The study represents an excretory urogram.
Findings
- Best seen during the pyelographic phase of the examination, the right renal pelvis is moderately dilated.
- The right ureter is diffusely moderately to severely dilated and tortuous with sacculation, most severe distally at the level of the ureterovesicular junction. The contrast medium within the right ureter is seen coursing along the dorsal margin of the urinary bladder neck and abruptly terminates within the mid pelvic canal, with a large volume of contrast medium noted within the penile urethra.
- The left ureter is seen and noted to be within normal limits.
- A small volume of contrast medium is seen within the gravity dependent portion of the urinary bladder.
Conclusions
- Right hydronephrosis and hydroureter secondary to an ectopic ureter. The larger dilation at the ureter termination is thought to be most compatible with a ureterocele.
- Unremarkable left ureter.
Follow-up:
- Complete blood count, plasma biochemical analysis and urinalysis were all within normal limits.
- Urine culture revealed no growth.
- A right ureterovesicular anastomosis was recommended. The patient went home and was lost to follow-up.
A little bit more…
- Ureteral ectopia is defined as the abnormal insertion of one or both ureters caudal to the trigone. Although rare, it represent the most common congenital anomaly of the urinary tract in horses (Chaney et al.). It may be a consequence of abnormal development of the metanephric and mesonephric ducts (Coleman et al., Pringle et al., Blikslager et al.).
- Clinical signs most commonly include continuous or intermittent urinary incontinence with scalding of the pelvic limbs (and perineum in mares). In the absence of neurologic deficits, ectopic ureter(s) may be of greater consideration (Pringle et al., Blikslager et al.).
- No breed predilection has been reported (Coleman et al.). Various resources reports a higher incidence in female horses; while others report no sex predilection (Coleman et al., Pringle et al., Chaney et al.).
- Physical examination and bloodwork are usually unremarkable (Coleman et al..).
- Cystoscopy is the gold standard for direct visualization of the ureter insertion (Coleman et al., Blikslager et al.).
- CT is feasible is small/young horses able to fit within the bore of the unit. CT allows visualization of the ureters termination and course. IV contrast may help determine flow of urine from the ureter(s) largely into the urethra instead of the urinary bladder in horses with ectopic ureter(s) (Coleman et al.).
- CT may enhance the ability to identify ureteroceles in horses. A ureterocele represents a focal dilation of the distal ureter, most often congenital based on reported cases in humans and dogs. Ureteroceles in horses are rare (Coleman et al.).
- Coleman et al. reported a similar case using computer tomography:
- Blikslager et al. reported an unusual case of bilateral ectopic ureters with termination of the right ureter into the vagina and the left ureter into the urethra.
- Some horses may develop a urinary tract infection (Coleman et al., Pringle et al.)
- Common surgical approaches include ureterovesicular anastomosis or unilateral nephrectomy. The presence of uni- vs. bilateral ectopic ureters and concurrent renal disease may influence treatment recommendations (McLoughlin et al., Coleman et al.).
References:
- Coleman, M. C., M. K. Chaffin, C. E. Arnold, and B. D. Young. “The use of computed tomography in the diagnosis of an ectopic ureter in a Quarter Horse filly.” Equine Veterinary Education 23, no. 12 (2011): 597-602.
- Pringle, John K., Normand G. Ducharme, and John D. Baird. “Ectopic ureter in the horse: three cases and a review of the literature.” The Canadian Veterinary Journal 31.1 (1990): 26.
- Blikslager, Anthony T., Eleanor M. Green, Karen E. MacFadden, Bennett Fagin, and Gayle C. Johnson. “Excretory urography and ultrasonography in the diagnosis of bilateral ectopic ureters in a foal.” Veterinary Radiology & Ultrasound 33, no. 1 (1992): 41-47.
- McLoughlin, Mary A., and Dennis J. Chew. “Diagnosis and surgical management of ectopic ureters.” Clinical Techniques in Small Animal Practice 15, no. 1 (2000): 17-24.
- Chaney, Kristin P. “Congenital anomalies of the equine urinary tract.” Veterinary Clinics of North America: Equine Practice 23, no. 3 (2007): 691-696.
