Exposure of urine of domestic cats to different substrates: impact on urine specific gravity

ObjectivesUrine specific gravity (USG) is a crucial indicator of renal function and is integral in the monitoring of renal disease progression. Although USG is a readily quantifiable parameter, the process of urine collection in cats can induce stress. Utilizing both hydrophobic and non-hydrophobic substrates in litter trays may reduce this stress and enhance owner compliance with urine collection protocols. This study investigated changes in USG as a result of exposing urine to different substrates over different time periods. A second objective was to assess the impact of other urine parameters, including microhematuria, proteinuria, pyuria, glycosuria, crystalluria and cylindruria, on USG within the context of the substrates used.MethodsA total of 34 cat urine samples were exposed to different substrates (a hydrophobic substrate, waterproof sand and aquarium gravel). Urine absorption and USG values were evaluated 10, 30, 60 and 120 mins after exposure.ResultsThe use of aquarium gravel as a substrate was deemed unsuitable because it absorbed the urine samples, thereby hindering sequential evaluations. In contrast, the hydrophobic substrate (Kit4Cat) showed no significant influence on USG. The non-absorbent waterproof sand (Fantastic Sand) significantly increased the USG values of cat urine during exposure periods of 60 mins and 120 mins.Conclusions and relevanceThe hydrophobic substrate used in this study did not interfere with USG monitoring for up to 120 mins.