In dogs, urine cystatin B is predictive of progressive vs stable kidney disease, potentially since it is more likely to detect low-grade AKI or progressive nephron death.18 It is also possible that the discrepancy of increased urine cystatin B but not KIM-1 in urine is due to different cellular origins (pan-renal for cystatin B and specific proximal tubular segments for KIM-1), differences in stage of kidney disease or inclusion criteria, or other factors. Here, CSTB is linked to acute kidney injury.