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

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.

Molecular Markers in Urinary Bladder Cancer: Applications for Diagnosis, Prognosis and Therapy

Cancer of the urinary bladder is a neoplasm with considerable importance in veterinary medicine, given its high incidence in several domestic animal species and its life-threatening character. Bladder cancer in companion animals shows a complex and still poorly understood biopathology, and this lack of knowledge has limited therapeutic progress over the years. Even so, important advances concerning the identification of tumour markers with clinical applications at the diagnosis, prognosis and therapeutic levels have recently been made, for example, the identification of pathological BRAF mutations. Those advances are now facilitating the introduction of targeted therapies. The present review will address such advances, focusing on small animal oncology and providing the reader with an update on this field. When appropriate, comparisons will be drawn with bladder cancer in human patients, as well as with experimental models of the disease.

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.

Laparoscopic-assisted cutaneous ureterostomy in a canine patient with prostatic carcinoma

A 9‐year‐old neutered male Dachshund dog was assessed for stranguria. An enlarged prostate was identified on physical examination, and a diagnosis of prostatic carcinoma confirmed by cytology. Due to a neoplastic lower urinary tract obstruction, palliative surgical urinary diversion treatment was performed with laparoscopic assisted cutaneous ureterostomy (LACU). The dog recovered well without any major complications. Adjuvant chemotherapy was maintained and continued for post‐surgical medical therapy. This report describes a novel minimally invasive assisted technique in canine patients for palliative treatment of prostatic neoplasia.

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.

Implantação de stent autoexpansível para tratamento de estenose uretral em cão: relato de caso

RESUMO O stent endovascular autoexpansível pode ser utilizado como forma de tratamento para estenose uretral em cães. O stent de nitinol é composto por uma liga de níquel e titânio que permite mudanças em suas estruturas sob a influência da temperatura corporal e tem excelente biocompatibilidade na uretra canina. Este estudo relata o caso de um cão, sem raça definida, 14 anos de idade, com histórico de disúria há duas semanas, diagnosticado com grande quantidade de cálculos e microcálculos na bexiga, no colo vesical e na uretra prostática, também cistite e hiperplasia prostática. Depois de tratamento para cistite, orquiectomia e cistotomia para retirada dos cálculos, porém sem melhora clínica após 30 dias de acompanhamento, com o paciente apresentando disúria, foi realizada uretrocistografia retrógrada, que evidenciou estenose da uretra prostática. Esse paciente foi encaminhado para procedimento de implantação de um stent de nitinol na uretra prostática. Imediatamente após o procedimento e até o presente momento, o paciente apresenta micção espontânea, sem qualquer sinal de disúria, sendo este o primeiro relato no Brasil do uso dessa técnica.

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.

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.