Transposição e anastomose uretral pré-púbica em um cão com fístula uretral perineal secundária a miíase : relato de caso

Abstract

Urinary tract injuries in dogs are diverse, and the extent and location of the lesion address the appropriate technique for surgical correction. In the case of stenosis extensive urethral stenosis, not many approaches are available in the veterinary routine. The prepubic urethral transposition technique restore of urinary flow and maintenance of the urethral lumen and the preservation of the external genitalia. The present report aimed to describe the application of the prepubic urethral transposition and anastomosis technique in a patient with extensive stenosis of the membranous urethra due to myiasis. Case: An adult male mixed-breed dog was assisted at the Veterinary Hospital of the Federal University of Mato Grosso with a history of perineal urethral fistula, secondary to severe cutaneous myiasis in the scrotal and perineum pouches, which after complete healing presented a reduction in ostium, showing clinical signs of dysuria, strangulation, bladder tenesmus, and haematuria, with intense urinary retention and abdominal pain on physical examination. Positive contrast retrograde urethrocystogram (PCRU) showed an interruption of the contrast flow between the penile and membranous urethra, the patient was referred to the surgery sector to apply the transposition technique and prepubic urethral anastomosis. Twelve hours after the rocedure, a new PCRU was obtained and evidenced the presence of a contrast column evolving to the urinary bladder, with no signs of obstruction or leakage. At 35 days post-surgery, the urinary stream showed adequate caliber and signs of pollakiuria. In abdominal ultrasound, the bladder wall was thickened, suggesting cystitis, which was confirmed by urine culture test. In the PCRU, the progression of contrast to the bladder was seen, with dilation of the urethral lumen in the anastomosis region and absence of contrast leakage to the external environment. The patient received treatment for cystitis based on antibiotic susceptibility testing, and 116 days after surgery, the caliber of the urinary stream increased. New PCRU showed contrast flow to the bladder, no signs of stenosis and absence of contrast leakage. Discussion: Due to the lack of corrective surgeries for intrapelvic urethra extensive stenosis, avoiding complex procedures involving pubic osteotomy, prepubic urethrostomy associated or not with penile amputation is frequently used in veterinary routine. However, many complications are associated with this technique, such as cystitis, ammoniac dermatitis, and stenosis of the opening. Therefore, in the present report, the technique of transposition and prepubic urethral anastomosis was applied to restore urinary flow, avoiding tension in the anastomosis region and complications inherent to urethrostomy, since the external genitalia could be preserved. Besides, end-to-end spatulation of membranous and penile urethra allowed for correct coaptation of the edges and maintenance of an adequate urethral lumen, accompanied by PCRU, which favored the maintenance of a satisfactory urinary stream for bladder emptying. In conclusion, the prepubic urethral transposition and anastomosis consists of a practicable technique in the surgery routine for maintaining urinary flow in cases of extensive membranous urethral stenosis, with no need for pubic osteotomy and giving the patient anatomical and physiological conformation close to normal.