Low expression of cyclooxygenase-2 in chronic kidney disease in young dogs.

Chronic kidney disease (CKD) often results in end-stage renal failure in young dogs; however, the pathogenesis of this disease is not established. This study investigated renal expression of cyclooxygenase (COX)-1 and COX-2 proteins in three dogs with chronic kidney disease by immunohistochemistry. Histopathology showed asynchronous differentiation of renal tissues, including immature glomeruli. COX-1 signals were not detected in diseased or normal kidneys. COX-2 signals were low or undetectable in diseased kidneys, while normal kidneys showed clear positive signals in the macula densa (MD). Quantitative scores of COX-2 in diseased kidneys were significantly lower than those in normal kidneys. These findings demonstrate low renal COX-2 expression in CKD in young dogs, but whether this is correlated with disease pathogenesis remains unclear.