After surgery, some potential minor complications can occur. As with any incision, it can become infected or break open. The incision should be monitored daily for signs of swelling, redness, or discharge. Notify your veterinarian if these occur.
Occasionally, the "permanent" opening into the mouth can completely seal over and a swelling recur. This is not a likely occurrence, but if it happens, the original symptoms can recur.
Sometimes the space from which the mandibular salivary gland was removed fills with other body fluids. This causes another soft swelling called a seroma that usually resolves with time. Your veterinarian may have you applying hot compresses to the area to help the fluid reabsorb.
Frequently, bloody saliva continues for several days after marsupialization of a ranula. You may notice blood in the dog's water bowl after he drinks. This will usually clear up within a few days, but if it persists or becomes more profuse, contact your veterinarian.