Emaciated or young animals may not have sufficient abdominal fat to provide good tissue contrast. Radiographic visualization of the urinary bladder is reduced by insufficient abdominal fat, inadequate distention, and superimposition opacities. The thickness of the bladder wall or mucosa cannot be identified on survey radiographs because of border effacement by urine in the lumen. The peritoneum is adherent to the serosal surface, providing a separate fourth layer. The musculomembranous urinary bladder wall consists of mucosal, submucosal, and muscular layers. Bowel (black arrows) is superimposed over the vertex of the bladder. The rectus abdominis muscle (black arrowhead) is ventral to the bladder. The bladder neck (white arrow) is well visualized because of fat within the bladder ligaments. 39-2 Lateral radiograph of the caudal abdomen in a normal dog.