a. m. abbassi

Hydronephrosis occurs as a congenital or an acquired condition following obstruction of the urinary tract. In this study، a four month old male Holstein calf with emaciation، growth retardation and a poor dry scruffy hair coat was examined because of remarkable distention of right abdomen. At necropsy، right kidney was hydronephrotic as a very big fluid-filled round pelvis with the presence of multilocular cysts bulged from the cortical surface. With sectioning، more than 10 L of bloody fluid poured out from this sac. Microscopic examination showed severe atrophy of cortical tissue and fibrosis of the medulla. Also، the dilated pelvis was composed of fibrinous exudate and necrosis of epithelium associated with multifocal aggregations of neutrophils and bacterial microcolonies. In a culture and serotyping of isolated bacteria، Salmonella dublin was determined. In conclusion، S. dublin induced pyelonephritis secondary to congenital giant hydronephrosis is the first report in cattle in the world.