Outcome of ureteral stent placement for treatment of benign ureteral obstruction in dogs: 44 cases (2010-2013)

Medical dissolution of presumptive upper urinary tract struvite uroliths in 6 dogs (2012-2018)

BACKGROUND

Minimally invasive approaches are the standard for treatment of upper urinary tract uroliths in humans.

OBJECTIVE

To describe the medical dissolution of upper urinary tract uroliths in a series of dogs and report clinical outcomes.

ANIMALS

6 female dogs (9 kidneys).

METHODS

Retrospective case series. A review of medical records in dogs that underwent medical dissolution of upper urinary tract uroliths utilizing diet, administration of antibiotics, and double-pigtail ureteral stent(s) placement, when indicated, was performed. Medical management was generally continued for 4 weeks beyond urolith dissolution. Information on biochemical, microbiological, imaging, and clinical outcomes before and after dissolution were recorded.

RESULTS

Six dogs (9 kidneys) were included with bilateral (3) or unilateral (3) nephrolithiasis, ureterolithiasis, or a combination. A ureteral stent(s) was placed endoscopically in 5/6 dogs (6/9 kidneys) for obstructive ureterolithiasis (n = 5) or a nonobstructive massive nephrolith (n = 1). All dogs had a positive urine culture of Staphylococcus pseudintermedius with a median urine pH of 7.25 (range, 6.5-8) and 4/5 had pyonephrosis. All dogs had initial evidence of urolith dissolution at a median of 1.1 months (range, 0.42-5.9), with complete dissolution of ureteroliths at a median of 3.9 months (range, 1.5-7.6), nephroliths at 5.3 months (range, 1.5-7.6), and lower urinary tract uroliths at 0.87 months (range, 0.42-5.9). Stents were removed in 3/6 once dissolution was documented. The median follow-up time was 519 days (range, 177-2492 days).

CONCLUSION AND CLINICAL IMPORTANCE

Medical dissolution and decompression of upper urinary tract struvite uroliths should be considered a minimally invasive treatment for dogs before more invasive options.

Nephrology in Veterinary Medicine

Veterinary nephrology is a specialized field of veterinary medicine providing a high level of care for animals with all types of kidney disease. Veterinarians complete extensive training to become board-certified in veterinary nephrology-urology. Companion animal nephrology is the most advanced field; however, all species are afflicted by a variety of renal disorders. Most naturally occurring animal kidney diseases have similar disorders found in people; where veterinary research is lacking, clinical management is often modified from standard of care in people. Veterinarians have become adept at scaling down procedures to safely perform them on dogs and cats weighing only a few kilograms. Advanced diagnostics (renal biopsy, cystoscopy, fluoroscopic studies, etc. ) and therapeutics (renal replacement therapy, interventional endourology, etc. ) are commonly performed within the practice of veterinary nephrology-urology. Collaboration between veterinary and human nephrologists may advance both disciplines and improve care for people and animals alike.

Antimicrobial and Antiproliferative Coatings for Stents in Veterinary Medicine-State of the Art and Perspectives

Microbial colonization in veterinary stents poses a significant and concerning issue in veterinary medicine. Over time, these pathogens, particularly bacteria, can colonize the stent surfaces, leading to various complications. Two weeks following the stent insertion procedure, the colonization becomes observable, with the aggressiveness of bacterial growth directly correlating with the duration of stent placement. Such microbial colonization can result in infections and inflammations, compromising the stent's efficacy and, subsequently, the animal patient's overall well-being. Managing and mitigating the impact of these pathogens on veterinary stents is a crucial challenge that veterinarians and researchers are actively addressing to ensure the successful treatment and recovery of their animal patients. In addition, irritation of the tissue in the form of an inserted stent can lead to overgrowth of granulation tissue, leading to the closure of the stent lumen, as is most often the case in the trachea. Such serious complications after stent placement require improvements in the procedures used to date. In this review, antibacterial or antibiofilm strategies for several stents used in veterinary medicine have been discussed based on the current literature and the perspectives have been drawn. Various coating strategies such as coating with hydrogel, antibiotic, or other antimicrobial agents have been reviewed.

Renal Agenesis, Extramural Ectopic Ureter, and Nonfunctioning Urinary Bladder: A Difficult Clinical Case with an Innovative Approach

Summary. A 7-month-old female Jack Russell Terrier weighing 4.6 kg was referred to a veterinary hospital for persistent urinary incontinence. Blood test results and vital signs were within the normal range. Computed tomography allowed the diagnosis of extramural ectopic ureter and unilateral renal agenesis. After the first neoureterocystostomy surgery, the dog had severe complications, such as hydroureter and hydronephrosis, so a second surgery was performed. A commercial ureteral stent was not an option, and it was decided to fabricate a homemade stent to avoid euthanasia. The stent used was a soft, DEHP-free PVC tube with a lumen of 3 × 4.1 mm and a length of approximately 40 mm that connected the ureter to the urinary bladder. Two years after surgery, the dog is in good general condition, and the results of regularly performed blood and urine tests are within the normal range for dogs.

Safety and efficacy of nightly nitrofurantoin as prophylaxis in dogs with recurrent urinary tract infections: 13 cases (2015-2021)

OBJECTIVES

To report the protocol, efficacy and adverse events in dogs receiving nightly nitrofurantoin therapy as antimicrobial prophylaxis for recurrent urinary tract infections.

MATERIALS AND METHODS

Retrospective case series of dogs prescribed nitrofurantoin as prophylaxis for recurrent urinary tract infections. Data on urological history, diagnostic investigation, protocol, adverse events and efficacy (through serial urine cultures) were extracted from medical records.

RESULTS

Thirteen dogs were included. Before therapy, dogs had a median of 3 (range 3 to 7) positive urine cultures in the past year. In all but one dog, standard antimicrobial therapy was given before starting the nightly nitrofurantoin. The nightly nitrofurantoin was then prescribed at a median dose of 4.1 mg/kg orally every 24 hours for a median of 166 days (range 44 to 1740). The median infection-free interval on therapy was 268 days (95% confidence interval: 165 to undefined). Eight dogs had no positive urine cultures while on therapy. Of these, five (three which discontinued and two which remained on nitrofurantoin) had no return of clinical signs or bacteriuria at time of last follow-up evaluation or death, and three had suspected or confirmed bacteriuria 10 to 70 days after discontinuation. Five dogs developed bacteriuria on therapy, four of which were nitrofurantoin-resistant Proteus spp. Most other adverse events were minor; none were considered likely caused by the drug on causality assessment.

CLINICAL SIGNIFICANCE

Based on this small study group, nightly nitrofurantoin appears well tolerated and might be efficacious prophylaxis for recurrent urinary tract infections in dogs. Infection with nitrofurantoin-resistant Proteus spp. was a common reason for treatment failure.

Stents in Veterinary Medicine

Stenting in veterinary medicine has been a rapidly growing method of interventional surgery for several years. This procedure is usually performed in the respiratory and urinary tracts, but there are cases of stenting of blood vessels or gastrointestinal structures. It is based on maintaining the permeability of a given tubular structure, thus allowing the passage of gas or liquid. This procedure is often performed as a first-line treatment in situations where pharmacological agents do not work and as an alternative method, often cheaper than the classically performed ones. There are also cases where stenting is used as a palliative treatment, e.g., to enable defecation in colonic obstruction due to tumour infiltration of the colon wall. Stenting is often a life-saving or comfort-improving procedure for animals, but one should also be aware of possible postoperative complications and be prepared for any adversity. For this reason, this review provides an insight into the current knowledge in veterinary medicine about stenting and the consequences associated with this procedure.

Case Report: Successful Management and Long-Term Follow-Up of Bilateral Ureteral Ligation in a Dog Secondary to Cryptorchid Castration Utilizing Bilateral Ureteral Stents and a Neoureterocystostomy Procedure

Objective

To report the successful management of the bilateral ureteral obstruction secondary to ureteral ligation during unilateral cryptorchid surgery in a dog with the utilization of bilateral ureteral stent placement and a neoureterocystostomy procedure.

Summary

A 7-month-old male-castrated Weimaraner weighing 30 kg was presented to a university teaching hospital for evaluation of a 4-day history of lethargy, vomiting, and stranguria following exploratory laparotomy for a left-sided unilateral cryptorchid castration. Based on the concurrent presence of severe azotemia and ultrasonographic findings of bilateral hydronephrosis and hydroureter, the dog was diagnosed with the suspected bilateral ureteral obstruction. The dog underwent a laparotomy which revealed bilateral ureteral ligation which was corrected with a left-sided neoureterocystostomy and right-sided retrograde ureteral stent placement. Subsequent placement of a left-sided ureteral stent due to complications with the neoureterocystostomy site was performed later. Ultimately, both ureteral stents were able to be removed a few months later. The dog was clinically doing well with a baseline creatinine of 1.5 mg/dl (132.6 μmol/L) 532 days following initial bilateral ureteral ligation.

New or Unique Information Provided

This case report describes the successful long-term management of iatrogenic bilateral ureteral obstructions in a male dog using a combination of bilateral ureteral stents and neoureterocystostomy.

Clinical features, outcome, and illness severity scoring in 32 dogs with urosepsis (2017-2018)

OBJECTIVE

To describe the clinical features, outcome, and utility of illness severity scoring in dogs diagnosed with urosepsis.

DESIGN

Retrospective study (2017-2018).

SETTING

University teaching hospital.

ANIMALS

Thirty-two dogs diagnosed with urosepsis secondary to pyometra, prostatitis, or pyelonephritis.

INTERVENTIONS

 None.

MEASUREMENTS AND MAIN RESULTS

Urosepsis was identified in 32 dogs, consisting of 9 of 32 (28.1%) with pyometra, 7 of 32 (21.8%) with prostatitis, and 16 of 32 (50%) with pyelonephritis. In total, 28 (87.5%) dogs survived to discharge, with the following group-specific survival rates: pyometra, 9 of 9 (100%); prostatitis, 5 of 7 (71.4%); and pyelonephritis, 14 of 16 (87.5%). Positive bacterial cultures were obtained in 27 of 32 (84.1%) dogs. The most commonly implicated pathogens were Escherichia coli (14/37 [37.8%]), Klebsiella pneumoniae (8/37 [21.6%]), and Staphylococcus pseudintermedius (6/37 [16.2%]). Multiple organ dysfunction syndrome (MODS) was identified in 21 of 32 dogs (65.6%). Although the presence of MODS was not different between survivors and nonsurvivors (P = 0.6), nonsurvivors had more dysfunctional organs (P = 0.04). Nonsurvivors also had higher Acute Patient Physiology and Laboratory Evaluation (APPLE_FAST ) scores compared to survivors (P = 0.01).

CONCLUSIONS

Survival of dogs with urosepsis was good and may be higher than for other sources of sepsis. Compared to survivors, nonsurvivors had more dysfunctional organs and higher illness severity scores, which may be helpful in the assessment and management of dogs with urosepsis.

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

OBJECTIVES

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS AND RELEVANCE

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.

Urolithiasis in dogs: Evaluation of trends in urolith composition and risk factors (2006-2018)

BACKGROUND

Urolithiasis is a common and often recurrent problem in dogs.

OBJECTIVE

To evaluate trends in urolith composition in dogs and to assess risk factors for urolithiasis, including age, breed, sex, neuter status, urolith location, and bacterial urolith cultures.

SAMPLE POPULATION

A total of 10 444 uroliths and the dogs from which they were obtained.

METHODS

The laboratory database at the UC Davis Gerald V. Ling Urinary Stone Analysis Laboratory was searched for all urolith submissions from dogs between January 2006 and December 2018. Mineral type, age, breed, sex, neuter status, urolith location, and urolith culture were recorded. Trends were evaluated and variables compared to evaluate risk factors.

RESULTS

Calcium oxalate (CaOx) and struvite-containing uroliths comprised the majority of all submissions from dogs, representing 47.0% and 43.6%, respectively. The proportion of CaOx-containing uroliths significantly decreased from 49.5% in 2006 to 41.8% in 2018 (P = .006), with no change in the proportion of struvite-containing urolith submissions. Cystine-containing uroliths comprised 2.7% of all submissions between 2006 and 2018 and a significant nonlinear increase in this mineral type occurred over time (1.4% of all submissions in 2006 to 8.7% in 2018; P < .001). Of all cystine-containing uroliths, 70.3% were from intact male dogs. Age, breed, and sex predispositions for uroliths were similar to those previously identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Although calcium oxalate- and struvite-containing uroliths continue to be the most common uroliths submitted from dogs, a decrease in the proportion of CaOx-containing uroliths and an increase in the proportion of cystine-containing uroliths occurred during the time period evaluated.

Removal and repositioning of urinary tract implants by use of an endovascular snare system in dogs and cats (2013-2019)

OBJECTIVE

To report the fluoroscopic removal or repositioning of urinary tract implants in dogs and cats by use of an endovascular snare system (ESS) and to report procedural usefulness and complications in dogs and cats.

ANIMALS

3 cats and 14 dogs.

PROCEDURES

A medical records review was performed to identify dogs and cats that underwent removal or repositioning of urinary tract foreign bodies or implants by use of an ESS with fluoroscopic guidance at a veterinary teaching hospital from 2013 to 2019.

RESULTS

Dogs had a median weight of 25 kg (55 lb) with a range of 3.5 to 60.6 kg (7.7 to 133.3 lb), and cats had a median weight of 5 kg (11 lb) with a range of 4.2 to 5.4 kg (9.2 to 11.9 lb). By use of an ESS, 12 patients (2 cats and 10 dogs) underwent transurethral retrieval of retained vesicourethral implants or ureteral stents, 2 dogs underwent transurethral ureteral stent repositioning, 1 cat and 2 dogs underwent transnephric retrieval of ureteral stents, and 1 dog underwent cystoscopic-assisted transureteral ureteral stent retrieval. All procedures were successfully performed, and there were no associated procedural complications.

CONCLUSIONS AND CLINICAL RELEVANCE

Retained vesicourethral implants or ureteral stents were successfully retrieved by use of an ESS in dogs and cats transurethrally or with an open or percutaneous transnephric approach and fluoroscopic guidance. These techniques should be considered as an alternative or adjunct to more invasive methods for implant retrieval or manipulation.

Placement of ureteral stents in three rabbits for the treatment of obstructive ureterolithiasis

Management of ureteral obstruction with stenting is often associated with a lower rate of complications than ureterotomy in domestic carnivores, but this treatment has not been previously evaluated in rabbits. Three rabbits (7, 6 and 10 years old) were diagnosed with unilateral obstructive ureterolithiasis associated with hydronephrosis and hydroureter on abdominal ultrasound. Decreased overall renal function was confirmed in all three cases. Ureteral stents were placed retrogradely via cystotomy without complication in two cases and anterogradely via nephrostomy in the third case. Survival after stent placement was 30, 3 and 8 months, with encrustation of the stent and re-obstruction occurring 18, 1 and 6 months after stent placement in successive cases. Ureteral stenting can be considered for short-term management of ureterolithiasis in rabbits to improve renal function and maintain quality of life. Ultrasound or radiographic monitoring is recommended to detect encrustation of the stent. Studies comparing ureteral stenting to ureterotomy in rabbits are needed to determine the effectiveness of these techniques.

Endoscopic nephrolithotomy for the removal of complicated nephroliths in dogs and cats: 16 kidneys in 12 patients (2005-2017)

OBJECTIVE

To describe techniques and outcomes for dogs and cats undergoing endoscopic nephrolithotomy (ENL) for the removal of complicated nephroliths.

ANIMALS

11 dogs and 1 cat (n = 16 renal units) with complicated nephroliths that underwent ENL via a surgically assisted ENL approach (12 renal units) or a percutaneous nephrolithotomy approach (4 renal units) between December 2005 and June 2017.

PROCEDURES

Data were obtained from the medical records regarding preoperative, operative, and postoperative findings. Follow-up information on complications and outcomes was also collected.

RESULTS

Indications for nephrolith removal included massive calculi displacing parenchyma (n = 7), recurrent urinary tract infections (5), and ureteral outflow obstruction (4). Median nephrolith diameter was 2.5 cm (range, 0.5 to 5.7 cm). Nephrolith composition differed among patients; calcium oxalate was the most common type (n = 7 [including 2 mixed nephroliths containing ≥ 60% calcium oxalate]). Following ENL (median duration, 180 minutes), 15 of 16 renal units were completely nephrolith free. Procedure-related complications included renal puncture-associated hemorrhage requiring a blood transfusion (n = 1), renal capsule tear (1), and ureteral puncture (1); all were managed without adverse consequence. Five of 12 patients remained alive at the final follow-up (median, 557 days after ENL), and none died from the procedure.

CONCLUSIONS AND CLINICAL RELEVANCE

ENL as performed was safe and effective in removing complicated nephroliths in a renal-sparing manner for the patients in this study. This procedure requires technical training and could be considered for the treatment of complicated nephrolithiasis in dogs and possibly cats.

Endoscopic-guided laser lithotripsy for removal of an encrusted ureteral stent in a dog

CASE DESCRIPTION

An 8-year-old spayed female Dalmatian was evaluated because of recurrent urinary tract infections following ureteral stent placement 3 years earlier.

CLINICAL FINDINGS

Polyuria, pollakiuria, and hematuria were reported by the owner. Abdominal radiography revealed well-defined, faintly mineralized material superimposed over the distal portion of the previously placed ureteral stent. Abdominal ultrasonography revealed thickening of the bladder wall, right hydroureter, and right pyelectasia; the ureteral stent appeared to extend into a region containing cystic calculi. Cystoscopy revealed small uroliths and mineralized encrustation of the distal portion of the ureteral stent.

TREATMENT AND OUTCOME

A holmium:yttrium-aluminum-garnet laser was used to fragment mineralized material from the distal end of the stent and allow endoscopic transurethral removal. Stone analysis revealed ammonium urate as the major component of the mineralized material. The owner was instructed to feed the dog a diet formulated to decrease the likelihood of urate stone recurrence and to administer marbofloxacin for 6 weeks because of suspected pyelonephritis. Follow-up bacterial culture of a urine sample and abdominal ultrasonography revealed resolution of urinary tract infection, pyelectasia, hydroureter, and associated clinical signs.

CLINICAL RELEVANCE

Results suggested that endoscopic-guided laser lithotripsy can be used as a minimally invasive alternative to surgery for removal of severely encrusted ureteral stents in dogs.

Outcome of SUB placement for the treatment of benign ureteral obstruction in dogs: nine dogs and 12 renal units (2013 to 2017)

OBJECTIVES

To describe a group of dogs with benign ureteral obstruction(s) treated by subcutaneous ureteral bypass and report the intra-operative, peri-operative, short- and long-term outcomes.

MATERIALS AND METHODS

Review of medical records of dogs that underwent subcutaneous ureteral bypass.

RESULTS

Nine dogs (12 renal units) were included. Causes of obstruction included: ureterolithiasis (n=9) extraluminal compression (n=2), and stricture (n=1). Eleven of 12 ureters had a previously placed stent and required subcutaneous ureteral bypass for: recurrent stricture (n=4), diffuse ureteritis (n=4) or stent migration (n=3). Placement was successful in all renal units and there were no peri-operative or procedure-related deaths. Median hospitalisation time was 3 days. The median creatinine values pre-operatively and 3 month post-operatively were 186 and 106 μmol/L, respectively. No dog had worsening azotaemia in the short-term. The most common long-term complication was mineralisation of six devices, of which four required exchange. All dogs that were infected post-operatively (n=5) had a history of at least one urinary tract infection pre-operatively. One of the nine dogs had a chronic post-operative urinary tract infection and had been chronically infected before placing the bypass. The median survival time was >774 days, with five of nine dogs alive at the time of publication.

CLINICAL SIGNIFICANCE

Placement of a subcutaneous ureteral bypass was an effective short-term treatment option for benign ureteral obstructions in dogs but there was a high rate of device mineralisation.

Uretero-Cutaneous Fistula and Renal Abscessation as a Complication of Ureteral Stenting in a Dog

An 11 yr old female spayed shih tzu was referred for treatment of left ureterolithiasis with complete obstruction of the left ureter and pyonephrosis. A ureteral stent was placed surgically to relieve the obstruction and pyonephrosis was treated with antibiotics. Three and a half years following stent placement, the patient developed an abscess on the left flank with chronic purulent discharge. Diagnostic imaging confirmed the presence of a left uretero-cutaneous fistula and renal abscess. A left ureteronephrectomy was performed. The dog was euthanatized 4 mo later for cardiac insufficiency unresponsive to medical treatment. This is the first report of a uretero-cutaneous fistula and renal abscessation as a complication of ureteral stenting in a dog.

Permanent Implantable Medical Devices in Exotic Pet Medicine

Medical devices are defined as implantable if they are intended to remain in the body after the procedure. In veterinary medicine, use of such devices is marginal but may find some indications. Use in exotic pet medicine is even more challenging due to size restriction and the limited data available. This review focuses on the esophageal and tracheal stent in the case of stricture, ureteral stent and subcutaneous ureteral bypass in the case of ureteral obstruction, permanent urinary diversion in the case of bladder atony, and pacemaker in the case of severe arrythmias. Comparative aspects are developed.