Ultrasound-Guided Diagnosis of Interstitial Nephritis in a Rescued Korean Raccoon Dog (Nyctereutes procyonoides koreensis)-A Case Report

This case report describes the first confirmed diagnosis of interstitial nephritis in a wild Korean raccoon dog (Nyctereutes procyonoides koreensis) using ultrasonographic evaluation and ultrasound-guided renal biopsy, demonstrating the diagnostic value of imaging even in the absence of azotemia. Although serum biochemical parameters, including blood urea nitrogen (BUN) and creatinine, were within normal ranges based on canine reference values, ultrasonography revealed increased renal cortical echogenicity and loss of corticomedullary distinction in both kidneys. These sonographic findings suggested chronic renal pathology, including tubulointerstitial nephritis or diffuse neoplasia. Urinalysis also suggested a bacterial infection, although confirmatory testing was not performed. To obtain a definitive diagnosis and assess prognosis, ultrasound-guided percutaneous renal biopsy was performed. Histopathological examination revealed interstitial infiltration of mononuclear inflammatory cells consistent with interstitial nephritis. This case highlights the value of ultrasonographic and histopathological approaches in detecting renal disease in wildlife, especially when standard biochemical indicators, such as azotemia, are absent or inconclusive.