The transitional cell carcinoma (TCC) is the most common form of canine urinary bladder cancer and it's most often trigonal in location and can result in partial or complete urinary tract obstruction. The etiology of canine bladder cancer is most likely multifactoral. Bacterial and virus infections and you capsize as being one the involved causes in vesical carcinogenesis. The enrofloxacin efficiency in controlling the urinary infections associates the vesical neoplasias was studied. Eleven dogs, male and female, with papillary infiltrative transitional cell carcinoma associated with urinary infection caused by Eschechiria coli and Proteus Mirabilis, had been treated by means of tumoral resection in association with 90-Strontium beta therapy (3.000 cGy) with bladder preservation. The respective infections had been treated during 15 days with enrofloxacin after surgery and beta therapy. The animals were observed during one year and they did not have the disease returns, which was confirmed by clinical and uroculture laboratory analysis. Finally, in this study the enrofloxacin demonstrated to be efficient in controlling the urinary infection in these cases.