The infection could be bacterial, yeast, or a combination. Usually
urinary tract infections are accompanied by the symptoms of increased frequency of urination, and/or drinking, dribbling, or inappropriate urination. However, occasionally the only symptom is licking the vulvar area. It would be best to have your dog examined by a vet of course, but at least bring a fresh urine sample to your vet for urinalysis to help differentiate between a urinary tract infection and vaginal infection.