Urinary bladder incarceration and infarction by an intra-abdominal fat pad in a Virginia opossum (Didelphis virginiana).

A 2.5-year-old, female opossum had acute stranguria. Based on radiography and ultrasonographic examination a cystic structure was identified in the caudal abdomen associated with bilateral hydroureter and hydronephrosis. This structure contained a neutrophilic fluid, determined to be urine. There was a neutrophilic leukocytosis. Serum chemistry values were within normal limits. The opossum was euthanized. An intra-abdominal fat pad incarceration of the urinary bladder above the trigone was present, resulting in complete obstruction of the urinary bladder and partial obstruction of the ureters. Vessels to the bladder were involved in the incarceration which resulted in vascular compromise and infarction of the bladder. Mild to moderate hydroureter and hydronephrosis were present.