Non-Oliguric IRIS Grade V Acute Kidney Injury Associated with Suspected Leptospirosis in an Urban Dog Unvaccinated Against Leptospirosis from the Republic of Korea: A Case Report.

Leptospirosis is a zoonotic disease that can cause severe acute kidney injury (AKI) in dogs. A three-year-old intact male Border Collie, unvaccinated against leptospirosis, with a history of exposure to urban stagnant water presented with acute vomiting, diarrhea, and moderate dehydration. Initial evaluation revealed extreme azotemia (blood urea nitrogen, 175.8 mg/dL; creatinine, 11.10 mg/dL) and hyperphosphatemia (13.6 mg/dL), consistent with International Renal Interest Society (IRIS) AKI Grade V; urine output remained within the non-oliguric range (2.15-3.0 mL/kg/h) throughout the catheterized period (Day 0-4). Clinical and imaging findings supported acute intrinsic renal injury over chronic kidney disease. A multiplex real-time PCR targeting the Leptospira LipL32 gene was positive in urine (Ct 31.10), providing molecular evidence supporting active infection or shedding of pathogenic Leptospira spp., without identifying the infecting serovar. Empirical antimicrobial therapy targeting suspected leptospirosis, together with intravenous fluid therapy, was initiated on clinical suspicion prior to the PCR result. Renal and inflammatory biomarkers improved progressively over 22 days without extracorporeal kidney support; the patient's non-oliguric status, hemodynamic stability, and objective clinical improvement supported this management approach. This report documents, in detail, the clinicopathological recovery trajectory of a dog with non-oliguric IRIS Grade V AKI associated with suspected leptospirosis, information that may assist clinicians in recognizing and managing similarly severe presentations without assuming that dialysis is always required.