Catheterization of the urethra in female pigs

Urinary bladder catheterisation of female pigs: Influence of bladder content and Escherichia coli urinary tract infection on procedural outcome

Catheterisation of the urinary bladder is needed in many types of human disease models in pigs. Based on our extensive experience with the pig as an infection model, we here demonstrate an approach of catheterising domestic pigs (40 attempts) and Göttingen minipigs (10 attempts) using a blinded method, that is, without speculums or videoscopes to visualise the urethral opening. The procedure was tested on control animals and pigs with experimental Escherichia coli urinary tract infection (UTI) to assess the potential influence of this condition on procedural outcome. Lastly, we performed cystoscopy in three animals to visualise the route to the urethra and to localise potential anatomical obstacles. All domestic pigs were catheterised successfully in an average of 2 minutes and 23 seconds, and this was not influenced by UTI (p  =  0.06) or bladder urine content at the time of catheterisation (p = 0.32). All Göttingen minipigs were successfully catheterised in an average of 4 minutes and 27 seconds. We conclude that blinded catheterisation is a fast and reliable approach that can be performed in pigs with or without UTI with minimal risk of trauma or contamination.

Reduced Sliding Friction of Lubricant-Impregnated Catheters

During urethral catheterization, sliding friction can cause discomfort and even hemorrhaging. In this report, we use a lubricant-impregnated polydimethylsiloxane coating to reduce the sliding friction of a catheter. Using a pig urethra attached to a microforce testing system, we found that a lubricant-impregnated catheter reduces the sliding friction during insertion by more than a factor of two. This suggests that slippery, lubricant-impregnated surfaces have the potential to enhance patient comfort and safety during catheterization.

Assessment of glomerular filtration and tubular secretion in baboons with life-supporting pig kidney grafts

With pig kidney xenotransplantation nearing clinical reality, it is imperative to measure pig kidney function in the graft recipients. Our aims were (i) to compare inulin clearance after a short intravenous (IV) bolus with steady-state inulin IV infusion, (ii) to use this method to measure the glomerular filtration rate (GFR), and (iii) to determine the tubular secretory function using cefoxitin in a pig-to-baboon renal transplant model. A short IV infusion of inulin and cefoxitin were followed by a maintenance IV infusion of inulin over 5 h in seven healthy baboons, three healthy pigs, and five baboons after bilateral native nephrectomy and intra-abdominal pig renal transplantation. Blood and urine samples were collected. Serum and urinary inulin and serum cefoxitin concentrations measured by validated assays were used to calculate GFR and renal secretion. GFR calculated were similar by both methods. The body weight normalized total body clearance of inulin was similar in pigs and baboons despite differences in absolute clearances. Pig kidney transplanted into baboons provided similar clearance in baboons when normalized to baboon body weight and sustained filtration and secretory functions. The study documented that pig kidneys support the physiologic needs of baboons and are likely to support human recipients as well.

Clean-catching urine from pigs: A method for collecting quality specimens for urinalysis and microbiological culturing in a laboratory environment

Urine is an important biological specimen for assessing various metabolic functions and drug clearance. In urinary tract infection research, urine is particularly important as urinary bacterial titres constitute the main diagnostic outcome for assessing the course of infection. Collecting uncontaminated urine samples from pigs can be done by bladder catheterization or suprapubic bladder aspiration, which are both laborious and invasive procedures that require the need for anaesthesia. To improve animal welfare and optimize urine sampling protocols, we developed a method of clean-catching midstream urine specimens from pigs during spontaneous micturition. The quality of urine specimens collected by clean-catch, bladder catheter and suprapubic bladder aspiration were compared using microbiological culturing. We show that urine specimens collected by clean-catch are only minimally contaminated by skin- and vaginal-commensals with no influence on urinary bacterial titres during ongoing infection. In conclusion, we describe a method in which spontaneous micturition can be prompted in pigs, facilitating fast and reliable collection of quality specimens suitable for microbiological culturing. The method supersedes the need for anaesthesia, which not only represents a considerable refinement in terms of animal welfare but also facilitates more frequent collection of specimens that can enhance the scientific outcome of experimental animal studies in pigs.

Video laryngoscope-guided urethral catheterization in female minipigs

OBJECTIVE

The objective of this work was to anatomically locate the urethral orifice in female minipigs and describe the use of video laryngoscopes in urethral catheterization.

METHODS

Urethral catheterization guided by a video laryngoscope was attempted in 16 adult female Bama minipigs. The anatomical location of urethral orifices, operating time and complications (mucosal edema and bleeding in the vaginal vestibule, and the numbers of red blood cells (RBCs) and white blood cells (WBCs) in mid-stream urine samples) were recorded.

RESULTS

The anatomical location of the urethral orifice: the depth of the urethral orifice in female Bama minipigs was 4.2 ± 1.2 cm; all the urethral orifices were covered by mucosal folds of the vaginal vestibule. In the supine position, the orifice of the urethra at 9-12 and 1-3 o'clock accounted for 6.25%, 6.25%, 18.75%, 50%, 12.5%, 6.25% and 6.25%, respectively. All animals were successfully catheterized and the operating time was 9.0 (6.0-12.8) min. Complications: no bleeding in the vaginal vestibule was observed; the incidence of mucosal edema was 12.5%, all of which were mild; of urine samples collected 1 h after catheterization, 12.5% were found to contain RBCs and no RBCs were detected 6 h after catheterization; no WBCs were detected 1 h or 6 h after catheterization.

CONCLUSIONS

The urethral orifice of female minipigs was located deep in the vagina at variable clock directions and was unexceptionally covered by mucosal folds. Applying a video laryngoscope in urethral catheterization allowed quick and accurate exposure of the urethral orifice and minimal operational injury in female minipigs.

Transurethral catheterization of female domestic pigs with a Foley catheter

This report describes transurethral catheterization with a Foley catheter in 19 anaesthetized, laterally recumbent female pigs with a chest circumference of 72.1 ± 4.2 cm and weighing approximately 40 kg. Catheterization within five minutes was successful in 78.9% of the pigs. Catheterization depth, measured as the distance between the bladder neck and the mucocutaneous junction of the vulva, was 14.5 ± 1.3 cm and correlated with chest circumference but not body length. Measurement of catheterization depth aids in optimal positioning and may prevent inflation of the Foley catheter in the urethra.

Investigation of a method for long-term preservation of the vascular allograft

BACKGROUND/OBJECTIVE

During multiple organ procurement, blood vessels are routinely retrieved and stored in University of Wisconsin solution and then discarded after two weeks, if not used at organ transplantation owing to lack of a method for long-term preservation. Therefore, the aim of this study is to investigate a method for long-term preservation of vascular allografts in ethanol.

METHODS

Aorta and vena cava allografts were retrieved and stored in 75% ethanol solution for 12 months at 4°C. Four pigs were divided into two groups. A segment of aorta was excised and replaced by insertion of preserved aorta graft (Group A) or vena cava graft (Group V). The pigs were observed for six weeks. A laparotomy was performed and the vascular graft was harvested for histopathology followed by euthanasia at the end of study.

RESULTS

Three pigs recovered uneventfully, while one pig died from venous graft rupture in the third week after surgery. There was no aneurysmal formation or thrombosis in the grafts. Some calcification was seen over aorta allograft. On histopathology, the elastic pattern was almost normal, although the endothelial cells degenerated after preservation. After implantation, the formation of the endothelium cell-like layer was seen in both aorta and vena cava allografts.

CONCLUSION

Vascular allografts were functional after preservation for 12 months. The vena cava grafts had much less wall calcification than the aorta grafts. Further studies are necessary to investigate vascular graft remodelling with a longer observation period after implantation.

Image-guided study of swine anatomy as a tool for urologic surgery research and training

PURPOSE

To describe the anatomy of the swine urinary system using computed tomography and to discuss the role of this animal as an experimental model for urological procedures.

METHODS

Three male Landrace pigs underwent computed tomography and the anatomy of the urinary system and renal circulation was analyzed and described.

RESULTS

In all animals, 2 kidneys, 2 ureters and one bladder were identified. Each kidney presented a single renal artery vascularization, with a mean diameter on the right of 4.45 and 5.31 mm on the left (p < 0.0001) and single renal vein drainage, with a mean diameter on the right of 5.78 and 5.82 mm on the left (p = 0.0336). The average renal length was 9.85 cm on the right and 10.30 cm on the left (p < 0.0001). The average renal volume was 113.70 cm3 on the right and 109.70 cm3 on the left (p < 0.0001). The average length of the ureter was 19.78 cm on the right and 22.08 cm on the left (p < 0.0001). The average bladder volume was 423.70 cm3.

CONCLUSIONS

The data obtained show similarities with human anatomy, suggesting the viability of the swine model for planning preclinical trials, basic research, refinement in experimental surgery and surgical training for urological procedures.

Nursing and training of pigs used in renal transplantation studies

The pig is commonly used in renal transplantation studies since the porcine kidney resembles the human kidney. To meet the requirements of intense caretaking and examination without stress, a 2-week socialisation and training programme was developed. Conventional cross-breed pigs (n = 36) with high health status were trained for 15 min/day in a four-step training programme before kidney transplantation. The systematic training resulted in calm animals, which allowed for ultrasound examination, blood sampling and urine sampling without restraint. When a 2-methacryloyloxyethyl phosphorylcholine polymer-coated jugular catheter introduced via the auricular vein was used for post-operative blood sampling, clotting was avoided. To assess renal function, urinary output was observed and creatinine and cystatin C were measured; the latter was not found to be useful in recently transplanted pigs. The results presented contribute to the 3Rs (refine, reduce, replace).

Multiple refinements to the anaesthetic protocol for laparoscopic orthotopic kidney auto-transplantation in a pig model

Fifty-four pigs ( Sus scrofa, Large White cross) from a commercial pig farm were anaesthetised over a six-year period from October 2011. The procedural stages included initial instrumentation for intra-operative monitoring, laparoscopic nephrectomy, preparation of the kidney graft, orthotopic auto-transplantation by either a laparoscopic approach or an open surgical approach, and ligation of the contralateral ureter. During the evolution and establishment of this pig model multiple refinements were introduced: (1) a heat pad was changed to a circulating warm air blanket; (2) routine administration of anticholinesterase and antimuscarinic drugs for reversal of neuromuscular blockade; (3) a technique for urethral catheterisation was developed; (4) ultrasound guidance for placement of a central venous line was learned; (5) intravenous infusions of morphine and ketamine were instituted for a more stable and balanced anaesthetic protocol; and (6) post-operative monitoring was performed by two technical staff for at least the first six hours after extubation of the trachea. The combination of refinements to the anaesthesia protocol for laparoscopic orthotopic kidney auto-transplantation over the first 54 pigs has translated to improved outcomes. This conclusion is entirely subjective as accurate measurement of the impact of each refinement is impossible. Nevertheless, refinement is a continuous process and should be applied to the entire range of procedures involved in animal use for scientific purposes.

Establishment of laparoscopic live donor nephrectomy in a porcine model: techniques and outcomes in 44 pigs

BACKGROUND

Laparoscopic live donor nephrectomy has replaced open donor nephrectomy in most patients due to numerous benefits. A live animal model is required to equip surgeons with the necessary skills to perform such a procedure with minimal risk of complications. The aim of this study was to establish the technique for laparoscopic live donor nephrectomy in a porcine (Sus scrofa) model.

MATERIALS AND METHODS

This study was approved by the Animal Ethics Committee of the university. Forty-four pigs underwent laparoscopic live donor nephrectomy. The left kidney was removed with a standardized four-port technique, with a small suprapubic incision to facilitate kidney delivery.

RESULTS

All 44 procedures were performed successfully, with no intraoperative complications or conversion to open surgery. There was no apparent damage to any of the kidney grafts. The mean surgical time was 118.3 (±20.7) minutes. There was a small, but statistically insignificant, decrease in surgical time throughout the duration of the study. Several subjects had minor variations in the anatomy of the renal vasculature.

CONCLUSIONS

This series has developed and proven a training model for laparoscopic donor nephrectomy in pigs. This training model will allow surgeons to develop laparoscopic proficiency in a live donor, to be used in conjunction with human cadaveric training.

Repetitive urine and blood sampling in neonatal and weaned piglets for pharmacokinetic and pharmacodynamic modelling in drug discovery: a pilot study

Piglets are considered to be suitable animal models for predicting the pharmacokinetics and pharmacodynamics (PK/PD) of test drugs for potential use in the paediatric population. Such PK/PD studies require multiple blood and urine samplings. The goal of the present study was to determine a suitable blood collection strategy applicable in the youngest age categories of six days, four weeks and eight weeks of age, as well as a urine collection technique for male piglets in the same age categories. Blood was collected either by a surgically-placed jugular vein catheter (six days old [ n = 4] and four weeks old [ n = 2] piglets) or by direct venepuncture of the jugular vein (four weeks old [ n = 2] and eight weeks old [ n = 4] piglets). A non-invasive method for total volume urine collection in male piglets was also developed using a urine pouch. No specific complications were encountered during anaesthesia or surgery for jugular catheter placement. After a 24 h recovery period, urine and blood were easily collected without technical complications. One piglet was humanely killed at week 2 because of septicaemia. Histological analysis of both veins in all four piglets revealed negligible damage to the blood vessel wall. In conclusion, the presented techniques for blood (jugular catheter and direct venepuncture) and urine collection (pouches) are suitable for PK/PD studies in piglets.