Ultrasonographic appearance of the lower urinary tract in fifteen normal horses.

The purpose of this study was to describe the normal ultrasonographic appearance of the caudal portion of the equine ureters, pelvic urethra, and urinary bladder and to assess ureteral contractility. Fifteen horses with no evidence of urinary tract disease (five females, five intact males and five geldings) were studied. The lower urinary tract was evaluated ultrasonographically using a transrectal approach. The normal ultrasonographic appearance and anatomic location of structures of the lower urinary tract were evaluated and anatomic relationships described. Both ureters were identified dorsal to the bladder and at their openings into the bladder. Their relationship and different appearance from the male deferent ducts/ampullae and vesicular glands was noted. Ultrasonographic measurements of the diameter of the ureters and urethra were obtained and the ureteral, urethral, and urinary bladder wall thickness recorded. The normal parameters established in this study will be useful during sonographic examination of horses with suspected urinary tract disease. Transrectal ultrasonographic examination is valuable in assessing the presence and frequency of ureteral contractions as well as in detecting structural abnormalities of the lower urinary tract. The use of high-frequency transrectal ultrasound transducers allows for excellent visualization of the structures of the equine lower urinary tract.

Sonographic diagnosis of a presumed ureteral tear in a horse.

A 14-year-old thoroughbred gelding was presented for the evaluation of acute abdominal pain. Rectally, there was a soft fluctuant painful swelling dorsal to the bladder and to the right of the midline. The creatinine concentration of the peritoneal fluid was 15 mg/dl. Transrectal ultrasonographic examination of the urinary tract revealed a large collection of fluid dissecting from the pelvic portion of the right ureter ventrally through the right side of the bladder wall and into the retroperitoneal space, and a thickened right ureter and bladder wall at the level of the trigone. Cystoscopically there was moderate hemorrhage within the wall of the bladder. Ultrasonography revealed air within the retroperitoneal fluid collection after ureteral catheterization, confirming the preliminary diagnosis of a tear in the right ureter. The gelding was treated medically. After 48 h of hospitalization, nuclear scintigraphy revealed normal clearance from both kidneys and no apparent leakage from the right ureter. The ureteral tear and urinoma were monitored using transrectal ultrasound until resolution. The horse was successfully returned to racing. This case establishes the value of diagngstic ultrasound in the diagnosis and monitoring of a traumatic ureteral tear in a horse.