RESUMEN
A 4.5-month-old Standard-bred filly was referred for evaluation of pigmenturia. Initially, the pigmenturia had resolved with the administration of antibiotics, only to recur after their withdrawal. A dark red urine sample contained numerous RBC, WBC, and gram-negative rods (Escherichia coli). Ultrasonography revealed the right kidney to be large, with multiple cystic structures and a dilated renal pelvis and calices. Cystoscopy revealed a large blood clot within the bladder and urine coming from the left ureteral opening. Urine was not observed coming from the right ureter. It was suspected that the primary infection within the urinary tract was coming from the right kidney, with secondary ureteral obstruction and cystitis. Trimethoprim-sulfamethoxazole treatment was initiated. However, acute depression and abdominal pain developed several days later, and the foal died before assistance could be provided. Necropsy revealed a large abscess that had eroded into the right ureter and aorta and had ruptured, resulting in acute blood loss and death. The location and extensive nature of the lesion would have precluded surgical intervention.