The prepuce is a sheath of skin that folds over the head of the penis. A small amount of yellow-green discharge from the opening of the prepuce is normal. A copious discharge indicates infection, called balanoposthitis.
Awns, dirt, or pieces of straw can get caught beneath the foreskin and cause irritation, followed by infection and abscess within the sheath. Herpesvirus produces a chronic sheath infection that can be transmitted to the female during breeding. A strictured foreskin may cause a sheath infection. Transmissible venereal tumors may produce growths on the penis, and this type of cancer is contagious.
Signs of sheath infection are excessive licking at the penis and a foul-smelling discharge from the prepuce.
Treatment: Any purulent discharge from the prepuce should be investigated and treated by a veterinarian. Antibiotics are selected based on culture and sensitivity tests. Herpesvirus is difficult to culture, but serology testing is available. A rising antibody level suggests the diagnosis. Since herpes is a virus, there is no specific treatment. Most bitches develop immunity after once losing a litter to this virus, but still should be protected from stress the last three weeks of pregnancy and the first three weeks post whelping. There is a vaccine in use in Europe, but it is not yet available in North America.