Photomicrograph of the kidney of a >8–yr-old female river otter (Lontra canadensis) in San Juan County, Washington, USA with interstitial fibrosis and segmental glomerulopathy. Renal tubules and glomeruli are separated and isolated by moderately increased interstitial collagenous tissue (blue) consistent with fibrosis. Multifocally, glomerular tufts have segmental hypocellularity and increases in mesangial matrix. Masson's trichome. 20×.