The dog was starting to wake up when they brought it, so we gave it some more anesthetic but we still couldn't get the tube out. Drugs to relax the muscles were completely ineffective. I finally had to use a pry bar and force her mouth open enough to remove the tube. For a long time that dog's jaw hung slightly open from the damaged muscles, but I think it eventually recovered. Even more years ago I was asked to look at a horse that seemed to have trouble eating.
Horses often have trouble with their teeth.
The big molars in the back of their mouth can get broken. Their teeth continue to grow all their life and sometimes get too long and sharp. You use a big long handled rasp to file them down. He didn't seem nervous or tense, and was easy to work with, but I gave him a tranquilizer anyway, to relax his muscles. I still couldn't get his front teeth far enough apart to get my rasp in, or even to see anything.