The Subcutaneous Ureteral Bypass (SUB) device (Norfolk Vet Products) has been implanted in cats in the authors’ practice since 2009 for the treatment of all causes of ureteral obstruction (UO), including obstructive ureterolithiasis, strictures, obstructive pyonephrosis, traumatic ureteral ligation, and neoplasia.1–7 Traditionally, an implanted SUB consisted of 2 catheters entering the lumen of the renal pelvis/ureter and urinary bladder, which were then connected to an SC shunting port on the ventral abdomen, providing a bypass to ureteral outflow (Figure 1).1,7,8 A new version of the SUB (3.0) was developed to mitigate some of the more common complications seen with prior versions, like dynamic kinking of the tubing as it traverses the body wall. This was estimated to occur in approximately 15% of cases when they were evaluated during dynamic leg movement in flexion and extension under fluoroscopic guidance during follow-up assessment in the authors’ practice (Allyson Berent, DVM, DACVIM, Animal Medical Center, NY, 2020, unpublished data) and required further characterization. This complication could result in an intermittent ureteral obstruction, requiring a revision surgery as well as cycling of the tubing. To maintain SC access to the system to flush and sample the device, while removing the risk of kinking of the nephrostomy and cystostomy catheters, a “Y-connector” was introduced intra-abdominally to connect the tubing internally while also proving a conduit for a third tube that connects to the SC port. In cases of bilateral UOs, an “X-connector,” or a 4-way adapter, was introduced to allow for the connection of 2 nephrostomy catheters to a single cystostomy catheter or 2 “Y-connectors” to maintain 2 separate systems.
Comparison of Subcutaneous Ureteral Bypass (SUB) 2.0 and 3.0 devices: 121 devices in 80 cats (2017 through 2020). A—Lateral abdominal radiograph of a cat with a unilateral SUB 2.0 device. Notice the locking-loop pigtail catheter in the urinary bladder of the cystostomy tube and that the nephrostomy catheter is within the proximal ureter as a ureterostomy catheter. Both catheters are connected to a shunting port and are traversing the body wall to the port that is in the SC space. B—Schematic of the SUB 2.0 device. C–E—The SUB 3.0 device with a “Y-connector” that is unilaterally placed in the left ureter as seen in this ventrodorsal fluoroscopy image (C) or in the right renal pelvis (D). E—A schematic of the unilateral SUB 3.0 device. F and G—A bilateral SUB 3.0 device with an “X-connector” that is connecting 2 nephrostomy catheters to a single cystostomy catheter. (F) and (G) are fluoroscopy images showing the placement in a cat's abdomen in ventrodorsal projection (F) and in a lateral projection (G). H—A schematic of the bilateral SUB 3.0 device.
Citation: American Journal of Veterinary Research 2025; 10.2460/ajvr.24.09.0255
The objective of this study was to report the short-term postoperative outcomes of cats after SUB 3.0 placement for the treatment of benign UOs (BUOs) and compare that to a similar follow-up period with that of the prior SUB 2.0. The authors hypothesized that SUB 3.0s will achieve lower rates of kinking and shorter procedure times due to the design modifications without increasing rates of other short-term complications.
Methods
Case selection criteria and medical records review
The medical records of all cats seen at the Animal Medical Center, NYC, that underwent SUB placement by either author (ACB and/or CWW) for the treatment of BUOs were retrospectively reviewed. Included cats were seen from July 2017 through July 2020 where either a SUB 2.0 or 3.0 (Norfolk Vet Products) were used and had the electronic medical record available for review, including pre- and postoperative ultrasound imaging, serum biochemical and microbiological testing, and surgical and anesthesia records; documentation that each device was routinely flushed at least 2 times within the first 3 months of placement with 2% tetrasodium EDTA (tEDTA; Norfolk Vet Products); a follow-up period of at least 3 months by one of the two authors with at least 2 rechecks (1 month ± 1 week and 90 days ± 1 month), including SUB flushes; and a urine culture recorded at each visit. Exclusion criteria consisted of cases with < 3-month follow-up data available, failure to follow the recommended recheck schedule, and failure to have the device flushed with tEDTA at follow-up.
The diagnosis of BUO, as described in previous studies,1,9,10 was typically based on a combination of abdominal ultrasonography, abdominal radiography, antegrade ureteropyelography, and surgical assessment at the time of SUB placement.
Cats in this study were grouped according to which model of the SUB was implanted. Group 1 received either a unilateral or bilateral commercially available SUB 2.0, and group 2 received either a unilateral or bilateral SUB 3.0. Group 3 received bilateral SUB devices, where 1 2.0 and 1 3.0 were implanted during the same surgical procedure. Each device was considered separately for device complications (eg, kink and mineralization). Each cat was considered separately for systemic complications (eg, urinary tract infections [UTIs]), surgical times, hospitalization times, etc. A kink was defined as narrowing of some component of the tubing, resulting in impedance to fluid flow.
Preoperative evaluation
Before surgery, all cats underwent abdominal imaging, including an abdominal ultrasound and abdominal radiographs. If a heart murmur was present, thoracic radiographs and an echocardiogram were recommended. In all cats, a pyelocentesis and an antegrade ureteropyelogram were performed at the time of SUB placement. Urine from the pyelocentesis was submitted for aerobic bacterial culture. The ureteropyelogram was performed using fluoroscopic guidance, and documentation of the location and etiology of the BUO was generally confirmed with a combination of exploratory surgery and the ureterogram.
Preoperative management
As described in prior studies,1 cats in this study were medically managed for at least 24 hours prior to surgery whenever possible. For any cat with refractory hyperkalemia or evidence of anuria/oliguria, despite euhydration/overhydration, decompression was performed emergently.
Intraoperative management
Further details on this procedure have been described elsewhere1 and are available in the instruction-for-use manual for the device (Figure 1 and Figure 2). Despite the SUB version used, an esophagostomy tube (Mila International Inc) and a multilumen catheter (4 or 5.5 Fr) were placed during the same anesthesia. Cats with cystolithiasis underwent concurrent cystotomy; calculi obtained via cystotomy or during pyelocentesis were submitted for stone analysis. Procedure time was defined as the period from the abdominal incision to closure.
Surgical image of a cat (in dorsal recumbency, with cranial aspect at the top of the image) during SUB 3.0 device placement. A—The intra-abdominal Y-connector is placed with the bladder, kidney, and actuating tubing connected to it prior to being leak tested. Note that the orientation can either be that the kidney and actuating tubing are at the caudal aspect of the “Y-connector,” or the connector can be flipped to where the bladder and actuating tubing are on the cranial aspect of the “Y-connector” with the kidney at the caudal aspect. B—Tunneling of the actuating catheter through the body wall into the SC space on the left side of the cat. C—Placement of a Swirl port in the SC space on the left side of the cat.
Citation: American Journal of Veterinary Research 2025; 10.2460/ajvr.24.09.0255
Postoperative management
Cats were carefully monitored throughout hospitalization to ensure euhydration was maintained using serial measurements of body weight, urine output, serum electrolytes, renal biochemical parameters, PCV, and total solids. Postobstructive diuresis (defined as urine output > 2 mL/kg/h) was documented via either urinary catheter output or manual weighing of urinary pads. Cats not receiving antimicrobial drug therapy prior to surgery were administered marbofloxacin (2.75 to 5.5 mg/kg/d [1.25 to 2.5 mg/lb/d], PO) for 2 weeks after surgery.11,12 If growth was present from the urine culture, then an appropriate antimicrobial was chosen, and the cat was treated for 6 weeks. Prior to discharge, all devices were flushed by ultrasound guidance to ensure patency and slowly infused with 2 mL of tEDTA as described elsewhere.13,14 An esophagostomy tube was used postoperatively for nutrition, enteral hydration, and medications as needed.
Follow-up
All cats were recommended to return to the hospital 2 weeks after surgery for suture removal, E-tube removal, and bloodwork. Postoperative assessment and flushing as well as bloodwork and urine culture occurred at 1 and 3 months, every 3 months thereafter for 2 years, and then every 6 months. Postoperative bacteriuria was defined as the presence of bacteria in urine sediment or positive growth on urine culture; postoperative UTI was defined as bacteriuria with concurrent clinical signs. Abdominal radiographs, in flexion and extension, were recommended at a minimum of 3 months postoperatively and then every 6 months to monitor for bladder stones and kinking. Recheck schedules were adjusted if evidence of emerging complications, such as increasing creatinine concentrations, kinking, or difficulty flushing, arose.1,6,13,14
Persistently azotemic cats were prescribed a renal diet, and those that were nonazotemic with evidence of ureterolithiasis associated with presumptive calcium oxalate stones were recommended a commercially available neutralizing stone prevention diet based on preference and palatability. Cats with persistent ionized hypercalcemia were evaluated for hyperparathyroidism, and if idiopathic hypercalcemia was diagnosed, dietary fiber was recommended prior to oral alendronate (10 mg/wk). Stone formers were recommended to be started on potassium citrate and/or hydrochlorothiazide if tolerated.
Statistical analysis
Categorical variables for descriptive statistics and frequency analyses were carried out using Chi square analyses and Fisher exact tests for cell size less than 5. Continuous variables were described as mean and SD for normally distributed variables, whereas non-normally distributed variables were described as median and range. Normality of error residuals were verified by visual inspection. Differences between independent groups were compared by ANOVA. Univariate logistic regression was carried out for binary dependent variables. Significance was determined at unadjusted P values with an α < .05 unless otherwise specified, and all analyses were carried out using SAS, version 9.4 (SAS Institute Inc).
Results
Cats
Eighty cats met the criteria for inclusion. Of these, 43 had unilateral BUOs and 37 had bilateral BUOs, for a total of 117 obstructed ureters (Table 1). Additionally, 4 of 80 cats were originally unilaterally obstructed and then later presented with a second contralateral obstruction outside the 90-day follow-up period after the first device, giving additional 90-day data on a new device, creating 84 hospital entries in 80 cats and 121 obstructed ureters.
Comparison of Subcutaneous Ureteral Bypass (SUB) 2.0 and 3.0 devices: 121 devices in 80 cats (2017 through 2020).
| Group | No. of cats | Unilat device placements | Bilat device placements | Total No. of devices |
|---|---|---|---|---|
| Group 1 | 40 | 27 | 13a | 53 |
| Group 2 | 26 | 20 | 6b | 32 |
| Group 3 | 18 | 0 | 18 | 36 |
Bilat = Bilateral. Unilat = Unilateral.
Thirteen cats had 2 SUB 2.0s placed.
Two cats had bilateral SUB 3.0s placed as 2 separate devices with 2 “Y-connectors,” and 4 had an X-piece connector.
Cats that met the inclusion and exclusion criteria and their respective groups. Group 1: cats with unilateral or bilateral SUB 2.0 devices. Group 2: cats with unilateral or bilateral SUB 3.0 devices. Group 3: cats with 1 unilateral SUB 2.0 and 1 unilateral SUB 3.0 device.
History and preoperative clinical findings
The mean age of cats (in years) in groups 1, 2, and 3 was 9.5 (SD, 0.6), 10.1 (SD, 0.7), and 7.4 (SD, 0.9), respectively. The 40 cats in group 1 consisted of 20 castrated males (MC) and 20 spayed females (FS). Of the 26 cats in group 2, 15 were MC and 11 were FS; of the 18 cats in group 3, 11 were MC, 6 were FS, and 1 was an intact male. The mean body weight was 4.6 (SD, 0.2), 4.8 (SD, 0.3), and 5.1 (SD, 0.4) kg for groups 1, 2, and 3, respectively. A history of azotemia was documented in 19 of 40 cats in group 1 (47.5%), 10 of 26 in group 2 (38.5%), and 10 of 18 in group 3 (55.6%). A previous cystotomy for the removal of cystic calculi was performed in 5 of 40 cats in group 1 (12.5%), 2 of 26 in group 2 (7.7%), and none in group 3. No cats in group 1, 4 in group 2, and none in group 3 had a history of hypercalcemia, though limited data was available on historical ionized calcium concentrations. Six cats in group 1 (6 of 40 [15%]), 6 in group 2 (6 of 26 [23%]), and none in group 3 had a history of UTIs prior to hospital presentation. Preoperative clinical signs for cats in groups 1, 2, and 3 included hyporexia (67.5%, 73%, and 78%, respectively), vomiting (45%, 69%, and 56%, respectively), polyuria/polydipsia (25%, 19%, and 17%, respectively), hematuria (2.5%, 7.7%, and 5.5%, respectively), dysuria (12.5%, 23%, and 0%, respectively), and oliguria/anuria (20%, 15.4%, and 16.7%, respectively) based on a urine output < 1 mL/kg/h despite being well- or overhydrated. On physical examination in groups 1, 2, and 3, a heart murmur was detected in 57.5%, 61.5%, and 55.5%, respectively. Hydration status at presentation in groups 1 to 3 was reported as dehydrated (30%, 35%, and 33%, respectively), euhydrated (55%, 50%, and 61%, respectively), and overhydrated (15%, 15%, and 6%, respectively). Three cats in each group had been receiving antimicrobial therapy in the 72 hours prior to hospital admission.
The only significant difference detected on preoperative findings was that group 3 cats were younger than group 2 (P = .02). There were no statistically significant differences in sex, body weight, history of azotemia, history of cystotomy, history of hematuria, gastrointestinal signs, hyporexia, weight loss, dysuria, heart murmur, body condition score, hydration status, and history of bacteriuria. Preoperative hydration status was significantly associated with median hospitalization time, with dehydrated cats having a 1.9-day longer mean duration of hospitalization (P = .04) when compared to those euhydrated or overhydrated.
Clinicopathologic findings
For all 84 hospital admissions, preoperative PCV, total solids, BUN, creatinine, sodium, potassium, phosphorus, total calcium, and ionized calcium concentrations are summarized in Table 2 and Supplementary Table S1. There were no statistically significant differences between groups 1, 2, and 3 for any of the above clinicopathologic findings. The mean creatinine concentration in cats with bilateral ureteral obstructions was 11.5 mg/dL (SD, 0.99; reference range, 0.8 to 2.1) compared to 8.3 mg/dL (SD, 0.88) for those with unilateral obstructions (P = .02). Seventy-five of 84 cats (89.3%) had a serum creatinine concentration above the normal range at the time of admission. There was no significant difference in preoperative creatinine concentrations when each group was compared.
Preoperative data for groups 1, 2, and 3.
| Total | Group 1 | Group 1a | Group 1b | Group 2 | Group 2a | Group 2b | Group 3 | |
|---|---|---|---|---|---|---|---|---|
| Pre-Creat-SX (mg/dL) | 7.1 | 8.57 (0.96) | 7.6 (1.1) | 10.6 (1.7) | 7.6 (1.2) | 7.0 (1.3) | 9.68 (2.5) | 10.83 (1.5) |
| Pre-SDMA (mg/dL) | 47 | 51.1 (5.1) | 51.5 (6) | 49.9 (10.4) | 46.2 (7.5) | 43.8 (8) | 62 (10.5) | 61.9 (8.4) |
| Pre-IRIS | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
| Pre-PCV (%) | 31 | 30.7 (1.3) | 31.35 (1.6) | 29.5 (2.5) | 33.2 (1.7) | 33.3 (1.8) | 32.8 (3.7) | 32.2 (2.0) |
| Pre-TP (g/dL) | 7.8 | 7.6 (0.17) | 7.68 (0.2) | 7.53 (0.3) | 8.0 (0.21) | 7.9 (0.2) | 8.3 (0.4) | 8.21 (0.25) |
| Pre-BUN (mg/dL) | 118.5 | 115.8 (10.8) | 106.9 (14.3) | 134.5 (16.3) | 107.6 (13.3) | 109.2 (16.6) | 102.3 (24) | 134 (130.3, 39–290) |
| Pre-K (mg/dL) | 4.3 | 4.6 (0.2) | 4.53 (0.2) | 4.70 (0.5) | 4.7 (0.3) | 4.5 (0.3) | 5.5 (0.7) | 4.8 (0.3) |
| Pre-Na (mg/dL) | 149 | 146 (1.9) | 145.2 (2.9) | 148.2 (1.9) | 148 (2.4) | 149 (3.4) | 144 (2.8) | 150 (2.9) |
| Pre-P (mg/dL) | 8.35 | 9.2 (0.9) | 9.6 (1.1) | 8.6 (1.4) | 9.6 (1.4) | 9.6 (1.6) | 9.5 (1.6) | 10.2 (1.5) |
| Pre-TCa (mg/dL) | 9.6 | 9.6 (0.2) | 9.7 (0.2) | 9.4 (0.3) | 9.6 (0.3) | 9.5 (0.3) | 10.1 (0.7) | 9.7 (0.3) |
| Pre-iCa (mg/dL) | 1.09 | 1.0 (0.05) | 1.0 (0.08) | 1 (0.06) | 1.0 (0.07) | 1 (0.1) | 1.2 (0.1) | 1.1 (0.1) |
| Pre-USG | 1.015 | 1.016 (0.001) | 1.016 (0.002) | 1.018 (0.002) | 1.018 (0.002) | 1.019 (0.002) | 1.014 (0.004) | 1.016 (0.002) |
| Pre-UpH | 6.5 | 6.5 (0.1) | 6.5 (0.1) | 6.4 (0.2) | 6.33 (0.1) | 6.4 (0.1) | 6 (0.3) | 6.2 (0.1) |
| Pre-Prot-DS | 1 | 1 | 1 | 1 | 0.75 | 0.5 | 1 | 0.5 |
| 0 = none | ||||||||
| 0.5 = trace | ||||||||
| 1 = 1+ etc | ||||||||
| Hx-Pre-UTI | 12/84 (14%) | 6/40 (15%) | 6/27 (22%) | 0/13 | 6/26 (23%) | 6/26 (30%) | 0/6 | 0/18 |
| Pre-SX-UTI | 10/84 (12%) | 6/40 (15%) | 5/27 (19%) | 1/13 (8%) | 4/26 (15%) | 3/20 (15%) | 1/6 (17%) | 0/18 |
Total population continuous clinicopathologic data reported are median. Group continuous clinicopathologic data reported are mean (SD).
BUO = Benign ureteral obstruction. Hx-Pre-UTI = Documented history of UTIs prior to presentation for BUO. Pre-BUN = Serum BUN concentration prior to surgery. Pre-Creat-SX = Serum creatinine concentration prior to surgery. Pre-iCa = Serum ionized calcium concentration prior to surgery. Pre-IRIS = International Renal Interest Society chronic kidney disease stage prior to surgery. Pre-K = Serum potassium concentration prior to surgery. Pre-Na = Serum sodium concentration prior to surgery. Pre-P = Serum phosphorus concentration prior to surgery. Pre-PCV = PCV concentration prior to surgery. Pre-Prot-DS = Median urine protein concentration determined by urine dip stick. Pre-SDMA = Serum SDMA concentration prior to surgery. Pre-SX-UTI = Documented evidence of UTI during hospitalization for BUO prior to surgery. Pre-TCa = Serum total calcium concentration prior to surgery. Pre-TP = Plasma total protein concentration prior to surgery. Pre-UpH = Urine pH prior to surgery. Pre-USG = Urine specific gravity prior to surgery. UTI = Urinary tract infection.
Group 1: cats with unilateral or bilateral SUB 2.0 devices. Group 1a: cats with unilateral SUB 2.0 devices. Group 1b: cats with bilateral SUB 2.0 devices. Group 2: cats with unilateral or bilateral SUB 3.0 devices. Group 2a: cats with unilateral SUB 2.0 devices. Group 2b: cats with unilateral SUB 3.0 devices. Group 3: cats with 1 unilateral SUB 2.0 and 1 unilateral SUB 3.0 device.
Preoperative urinalysis results were available from 72 cats (35 of 40 for group 1, 21 of 26 for group 2, and 16 of 16 for group 3; Table 2 and Supplementary Table S1) with a mean urine specific gravity of 1.015 (SD, 0.001; reference range, > 1.035) and a urine pH of 6.5 (SD, 0.11; reference range, 6 to 7). There was no significant difference among groups in hematuria, pyuria, crystalluria, bacteriuria, or presence of urinary casts or epithelial cells on urinalysis. In 77 of 84 hospital admissions where a urine culture and/or urinalysis were performed before or during surgery, 10 cats (13%; 6 of 39 in group 1, 4 of 22 in group 2, and 0 of 16 in group 3) had bacteriuria in urine from the bladder or renal pelvis, with no difference between groups. The microorganisms identified in these cats were Escherichia coli (n = 4), Enterococcus spp (n = 3), both E coli and Enterococcus spp (n = 1), Staphylococcus spp (n = 1), and Erysipelothrix rhusiopathiae (n = 1). The culture of urine from 58 renal units via pyelocentesis identified bacteria in 5 cats (8.6%; 4 in group 1 and 1 in group 3). All 5 of these cats had positive urine cultures preoperatively from the bladder, consistent with the renal pelvis. No cat with a positive urine culture from pyelocentesis had a negative urine culture from preoperative cystocentesis.
Diagnostic imaging findings
Obstructed ureters were documented in 121 ureters in 80 cats during 84 hospitalizations, with bilateral obstructions in 37 (44%) and unilateral obstructions in 47 (56%). The median diameter of the ipsilateral renal pelvis in a transverse plane in all cats and groups 1, 2, and 3 was 7 (mean, 8.8; range, 1.2 to 44; reference range, < 1 mm), 7.9, 11, and 8.1 mm, respectively. Preoperative renal pelvis diameter was not significantly different between groups. Hydroureter was documented in 83 of 121 ureters, with a mean ureteral diameter of 3.9 mm (SD, 0.4; reference range, < 0.3 mm). The location of the ureteral obstruction was reported for 102 ureters and was classified at the ureteropelvic junction (UPJ) in 8 (7.8%), proximal ureter (< 4 cm from the ureteropelvic junction) in 50 (49%), midureter (4 to 8 cm from the ureteropelvic junction) in 18 (17.6%), and distal ureter in 21 (20.6%) and was classified as multifocal in 5 (4.9%).
Subcutaneous Ureteral Bypass device placement
A SUB device was successfully placed for all 121 ureters in which it was attempted. The commercially available SUB 2.0 was placed in 71, and the SUB 3.0 was placed in 50. In all surgical procedures, a pigtail nephrostomy catheter was used, with the catheter coiled and locked in the renal pelvis in 78 of 121 (64.5%; 49 of 71 SUB 2.0 [69%] and 29 of 50 SUB 3.0 [58%]) or passed into the proximal portion of the ureter in 43 of 121 (35.5%; 23 of 7 SUB 2.0 [31%] and 21 of 50 SUB 3.0 [42%]). A cystotomy was performed in 6 of 84 cases (7%) at the time of surgery for bladder stone removal (1 in group 1, 4 in group 2, and 1 in group 3).
A urinary catheter was placed for postoperative urine quantification in 10 of 84 surgical events (2 in group 1, 4 in group 2, and 4 in group 3). Of these 10 cats, 5 were anuric/oliguric at presentation.
The mean procedure time for unilateral SUB placement was longer for group 1 (73.6 minutes; SD, 4.4) than group 2 (60.4 minutes; SD, 5.3) but not significant (P = .06). The mean procedure time for bilateral device placement for groups 1, 2, and 3 was 118.5 (SD, 7), 76.8 (SD, 10.4), and 102.5 (SD, 5.9), respectively, which was statistically significant between groups 1 and 2 (P = .002) and groups 2 and 3 (P = .04). Overall, the median procedure time for all surgeries in this study was 80 minutes (range, 30 to 160).
Follow-up data—The PCV, total solids, and serum creatinine prior to discharge and BUN and creatinine concentrations for cats at 24 hours, 2 weeks, 1 month, and 3 months after SUB placement are summarized in Tables 3 and 4 and Supplementary Tables S2 and S3.
Postoperative data until discharge for groups 1, 2, and 3.
| Total | Group 1 | Group 1a | Group 1b | Group 2 | Group 2a | Group 2b | Group 3 | |
|---|---|---|---|---|---|---|---|---|
| Uroabdomen postop | 1/84 (0.2%) | — | — | — | — | — | — | 1/18 (5.6%) |
| pRBCs needed | 22/84 (26.2%) | 14/40 (35%) | 6/27 (22.2%) | 6/13 46.2% | 4/26 (15.4%) | 2/20 (10%) | 2/6 (33.3%) | 4/18 (22.2%) |
| pRBCs preop | 6/84 (7.1%) | 3/40 (7.5%) | 2/27 (7.4%) | 1/13 (7.7%) | 2/26 (7.7%) | 1/20 (5%) | 1/6 (16.7%) | 1/18 (5.6%) |
| pRBCs postop | 9/84 (10.7%) | 6/40 (15%) | 4/27 (14.8%) | 2/13 (15.4%) | 1/26 (3.8%) | 1/20 (5%) | 0 | 2/18 (11.1%) |
| pRBCs pre- and postop | 7/84 (8.3%) | 5/40 (12.5%) | 2/27 (7.4%) | 3/13 (23.1%) | 1/26 (3.8%) | 0 | 1/6 (16.7%) | 1/18 (5.6%) |
| Fluid overload postop | 6/84 (7.1%) | 4/40 (10%) | 2/27 (7.4%) | 2/13 (15.4%) | 2/26 (7.7%) | 1/20 (5%) | 1/6 (16.7%) | — |
| POD developed | 38/84 (45.2%) | 20/40 (50%) | 13/27 (48.1%) | 7/13 (53.8%) | 9/26 (34.6%) | 6/20 (30%) | 3/6 (50%) | 9/18 (50%) |
| Creat 24 h (mg/dL) | 3.75 | 5.7 (0.6) | 5.3 (0.7) | 6.4 (1.1) | 3.4 (0.7) | 3.3 (0.8) | 6 (1.6) | 5.7 (0.9) |
| BUN 24 h (mg/dL) | 78.5 | 89.2 (7.7) | 84.9 (10.0) | 98 (12.1) | 71.4 (9.6) | 65.4 (11.7) | 91.5 (11.9) | 80.6 (11.5) |
| Discharge Creat (mg/dL) | 2.8 | 3.8 (0.3) | 3.7 (0.4) | 4.0 (0.6) | 2. 9 (0.4) | 2.7 (0.5) | 4.0 (1.1) | 2.4 (0.5) |
| Discharge SDMA (mg/dL) | 25 | 38.9 (3.9) | 43.5 (5.6) | 30.3 (4.1) | 22.1 (6.6) | 19 (8.1) | 47 (4.3) | 22.5 (5.9) |
| Discharge PCV (%) | 26.5 | 27.6 (0.95) | 27.2 (1.2) | 28.3 (1.6) | 27.8 (1.2) | 28.2 (1.4) | 26 (2.86) | 26.8 (1.5) |
| Discharge TP (mg/dL) | 6.8 | 6.9 (0.1) | 6.9 (0.2) | 6.8 (1.2) | 7 (0.2) | 7 (0.2) | 7.1 (0.3) | 6.5 (0.2) |
| Best hospital Creat (mg/dL) | 2.5 | 3.5 (0.4) | 3.4 (0.4) | 3.8 (0.7) | 2.7 (0.5) | 2.3 (0.50 | 4.3 (0.8) | 2.9 (0.5) |
| Days to best Creat (mg/dL) | 3 | 4.8 (0.6)a | 4.7 (0.9) | 5 (0.5)a | 2 (2.2 (0.8)a | 2 (1.1) | 3 (0.8) | 3.4 (0.9) |
| Hospital time (d) | 5.5 | 7.1 (0.6) | 7.3 (0.9) | 6.5 (0.6) | 5.7 (0.7) | 5.2 (1.0) | 7.5 (0.8) | 5.3 (0.9) |
| Stone analysis performed | 22 | 11 | 6 | 5 | 5 | 5 | 0 | 6 |
| Stone analysis: CaOxMono | 12 | 5 | 3 | 2 | 3 | 3 | 0 | 4 |
| Stone analysis: CaOxDi | 1 | — | — | — | 1 | 1 | — | — |
| Stone analysis: struvite | 1 | — | — | — | — | — | — | 1 |
| Stone analysis: CaOxMono and CaOxDi | 1 | 1 | — | 1 | — | — | — | — |
| Stone analyis: CaOxMono and struvite | 1 | — | — | — | 1 | 1 | — | — |
| Stone analysis: DSB | 6 | 5 | 3 | 2 | 0 | 0 | 0 | 1 |
Total population continuous clinicopathologic data reported are median. Group continuous clinicopathologic data reported are mean (SD).
Best hospital Creat = Lowest recorded serum creatinine concentration during hospitalization. BUN 24 h = Serum BUN concentration 24 hours after surgery. CaOxDi = Calcium oxalate dihydrate. CaOxMono = Calcium oxalate monohydrate. Creat 24 h = Serum creatinine concentration 24 hours after surgery. Days to best Creat = Days from SUB placement to lowest recorded serum creatinine concentration. Discharge Creat = Serum creatinine concentration on the day of discharge. Discharge PCV = PCV on the day of discharge. Discharge SDMA = Serum SDMA concentration on the day of discharge. Discharge TP = Total protein concentration on the day of discharge. DSB = Dried solidified blood. Fluid overload postop = Number of cats that were assessed as developing fluid overload after surgery. POD developed = Number of cats determined to be undergoing postobstructive diuresis after surgery. pRBCs needed = Number of cats that required 1 or more transfusions of packed RBCs (pRBCs) at any point during their hospitalization. pRBCs postop = Number of cats requiring 1 or more pRBC transfusions after surgery. pRBCs pre- and postop = Number of cats requiring multipe pRBC transfusions before and after surgery. pRBCs preop = Number of cats requiring 1 or more pRBC transfusions before surgery. Stone analysis performed = Number of cats that had uroliths or nephroliths submitted for stone analysis. Uroabdomen postop = Development of a uroabdomen after device placement prior to cats’ discharge.
P = .009 (group 1 vs group 2).
Group 1: cats with unilateral or bilateral SUB 2.0 devices. Group 1a: cats with unilateral SUB 2.0 devices. Group 1b: cats with bilateral SUB 2.0 devices. Group 2: cats with unilateral or bilateral SUB 3.0 devices. Group 2a: cats with unilateral SUB 2.0 devices. Group 2b: cats with unilateral SUB 3.0 devices. Group 3: cats with 1 unilateral SUB 2.0 and 1 unilateral SUB 3.0 device.
Survival and clinicopathologic data from discharge to 90 days postplacement.
| Total | Group 1 | Group 1a | Group 1b | Group 2 | Group 2a | Group 2b | Group 3 | |
|---|---|---|---|---|---|---|---|---|
| Survive to discharge | 79/84 (94%) | 38/40 (95%) | 26/27 (96%) | 12/13 (92%) | 24/26 (92%) | 20/20 (100%) | 4/6 (67%) | 17/18 (94%) |
| Survive to 90 d | 69/84 (82%) | 30/40 (75%) | 19/27 (70%) | 11/13 (85%) | 22/26 (85%) | 19/20 (95%) | 3/6 (50%) | 17/18 (94%) |
| Creat 1 wk | 2.7 | 3.9 (0.3)a | 3.9 (0.4) | 4 (0.5) | 3.2 (0.4) | 3.0 (0.4) | 4 (0.7) | 2.5 (0.5)a |
| SDMA 1 wk | 25.5 | 35.1 (3.4) | 36.9 (4.9) | 31.9 (4.7) | 26.7 (6.4) | 23.8 (4.3) | 36.5 (11) | 21 (5.5) |
| BUN 1 wk | 45.5 | 65.3 (6.4) | 62.6 (7.5) | 70.8 (11.8) | 59.6 (8.1) | 56.3 (8.6) | 76.3 (21.3) | 42.2 (9.7) |
| Potassium 1 wk | 4.4 | 4.5 (0.1)a | 4.5 (0.2) | 4.6 (0.2) | 4.0 (0.1)a | 3.9 (0.2) | 4.4 (0.3) | 4.4 (0.2) |
| Phosphorus 1 wk | 5.35 | 7.2 (0.7) | 7.4 (1.0) | 6.8 (0.9) | 6.7 (1.2) | 5.8 (1.2) | 9 (1.9) | 5.4 (1.2) |
| Calcium 1 wk | 9.9 | 10 (0.2) | 10.2 (0.2) | 9.7 (0.4) | 10.5 (0.3) | 10.5 (0.3) | 10.6 (0.7) | 9.9 (0.3) |
| PCV 1 wk | 26 | 25.8 (1.1) | 25.6 (1.3) | 26.1 (2.3) | 28.4 (1.3) | 28.4 (1.4) | 28.5 (2.2) | 26.9 (1.5) |
| Creat 1 mo | 2.3 | 3.4 (0.4) | 3.0 (0.4) | 3.9 (0.7) | 2.8 (0.4) | 2.9 (0.4) | 2.7 (1.4) | 2.3 (0.5) |
| Creat 3 mo | 2.4 | 3.0 (0.3) | 3.1 (0.4) | 3.0 (0.5) | 3.1 (0.4) | 3.1 (0.4) | 2.6 (1.0) | 2.2 (0.4) |
| Kink | 11/121 (9%) | 8/53a (15%) | 6/27a (22%) | 2/26a (8%) | 0a | 0a | 0a | 3/36a (all SUB 2.0; 8%) |
| Kink: exchange needed | 4/121 (3%) | 4/53 (8%) | 0 | 0 | 0 | 0 | 0 | 0 |
| Mineralized: 90 d | 4/121 (3%) | 1/53 (2%) | 1/27 (4%) | 0 | 3/32 (9%) | 3/20 (15%) | 0 | 0 |
| Periop clot occlusion | 12/121 (10%) | 8/53 (15%) | 3/27 | 5/26 | 1/32 | 1/20 | 0/12 | 3/36 (2 SUB 2.0, 1 SUB 3.0) |
Total population continuous clinicopathologic data reported are median. Group continuous clinicopathologic data reported are mean (SD).
BUN 1 wk = Serum BUN concentration at 1-week recheck. Calcium 1 wk = Serum total calcium concentration at 1-week recheck. Creat 1 mo = Serum creatinine concentration at 1-month recheck. Creat 1 wk = Serum creatinine concentration at 1-week recheck. Creat 3 mo = Serum creatinine concentration at 3-month recheck. Kink = Number of devices that demonstrated kinking during the follow-up period. Kink: exchange needed = Number of devices that demonstrated kinking and required partial or complete device replacement. Mineralized: 90 d = Number of devices that demonstrated some degree of mineralization on repeat ultrasound monitoring during the follow-up period. PCV 1 week = PCV at 1-week recheck. Periop clot occlusion = Number of devices occluded with blood clots in the perioperative period. Phosphorus 1 wk = Serum phosphorus concentration at 1-week recheck. Potassium 1 wk = Serum potassium concentration at 1-week recheck. SDMA 1 wk = Serum SDMA concentration at 1-week recheck. Survive to 90 d = Number of cats that survived to 90 days post device placement.
P = .02 (all SUB 2.0 devices vs all SUB 3.0 devices).
Group 1: cats with unilateral or bilateral SUB 2.0 devices. Group 1a: cats with unilateral SUB 2.0 devices. Group 1b: cats with bilateral SUB 2.0 devices. Group 2: cats with unilateral or bilateral SUB 3.0 devices. Group 2a: cats with unilateral SUB 2.0 devices. Group 2b: cats with unilateral SUB 3.0 devices. Group 3: cats with 1 unilateral SUB 2.0 and 1 unilateral SUB 3.0 device.
Group 1—For group 1, prior to hospital discharge, the mean serum creatinine concentration was 3.8 mg/dL (SD, 0.35). Postobstructive diuresis was documented in 20 of 40 hospitalizations in which urine output was quantified. Postobstructive diuresis was seen in 13 of 27 that received a unilateral device (48.1%) and 7 of 13 with bilateral devices (53.8%). Stone analysis was performed in 11 cats, with calcium oxalate in 6 (monohydrate in 5 and a combination of monohydrate and dihydrate in 1) and dried, solidified blood stones in 5.
The mean hospitalization time for group 1 was 7 days (SD, 0.6). Two cats were euthanized prior to hospital discharge because of azotemia recovery failure. A mean of 4.7 days (SD, 0.6) was needed to reach the lowest in-hospital creatinine. Those with a unilateral device took a mean 4.6 days (SD, 0.9), and those with a bilateral device took a mean of 5 days (SD, 0.5).
At 2 weeks postoperatively, the mean creatinine, BUN, and PCV in group 1 cats with a unilateral and bilateral devices were 3.9 mg/dL (SD, 0.3), 62.6 mg/dL (SD, 6.4), and 25% (SD, 1.1) and 2.6 (SD, 0.4), 70.8 (SD, 8.1), and 26.1% (SD, 1.0), respectively.
The mean creatinine for group 1 cats that received a unilateral or bilateral device at 1 month and 3 months postoperatively were 2.9 (SD, 0.37) and 3.9 (SD, 0.66) mg/dL and 3.1 (SD, 0.4) and 3.0 (SD, 0.3) mg/dL, respectively.
One cat in group 1 (1 of 40 [2.5%]) was treated for a symptomatic UTI during the 90-day follow-up period. Enterococcus spp was identified on urine culture prior to SUB placement and persisted at the time of first recheck but resolved at the time of subsequent visits. Acute dysuria was reported in 3 cats in group 1 (3 of 40 [7.5%]), all of which received a unilateral SUB 2.0, and none had evidence of bacteriuria at the time of or after device placement. This resolved within the short-term follow-up period spontaneously.
Group 2—Prior to hospital discharge, the mean serum creatinine concentration for group 2 was 2.9 mg/dL (SD, 0.5). Postobstructive diuresis was documented in 9 of 26 hospitalizations in which urine output was quantified (35%). Postobstructive diuresis was seen in 6 of 20 (30%) that received a unilateral device and in 3 of 6 with a bilateral device. Stone analysis was performed in 5 cats, with calcium oxalate in all (3 monohydrate, 1 dihydrate, and 1 a combination of monohydrate and struvite).
The mean hospitalization time for group 2 was 5.7 days (SD, 0.7). Two cats were euthanized prior to hospital discharge: 1 for persistent azotemia without clinical improvement and 1 for clinical decline despite an improved creatinine. A mean of 2.2 days (SD, 0.8) was needed to reach the lowest in-hospital creatinine. Those with a unilateral device took a median of 2 days, and those with a bilateral device took 3.
At first recheck, approximately 2 weeks postoperatively, the mean creatinine, BUN, and PCV in group 2 cats with a unilateral and bilateral devices were 2.9 mg/dL (SD, 0.4), 56 mg/dL (SD, 7.2), and 28% (SD, 2.1) and 4.0 (SD, 0.5), 76 (SD, 8.2), and 28.5% (SD, 2.8), respectively.
The median creatinine for group 1 that received a unilateral or bilateral device at 1 month and 3 months postoperatively was 2.9 (SD, 0.4) and 2.7 mg/dL (SD, 1.4) and 3.1 (SD, 0.4) and 2.6 (SD, 0.9) mg/dL, respectively.
One cat in group 2 (1 of 26 [3.8%]) was treated for a UTI during the 90-day follow-up period. Klebsiella spp was identified on urine culture. This cat did not have a positive culture preoperatively. No cat had reported dysuria in group 2.
Group 3—For group 3, prior to hospital discharge, the mean serum creatinine concentration was 2.4 mg/dL (SD, 0.5). Postobstructive diuresis was documented in 9 of 18 hospitalizations in which urine output was quantified. Stone analysis was performed in 6 cats (calcium oxalate monohydrate [n = 4], struvite [n = 1], and dried, solidified blood stones [n = 1]).
The mean hospitalization time for group 3 was 5.3 days (SD, 0.9). One cat was euthanized prior to hospital discharge due to persistent azotemia and failed clinical improvement. A mean of 3.4 days (SD, 0.9) was needed to reach the lowest in-hospital creatinine.
At first recheck, approximately 2 weeks postoperatively, the mean creatinine, BUN, and PCV for group 3 cats were 2.5 mg/dL (SD, 0.5), 42.2 mg/dL (SD, 9.7), and 26.9% (SD, 1.5), respectively.
The mean creatinine for group 3 cats at 1 month and 3 months postoperatively was 2.3 (SD, 0.5) and 2.2 mg/dL (SD, 0.38), respectively.
No cats in group 3 presented with a UTI during the follow-up period. Dysuria was reported in 2 of 18 cats in group 3 (11.1%) in the short-term period and resolved in both during this study period.
Cats in group 3 had significantly lower serum creatinine (P = .026) and BUN (P = .049) concentrations during the first 2 weeks of follow-up postoperatively than group 1. Cats in group 1 had significantly higher serum potassium concentrations than in group 2 (P = .01). There were no significant differences between groups in serum phosphorus, calcium, or PCV during this time. Cats in group 2 reached their lowest creatinine in fewer days than group 1 (P = .009). There was no significant difference in duration of hospitalization between device groups.
There was no significant association overall between laterality (unilateral vs bilateral) and serum creatinine at either the 1-month (P = .85) or 3-month (P = .16) recheck visits. Additionally, there was no significant association between device group and serum creatinine concentration at either the 1-month (P = .30) or 3-month (P = .40) recheck visits.
Complications
Intraoperative complications—Intraoperative leaking of the device noted during surgery and repaired was reported in 2 of 121 devices implanted during surgery: 1 SUB 3.0 in group 2 and 1 SUB 3.0 in group 3. Intraoperative kinking was identified in 7 of 121 devices (5.8%), with 4 of 53 in group 1 (7.5%), 1 of 32 in group 2 (3.1%), and 2 of 36 in group 3 (5.5%), both of which in the SUB 3.0 component. All kinks were adjusted prior to abdominal closure before any consequences occurred. Bleeding during nephrostomy tube placement into the renal pelvis was reported in 3 of 121 devices (2.5%), 2 in group 1 (2 of 53 [3.7%]) and 1 in group 2 (1 of 32 [3.1%]). These were self-limiting. No cat died during device placement.
Perioperative complications (≤ 8 days postoperatively)—Blood clot occlusion of the SUB was documented in 12 of 121 (10%) devices during the perioperative period, affecting the nephrostomy catheter in 5 or cystostomy in 7. One of the 12 SUBs (8%) that occluded with a blood clot required replacement of the catheter during the perioperative period. Only 1 occurred in a cat that had intraoperative bleeding documented during placement (n = 3), and the rest had no documentation of bleeding during the procedure. Of these occlusions, 10 occurred in a SUB 2.0 (10 of 71 [14%]) and 2 in a SUB 3.0 (2 of 50 [4%]). This was not statistically different (P = .21).
Transfusions of packed RBCs (PRBCs) were required during 9 of 84 hospitalizations (10.7%) based on the PCV and presence of clinical signs associated with anemia (6 in group 1, 1 in group 2, and 2 in group 3). The need for postoperative PRBC transfusion was significantly associated with the duration of hospitalization, with those requiring a transfusion having longer hospitalization times, with a mean 4 days longer than cats that did not need a transfusion (P < .001). In all cats, a lower PCV at presentation was significantly (P < .001) associated with an increased need for a PRBC transfusion in the perioperative period. For every 1% decrease in PCV, the likelihood of receiving a PRBC transfusion increased by 19%.
Short-term complications (8 to 90 days)—Kinks in any catheter were reported in 11 of 121 SUBs (9%) during the 90-day follow-up period. All 11 cases were in the SUB 2.0 (11 of 71 [15.5%]), with none in the SUB 3.0 (P = .02). Four of 11 kinked devices (36%) required a repair due to occlusion of urine flow and recurrent outflow tract obstruction, and 7 kinked devices did not result in the recurrence of hydronephrosis, avoiding the need to repair.
The following factors were not significantly associated with an incidence in kinking: cystostomy catheter being a locking-loop pigtail or straight catheter (P = .56), a nephrostomy catheter being advanced down the ureter or coiled in the pelvis (P = .17), etiology of obstruction (P = .94), weight at presentation (P = .34), presence of a UTI prior to device placement (P = .39), or whether the cat received unilateral or bilateral SUBs (P = .35).
All cats had ultrasound imaging at the 90-day follow-up. Mineralization was documented on ultrasound by evidence of shadowing on the device in 4 SUBs during the 90-day follow-up period, with 1 affecting device patency (SUB 3.0). Three of 4 devices showed mineralization in the nephrostomy catheter and 1 in the cystostomy catheter. All 4 occurred in cats receiving a unilateral SUB (1 SUB 2.0 and 3 SUB 3.0s). Device type was not statistically associated with mineralization (P = .92). In these few cats, the median time to visualization of mineralization on ultrasound was 46 days (mean, 49.3 days; range, 35 to 70 days) without evidence of occlusion.
Outcome—Overall, 95% (38 of 40), 92.3% (24 of 26), and 94.4% (17 of 18) of cats in groups 1, 2, and 3, respectively (total, 79 of 84), survived to discharge (P = .38), and 75% (30 of 40), 84.6% (22 of 26), and 94.4% (17 of 18) of cats in groups 1, 2, and 3, respectively (total, 69 of 84), survived to the 90-day follow-up time point (P = .43). Five animals died or were euthanized between discharge and day 30 (5 of 79 [6.3%]) and 5 between 30 and 90 days (5 of 74 [6.8%]). The reasons for euthanasia included progression of azotemia (n = 9) and uncontrolled seizures (n = 1), and 69 of 84 cats (82%) were alive > 90 days after SUB placement.
Discussion
The results of the present study suggest that the SUB 3.0 successfully managed BUOs in cats over a 90-day follow-up period. This device was associated with improved procedure times, postoperative kinking, and perioperative blood clot development when compared to the SUB 2.0. There was no evidence of an increased risk of intraoperative, perioperative, or short-term complications, thus supporting the authors’ hypotheses.
There was no difference in preoperative parameters between groups other than cats in group 3 being younger than group 2. As in previous studies, all intraoperative complications were either corrected or self-limiting and considered minimal in all groups. Preoperative clinicopathologic parameters were not significantly different between groups, namely PCV, creatinine, BUN concentrations, and imaging findings. The hospitalization times were similar between device groups as well as in unilateral compared to bilateral devices. Furthermore, serum creatinine concentrations were not statistically different between groups at either the 1-month or 3-month recheck visits.
Cats that were described as dehydrated on physical examination at the time of presentation had a statistically longer hospitalization time than those euhydrated, remaining hospitalized a mean of 1.9 days longer. Cats treated for bilateral obstructions had significantly higher creatinine concentrations at presentation; however, there was no significant difference in serum creatinine at 1 month or 3 months postoperatively, supporting the fact that the severity of azotemia or laterality of the obstruction is not associated with prognosis.
Surgical procedure times were shorter in cats receiving the SUB 3.0 when compared to the SUB 2.0, and this was consistent in both unilateral and bilateral devices. When comparing cats undergoing bilateral device placement, procedure times were significantly shorter in group 2, which received 2 SUB 3.0s, than in group 1 or group 3. However, the difference between procedure times among cats receiving bilateral devices in groups 1 and 3 did not reach significance. This is likely because the requirement to pass both the nephrostomy and cystostomy catheters of the SUB 2.0 through the body wall and connect to the shunting port is more time consuming.
Device kinking was not identified with the SUB 3.0, which is likely secondary to the presence of the third actuating tubing connecting the port to the Y- or X-connector. This prevents the nephrostomy and cystostomy catheter from traversing the body wall, which can have excessive motion in different positions, disrupting urine flow from the kidney to the bladder. The third actuating tubing has a very gentle bend and allows for more mobility. In addition, the development of blood clots was less common in the SUB 3.0. It is unclear why this is the case but could be due to less movement of the nephrostomy/cystostomy catheters during body wall movement within the renal pelvis and bladder, which could potentially lead to bleeding.
Due to the limited follow-up period of 90 days for this study, the authors were not able to evaluate long-term rates of mineralization, occlusion, or chronic UTIs of either device model. In previous studies,1 the median time to device obstruction due to mineralization was 463 days after placement. Therefore, this short-term follow-up period was not sufficient to evaluate this variable. Mineralization of the SUB has been reported as the most common long-term complication, and further studies are underway to assess long-term complication rates in SUBs, but that was not the purpose of this study. The routine use of tEDTA in SUB flushes seems to have decreased the risk of long-term mineralization and infections despite the model of the SUBs,6,13–15 but a large comparative study is being conducted in the authors’ practice.
Previous studies1 have reported an incidence of a positive urine culture in 24% of cats during the follow-up period after SUB placement, with chronic bacteriuria reported in 13% of cats. Despite 15% of cats in this study having bacterial growth on urine culture at the time of hospital admission, only 2 cats (2.5%) had positive urine cultures during the follow-up period. The shorter duration of follow-up in this study than those previously reported may contribute to the decreased rates of bacteriuria, and long-term studies are currently being conducted to document the incidence of bacteriuria and UTIs. All devices in this study were routinely flushed with tEDTA, whose antibacterial effects are likely to contribute to a decreased incidence of UTI, as previously reported.14,15
This study had several limitations, including its retrospective nature and the short-term follow-up period. This was purposefully chosen to focus on the short-term risks and benefits in this newly introduced device because kinks, 1 of the most common complications with prior SUB 1.0 and 2.0 devices,1 are generally documented within days to weeks of placement and would be captured within this 90-day follow-up period. In this study, the cause of death was not always determined, but the number of cats surviving to discharge was consistent, or improved, compared to previous studies. Because the authors were involved in the management of all cases included in the study, including their surgery and postoperative care, the procedural decisions and follow-up recommendations were generally consistent despite the retrospective nature.
In conclusion, the SUB 3.0 is a viable treatment option for cats with BUO. Utilization of this device reduced surgical procedure times and rates of device obstruction due to kinking or blood clots compared with the previous models without increasing the rate of other complications in the short-term period. The long-term complication rates are currently being investigated in longer-term investigations.
Supplementary Materials
Supplementary materials are posted online at the journal website: avmajournals.avma.org.
Acknowledgments
The authors want to thank Guillermo Mejia for his support in technical aspects of this report.
Disclosures
Dr. Berent and Dr. Weisse are consultants for Norfolk Vet, which is the company that distributes the Subcutaneous Ureteral Bypass device.
No AI-assisted technologies were used in the composition of this manuscript.
Funding
The authors have nothing to disclose.
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