Veterinary Interventional Oncology

Interventional oncology (IO) is a rapidly growing field in veterinary medicine and has been accepted as a fourth pillar of treatment of neoplastic disease with other modalities including surgery, chemotherapy, and radiation therapy. The major categories of IO therapies in companion animals are focused on the use of locoregional therapies and stenting of malignant obstructions. Although significant assessment of veterinary IO techniques is still necessary, early evaluation of these varying techniques is demonstrating promising results.

Canine Prostate Cancer: Current Treatments and the Role of Interventional Oncology

Prostate carcinoma is one of the most common cancers worldwide in men, with over 3 million men currently living with prostate carcinoma. In men, routine screening and successful treatment schemes, including radiation, prostatectomy, or hormone therapy, have allowed for high survivability. Dogs are recognized as one of the only mammals to spontaneously develop prostate neoplasia and are an important translational model. Within veterinary medicine, treatment options have historically been limited in efficacy or paired with high morbidity. Recently, less invasive treatment modalities have been investigated in dogs and people and demonstrated promise. Below, current treatment options available in dogs and people are reviewed, as well as a discussion of current and future trends within interventional treatment for canine PC.

Surgical management of urethral obstruction secondary to perineal liposarcoma in a dog: a case report

BACKGROUND

Swelling of the perineal region in male dogs is most commonly caused by a perineal hernia. Clinical signs associated with perineal hernia are constipation, tenesmus or stranguria. This case report documents a rare cause of perineal swelling created by the growth of a malignant tumour leading to urethral obstruction and subsequent stranguria.

CASE PRESENTATION

An 11-year-old neutered male German Shepherd was presented for swelling in the perineal region and stranguria for three days. Complete blood count and serum biochemistry were unremarkable. Ultrasound revealed a heterogeneous mass in the perineal region. Retrograde urethrography showed a severe narrowing of the urethra caudal to the pelvis. A fine-needle aspirate of the mass was highly suspicious for liposarcoma. Staging was performed by computed tomography (CT) of the thorax and abdomen. Total penile amputation in combination with pubic-ischial pelvic osteotomy, transposition of the remaining urethra through the inguinal canal, V-Y-plasty cranial to the prepuce and preputial urethrostomy were performed to remove the tumour. Histopathology confirmed a well-differentiated liposarcoma with complete histological margins. Six months after the surgery the dog was doing well and there were no signs indicating local tumour recurrence.

CONCLUSIONS

Wide surgical excision is generally recommended for soft tissue sarcomas, however this is sometimes not feasible for large tumours. In the case reported here, tumour resection was achieved by a combination of several surgical techniques with a good clinical outcome.

ACVIM consensus statement on diagnosis and management of urinary incontinence in dogs

Urinary incontinence (UI) is a disorder of micturition that can occur in dogs of any age, sex, and breed depending on the underlying cause and time of onset. Diagnosis and treatment for various causes of UI in dogs have been described by multiple comprehensive single author review articles, but large prospective clinical trials comparing treatment outcomes in veterinary medicine are lacking. The objectives of this consensus statement therefore are to provide guidelines on both recommended diagnostic testing and treatment for various causes of UI in dogs. Specifically, pathophysiology directly related to the canine urinary system will be reviewed and diagnostic and therapeutic challenges will be addressed. A panel of 12 experts in the field (8 small animal internists [L. Adams, J. Bartges, A. Berent, J. Byron, J. Foster, A. Kendall, S. Vaden, J. Westropp], 2 neurologists [J. Coates, N. Olby], 1 radiologist [G. Oetelaar], and 1 surgeon [C. Adin]) was formed to assess and summarize evidence in the peer-reviewed literature and to complement it with consensus recommendations using the Delphi method. Some statements were not voted on by all panelists. This consensus statement aims to provide guidance for management of both male and female dogs with underlying storage or voiding disorders resulting in UI.

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.

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.

Evaluation of urethral thickness using ultrasonography in healthy small-breed dogs

Introduction

Urethral thickness measurements can be indicative of the pathological state of a patient; however to the best of our knowledge, no measurement reference range has been established in small-breed dogs. This study aimed to establish reference ranges for total urethral thickness and urethral wall thickness in healthy small-breed dogs; "urethral wall thickness" was assumed to be 1/2 of the "total urethral thickness."

Methods

Total urethral thickness was measured by ultrasonography in 240 healthy small-breed dogs. In both female and male dogs, the thickness was measured in the mid-sagittal plane. In female dogs, it was measured immediately before the pelvic bone. In male dogs, it was measured caudal to the prostate and cranial to the pelvic bone. The total urethral thickness we measured is the total thickness of the collapsed urethra, which is the sum of the thicknesses of the dorsal and ventral urethral wall.

Results

The mean value of total urethral thickness was 3.15 ± 0.83 mm (urethral wall thickness, 1.58 ± 0.41 mm) in 240 small-breed dogs. The total urethral thickness was significantly greater in male dogs than in female dogs (p < 0.001), even when compared among the same breeds (p < 0.05). The mean value of the total urethral thickness in females was 2.78 ± 0.60 mm (urethral wall thickness, 1.39 ± 0.30 mm), and 3.53 ± 0.86 mm (urethral wall thickness, 1.76 ± 0.43 mm) in males. There was very weak positive correlation between body weight (BW) and total urethral thickness (R2 = 0.109; β = 0.330; p < 0.001). Intraobserver reliability measured by intraclass correlation coefficient (ICC) was 0.986 (p < 0.001) and interobserver reliability measured by ICC was 0.966 (p < 0.001).

Discussion

This study described the differences in total urethral thickness between breeds, sexes, and sterilization status, and the correlation between BW and total urethral thickness. Furthermore, this is the first study to provide reference ranges of total urethral thickness and urethral wall thickness in small-breed dogs using ultrasonography, and is expected to be useful for urethral evaluation in veterinary diagnostic imaging.

Preputial urethrostomy with preservation of the local anatomy in 4 dogs

OBJECTIVE

To describe a novel modified preputial urethrostomy with preservation of the local anatomy in 4 dogs.

STUDY DESIGN

Short case series.

ANIMALS

Four client-owned male dogs.

METHODS

Dogs presented for dysuria and urethral obstruction and underwent a modified preputial urethrostomy as a salvage procedure after the failure of previous treatments. Urethral stenosis or tear was confirmed by cysto-urethrography in all dogs. The preputial urethrostomy involved anastomosis of the pelvic urethra with the preputial mucosa after caudal laparotomy, without dissection of the prepuce or amputation of the penis. Owner follow up was obtained by telephone interview.

RESULTS

Urinary obstruction was due to urethral stenosis in 3 dogs and severe complications following perineal urethrostomy in 1 dog. The urinary obstruction was resolved in all dogs by the modified preputial urethrostomy. None of the dogs had signs of dysuria, urinary tract infection, or dermatitis immediately postoperatively. Two dogs showed signs of urinary incontinence from 15 days to 1 month postoperatively, which persisted throughout the follow-up period.

CONCLUSION

A functional urethral stoma was obtained in all dogs. This technique may be an alternative to prepubic urethrostomy in male dogs.

Irreversible Electroporation Balloon Therapy for Palliative Treatment of Obstructive Urethral Transitional Cell Carcinoma in Dogs

Progression of transitional cell carcinoma (TCC) in dogs often leads to urinary obstruction. This observational pilot study aimed to evaluate the safety and efficacy of irreversible electroporation (IRE) balloon therapy for the palliative treatment of TCC with partial urethral obstruction. Three client-owned dogs diagnosed with TCC causing partial urethral obstruction were enrolled. After ultrasonographic and cystoscopic examination, IRE pulse protocols were delivered through a balloon catheter device inflated within the urethral lumen. After the procedure, the patients were kept overnight for monitoring and a recheck was planned 28 days later. No complication was observed during the procedure and postprocedural monitoring. After 28 days, one dog had a complete normalization of the urine stream, one dog had stable stranguria, and one dog was presented with a urethral obstruction secondary to progression of the TCC. On recheck ultrasound, one dog had a 38% diminution of the urethral mass diameter whereas the other two dogs had a mass stable in size. IRE balloon therapy seems to be a feasible and apparently safe minimally invasive novel therapy for the palliative treatment of TCC causing urethral obstruction. Further studies are needed to better characterize the safety, efficacy, and outcome of this therapy.

Comparison of leakage pressures of vesicourethral anastomosis performed with intracorporeal suturing in a simulator and conventional suturing ex vivo in canine cadaveric tissue

OBJECTIVE

To compare conventional and intracorporeal vesicourethral anastomosis (VUA) in canine cadaveric tissue.

STUDY DESIGN

Cadaveric ex vivo study.

STUDY POPULATION

Twenty-eight canine bladders with urethra.

METHODS

Specimens after prostatectomy were randomly divided into intracorporeal (I) group or conventional (C) group. For the I group, VUA was performed in a simulator with laparoscopic needle holders and telescope. For the C group, the anastomosis was performed in vitro with standard instruments. The VUA was performed with 4-0 monofilament absorbable suture and was completed with two simple continuous sutures. Surgical time, leakage pressure, site of leakage, and number of suture bites were recorded.

RESULTS

Fourteen samples were entered in each group. The dorsal side of the anastomosis was initially performed, followed by the ventral side. The median suturing time was 30.8 minutes (range, 19.3-39.2) for the I group and 17.3 minutes (range, 9.2-21.3) for the C group (P < .0001). The median leakage pressure was 10.9 mm Hg (range, 4.1-29.7) for the I group and 10.8 mm Hg (range, 6.2-18.5) for the C group (P = .94). The median number of stitches was 20 (range, 14-26) for the I group and 19 (range, 11-28) for the C group (P = .96). The distribution of the site of leakage was similar between groups (P = .381).

CONCLUSION

Vesicourethral anastomosis can be performed with leakage pressures similar to intracorporeal and conventional suturing.

CLINICAL SIGNIFICANCE

This study represents the first step toward laparoscopic radical prostatectomy in dogs.

Novel surgical approach to neoplastic lesions in the distal part of the urethra: A pilot cadaver study comparing open and hybrid techniques

Tumours of the distal urethra in female dogs are often difficult to treat, and the surgical methods described thus far have technical limitations. This study aimed to present a novel approach to the surgical treatment of distal urethral tumours. This study used dog cadavers to evaluate the technical feasibility of surgically removing neoplastic lesions in the distal urethra and compared surgical outcomes of open surgery with those of hybrid surgery (combination of laparoscopy and open surgery). Open intact, open spayed, hybrid intact, and hybrid spayed dog cadaver groups underwent surgery (n = 6 per group). The novel surgical method was based on vulvovaginectomy (ovariohysterectomy in intact dogs), resection of the distal part of the urethra, and pre-pubic urethrostomy. Outcomes of interest included technical feasibility of each procedure, using both surgical techniques, wound length, time required to complete the procedure, and the incidence of intraoperative ureter and rectum injuries. Surgical technique and reproductive status affected operating time. Technique choice affected wound length; the surgical wound was longer in the open group than in the hybrid group. Macroscopic evaluation of the rectum did not reveal any damage to the wall. There was no evidence of ureter leakage or obstruction in any case. The present findings suggest that both open and hybrid surgery can be used to treat distal urethral tumours.

Stenting of Malignant Urinary Tract Obstructions in Humans and Companion Animals

Urine retention secondary to neoplastic obstructions of the upper and lower urinary tracts is a life-threatening condition in both humans and companion animals. Stents can be placed to temporarily or permanently open obstructed urinary tract lumens and are often able to be placed using minimally invasive techniques with guidance via ultrasonography or fluoroscopy. The literature for these techniques is vast for humans and growing for companion animals. The below review provides a discussion of the principles of stenting and types of ureteral and urethral stents, as well as the techniques for placing these stents in humans and companion animals.

Case report laparoscopy-assisted pre-pubic urethrostomy as a palliative procedure for resection of distal urethral tumor in a female dog

Background

This paper presents the first described case of laparoscopy-assisted prepubic urethrostomy and laparoscopic resection of a tumor of the distal part of the urethra in a female dog as a palliative treatment.

Case presentation

An intact, 11 -year-old, mixed breed female dog, weighing 15 kg, was admitted with signs of urinary obstruction and difficulty with catheterization. Vaginal, rectal, and endoscopic examinations revealed a firm mass in the pelvic cavity at the level of the pelvic urethra. Ultrasound and computed tomography examination showed enlargement of the urethral wall (5.5 cm width and 3 cm thick), which was significantly restricting the patency of the urethra. The lesion affected only the distal part of the urethra without the presence of local or distant metastatic changes.

The affected portion of the urethra was laparoscopically removed while performing pre-pubic urethrostomy with laparoscopy. The patient regained full consciousness immediately after the end of anesthesia, without signs of urinary incontinence. Histopathological examination of the removed urethra revealed an oncological margin only from the side of the bladder. In the period of 2.5 months after the procedure, the owner did not notice any symptoms that could indicate a postoperative recurrence, which was diagnosed three months after the procedure.

Conclusions

Pre-pubic urethrostomy can be successfully performed with the assistance of laparoscopy. The use of minimally invasive surgery will allow, in selected cases, removal of the urethral tumor, and in inoperable cases, to perform a minimally invasive palliative pre-pubic urethrostomy.

NEOURETEROCYSTOSTOMY AND URETHRAL STENT PLACEMENT IN A BLACK-HANDED SPIDER MONKEY (ATELES GEOFFROYI)

A 27-y-old female black-handed spider monkey (Ateles geoffroyi) was evaluated 13 d after an ovariohysterectomy because of abdominal distension, anorexia, and absent urination. The animal was diagnosed with a uroabdomen and urethral obstruction from computed tomographic findings and fluid creatinine levels. During exploratory laparotomy, a defect in the right ureter was confirmed as the source of the uroabdomen. Utilizing intraoperative fluoroscopy, a urethral obstruction with an irregular luminal filling defect was evident. A self-expanding nitinol urethral stent was placed, and a ureteral transposition was performed. Two months after the procedure, the animal developed dysuria, a urinary tract infection, recurrent bladder distension and a partial urethral obstruction. Treatment with prazosin 1 mg/kg PO q12h improved urination. Reobstruction of the urethra occurred 17 mo postsurgery, and the animal was euthanatized. On postmortem examination, the animal had ingrowth into the stent with proliferative granulation tissue, detrusor muscle degeneration, pelvic adhesions, cystitis, pyelonephritis, and hydronephrosis.

Creation of a Continent Urinary Bladder Reservoir Vascularized by Omentum as a Possible Surgical Option for Canine Trigonal/Urethral Urothelial Carcinoma

Surgical procedures that maintain continence with minimal complication following resection of trigono-urethral urothelial carcinoma (UC) are limited in canines; therefore, palliative options are often pursued. A feasible tumor resection option may improve disease control and survival. The study's objective was to evaluate a continent urine reservoir created from the urinary bladder body and vascularized solely by omentum. We hypothesized that a viable urine reservoir could be created, and staged omentalization would provide improved vascularity. Nine normal female Beagles were randomized to one of three groups. Group A urinary bladders were transected cranial to the ureteral papillae to create a closed bladder vesicle which was concomitantly omentalized. Group B underwent omentalization two weeks prior to vesicle creation. Based on Group A and B results, Group C underwent neoureterocystostomy and omentalization followed by neoreservoir formation and tube cystostomy 2 weeks later. Serial ultrasounds and histopathology confirmed adequate omental neovascularization in Groups B and C with continent Group C neoreservoirs maintained for 2 months. Some pylectasia and ureteral dilation was documented in all Group C dogs at variable timepoints. Progressive hydroureteronephrosis developed in 2/6 kidneys. Transient azotemia was noted in only 1 Group C dog, although all developed treatable urinary tract infections. The sample size is limited, and the efficacy of this technique in providing disease control for UC is unknown. However, this novel option could allow for primary UC resection while providing continence and limiting complications. Postoperative local or systemic adjuvant therapy, ultrasonographic neoreservoir monitoring, and BRAF analysis would be indicated.

Retrospective study of proliferative urethritis in dogs: Clinical presentation and outcome using various treatment modalities in 11 dogs

BACKGROUND

Proliferative urethritis (PU) is an uncommon inflammatory and infiltrative disease of the urethra in female dogs, often associated with urinary tract infection (UTI). It typically presents with evidence of urethral obstruction (UO).

OBJECTIVES

Identify clinical features in dogs with PU and determine outcome after different treatment modalities.

ANIMALS

Eleven client-owned dogs.

METHODS

Medical records of dogs with histopathologic diagnosis of PU from 2011 to 2020 were retrospectively evaluated, including information on clinical pathology, imaging, and histopathology. Outcomes of various treatment modalities were recorded and compared. Long-term urethral patency (>6 months) was considered treatment success.

RESULTS

All dogs were female and presented with UO. Eight (73%) had a history of UTI. Ten of 11 survived to discharge and were used for long-term data collection. Seven of 10 (70%) were treated using an effacement procedure (balloon dilatation [BD], stent, or both) and 6/7 (86%) achieved long-term urethral patency (>6 months). Seven of 10 had UO recurrence after their first procedure, including 3/3 (100%) that did not have effacement and 4/7 that did (57%), at a median of 101 days and 687 days, respectively. After effacement, the duration of patency was longer for those treated using a stent than BD alone (median, 843 days and 452 days, respectively).

CONCLUSIONS AND CLINICAL IMPORTANCE

Proliferative urethritis is a recurrent disease often associated with UTI. The best outcome of long-term urethral patency occurred after lesion effacement, either by BD or stenting. Future prospective studies should determine the impact of immunosuppressive treatment.

A combined protocol with piroxicam, chemotherapy, and whole pelvic irradiation with simultaneous boost volumetric modulated arc radiotherapy for muscle-invasive canine urinary transitional cell carcinoma: First clinical experience

The aims of this pilot study were to evaluate the feasibility and efficacy of high-dose hypofractionated volumetric modulated arc radiotherapy (VMAT) applied to whole pelvic region radiotherapy (WPRT) with multilevel simultaneous integrated boost (MLSIB) combined with piroxicam and chemotherapy for the treatment of canine transitional cell carcinoma (TCC) of the lower urinary tract with muscle invasion TCC. Twelve dogs were enrolled, according to stage, in two groups: group 1, TCC confined to the urinary tract; group 2, TCC with metastasis. The planning target volume dose was tailored from 36 to 42 Gy in 6 fractions. All dogs were prescribed piroxicam and radiosensitizing carboplatin, and six received chemotherapy after radiotherapy. Serial follow-ups with computed tomography and magnetic resonance imaging were performed. Disease control and toxicity effects were evaluated according to the Response Evaluation Criteria in Solid Tumors and Veterinary Radiation Therapy Oncology Group criteria. The treatment was well tolerated, and no high-grade side effects were reported. The median overall survival times for groups 1 and 2 were 1,230 and 150 days, respectively. A considerable percentage of patients in group1 (50%) were still alive at the time of writing this paper, and a longer follow-up could enable a more accurate survival analysis. This preliminary analysis shows that VMAT applied to the WPRT with MLSIB is an effective and safe option for dogs with lower urinary TCC, although the presence of metastases worsens the prognosis.

Outcomes following balloon dilation for management of urethral obstruction secondary to urothelial carcinoma in dogs: 12 cases (2010-2015)

OBJECTIVE

To describe outcomes for dogs that underwent balloon dilation for palliative treatment of urethral obstruction caused by urothelial carcinoma.

ANIMALS

12 client-owned dogs.

PROCEDURES

Medical records were searched to identify dogs with urothelial (bladder, urethra, or prostate) carcinoma that underwent balloon dilation for treatment of urethral obstruction between April 2010 and December 2015. Information regarding history, signalment, clinical signs, diagnostic imaging findings, balloon dilation technique, clinical outcomes, complications, and additional treatments was obtained by review of medical records.

RESULTS

Improvement in clinical signs of urethral obstruction was observed after the initial dilation procedure for 9 of 12 dogs. Urethral obstruction was known to recur in 5 dogs 48 to 296 days after the initial procedure. Three of these dogs underwent a second dilation procedure, with clinical improvement in all 3 dogs for 41 to 70 days. One of 2 dogs that had a third procedure after the second reobstruction had clinical improvement in urinary tract signs until subsequent death from metastatic disease 22 days later. Complications included hematuria, urinary incontinence, and dysuria; these resolved within a few days after treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Urethral balloon dilation was a minimally invasive procedure that provided relief of urethral obstruction from urothelial carcinoma in most dogs of the study population. Prospective studies are needed to identify optimal techniques for balloon dilation in dogs with neoplastic urethral obstructions and to identify patients that are likely to benefit most from the treatment.

Use of transrectal ultrasonography for assessment of the size and location of prostatic carcinoma in dogs

OBJECTIVE

To evaluate the use of transrectal ultrasonography (TRUS) for the assessment of prostatic tumors in dogs and to compare results for TRUS with results for other imaging modalities.

ANIMALS

10 client-owned male dogs.

PROCEDURES

Client-owned dogs identified with prostatic carcinoma were enrolled. Fluoroscopy, transabdominal ultrasonography (TAUS), TRUS, and MRI were performed on all dogs. Tumor measurements, urethral penetration (identification of abnormal tissue within the urethral lumen), and tumor extension into the urinary tract were recorded for all imaging modalities. Agreement between results for MRI (considered the criterion-referenced standard) and results for other modalities were compared.

RESULTS

Median body weight of the 10 dogs was 26.3 kg (range, 9.4 to 49.5 kg). No complications were encountered during or after TRUS. Significant moderate to good agreements (intraclass correlation coefficients, 0.60 to 0.86) among TAUS, TRUS, fluoroscopy, and MRI were identified for tumor length and height. Assessments of urethral penetration and tumor extension into the bladder with TRUS did not differ significantly from those made with MRI and were superior in terms of absolute agreement with MRI when compared with those for TAUS.

CONCLUSIONS AND CLINICAL RELEVANCE

TRUS was successfully and safely used to evaluate prostatic carcinoma in dogs. There was moderate to good agreement with MRI results for tumor height and length measurements, and TRUS was found to be superior to TAUS for some assessments. Transrectal ultrasonography can be considered an adjunctive imaging modality for the performance of prostatic interventional procedures or assessment of response to treatment.

Significant advances in veterinary oncology - 60 years on

The first edition of the Journal of Small Animal Practice published in February 1960, contained a paper entitled "Recent Treatments of Malignant Neoplasia" by Dr Larry Owen. Now we have reached the 60th anniversary of JSAP, that article provides a baseline from which to review subsequent advances in veterinary oncology, which now includes worldwide networks that have resulted in veterinary oncology becoming the multidisciplinary speciality that it is today. There certainly have been many advances in understanding of the pathology and epidemiology of animal cancers and in methods of diagnosis and treatment. However, the subject has become so large and diverse that not all aspects can be covered in detail here. It should also be acknowledged that there are still many gaps in knowledge in this field and that, because of a lack of randomised clinical trials, the evidence base for what is often regarded as "standard of care" is weak.

Private Practice Oncology: Viewpoint on End-of-Life Decision-Making

Veterinary oncology has evolved rapidly over the past 30 years, with combinations of surgery, chemotherapy, immunotherapy, and radiation therapy now representing standard practice for managing pets with cancer. Recently, additional effort has been directed toward optimizing palliative strategies for mitigating clinical signs associated with advanced-stage disease, thereby reducing patient morbidity as pet owners navigate end-of-life decision making. This is a multi-dimensional, individualized process, which demands attention to the primary neoplastic condition, concurrent diseases, and emotional needs of the family. An approach to oncologic referral and end-of-life care is described, with attention to the dynamics between oncologist, referring veterinarian, and client.

Interventional Therapies of the Urinary Tract

Minimally invasive interventional therapies are the new standard of care in veterinary medicine. In comparison with standard surgical procedures, they are associated with minimal tissue injury, leading to shorter, smoother recovery and decreasing the perioperative morbidity and mortality. A thorough understanding of the therapeutic options available is essential to properly educate and inform clients. Proper equipment, technical expertise, and experience are essential prerequisites to many of these procedures.

Lower Urinary Tract Neoplasia

Lower urinary tract neoplasia in companion animals is a debilitating and often life-threatening disease. Tumors of the bladder, urethra, and prostate often occur independently, although extension of these tumors into adjacent regions of the lower urinary tract is documented frequently. The most common lower urinary tract tumor in dogs and cats is transitional cell carcinoma (TCC). In both dogs and cats, TCC affecting the urinary bladder is generally considered to be highly aggressive with both local and metastatic disease potential, and this disease poses unique treatment challenges. Whereas much literature exists regarding the TCC disease process, treatment options, and prognosis in dogs, relatively few studies on feline TCC have been published due to the lower incidence of TCC in this species. Prostate tumors, most commonly adenocarcinomas, occur less commonly in dogs and cats but serve an important role as a comparative model for prostate neoplasia in humans. This article serves as a review of the current information regarding canine and feline lower urinary tract neoplasia as well as the relevance of these diseases with respect to their human counterparts.

Interventional Management of Urethral Obstructions

Lower urinary tract (LUT) emergencies are common reasons for small animal patients to be presented to their veterinarians. Patient stabilization and management of life threatening problems is a priority in this population. Urethral obstruction is a common LUT emergency. Urethral stent placement has gained popularity over the past decade allowing for a minimally invasive, image-guided method for relief of urethral obstruction in some patient populations. This article focuses on candidate selection, diagnostic workup, stent placement technique, and the expected outcome and complications for patients undergoing urethral stent placement and addresses some additional strategies for interventional management of LUT emergencies.

Submucosal Collagen Injection for Management of Urinary Incontinence Following Urethral Stent Placement

An 8-year-old, entire, male British Bulldog was referred for a week-long history of severe stranguria and dysuria. A prostatic wash was diagnostic of prostatic carcinoma. A transluminal urethral stent was placed in the proximal urethra, which resulted in resolution of the urinary obstruction, however, the dog developed severe urinary incontinence after the procedure. Cystoscopically-guided submucosal collagen injections were performed immediately proximal to the os penis. The dog's incontinence resolved with a single collagen injection for the 10-month follow-up period.

Urethral Stenting for Obstructive Uropathy Utilizing Digital Radiography for Guidance: Feasibility and Clinical Outcome in 26 Dogs

Background

Urethral stent placement is an interventional treatment option to alleviate urethral outflow obstruction. It has been described utilizing fluoroscopy, but fluoroscopy is not as readily available in private practice as digital radiography.

Objectives

To describe the use of digital radiography for urethral stent placement in dogs with obstructive uropathy.

Animals

Twenty‐six client‐owned dogs presented for dysuria associated with benign and malignant causes of obstructive uropathy that underwent urethral stent placement.

Methods

Retrospective study.

Results

Causes of obstructive uropathy included transitional cell carcinoma, prostatic carcinoma, hemangiosarcoma, obstructive proliferative urethritis, compressive vaginal leiomyosarcoma, and detrusor‐sphincter dyssynergia. Survival time range was 1–48 months (median, 5 months). All dogs were discharged from the hospital with urine outflow restored. Intraprocedural complications included guide wire penetration of the urethral wall in 1 dog and improper stent placement in a second dog. Both complications were successfully managed at the time of the procedure with no follow‐up problems noted in either patient.

Conclusion and Clinical Importance

Urethral stent placement can be successfully performed utilizing digital radiography. The complications experienced can be avoided by more cautious progression with each step through the procedure and serial radiography. The application of digital radiography may allow treatment of urethral obstruction to become more readily available.

A pilot study of toceranib/vinblastine therapy for canine transitional cell carcinoma

Background

Effective therapies for transitional cell carcinoma (TCC) are limited, with objective response rates to most chemotherapeutic regimens below 20%. The purpose of this study was to investigate the biologic activity of combined toceranib phosphate and vinblastine chemotherapy for treatment of TCC. A secondary objective was to compare the utility of Computed Tomography (CT) and abdominal ultrasound (AUS) in tumor response assessments.

Results

Dogs with TCC received vinblastine at 1.6 mg/m2 every 2 weeks and toceranib at 2.5–2.75 mg/kg on Monday/Wednesday/Friday. Tumor monitoring was achieved through CT and AUS. Five patients completed the 16-week study. Based on AUS assessments, 3 dogs experienced biologic response to therapy including partial responses (PR, n = 2) and stable disease (SD, n = 1). Based on CT, 5 dogs experienced a biologic response (n = 2 PR, n = 3 SD). Both imaging modalities (ultrasound and CT) were found to provide repeatable measurements between operators, however agreement between operator measurements was greater when CT images were used to assess tumor size.

Conclusions

The combination of toceranib and vinblastine did not result in improved response rates. While agreement in tumor volume assessments between both AUS and CT were excellent between operators, this did not extend to assessment of tumor response. The higher rate of concordance between operators when assessing response to treatment with CT suggests that CT should be considered for future clinical trials involving canine bladder TCC to improve the accuracy and repeatability of tumor measurement. The data suggest that response to therapy as assessed by AUS or CT do not predict duration of clinical response.

Urinary bladder retroversion and neourethrocystostomy for treatment of inadvertent prostatectomy and urethrectomy in a dog

CASE DESCRIPTION A 15-month-old male Newfoundland was examined because of an inability to urinate, lethargy, inappetence, and intermittent vomiting that first became evident after bilateral cryptorchidectomy 2 days previously. The patient was referred for further evaluation and treatment. CLINICAL FINDINGS Results of physical examination, serum biochemical analysis, and abdominocentesis led to a diagnosis of uroperitoneum. Retrograde cystography indicated urinary tract obstruction. In view of the history of recent elective cryptorchidectomy, a diagnosis of uroperitoneum with urethral obstruction secondary to iatrogenic prostatectomy and urethrectomy was made. TREATMENT AND OUTCOME During a ventral midline celiotomy, the inadvertent prostatectomy and urethrectomy were found to have resulted in insufficient urethral length for primary repair. Surgical repair of the urethral defect was achieved by means of a novel technique of bladder retroversion and neourethrocystostomy at the apex of the bladder. A urethral stricture evident 1.5 months after surgery was initially treated with balloon dilatation, followed by temporary and then permanent placement of a self-expanding metallic stent. At the last follow-up 6.6 years after stent placement, the dog remained continent while receiving phenylpropanolamine and the owner was highly satisfied with the outcome. CLINICAL RELEVANCE Caudal intraabdominal bladder retroversion with apex neourethrocystostomy may be a viable alternative to more complex urethral lengthening procedures in dogs and can potentially preserve lower urinary tract function. This treatment might be considered for patients with urethral trauma or malignant neoplasia necessitating extensive urethral resection. Urethral strictures may be effectively managed with stenting.

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.

Lower urinary tract cancer

Lower urinary tract neoplasia is uncommon in dogs and cats, though transitional cell carcinoma (TCC) is the most common tumor of the lower urinary tract in both species. Clinical signs are not specific for neoplasia, but neoplasia should be considered in patients that are older, have specific risk factors, or have persistent, severe, or relapsing signs. Local disease is often the cause of death or euthanasia; local control is challenging owing to tumor size and location. Systemic therapy is the mainstay of treatment. Prognosis is generally guarded, but therapy can result in improvement in clinical signs and quality of life.

Management of transitional cell carcinoma of the urinary bladder in dogs: a review

Transitional cell carcinoma (TCC), also referred to as urothelial carcinoma, is the most common form of urinary bladder cancer in dogs, affecting tens of thousands of dogs worldwide each year. Canine TCC is usually a high grade invasive cancer. Problems associated with TCC include urinary tract obstruction, distant metastases in >50% of affected dogs, and clinical signs that are troubling both to the dogs and to their owners. Risk factors for TCC include exposure to older types of flea control products and lawn chemicals, obesity, female sex, and a very strong breed-associated risk. This knowledge is allowing pet owners to take steps to reduce the risk of TCC in their dog. The diagnosis of TCC is made by histopathology of tissue biopsies obtained by cystoscopy, surgery, or catheter. Percutaneous aspirates and biopsies should be avoided due to the risk of tumor seeding. TCC is most commonly located in the trigone region of the bladder precluding complete surgical resection. Medical treatment is the mainstay for TCC therapy in dogs. Although TCC is not usually curable in dogs, multiple drugs have activity against it. Approximately 75% of dogs respond favorably to TCC treatment and can enjoy several months to a year or more of good quality life. Many promising new therapies for TCC are emerging and with the close similarity between TCC in dogs and high grade invasive bladder cancer in humans, new treatment strategies found to be successful in canine studies are expected to help dogs and to be subsequently translated to humans.

Evaluation of urethral stent placement for benign urethral obstructions in dogs

Background

Benign urethral obstructions (BUO) in dogs result in substantial morbidity because of challenges with conventional therapies. Treatment of malignant urethral obstructions with intraluminal urethral stents is reported to successfully relieve obstructions.

Hypothesis/Objectives

To evaluate the efficacy and outcome of urethral stent placement for treatment of BUO in dogs.

Animals

Eleven client‐owned animals with urethral stents placed for treatment of BUO.

Methods

Retrospective study in which medical records were reviewed in dogs diagnosed with BUO and treated with a metallic urethral stent. Data collected included signalment, cause of benign obstruction, procedure time, size and type of stent, complications, and short‐ and long‐term outcome.

Results

Eleven dogs with 15 urethral stents were included. Intraluminal urethral stent(s) relieved the obstructions in all dogs. Four dogs had 2 stents placed in separate procedures because of incomplete patency after treatment (n = 1), inadvertent compression of the stent (n = 1), or tissue ingrowth through the stent (n = 2). The median continence score after stent placement was 10 of 10 (range 3–10) with 6 dogs being continent, 3 mildly incontinent, and 1 each moderately and severely incontinent. All owners considered their dog to have an excellent long‐term clinical outcome with long‐term urethral patency. The median follow‐up time was 24 months (range 4–48).

Conclusions and Clinical Importance

Urethral stents appear to be an effective treatment for benign urinary obstructions. Moderate to severe incontinence developed in a minority (12.5%) of dogs. Stents relieved obstructions in all dogs with an excellent long‐term outcome.

Use of an aortic stent graft extension for the treatment of urethral stricture in a dog

A 2-year-old male mixed dog was referred to us for further evaluation and treatment of a 4-week-history of oliguria and abdominal distension after a surgical repair of urethral injury. To relieve the urethral stricture, we placed a self-expanding aortic stent graft extension with a partial coverage with an expanded polytetrafluoroethylene (ePTFE). After the placement of the stent, the dog presented with a normal urinary voiding, despite the presence of urinary incontinence. The current case indicates that the ePTFE-covered, self-expanding ASGE is an effective intervention for the treatment of severe urethral stricture in the dog.