We have a blog about rodent ulcers here: http://blog.nhvnaturalpetproducts.com/vet-talk-rodent-ulcers/
In the blog Dr. Cook mentions quite a few supplements, however I recommend you start with NHV Alge-Ex, Natures Immuno and ES Clear. Together they can fight the inflammation and help the body to react more appropriately to the irritants causing the ulcers. We have seen success with these supplements and other cases of rodent ulcers.