A venereal ulcer, also known as a chancre, is a sore that appears on the genitals or around the mouth. It is caused by a sexually transmitted infection and is usually painless. Chancres are typically round or oval in shape and can range in size from a few millimeters to several centimeters. They may be accompanied by other symptoms such as itching, burning, or discharge. Treatment for venereal ulcers typically involves antibiotics and topical medications.