Cancel the surgery!
I'm with Boston Brigade Rescue and foster a lot of dogs. A few months back one of my boston terriers came down with mouth warts. Before we knew it 3 turned into 33. Rocco had so many they were hanging out the sides of his mouth, lined both sides of his tongue and roof of his mouth.
Rocco was treated with azithromycin (Zithromax)for 2 weeks. No change but we continued the treatment. It took 6 weeks and all the warts disappeared. Three other foster dogs came down with the warts but not near a bad. Two weeks on the azithromycin (Zithromax) and all were clear and none have reappeared.
Patti