Abstract

An 11-year-old female bottlenose dolphin (Tursiops truncatus) was previously diagnosed and treated for a vaginal calculus.¹ The purpose of this study was to rule out anatomic urinary anomalies that may have caused calculus development, most notably ectopic ureters. These can be unilateral or bilateral, intramural or extramural, and may enter the urethra, uterus, or vagina in females.^2,3 Recommended diagnostics include survey and contrast radiography, computed tomography (CT) (excretory urography, cystography, urethrography, vaginocystography, ureterography), cystoscopy, abdominal ultrasonography, and urodynamic assessments (urethral pressure profile, cystometrogram).^2,3,4,5,6 Two diagnostic methods were chosen based on practicality and success in other species: ultrasonographic ureteral jet assessment and computed tomographic excretory urography (CTEU). Neither technique has been described in cetaceans, although post-contrast abdominal CT has been performed.^7,8

Ultrasonographic evaluation of ureteral jets assesses periodic echogenic foci from the ureterovesicular junction (UVJ) into the urinary bladder lumen.^2,5 In dogs, administering a diuretic can be used to increase frequency and strength (conspicuity) of ureteral jets on ultrasound.⁵ Our study was performed voluntarily, dockside, with the patient in a left lateral position. UVJs and ureteral jets were not seen on pre-diuretic ultrasonography. Furosemide (1 mg/kg) was administered into the ventral tail fluke periarterial venous rete (PAVR) and flushed with 0.9% sodium chloride. Ultrasonography was performed for 18 minutes post-injection, assessing both sides without changing the animal’s position. Inconsistent ureteral jets were seen, but suspected to be bilaterally normal, with no clear evidence of anatomical anomalies.

CTEU is the gold standard for diagnosing ectopic ureters in human and veterinary medicine. The entire urinary tract can be evaluated accurately and noninvasively.⁶ For our study, CTEU was performed at a local human hospital. Thoracic and abdominal survey scans were performed. A 14-Fr urinary catheter was placed, urine drained, and the catheter clamped. Contrast was administered (Omnipaque 300 at 2.2 mL/kg) via an IV catheter in the lateral caudal subcutaneous vein,⁸ and multiple repeat abdominal scans were performed. A normal excretory urogram was present. No evidence of ectopic ureters or other congenital or acquired anatomical urinary tract pathology was identified.

Preliminary use of both techniques was successful in this patient. Although ureteral jets were confirmed following furosemide administration, the anatomy and contour of the genital slit presented a challenge ultrasonographically, as it precludes simultaneous evaluation of both UVJs on ventral midline. Shadowing from nearby pelvic vestiges can also significantly hinder visibility of the UVJs. In this animal, furosemide administration led to relatively infrequent poor conspicuity of ureteral jets compared to dogs,⁵ despite clear evidence of effective diuresis (notable urinary bladder expansion and voiding throughout assessment). The precise location of the ureteral papillae was challenging to see ultrasonographically. The papillae themselves appeared more cranial than expected based on CT anatomy, and the location of ureteral jets relative to the trigone seemed to vary considerably. CTEU is superior diagnostically in this (and other) species but may not be a diagnostic option for all cetaceans. In addition, the rapid administration of large volumes of IV contrast required is challenging in this species, but more feasible with IV catheter placement.

Acknowledgements

The authors would like to thank the animal care trainers and management at Dolphins Plus, the radiology department at Baptist Health South Florida, especially J.C. Holmes, for use of their CT and their time, and Steve McCulloch for photography.

*Presenting author

Literature Cited

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