@article{cruse_vaden_mathews_hill_robertson_2009, title={Use of Computed Tomography (CT) Scanning and Colorectal New Methylene Blue Infusion in Evaluation of an English Bulldog with a Rectourethral Fistula}, volume={23}, ISSN={["1939-1676"]}, DOI={10.1111/j.1939-1676.2009.0320.x}, abstractNote={Rectourethral fistulas are uncommonly reported in veterinary medicine having only been reported in 13 dogs.1-11 Seven were English Bulldogs and 3 were Miniature Poodles. The diagnosis of a rectourethral fistula is challenging. Survey radiography, double contrast cystography, pneumocystography, and colonoscopy are unreliable modalities for the diagnosis of a fistula.6-9 Four of the 13 previously reported dogs required more than 1 contrast imaging study to confirm the presence of a rectourethral fistula.2, 4, 7, 9 In 1 affected dog, 4 contrast cystourethrograms were performed over a 7-year period before identifying the fistula.4 To date, no case report in the veterinary literature has described use of computed tomography (CT) scanning or new methylene bluea as alternate methods for the diagnosis of rectourethral fistulas. Most rectourethral fistulas in people are acquired secondary to trauma, pelvic surgery, inflammatory bowel disease, or malignancy.12 The diagnosis can be made by witnessing fecaluria or by using advanced diagnostic procedures. Some physicians prefer the aid of contrast cystourethrography13, 14 whereas others have reported the usefulness of CT scanning for both establishing the diagnosis and for surgical planning.15 CT scanning for the detection of anorectal anomalies was first described in infants and has since become a valuable diagnostic tool.16, 17 To date, the most commonly utilized diagnostic techniques in people include cystourethroscopy, advanced imaging such as CT scanning or magnetic resonance imaging, and radiographic contrast imaging.13-19 This report describes the successful use of CT and cystourethrography to diagnose a rectourethral fistula in an English Bulldog. Whereas cystourethrography was used to determine that a fistula was present, the exact anatomic location could not be verified. In contrast, the CT scan was very useful in establishing an accurate anatomic localization of the fistula and surgical planning for repair. In addition, this report describes a technique of colorectal infusion of new methylene blue during cystourethroscopy, which may be a useful adjunctive procedure to verify the presence of an abnormal communication between the urinary and gastrointestinal tracts. A 1-year-old 26.1 kg male castrated English Bulldog was presented to the North Carolina State University Veterinary Teaching Hospital (NCSU-VTH) with a 4-month history of recurrent urinary tract infections. The owner reported pollakiuria, stranguria, and hematuria. Upon initial presentation to the referring veterinarian, gross hematuria, bacteriuria, and pyuria were detected in a voided urine sample. Clinical signs transiently abated after treatment with amoxicillin-clavulanic acidb (15 mg/kg PO q12h for 14 days). Approximately 21 days after initial presentation, a urine sample collected by cystocentesis grew Escherichia coli and Proteus mirabilis that were susceptible to amoxicillin-clavulanic acid. Although abdominal radiographs were unremarkable, small cystoliths, bilateral renal mineralization, and a thickened bladder wall were detected on abdominal ultrasonography. Urinary crystalline material analyzed by the Minnesota Urolith Centerc was identified as magnesium ammonium phosphate. Ninety days after initial presentation, urinalysis of a catheterized sample indicated hematuria and bacteriuria. Microbial culture of the same sample resulted in growth of Klebsiella pneumoniae and E. coli. Based on susceptibility test results, the dog was treated with amoxicillin-clavulanic acid (14 mg/kg PO q12h for 6 weeks) and marbofloxacin (8 mg/kg PO q24h for 6 weeks). At presentation to the NCSU-VTH, no abnormalities were detected during physical examination. Results of a CBC and biochemical profile were unremarkable. Urinalysis of a sample collected by cystocentesis indicated urine specific gravity of 1.014, urine pH of 8.0, trace bacteruria, and 0–5 white blood cells per high-power field. An aliquot of the same urine sample was submitted for microbial culture and resulted in light growth of a resistant strain of Enterococcus faecium. Abdominal ultrasonography identified a thickened irregular urinary bladder wall and small cystic calculi. A hyperemic bladder and urethral mucosa consistent with urinary tract inflammation, as well as particulate matter were identified during cystourethroscopy. Analysis of the particulate matter by the Minnesota Urolith Center identified a gelatinous material not consistent with urinary calculi, but rather a conglomerate of fungal hyphae, bacterial rods and cocci, and cellular material. A positive contrast retrograde urethrocystogram was performed after cystourethroscopy with fluoroscopic guidance. Approximately 20 mL of iohexold (240 mg/mL diluted with 0.9% saline to a concentration of 120 mg/mL) was infused over a 3–5-minute period through an 8-french Foley catheter placed into the urethra. The catheter balloon was positioned and inflated approximately 1 in. distal to the ischiatic tuberosity. At the level of the prostate gland, contrast medium exited the urethra within a tract that extended caudally and emptied into the rectum, indicating the presence of a rectourethral fistula. The dog represented 7 days later for surgical correction of the rectourethral fistula. Based on the owner's desire for a minimally invasive approach, initially laparoscopy was performed. Laparoscopic exploration of the area dorsal to the urethra failed to identify an obvious fistula, and the procedure was converted to a standard ventral midline laparotomy. A red rubber urinary catheter was placed to fill the bladder with saline. Pressure was applied to the urinary bladder while digitally obstructing the urethra in an attempt to force saline into the fistula as an aid to its identification. No abnormal tissue could be identified. Because of the potential risk to neurovascular structures associated with further dissection, and the potential morbidity associated with pelvic osteotomies, the decision was made to recover the animal from anesthesia and attempt to further characterize the anatomic location of the fistula with additional diagnostic techniques at a future date. The dog was discharged from the hospital the next day with instructions to be given amoxicillin-clavulanic acid (14 mg/kg PO q12h for 10 days). Thirty days after the initial surgery, colonoscopy was performed using a 1,680 mm length flexible Olympuse colonoscope with an outer diameter of 12.2 mm in an attempt to locate the fistula. Patient preparation consisted of a combination of a 24-hour fast, oral polyethylene glycol solution,f and warm water enemas. During colonoscopy, many small raised areas consistent with lymphoid follicles were noted, but a fistula was not visualized. After colonoscopy, cystourethroscopy was performed with a 600 mm length flexible Storzg cystoscope with an outer diameter of 3.8 mm. In another attempt to identify the location of the fistula, new methylene blue was instilled into the colon during urethroscopsy. A 24-french Foley catheter was advanced approximately 10 in. aborally into the descending colon. A 2nd 24-french Foley catheter was positioned in at the level of the rectum. The balloon of each catheter was filled with 30 mm 0.9% saline. Thirty milliliters of new methylene blue was diluted 1 : 1 with 0.9% saline to a total volume of 60 mm and instilled through the distal catheter, over a period of 10–15 seconds, into the space between the 2 catheter balloons where the fistula was believed to be located. The urine in the urethra became blue-tinged within minutes confirming translocation of the new methylene blue from the colon into the urethra. At the level of the prostatic urethra, several small depressions of the urethral mucosa were noted (Fig 1). Although the largest of these depressions was believed to be associated with the fistula, there was no definitive evidence of new methylene blue entering the urethra through these areas. Thus, the new methylene blue was useful in confirming the presence of the fistula but did not identify its location. (A) Cystourethroscopy before new methylene blue infusion. There are several small depressions and one larger depression in the urethral mucosa. The larger depression is believed to be associated with the fistula. (B) Cystourethroscopy after new methylene blue infusion. The urine became blue-tinged consistent with passage of new methylene blue from the colon to the urethra. 101 × 76 mm (300 × 300 DPI). After cystourethroscopy, CTh scanning was performed in conjunction with a positive contrast retrograde urethrogram. Iohexol was diluted and administered at a concentration of 80 mg of iodine per milliliter through an 8-french Foley catheter placed in the urethra. Contrast medium was present within the urethra, urinary bladder, colon, and rectum. A fistulous tract oriented in a caudodorsal direction connecting the urethra to the rectum immediately caudal to the prostate was readily apparent (2, 3). Retrograde urography. One millimeter transverse image of intrapelvic urethra and rectum immediately cranial to the coxofemoral joints. The white arrow is the urethra. The black arrow is the fistulous tract extending caudodorsally on the right. Contrast medium within the terminal colon is readily apparent. 101 × 76 mm (300 × 300 DPI). Sagittal CT reconstruction. There is contrast medium within the tract between the urethra and rectum. White arrows are urethra. Black arrows are the fistulous tract. 101 × 76 mm (300 × 300 DPI). The CT scan allowed more accurate anatomic localization and the dog was returned to surgery in a 2nd attempt to ligate the fistula, this time using a perineal approach. A lumen was identified and catheterized with an 8-french red rubber catheter directed toward the urethra. Both the rectal end and urethral end of the fistula were ligated and oversewn. A total of 6 urine samples were obtained by cystocentesis and submitted for microbial culture over the next year while the dog was not receiving antibiotics. All were negative for bacterial growth. A 1-year follow-up conversation with the owner indicated that the dog no longer had any clinical signs related to the lower urinary tract. Rectourethral fistulas are persistent communications between the rectum and urethra. Of the 13 dogs reported with rectourethral fistulas, 11 were suspected to be congenital in nature.2-10 The exact embryologic formation of a rectourethral fistula is not known. During normal canine development, the urorectal fold contacts the cloacal membrane, which subsequently ruptures, resulting in separate urogenital and digestive orifices. The caudal portion of the urogenital orifice further differentiates into the urethra. Fistulas can occur either secondary to failure of the urorectal septum to separate the cloaca into ventral urethrovesical and dorsal rectal segments or due to rupture of the cloacal membrane before contacting the urorectal fold.3, 20 Additionally, infectious or inflammatory processes can occur in utero that could lead to perforation of the rectum and subsequent fistula formation.10 In both humans and dogs with rectourethral fistulas, the most common presenting clinical signs are caused by recurrent cystitis and include dysuria, hematuria, pollakiuria, or stranguria.3-10, 13, 21 Ten of the 13 canine rectourethral fistulas reports included aerobic urine culture results. Aerobic culture yielded growth of ≥ 2 bacterial species in 6 of these reports.2, 4, 6, 8-10 The most common bacterial organisms reported were E. coli and Proteus spp.1-10 Neither of the dogs with acquired fistulas had positive aerobic urine cultures.1, 11 In 1 study of dogs with recurrent or persistent urinary tract infections, approximately 25% of the urine specimens yielded the growth of ≥ 2 bacterial species by aerobic bacterial culture, as was noted in the dog of this report.12 The presence of multiple organisms on urine culture specimen may raise clinical suspicion of systemic immunocompromise, anatomic defects along the lower urinary tract, or external contamination of the urine sample. Rectourethral fistula is an uncommon anatomic defect that can lead to recurrent or persistent urinary tract infections. In this dog, the fistula was oriented in a cranioventral to caudodorsal direction running between the prostatic urethra and the caudoventral rectum. This orientation made identification of the fistula at surgery difficult because it was closely associated with the dorsal aspect of the urethra cranioventrally. After CT scan, a different surgical approach was used and resulted in successful repair of the fistula. To the authors' knowledge, this is the 1st report of CT scanning and colorectal infusion of new methylene blue during cystourethroscopy for the evaluation of rectourethral fistulas in a dog, although these techniques have been described in humans.18, 22 Since evaluating the dog of this case report, we have performed colorectal infusion of new methylene blue in 2 additional young dogs that were presented for evaluation of recurrent urinary tract infections. Neither of these dogs had any discoloration of the urine after infusion with new methylene blue nor did they have fistulas. The infusion is an easily performed technique that can be incorporated into cystourethroscopy to identify if there is an abnormal communication between the urethra and rectum or colon. Specific patient preparation for this technique includes enemas to evacuate the descending colon and the placement of 2 Foley catheters. Although the location of the fistula may not be readily identifiable, a color change of the urine indicates the presence of an abnormal communication between the urinary and gastrointestinal tracts. In the dog of this report, advanced imaging was needed for precise anatomical localization. CT scanning may be useful to accurately localize the fistula, which can aid surgical planning and successful repair. aNew Methylene Blue 1% solution, Taylor Pharmaceuticals, Decatur, IL bClavamox; Pfizer Animal Health, Exton, PA cUniversity of Minnesota, St Paul, MN dOmnipaque 240 mg/mL, GE Healthcare, Princeton, NJ eOlympus America Inc, Center Valley, PA fGoLYTELY (PEG-3350 and electrolytes), Braintree Laboratories Inc, Braintree, MA gKarl Storz Endoscope, Roswell, GA hSiemens Sensation 16, Siemens Medical Solutions USA Inc, Malvern, PA This study was not supported by a grant.}, number={4}, journal={JOURNAL OF VETERINARY INTERNAL MEDICINE}, author={Cruse, A. M. and Vaden, S. L. and Mathews, K. G. and Hill, T. L. and Robertson, I. D.}, year={2009}, pages={931–934} }
 @article{cruse_booth_defrancesco_2008, title={ECG of the month}, volume={232}, ISSN={["1943-569X"]}, DOI={10.2460/javma.232.4.510}, number={4}, journal={JAVMA-JOURNAL OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION}, author={Cruse, Ashley M. and Booth, Margaret A. and DeFrancesco, Teresa C.}, year={2008}, month={Feb}, pages={510–512} }