Ureteral Obstruction In Cats Research Articles

A novel in vivo model of ureteral fibrosis induced by calcium oxalate beads in C57BL/6J mice.

The global incidence of ureteroliths in humans is increasing, particularly posing a problem in developed countries. The most common stone type is calcium oxalate, which is associated with a high recurrence rate. In veterinary medicine, stones are the most common cause of ureteral obstruction in cats, accounting for 72-87% of cases. In cats, stones cause irreversible ureteral damage, necessitating stone treatment as well as ureteral therapy. However, the mechanisms underlying the ureteral damage caused by stones remain unclear. Therefore, this study aimed to create a mouse model suitable for studying the ureteral fibrosis caused by oxalate stones by artificially embedding calcium oxalate in the ureter. Pathological tissue analysis was used to compare normal ureters without ligation and ureters with sham or oxalate bead implantation. The ureters of the sham and oxalate bead groups showed granulation tissue formation, transitional epithelium exfoliation, and densely packed connective tissue in the proprietary and muscle layer regions. Particularly in the oxalate bead group, infiltration of degenerated neutrophils, presence of foreign body giant cells, and hyperplasia of the transitional epithelium were observed. The proportion of fibrosis was higher in the oxalate group than in the sham group. Overall, this mouse model created using oxalate bead implantation has the potential to efficiently induce ureteral obstruction. This mouse model is expected to be used for elucidating the molecular mechanisms of ureteral fibrosis and evaluating therapeutic drugs in future.

Benign ureteral obstruction in cats: Outcome with medical management

Limited information is available regarding the outcome of medical management (MM) of benign ureteral obstruction in cats (BUO). Describe clinical characteristics and outcome of MM of BUO. Seventy-two client-owned cats with 103 obstructed kidneys. Medical records of cats diagnosed with BUO between 2010 and 2021 that received >72 hours of MM were retrospectively reviewed. Clinical data, treatment, and outcome were reviewed. Outcome was classified as success, partial success, or failure based on ultrasound findings. Factors associated with outcome were assessed. Seventy-two cats with 103 obstructed kidneys were enrolled. The causes of obstruction were uroliths in 73% (75/103), strictures in 13.5% (14/103), and pyonephrosis in 13.5% (14/103) of affected kidneys. Median serum creatinine concentration at presentation was 4.01 mg/dL (range, 1.30-21.3 mg/dL). Outcome after MM was considered a success in 30% (31/103), partial success in 13% (13/103), and failure in 57% (59/103) of kidneys. Success was reported in 23% (17/75) of kidneys with uroliths, 50% (7/14) with pyonephrosis, and 50% (7/14) with strictures. Median time to a successful outcome was 16 days (range, 3-115 days). Distal and smaller uroliths (median length, 1.85 mm) were significantly associated with success (P = .05 and P = .01, respectively). Median survival times were 1188 days (range, 60-1700 days), 518 days (range, 7-1812 days), and 234 days (range, 4-3494 days) for success, partial success, and failure, respectively. We found a higher success rate for MM of BUO than previously reported. Smaller distal uroliths (<1-2 mm) were more likely to pass.

Risk factors for upper urinary tract uroliths and ureteral obstruction in cats under referral veterinary care in the United Kingdom.

Cats presenting with upper urinary tract uroliths (UUTUs) and ureteral obstruction ("obstructive UUTU") are typically younger than cats with idiopathic CKD that often have incidental nephroliths. Cats with upper urinary tract urolith have 2 clinical phenotypes; a more aggressive phenotype at risk of obstructive UUTU at a young age and a more benign phenotype in older cats, with reduced risk of obstructive UUTU. Identify risk factors for UUTU and for obstructive UUTU. Eleven thousand four hundred thirty-one cats were referred for care over 10 years; 521 (4.6%) with UUTU. Retrospective VetCompass observational cross-sectional study. Multivariable logistic regression models were performed to identify risk factors for a diagnosis of UUTU vs no UUTU and additionally, obstructive UUTU vs nonobstructive UUTU. Risk factors for UUTU included female sex (odds ratio [OR] 1.6, confidence interval [CI] 1.3-1.9; P < .001), British shorthair, Burmese, Persian, Ragdoll or Tonkinese (vs non-purebred ORs 1.92-3.31; P < .001) breed and being ≥4 years (ORs 2.1-3.9; P < .001). Risk factors for obstructive UUTU were female sex (OR 1.8, CI 1.2-2.6; P=.002), having bilateral uroliths (OR 2.0, CI 1.4-2.9; P=.002) and age, with the odds of obstructive UUTU increasing as age at diagnosis of UUTU decreased (≥12 years, reference category; 8-11.9 years, OR 2.7, CI 1.6-4.5; 4-7.9 years, OR 4.1, CI 2.5-7.0; 0-3.9 years, OR 4.3, CI 2.2-8.6; P < 0.001). Cats diagnosed with UUTU at a younger age have a more aggressive phenotype with higher risk of obstructive UUTU compared to cats over 12 years of age diagnosed with UUTU.

Multicenter retrospective evaluation of transmural migration of subcutaneous ureteral bypass devices within the digestive tract in cats.

BackgroundPlacement of a subcutaneous ureteral bypass (SUB) device is an effective method to relieve all causes of ureteral obstruction in cats. Complications involving migration within the gastrointestinal tract have been seldomly described.ObjectivesTo characterize transmural migration of SUB devices within the digestive tract in cats.AnimalsEleven migrated SUB catheters identified in 8 cats between 2017 and 2021.MethodsRetrospective review of medical records of cats with a SUB device in which migration into the gastrointestinal tract was identified.ResultsThe median time from SUB device placement to implant migration was 928 days (201‐2298 days). Seven cats had obstruction of the SUB device and a positive urine culture at diagnosis. The migration was identified by ultrasound in 6/11, pre‐operative contrast radiography in 2/2, and only at time of surgery in 3 SUB devices. All cats underwent surgical correction. Four nephrostomy and 7 cystotomy catheters migrated. Migration occurred into the duodenum (3/11), jejunum (7/11), and colon (1/11). SUB devices were removed in 7 cats and replaced in 2 cats, with 1 cat diagnosed with 2 migration events. Gastrointestinal resection and anastomosis were performed in 7/8 cats and an enterotomy in 2 cats. Six cats survived to discharge. The median follow‐up time after migration diagnosis was 365 days (range, 0‐1114 days) and 2 cats are still alive.Conclusions and Clinical ImportanceAlthough a rare complication, migration of SUB device should be considered in cats with SUB device obstruction and a positive urine culture.

Feline ureteral obstruction: a case-control study of risk factors (2016-2019).

Ureteral obstruction (UO) in cats causes acute kidney injury and typically requires surgical intervention. Information is required about potentially modifiable risk factors to inform prevention strategies. A case-control study was performed to assess risk factors associated with feline UO. Cases were defined as cats with either of the following: (1) ureteral obstruction (ureteroliths: 13/18; unknown: 5/18) confirmed with pyelography; or (2) a creatinine concentration >140 µmol/l with both UO (ureteroliths: 6/10; blood clots: 3/10; pyonephrosis: 1/10) and pyelectasia ⩾5 mm on abdominal ultra sonography. Controls were defined as cats without evidence of UO on history, physical examination and abdominal ultrasound. Age, sex, breed (domestic shorthair/longhair), diet (predominantly dry, mixed or predominantly moist food), housing (indoors or mixed) and plasma total calcium were evaluated for their association with UO using multivariable logistic regression. A receiver operator characteristic (ROC) curve was created to evaluate the predictive ability of the final model. In total, 168 cats (28 cases, 140 controls) were included. Age, sex, breed, housing and total calcium were not significantly associated with UO; however, diet was. Compared with cats eating a predominantly moist food diet, cats fed a predominantly dry food diet were 15.9 times more likely to develop a UO (95% confidence interval 2.9-295; P = 0.009). There was no difference in the association between diet and UO in cats fed a mixed diet vs cats fed a predominantly moist food diet (P = 0.25). The area under the ROC curve was 72%. Changes in diet formulation could provide a simple and economical method to reduce the risk of UO.

Minimal renal pelvis dilation in cats diagnosed with benign ureteral obstruction by antegrade pyelography: a retrospective study of 82 cases (2012-2018).

The aim of the study was to describe renal pelvis (RP) and ureteral ultrasonographic measurements in a population of cats with confirmed benign ureteral obstruction (UO) by antegrade pyelography. The secondary objective was to further describe clinical findings associated with minimally dilated obstructed kidneys in an attempt to better understand its occurrence. Retrospective case series of cats diagnosed with benign UO were confirmed by antegrade pyelography. Medical records were reviewed and signalment, diagnostic imaging results, serum creatinine (SCr) concentration and urine culture results were recorded. Each obstructed kidney was categorized into two groups: group 1 included all RP measurements ⩽4 mm and group 2 included all RP measurements >4 mm. A total of 82 cats with 114 obstructed ureters met the inclusion criteria. Fifty (61%) cats had a unilateral UO and 32 (39%) had a bilateral UO. Thirty (26%) kidneys were included in group 1 while 84 (74%) were included in group 2. Nine (8%) kidneys had an RP dilation ⩽2 mm. Median RP and ureteral diameters were 6.6 mm (range 1.1-37.0 mm) and 3.2 mm (range 0.0-11.0 mm), respectively. RP size correlated positively with ureteral diameter in the study population (P <0.0001), but not in group 1 when analyzed separately (P = 0.47). UO was secondary to stones in 80 (70%) ureters. Seventeen (21%) cats had a positive urine culture. At admission, 79 (96%) cats were azotemic with a median preoperative SCr concentration of 444 µmol/l (range 108-1326 μmol/l). The mean (95% confidence interval [CI]) preoperative SCr concentration was significantly higher in group 1 (762 µmol/l [498-1165 μmol/l]) than in group 2 (409 µmol/l [333-502 μmol/l]). RP size in the two groups correlated negatively with preoperative SCr concentration (P = 0.0002). Feline UO may be associated with minimal RP dilation and the severity of RP and ureteral dilation can be highly variable. Absence of significant RP dilation does not rule out UO in cats.

Postoperative outcomes of 12 cats with ureteral obstruction treated with ureteroneocystostomy.

To report complications and long-term outcomes of cats with benign ureteral obstruction treated with ureteroneocystostomy and to determine the effects of double pigtail catheter (DPT) placement on postoperative outcomes. Retrospective study. Twelve client-owned cats with ureteral urolithiasis treated with ureteroneocystostomy. Records were reviewed for signalment, location of the obstruction, diagnostic tests, surgical technique, perioperative complications, long-term measurements of kidney function, and survival. Cats were divided into two groups; in one group, a DPT was placed at the time of ureteroneocystostomy, and, in the other group, a DPT was not placed at the time of ureteroneocystostomy (NDPT). A DPT was placed in six of 12 cats. The NDPT group included four cats with temporary catheters and two cats with no catheter. Median creatinine concentration decreased from 10.4 mg/dL (range, 1.6-20.3) to 2.2 mg/dL (range, 1.1-3.6) at the time of discharge (P = .015) in all cats. Two cats in the NDPT group required revision surgery for uroabdomen. Eleven cats were discharged from the hospital. Long-term complications (hematuria, pollakiuria, urinary tract infections) were more common in the DPT group (P = .047). Seven cats were alive a median of 329 days (range, 8-1772) after surgery. Median creatinine concentration was 2.0 mg/dL (range, 0.6-6.4) at a median of 157 days (range, 43-1772) after surgery. Ureteroneocystostomy resulted in acceptable long-term outcomes in 11 of 12 cats. The placement of a DPT did not influence the long-term outcome in this small population. Ureteroneocystostomy with or without intraoperative placement of a DPT should be considered to relieve benign ureteral obstructions in cats.

Therapeutic use of tetrasodium ethylenediaminetetraacetic acid solution for treatment of subcutaneous ureteral bypass device mineralization in cats.

BackgroundSubcutaneous ureteral bypass (SUB) device placement is an increasingly popular treatment option for decompression of ureteral obstruction in cats. Mineralization occlusion of the device occurs in a minority of cases but is the most common complication.ObjectiveTo evaluate a 2% tetrasodium ethylenediaminetetraacetic acid (tEDTA) solution for treatment of mineralization occlusion in cats with SUBs.AnimalsSix client‐owned cats (8 obstructed devices).MethodsCase series. Each cat was found to have device occlusion based on a combination of ultrasound examination, SUB irrigation, and failure to identify another cause of device obstruction. Each SUB was drained, irrigated using sterile saline, and infused with 1‐2 mL of 2% tEDTA solution. Success was defined as normalization of flow during subsequent ultrasound visualization while irrigating. The volume and frequency of tEDTA instillations, time to achieve device patency, follow‐up biochemical and ultrasound findings, and future reobstruction events were recorded.ResultsResolution of mineralization was documented in all 8 SUBs. Reobstruction events occurred in 2 cats, all of which resolved after additional tEDTA infusions, but 1 cat ultimately required device exchange at 356 days from the first tEDTA infusion. In 1 cat, a single infusion was prematurely discontinued because of persistent pelvic dilatation after 1.25 mL of tEDTA had been instilled. No complications were observed.Conclusions and Clinical ImportanceTetrasodium EDTA infusions can be safely considered as a treatment option for mineralized SUB devices in cats. This solution was easily infused, well tolerated, and avoided the need for SUB device exchange in the majority of cats in which it was used.

Factors associated with postobstructive diuresis following decompressive surgery with placement of ureteral stents or subcutaneous ureteral bypass systems for treatment of ureteral obstruction in cats: 37 cases (2010-2014).

To describe postobstructive diuresis (POD) in cats undergoing surgical placement of ureteral stents or subcutaneous ureteral bypass systems for treatment of ureteral obstruction in cats and to identify factors associated with duration and maximum severity of POD. Retrospective case series. 37 client-owned cats with ureteral obstruction treated between August 2010 and December 2014. Medical records were reviewed, and data extracted included signalment, history, results from physical examinations and clinical laboratory analyses, treatment, urine output, and outcome. Data were evaluated to identify factors associated with POD duration and maximum severity, alone or in combination. Serum concentrations of creatinine, potassium, phosphorus, and BUN before surgery positively correlated with duration and maximum severity of POD. Absolute changes in serum concentrations of creatinine, potassium, and BUN from before surgery to after surgery positively correlated with POD duration. Cats with anuria before surgery had longer POD than did other cats; however, there was no difference in POD duration or maximum severity with unilateral versus bilateral ureteral obstruction. Thirty-four of 37 (92%) cats survived to hospital discharge, which was not associated with whether ureteral obstruction was unilateral or bilateral. Azotemia resolved in 17 of the 34 (50%) cats that survived to hospital discharge. Results of the present study indicated that several factors were associated with POD duration and maximum severity, alone or in combination, and that with intensive management of fluid and electrolyte derangements, regardless of the extent of the original azotemia, a high percentage of cats survived to hospital discharge.

Diagnostic utility of ultrasonography for detection of the cause and location of ureteral obstruction in cats: 71 cases (2010-2016).

OBJECTIVE To assess the utility of ultrasonography to detect the cause and location of ureteral obstruction in cats and to identify factors associated with agreement between ultrasonographic and surgical findings. STUDY DESIGN Retrospective case series. ANIMALS 71 cats. PROCEDURES Medical records were searched to identify cats that had ureteral obstruction diagnosed ultrasonographically and that subsequently underwent exploratory laparotomy. Patient signalment, ultrasonographic findings, interventions performed, and surgical findings were recorded. Cause and location of ureteral obstruction as assessed by ultrasonography were compared with surgical findings. Sensitivity, specificity, and positive predictive value of ultrasonography for detection of ureteroliths and strictures were calculated. Statistical analysis was performed to identify factors associated with agreement between ultrasonographic and surgical findings. RESULTS There was significant, moderate agreement between ultrasonographic and surgical findings for the cause and location of ureteral obstruction. Signalment variables, ureter affected (left vs right), and presence of retroperitoneal effusion were not associated with this agreement. Sensitivity was 98% and 44%, specificity was 96% and 98%, and positive predictive value was 98% and 88% for detection of ureteroliths and strictures, respectively, by ultrasonography. CONCLUSIONS AND CLINICAL RELEVANCE Ultrasonography was highly sensitive for detection of ureteroliths that caused ureteral obstruction but was considerably less sensitive for detection of ureteral strictures in the study population. Future prospective studies are needed to determine the role of advanced imaging in assessing cats with ureteral abnormalities. (J Am Vet Med Assoc 2019;254:710-715).

Use of a subcutaneous ureteral bypass device for treatment of benign ureteral obstruction in cats: 174 ureters in 134 cats (2009-2015).

OBJECTIVE To determine outcomes of subcutaneous ureteral bypass (SUB) device placement for treatment of benign ureteral obstruction in cats. DESIGN Retrospective case series. ANIMALS 134 cats with SUB devices placed in 174 obstructed ureters during 144 hospitalizations. PROCEDURES Medical records of cats that underwent SUB device placement for treatment of benign ureteral obstruction between 2009 and 2015 were reviewed. The SUB device was placed by use of fluoroscopic and surgical methods. Signalment, history, diagnostic imaging results, postprocedural results, duration of hospitalization, complications, and short- and long-term outcomes were recorded. RESULTS Ureteral obstructions were caused by ureterolithiasis (114/174 [65.5%]), stricture (28/174 [16.1%]), both ureterolithiasis and stricture (29/174 [16.7%]), or pyonephrosis (1/174 [0.6%]); in 2 (1.1%) cats, the cause was not recorded. Fifty-two of the 134 (39%) cats had bilateral ureteral obstruction. At admission, 127 (95%) cats were azotemic. Median serum creatinine concentrations at admission and 3 months after SUB device placement were 6.6 and 2.6 mg/dL, respectively. Median renal pelvis diameters before and after the procedure were 9.2 and 1.5 mm, respectively. Postsurgical complications included device occlusion with blood clots (14/172 [8.1%]), device leakage (6/172 [3.5%]), and kinking of the device tubing (8/174 [4.6%]). Cats survived to hospital discharge after 135 of the 144 (94%) hospital admissions. The most common long-term complication was catheter mineralization (40/165 [24.2%]), which was documented a median of 463 days after device placement. A high postoperative serum ionized calcium concentration was significantly associated with SUB device occlusion. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that SUB device placement may be a viable option for treatment of cats with benign ureteral obstruction.

Comparison between double-pigtail ureteral stents and ureteral bypass devices for treatment of ureterolithiasis in cats.

OBJECTIVE To compare the complication rates and outcomes in cats with ureteral obstruction treated by placement of double-pigtail ureteral stents or ureteral bypass (UB) devices. DESIGN Retrospective cohort study. ANIMALS Cats with unilateral or bilateral ureterolithiasis that received double-pigtail ureteral stents (30 stents in 27 cats; stent group) or UB devices (30 devices in 23 cats; UB group). PROCEDURES Medical records were reviewed to collect data on signalment, clinical signs, serum biochemical data, surgical procedure, duration of hospitalization, complications, and follow-up (≥ 6 months after placement) information. Outcomes were compared between device types. RESULTS Median durations of surgery and hospitalization were significantly longer in the stent versus UB group. Perioperative mortality rate was 18% (5/27) in the stent group and 13% (3/23) in the UB group. Median survival time was shorter in the stent versus UB group. Stent placement was associated with a greater risk of lower urinary tract-related signs, such as hematuria (52% [14/27]) and pollakiuria or stranguria (48% [13/27]). The risk of device occlusion was also greater in the stent (26% [7/27]) versus UB (4% [1/23]) group. The percentage of cats requiring additional procedures to treat complications was greater in the stent (44%; complications included uroabdomen, stent occlusion, and refractory cystitis) versus UB (9%; complications included UB occlusion and urethral obstruction) group. CONCLUSIONS AND CLINICAL RELEVANCE Although the benefits of stent placement in the treatment of ureteral obstruction in cats have been established, results suggested that cats treated with UB devices had a lower risk of complications and a longer survival time than those treated with double-pigtail ureteral stents.

Placement of subcutaneous ureteral bypasses without fluoroscopic guidance in cats with ureteral obstruction: 19 cases (2014-2016).

Objectives The purpose of this study was to describe the perioperative and postoperative complications as well as short-term and long-term outcomes in cats with ureteral obstructions treated by placement of a subcutaneous ureteral bypass (SUB) device without imaging control. The second objective of this study was to compare cats treated by SUB device with cats treated by traditional surgical intervention. Methods Data were obtained retrospectively from the medical records (2014-2016) of cats that underwent SUB placement (SUB cats) and cats that underwent traditional ureteral surgery (C cats). Results Nineteen SUB devices were placed without fluoroscopic, radiographic or ultrasonographic guidance in 13 cats. Fifteen traditional interventions (ureterotomy and neoureterocystostomy) were performed in 11 cats. Successful placement of the SUB device was achieved in all cats with only one major intraoperative complication (kinking of the kidney catheter) and one minor intraoperative complication (misplacement of the kidney catheter). Eleven SUB cats recovered from the surgical procedure; two SUB cats and three C cats died during the anaesthesia recovery period. Postoperative SUB complications included anaemia (n = 2), urinary tract infection (UTI) (n = 4), non-infectious cystitis (n = 5) and SUB device obstruction (n = 1). Postoperative traditional surgery complications included anaemia (n = 7), UTIs (n = 6), non-infectious cystitis (n = 1), re-obstruction (n = 4) and ureteral stricture (n = 1). Median postoperative duration of hospitalisation (3 days) was significantly shorter for SUB cats than for C cats ( P = 0.013). Ten SUB cats (76.9%) and four C cats (40%) were still alive at a median follow-up of 225 days and 260 days, respectively. Owners were completely (90%) or mostly (10%) satisfied with the SUB device placement. Conclusions and relevance SUB device placement appears to be an effective and safe option for treating ureteral obstruction in cats, and this study has shown that fluoroscopic guidance is not essential in all cases.

Respective associations between ureteral obstruction and renomegaly, urine specific gravity, and serum creatinine concentration in cats: 29 cases (2006-2013).

To determine the respective associations between ureteral obstruction and renomegaly, urine specific gravity (USG), and serum creatinine concentration and to assess the reliability of abdominal palpation for detection of renomegaly in cats. Retrospective case series. 89 client-owned cats with (n = 29) or without ureteral obstruction and with (30) or without (30) kidney disease. Medical records of cats that underwent abdominal ultrasonography at a veterinary teaching hospital from January 2006 through April 2013 were reviewed. Cats were categorized as having ureteral obstruction (obstructed group) or no ureteral obstruction with (KD group) or without kidney disease (NKD group). Renomegaly and renal asymmetry were defined on the basis of mean renal length for NKD cats. Prevalence of renomegaly and renal asymmetry, mean USG and serum creatinine concentration, and abdominal palpation and ultrasonographic findings were compared among the groups. Renomegaly was identified in 2 obstructed cats and 1 KD cat and was not associated with ureteral obstruction. Renal asymmetry was detected in 18 obstructed cats and 11 KD cats. For obstructed and KD cats, the mean USG was significantly lower and the mean serum creatinine concentration was significantly greater than those for NKD cats. Twenty-eight of 29 cats with ureteral obstruction had hypercreatininemia. Abdominal palpation was not a reliable method for detection of renomegaly. Results indicated renomegaly was not associated with ureteral obstruction in cats, and abdominal palpation was an unreliable method for detection of renomegaly. The most consistent abnormal finding for cats with ureteral obstruction was hypercreatininemia.

Clinical presentation and outcome of cats with circumcaval ureters associated with a ureteral obstruction.

BackgroundCircumcaval ureters (CU) are a rare embryological malformation resulting in ventral displacement of the caudal vena cava, which crosses the ureter, potentially causing a ureteral stricture.ObjectivesTo evaluate cats with obstructed CU(s) and report the presenting signs, diagnostics, treatment(s), and outcomes. Cats with obstructed CU(s) were compared to ureterally obstructed cats without CU(s).Animals193 cats; 22 circumcaval obstructed (Group 1); 106 non‐circumcaval obstructed (Group 2); 65 non‐obstructed necropsy cases (Group 3).MethodsRetrospective study, review of medical records for cats treated for benign ureteral obstructions from AMC and University of Pennsylvania between 2009 and 2013. Inclusion criteria: surgical treatment of benign ureteral obstruction, complete medical record including radiographic, ultrasonographic, biochemistry, and surgical findings.ResultsSeventeen percent (22/128) of obstructed cats had a CU (80% right‐sided) compared to 14% (9/65) non‐obstructed necropsy cats (89% right‐sided). Clinical presentation, radiographic findings, and creatinine were not statistically different between Groups 1 and 2. Strictures were a statistically more common (40%) cause of ureteral obstruction in Group 1 compared to Group 2 (17%) (P = .01). The MST for Groups 1 and 2 after ureteral decompression was 923 and 762 days, respectively (P = .62), with the MST for death secondary to kidney disease in both groups being >1,442 days. Re‐obstruction was the most common complication in Group 1 (24%) occurring more commonly in ureters of cats treated with a ureteral stent(s) (44%) compared to the subcutaneous ureteral bypass (SUB) device (8%) (P = .01).Conclusions and Clinical ImportanceUreteral obstructions in cats with a CU(s) have a similar outcome to those cats with a ureteral obstruction and normal ureteral anatomy. Long‐term prognosis is good for benign ureteral obstructions treated with a double pigtail stent or a SUB device. The SUB device re‐obstructed less commonly than the ureteral stent, especially when a ureteral stricture was present.

Technical and clinical outcomes of ureteral stenting in cats with benign ureteral obstruction: 69 cases (2006–2010)

OBJECTIVE--To evaluate the technical, short-term, and long-term outcomes in cats with benign ureteral obstructions treated by means of double-pigtail ureteral stent placement. DESIGN--Retrospective case series. ANIMALS--69 cats (79 ureters). PROCEDURES--The diagnosis of benign ureteral obstruction was made via abdominal ultrasonography, radiography, and ureteropyelography. Ureteral stent placement was attempted endoscopically, surgically, or both, with fluoroscopic guidance. The medical records were reviewed for pre-, intra-, and postoperative data; complications; and outcome. RESULTS--69 cats (79 ureters) had stent placement attempted for various causes: ureterolithiasis (56/79 [71%]), stricture (10/79 [13%]), both ureterolithiasis and stricture (12/79 [15%]), or a purulent plug (1/79 [1%]). Stent placement was successful in 75 of 79 ureters (95%). Median number of stones per ureter was 4 (range, 0 to > 50), and 67 of 79 (85%) had concurrent nephrolithiasis. Preoperative azotemia was present in 95% (66/69) of cats (median creatinine concentration, 5.3 mg/dL [range, 1.1 to 25.8 mg/dL]), and 71% (49/69) remained azotemic (median, 2.1 mg/dL [range, 1.0 to 11.8 mg/dL]) after successful surgery. Procedure-related, postoperative (< 7 days), short-term (7 to 30 days), and long-term (> 30 days) complications occurred in 8.7% (6/69; 7/79 ureters), 9.1% (6/66), 9.8% (6/61), and 33% (20/60) of cats, respectively; most of these complications were minor and associated with intermittent dysuria or the need for ureteral stent exchange. The perioperative mortality rate was 7.5% (5/69), and no deaths were procedure related. The median survival time was 498 days (range, 2 to > 1,278 days). For patients with a renal cause of death, median survival time was > 1,262 days, with only 14 of 66 cats (21%) dying of chronic kidney disease. Nineteen (27%) cats needed a stent exchange (stricture in-growth [n = 10], migration [4], ureteritis [2], dysuria [2], pyelonephritis [1], or reflux [1]). No patient died of the procedure or recurrent ureteral obstruction. CONCLUSIONS AND CLINICAL RELEVANCE--Results of the present study indicated that ureteral stenting is an effective treatment for benign ureteral obstructions in cats regardless of obstructive location, cause, or stone number. The perioperative morbidity and mortality rates were lower than those reported with traditional ureteral surgery. The short- and long-term complications were typically minor but may necessitate stent exchange or use of an alternative device, particularly with ureteral strictures. The prognosis for feline ureteral obstructions after ureteral stenting could be considered good when the procedure is performed by trained specialists.

Prevalence of circumcaval ureters and double caudal vena cava in cats

To determine the prevalence of circumcaval ureters and other caudal vena cava variations in cats and determine whether circumcaval ureters were associated with macroscopic evidence of ureteral obstruction. 301 domestic cat cadavers obtained from an animal shelter. All cat cadavers were examined, and anatomic variations of the ureters and caudal vena cava were recorded. In cadavers with a circumcaval ureter, kidney length, width, and height were measured, and the ureters were examined macroscopically to determine whether there was gross evidence of ureteral obstruction in cats with circumcaval ureters. At least 1 circumcaval ureter was present in 106 of the 301 (35.2%) cats, with a right circumcaval ureter identified in 92 (30.6%) cats, a left circumcaval ureter identified in 4 (1.3%), and bilateral circumcaval ureters identified in 10 (3.3%). Twenty-one (7.0%) cats had a double caudal vena cava, including 2 cats in which the double caudal vena cava was the only anatomic abnormality identified. No sex predilection for anatomic abnormalities was found. Mean right kidney length was significantly greater than mean left kidney length in cats with a right circumcaval ureter. Circumcaval ureter was present in approximately a third of cats in this study. Variation in the development of the caudal vena cava is the proposed cause. The clinical relevance of this variation is unknown.

Indwelling double pigtail ureteral stent combined or not with surgery for feline ureterolithiasis: complications and outcome in 15 cases.

Ureteral obstruction secondary to ureterolithiasis in cats is a challenging situation. Ureteral stenting has recently been introduced to prevent complications that often occurred after ureterotomy or other invasive surgeries. The purpose of this study is to describe the stenting technique and perioperative difficulties, as well as long-term outcome and complications with ureteral stenting in 12 cats with ureteroliths. Fifteen 2.5 Fr soft double pigtail multi-fenestrated ureteral stents were placed in an anterograde fashion under open surgical approaches and with fluoroscopic guidance in 12 cats. Nine cats received a unilateral stent and three received bilateral stents. Ureterotomy or ureteral resection and end-to-end anastomosis were performed in three and four cases, respectively. In six cats, papillotomy was performed to facilitate dilatator and stent placement. All cats recovered well from the surgical procedure, except one cat, which died during the anaesthesia recovery period. Postoperative complications included dysuria (three cases, diagnosed at 15 days, 1 month and 3 months, respectively), urinary tract infection (one case, 1 month after surgery), stent migration requiring stent replacement (one case, 19 months after surgery) and stent obstruction requiring stent removal (three cases with previously end-to-end anastomosis between 2 and 8 months after surgery). Nine cats (75%) were alive at a mean follow-up of 453 ± 194 (123-720) days. The median survival time was >415 days. Stent placement appeared to be a valuable and safe option for treating ureteral obstruction in cats. However, periodic and long-term monitoring of stents is warranted.

Successful replacement of an obstructed ureter with an ileal graft in a cat

A 10-year-old spayed female domestic shorthair cat with a 1-week history of vomiting, lethargy, and anorexia was examined. Abdominal radiography and ultrasonography revealed that calculi and a nonpatent stricture obstructed the right ureter, which resulted in secondary dilatation of the ureter proximal to the obstruction and severe hydronephrosis. The left kidney was small and suspected to be failing. Concentrations of BUN and creatinine were elevated. Despite administration of fluids, azotemia persisted. Surgery was performed. The obstructed right ureter was replaced with a vascularized segment of ileum. Azotemia resolved, and the cat improved with regard to clinical signs. The cat was clinically normal for > 36 months after the surgery. An ileal graft can successfully be used as a surgical option for ureteral obstruction in cats.

Acute ureteral obstruction in cats: Diagnosis, management options, and outcomes

Acute ureteral obstruction in cats: Diagnosis, management options, and outcomes