An abnormal mucosal pattern with contrast radiography characterized by mucosal irregularity may be seen secondary to inflammatory and neoplastic diseases. Mucosal irregularity as a distinct entity, separate from mural disease, with fixation and rigidity to the wall of the urethra, is less frequently encountered. Patients with superficial urethritis may have no radiographic abnormalities on contrast urethrography. Mucosal irregularity may be focal, multifocal, or segmental and may be observed at a site of urethral obstruction secondary to uroliths, traumatic catheterization, or indwelling urethral catheters. Mural disease observed using contrast radiography, may be focal, multifocal, or segmental.
Mural disease occurs most frequently secondary to inflammatory or neoplastic strictures.
Obstructing uroliths may result in stricture and mural lesions. Traumatic catheterization may induce stricture formation and is most often reported in the male dog in the area of the ischial arch at the junction between the membranous and penile urethra. Strictures must be differentiated from spasms of the smooth musculature of the urethra. Strictures may be focal, multifocal, or segmental. Spasm can be differentiated from a stricture by performing subsequent radiographic studies to determine if the site of luminal narrowing will distend on subsequent injections of contrast media.