[header] How to recognize and treat salivary mucocele in dogs [title] Look for swelling of the chin. [step] One of the major signs that a dog might have a salivary mucocele is swelling under the chin. The swelling occurs in the angle of the jaw. 
In the early stages, the swelling sits to either the left or the right side. The longer the mucocele has been present, the more it spreads and it can be difficult to tell which side it arose from.