CLINICAL FINDINGS
The physical examination revealed a bright, alert, responsive horse. The rectal temperature was 37.5°C, heart and respiratory rate were within normal limits. Body condition score was 5/9. Complete blood count (CBC) including leucocyte differential count (LDC), serum creatinine and urea as well as symmetric dimethylarginine (SDMA) were within the normal range on venous blood.
During hospitalisation no polyuria and stranguria could be observed.
Transabdominal ultrasonography (5 Mhz curved array probe, Fa. GE Health Care, Vivid iq) showed both kidneys to be of physiologic size, shape, and echogenicity. The ureter could not be seen from this view.
Upon transrectal palpation the bladder was of physiologic size and no urinary calculus could be palpated. The cranial 15 cm of the right ureter were palpable and had an extended diameter of about 2-3 cm. The left kidney could be reached butright kidney could not be palpated.
Transrectal ultrasonography (5 MHz rectal transducer, Fa. GE Health Care, Vivid iq) demonstrated an approximately 3-4 cm large inhomogeneous hyperechogenic structure in the area of the caudal pole of the urinary bladder, which could be traced to the right ureter. The right ureter had a maximum diameter of 2.3 cm in the orifice area and the lumen was filled by this hyperechogenic structure in the caudal 10-15 cm. (Fig. 1)
The horse was sedated with detomidine hydrochloride1(0.01 mg/kg bwt intravenously (iv)), butorphanol tartrate2 (0.025 mg/kg bwt, iv) and azepromazin3 (10 mg/kg bwt, iv), and a urine sample was obtained by means of a urinary catheter. The urine showed physiological characteristics.
Urinalysis revealed a specific gravity of 1026 (reference range\([\text{rr}]\): > 1024), haemoglobinuria, proteinuria and crystalluria consisting mostly of calcium carbonates and calcium oxalate monohydrates. No bacteria were cultured from the urine.
A cystoscopy (180 cm long, 10.4 mm diameter flexible endoscope, Fa. Storz) revealed the urethra and bladder had no signs of inflammation. Low-grade sediment deposits were visible on the bladder floor. A pedunculated cauliflower-like mass measuring approximately 2-3 cm was protruding in the bladder from the right ureteral orifice with periodic movement (ureteric peristalsis) (Fig.2). The surface was bulging, partly bloody, smoothly moist and reddend. During the endoscopy the mass sometimes retracted inside the orifice, coming back into the bladder vision immediately after. The urine outflow from the ureter was normal and no mucosal swelling was present around the right ureteral orifice. At ureteroscopy the mucosa of the right ureter showed no signs of inflammation, and the small base of the mass could be located approximately 10 cm cranial of the ureteral orifice (Fig. 3). Urine was collected from the right and the left ureter. The urine GGT:creatinine ratio of the left ureter was 19 IU/gKr (rr < 25 IU/gKr) and it was 25 IU/gKr for the right ureter. Fractional electrolyte excretion showed slightly increased sodium-, potassium- and chloride-excretion from both kidneys.
Based on these findings, polypectomy via endoscopic resection utilizing a snare was performed the next day as an elective procedure to restore the restricted volume of the ureter and to prevent backflow into the renal pelvis.