easily and quickly in dogs with EDR, and EDR is suitable for clinical use.