Total resection of the lower urinary tract without the need of pelvic osteotomy in the treatment of urethral neoplasia in a dog

ABSTRACT

Background: Urethral neoplasias are rare in small animals and normally have slow growth, but tissue invasion and urethral obstruction are frequent. Prognosis usually is poor due to the high degree of malignity of the main neoplasias involved. Surgical excision is the main form of treatment, but it should be complete with wide safety margins, making partial or complete removal of the bladder with transplantation of the ureters necessary. This report aims at describing a surgical technique, used in a bitch with urethral tumor, which involved complete resection of vulva, vagina and bladder, followed by ureterocolic anastomosis without pelvic osteotomy. Case A 10-year-old female White Swiss Shepherd dog, weighing 35 kg, was presented with partial ischuria and haematuria for approximately 30 days, with final development of complete ischuria, vomit and anorexia. Urethral swab was performed, and the material obtained was fixed for cytological examination, which revealed the presence of malignant epithelial neoplasias, giving the case a direction. Staging was achieved through thoracic radiographs in two recumbent views, and metastatic lesions were not found. A radical surgery was proposed to the owner for the treatment of the patiente. The surgical procedure involved complete removal of the lower urinary tract, vagina and vulva, followed by reimplantation of the ureters in the colon (ureterocolic anastomosis). The patient recovered well from surgery, and urinary continence was maintained, along with quality of life. Transitional carcinoma in the urethral mucosa was characterized by histological diagnose, which revealed safe margins. Clinical evaluations were made daily, with detailed observation of urination, urine volume and color. From the second postoperative day on, fecal consistency from pasty to liquid and fetid odor were observed. Control of urination was only achieved after the fifth day. Ten days after the surgery, the patient was discharged, when the external sutures were removed. The patient lived well for six months, when it died of an indeterminate cause. Necropsy was not allowed by the owner. Discussion: Although primary urethral neoplasias are considered to be rare in dogs, its incidence is higher in females with age around 10 years, as was observed in this case report. Surgery may be the most promising treatment for urethral neoplasias in dogs, since they are not considered chemosensitive and the results of radiotherapy do not seem satisfactory. Urethral reimplantation on the digestive tract is an old technique described in the literature with satisfactory results, but with a lot of reports of postoperative complications which did not occurred in this case. Cystectomy followed by ureterocolic anastomosis allows the bladder to be completely excised while maintaing urinary continence and quality of life. The technique used was proved suitable for the treatment of urethral neoplasias that require complete removal of lower urinary tract so that wide margins are achieved. The approach used, as described, is less complicated than the ventral approach with pubic osteotomy. The described technique, without pelvic osteotomy, may benefi t patients with urethral neoplasias, once it is a less painful procedure, with fewer post-operative complications. Good patient recovery and wide margins obtained are sufficient to valorize this surgical technique.