Effects of sterilized micropulverized barium sulfate suspension and meglumine iothalamate solution on the genitourinary tract of healthy male dogs after retrograde urethrocystography.

A sufficient quantity of 30% w/v sterile barium sulfate suspension was infused into the caudal portions of urinary tracts of 12 young adult healthy male Beagles to induce vesicoureteral reflux. A control group of dogs was infused with a 7.5% solution of meglumine iothalamate. The dogs were radiographed at 1, 6, 13, and 29 days later. Three dogs from each group were euthanatized and necropsied (1 each) after radiography at each of these times. In some dogs, radiopacity in the prostate, urinary bladder, and renal pelvic diverticula due to barium persisted throughout the 30-day observation period. Opacity at or beyond 24 hours was not found in dogs infused with iothalamate. Light microscopy revealed barium either free or within macrophages in the submucosa of the bladder, in glandular and stromal areas of the prostate, and in the kidney. Renal barium was limited to pelvic diverticula (3 dogs), in a medullary tubule (1 dog), and in cortical tubules (2 dogs). Significant lesions attributable to barium were not seen in kidneys of dogs in the barium group. Iothalamate induced focal to multifocal inflammatory responses in some prostates; barium was phagocytosed by macrophages. Focal transient inflammatory and ulcerative lesions induced by bladder distention were observed in the bladder and urethral mucosa in both groups.