Evaluation of and the prognostic factors for cats with big kidney‐little kidney syndrome

Abstract Background The term big kidney‐little kidney syndrome in cats has been used for many years, but the definitions are not consistent and relevant research is limited. Objective To determine the factors that differ between normal and BKLK cats, as well as to develop models for predicting the 30‐day survival of cats with ureteral obstruction (UO). Animals Sixteen healthy cats and 64 cats with BKLK. Methods Retrospective study. To define BKLK by reference to data from clinically healthy cats. The demographic and clinicopathological data among groups were statistically analyzed. Results Big kidney‐little kidney syndrome cats had higher blood urea nitrogen (BUN) (median [interquartile range] 69 [28‐162] vs 21 [19–24] mg/dL, P < .001), creatinine (5.6 [1.9‐13.3] vs 1.3 [1.05‐1.40] mg/dL, P < .001), and white blood cells (10 800 [7700‐17 500] vs 6500 [4875‐9350] /μL, P < .001) and lower hematocrit (32.8 [27.1‐38.4] vs 39.1 [38.1‐40.4]%, P < .001), urine specific gravity (1.011 [1.009‐1.016] vs 1.049 [1.044‐1.057], P < .001) and pH (5.88 [5.49‐6.44] vs 6.68 [6.00‐7.18], P = .001) compared to the control cats. A lower body temperature (BT; 38.1 [37.9‐38.2] vs 38.7 [38.3‐39.2]°C, P = .009), higher BUN (189 [150‐252] vs 91 [36‐170] mg/dL, P = .04), and creatinine (15.4 [13.3‐17.4] vs 9.0 [3.1‐14.2] mg/dL, P = .03) were found among the UO cats that were not 30‐day survivors. A combination of BUN, phosphorus, and BT can predict 30‐day survival among UO cats with an area under receiver operating characteristic curve of 0.863. (P = .01). Conclusion An increase in the length difference between kidneys can indicate UO, but cannot predict outcome for BKLK cats.