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.

Ultrasonographic and contrast-enhanced CT imaging diagnosis of idiopathic renal hematuria with bilateral hydronephrosis and hydroureter in a dog

A 5-year-old spayed female Maltese presented with a 1-week history of severe hematuria. Abdominal ultrasonography and thoracic, and abdominal computed tomography identified bilateral hydronephrosis and hydroureter due to an obstruction at the left ureter and urinary bladder lesion with no evidence of metastasis. After surgical removal of the material and placement of a temporary ureteral stent, the patient was able to urinate normally. Histological examination revealed a massive blood clot. Based on our review of the literature, this is the first published report describing the imaging diagnosis of obstructive hydronephrosis and hydroureter induced by idiopathic renal hematuria in a dog.

A retrospective study of canine idiopathic renal haematuria: clinical findings and outcome following medical treatment

OBJECTIVES

To characterise and document the progression of idiopathic renal haematuria in a large cohort of medically managed UK dogs.

MATERIALS AND METHODS

Retrospective study of 41 client-owned dogs with confirmed (n=14), or suspected (n=27) idiopathic renal haematuria from 4 UK-based referral centres. Clinical findings and outcomes of dogs (2001 to 2018) were determined from the review of medical records and telephone follow-up.

RESULTS

Median survival time from diagnosis was long [1482 (152 to 1825) days] irrespective of treatment and clinical response. Only 1 case was euthanased due to idiopathic renal haematuria, and anaemia or azotaemia occurred infrequently. In total, 25 dogs received angiotensin-converting enzyme-inhibitor or angiotensin receptor blocker therapy, of which 23 received benazepril [0.44 (0.19 to 0.82) mg/kg/24 hours], two received enalapril (0.40 and 0.78 mg/kg/24 hours) and one received telmisartan (1 mg/kg/24 hours). In cases with follow-up urinalyses, complete resolution of haematuria was documented in eight of 19 (42%) dogs following angiotensin-converting enzyme-inhibitor/angiotensin receptor blocker treatment, with partial improvement in five of 19 (26%) and no improvement in six of 19 (31%). Conversely, of the two untreated dogs where outcome was available, one had partial improvement and the other had no improvement.

CLINICAL SIGNIFICANCE

In this study, idiopathic renal haematuria was associated with a good prognosis and low complication rate. Resolution or improvement in haematuria occurred in both angiotensin-converting enzyme-inhibitor/angiotensin receptor blocker-treated and untreated dogs, indicating that further studies are required to evaluate the effectiveness and safety of these interventions.

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.

Ureteroscopic Diagnosis and Povidone Iodine Treatment for Chronic Unilateral Hematuria Caused by Benign Lesions

BACKGROUND The management of chronic unilateral hematuria (CUH) caused by benign lesions is a therapeutic challenge to many urologists. The aims of this study were to evaluate the efficacy and safety of povidone iodine sclerotherapy for CUH. MATERIAL AND METHODS We identified 20 patients who underwent povidone iodine sclerotherapy to treat CUH between September 2013 and August 2017. Radiologic and hematologic tests were normal, no definite cause of hematuria was revealed, and the malignant lesions were excluded. Cystoscopy and ureteroscopy indicated the lesions were located in the renal pelvis. The goal of successful treatment was no recurrence of hematuria during follow-up. RESULTS The present study analyzed 20 patients (9 females and 11 males), 24-73 years old (mean age 44.6) with mean follow-up of 23.8 (range 13-60) months. Endoscopic findings included discrete lesions, diffuse lesions, and no obvious lesion. Discrete lesions were identified as hemangioma (4/20, 20%), minute venous rupture (12/20, 60%), and varix (1/20, 5%). Diffuse lesions were founded via ureteroscopy in 2 (2/20, 10%) patients. In the remaining 1 (1/20, 5%) patient, no obvious lesion was found. All patients with CUH were treated with 0.5% povidone iodine for pelvicalyceal system instillation, which was given at 12-h intervals for 3 days. Only 1 patient experienced recurrent gross hematuria, after 24 months postoperatively. The overall success rate, defined as resolution of gross hematuria after povidone iodine sclerotherapy, was 95%. No complications were recorded. CONCLUSIONS The present study indicates that povidone iodine sclerotherapy could be an effective, safe, and minimally invasive treatment for chronic unilateral hematuria caused by benign lesions.

Use of cystoscopy or cystourethroscopy in treating benign macroscopic hematuria caused by lower urinary tract hemorrhage in three dogs

CASE DESCRIPTION

A 5-year-old 11.5-kg (25.3-lb) castrated male Boston Terrier (dog 1), an 8-year-old 27.8-kg (61.2-lb) castrated male Boxer (dog 2), and a 10.5-year-old 15.9-kg (35.0-lb) spayed female Pembroke Welsh Corgi (dog 3) were evaluated because of severe, gross hematuria and suspected idiopathic renal hematuria.

CLINICAL FINDINGS

All 3 dogs had hematuria, anemia, blood clots in their urinary bladders, and unremarkable findings on coagulation and mucosal bleeding time assessments. With cystourethroscopy, lower urinary tract hemorrhage originating from a small lesion in the urinary bladder (n = 2) or urethra (1) and normal-appearing yellow urine jetting from both ureterovesicular junctions were visualized in each dog.

TREATMENT AND OUTCOME

Cystoscopically guided surgical resection of a hemorrhagic lesion of the urinary bladder was performed on dog 1, and histologic evaluation of the resected tissue confirmed urinary bladder telangiectasia. Dogs 2 and 3 each underwent cystourethroscopically guided laser ablation of a hemorrhagic lesion (presumptively diagnosed as hemangioma, angioma, or telangiectasia) in the urinary bladder (dog 2) or urethra (dog 3). The longest follow-up duration was 7 years, and none of the 3 dogs had subsequent recurrence of gross hematuria.

CLINICAL RELEVANCE

Findings suggested that cystourethroscopy should be considered part of the diagnostic plan for hematuria in dogs before pursuing major surgical treatment or when results of conventional diagnostic procedures do not indicate the underlying cause. In addition, histologic results for dog 1 indicated urinary bladder telangiectasia, previously an unreported cause of severe, chronic lower urinary tract hematuria in dogs.

Use of contrast-enhanced ultrasound for the diagnosis of idiopathic renal hematuria in a dog

Background

Idiopathic renal hematuria (IRH) generally occurs in healthy large-breed dogs that are <2-years-old. It is characterized by recurrent bleeding from the kidneys of unidentified cause. The final diagnosis is reached through the exclusion of primary urinary system and systemic causes of hematuria along with the direct visualization by cystoscopy of hematic urine jets at the ureteral orifice.

Case Description

An 8-year-old female neutered Whippet was presented for investigation of a 4-week history of chronic intermittent macroscopic hematuria. Physical examination, systolic blood pressure, extensive laboratory workup (including coagulation profile and platelet count), urine culture, thoracic and abdominal radiographs, pneumocystogram, and double-contrast cystography were all unremarkable. B-mode ultrasound showed no abnormalities apart from a moderate amount of suspended echogenic amorphous material visible within the urinary bladder lumen. In the contrast-enhanced ultrasound (CEUS) study, a large amount of echogenic ill-defined material was noted projecting into the urinary bladder lumen from the right ureterovesical junction in the fundamental mode. This material was more conspicuous and markedly contrast-enhancing in the harmonic mode. Ultrasound contrast medium has the unique property to strictly remain within the vessels without interstitial trapping or elimination by the kidneys. Indeed, the presence of the micro-bubbles into the urinary tract lumen in the CEUS study was interpreted as a direct sign of active urinary tract bleeding. A diagnosis of IRH was reached through CEUS and B-mode ultrasound along with an extensive laboratory workup and periodic follow-up of the patient. No therapy was administered and at a 1-year follow-up, the patient was alive with no current episodes of macroscopic hematuria reported.

Conclusion

To the authors' knowledge, this is the first report describing the use of CEUS for the characterization of IRH. CEUS could represent a safe, non-invasive, affordable novel alternative technique to cystoscopy or cystotomy for the real-time diagnosis of IRH.

Interventional Radiology and Interventional Endoscopy in Treatment of Nephroureteral Disease in the Dog and Cat

Interventional endoscopy and interventional radiology have led to the development of minimally invasive techniques for management of kidney and ureteral diseases in the dog and cat including idiopathic renal hematuria, ureteral obstruction, and ectopic ureters. Sclerotherapy is a renal-sparing chemical cauterization technique used in cases of idiopathic renal hematuria. Diagnosis of ureteral obstruction is challenging in some cases based on ultrasound alone and antegrade pyelography should be considered. Treatment options for obstructions include nephrostomy tubes, ureteral stents, and subcutaneous ureteral bypass devices. Treatment with cystoscopic-guided laser ablation provides similar outcomes to surgery in dogs with intramural ectopic ureters.

Rigid urethrocystoscopy via a percutaneous fluoroscopic-assisted perineal approach in male dogs: 19 cases (2005-2014)

OBJECTIVE To describe the technique and outcome for male dogs undergoing rigid urethrocystoscopy via a novel percutaneous, fluoroscopic-assisted perineal approach. DESIGN Retrospective case series. ANIMALS 19 client-owned male dogs. PROCEDURES Medical records of male dogs that underwent urethrocystoscopy via a percutaneous perineal approach for treatment of a variety of conditions from 2005 through 2014 were reviewed. Signalment, history, pertinent diagnostic imaging results, endourologic and postprocedure details, duration of hospitalization, complications, and outcome (short-term, < 1 month; long-term, ≥ 1 month) were recorded. After flexible urethrocystoscopy, direct percutaneous perineal needle puncture and guidewire placement by means of fluoroscopic guidance (with or without ultrasonography) allowed access to the urethral lumen. The perineal tract was subsequently serially dilated to accommodate a peel-away sheath and rigid endoscope. Rigid urethrocystoscopy was performed, and on completion of endourologic procedures, the access site was left to heal by second intention. RESULTS 19 male dogs successfully underwent 20 procedures. No intraoperative complications were reported. Short-term outcome was good (ie, mild perineal urine leakage) for 3 dogs and excellent (ie, no abnormalities with urination) for 16. Long-term outcome was excellent for the 17 dogs for which follow-up information was available. CONCLUSIONS AND CLINICAL RELEVANCE A percutaneous fluoroscopic-assisted perineal approach (with or without ultrasonography) allowed access to the pelvic urethra with no major complications in the present series of patients. This minimally invasive approach may be a valuable tool for endourologic procedures in male dogs.

Cystoscopy in dogs and cats

Cystoscopy has become an important and widely available component of the diagnostic evaluation of diseases of the lower urinary tract in dogs and cats. In addition, a large number of cystoscopic guided procedures have been described that can be used to treat disease processes that were previously treatable only with invasive surgical procedures. This article reviews the indications and contraindications for cystoscopy, cystoscopy equipment and techniques for male and female dogs and cats, potential complications associated with cystoscopy, and management options for these complications.

Advances in Urinary Tract Endoscopy

The use of endoscopy in veterinary medicine has become the mainstay of diagnosis and treatment in the subspecialty of small animal urology over the past decade. This subspecialty is termed endourology. With the common incidence of urinary tract obstructions, stones disease, renal disease, and urothelial malignancies, combined with the recognized invasiveness and morbidity associated with traditional surgical techniques, the use of endoscopic-assisted alternatives using interventional endoscopic techniques has become appealing to both owners and clinicians. This article provides a brief overview of some of the most common urologic procedures being performed in veterinary medicine.

[Bilateral renal sclerotherapy as a treatment option in a mixed breed male dog with idiopathic renal haematuria]

A 2-year-old male castrated German Shepherd dog mix was presented with chronic macroscopic haematuria. Further diagnostics included abdominal ultrasound and urethrocystoscopy and led to a diagnosis of severe bilateral idiopathic renal haematuria (IRH). Medical treatment with Yunnan Baiyao was unsuccessful. Bilateral renal-sparing sclerotherapy was performed and, despite distal migration of both ureteral stents within 12 days, permanently resolved the macroscopic haematuria.

Interventional urology: endourology in small animal veterinary medicine

The use of novel image-guided techniques in veterinary medicine has become more widespread, especially in urologic diseases. With the common incidence of urinary tract obstructions, stones disease, renal disease, and urothelial malignancies, combined with the recognized invasiveness and morbidity associated with traditional surgical techniques, the use of minimally invasive alternatives using interventional radiology and interventional endoscopy techniques has become incredibly appealing to owners and clinicians. This article provides a brief overview of some of the most common procedures done in endourology in veterinary medicine to date, providing as much evidence-based medicine as possible when comparing with traditional surgical alternatives.

New techniques on the horizon

Practical relevance:

Interventional radiology and interventional endoscopy (IR/IE) uses contemporary imaging modalities, such as fluoroscopy and endoscopy, to perform diagnostic and therapeutic procedures in various body parts. The majority of IR/IE procedures currently undertaken in veterinary medicine pertain to the urinary tract, and this subspecialty has been termed ‘endourology’. This technology treats diseases of the renal pelvis, ureter(s), bladder and urethra. In human medicine, endourology has overtaken traditional open urologic surgery in the past 20–30 years, and in veterinary medicine similar progress is occurring.

Aim:

This article presents a brief overview of some of the more common IR/IE procedures currently being performed for the treatment of urinary tract disease in veterinary patients. These techniques include percutaneous nephrolithotomy for lithotripsy of problematic nephrolithiasis, mesenchymal stem cell therapy for chronic kidney disease, sclerotherapy for the treatment of idiopathic renal hematuria, various diversion techniques for ureteral obstructions, laser lithotripsy for lower urinary tract stone disease, percutaneous cystolithotomy for removal of bladder stones, hydraulic occluder placement for refractory urinary incontinence, percutaneous cystostomy tube placement for bladder diversion, urethral stenting for benign and malignant urethral obstructions, and antegrade urethral catheterization for treatment of urethral tears.

Evidence base:

The majority of the data presented in this article is solely the experience of the author, and some of this has only been published and/or presented in abstract form or small case series. For information on traditional surgical approaches to these ailments readers are encouraged to evaluate other sources.