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

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.