I wouldn't worry about it. Hobbs was SO extremely bad the first time I took him to the groomers. They called me at work and said it would be later than what they told me for when I could pick him up because they were only able to work on him 5 minutes at a time because he would pitch such a fit. They said that would just work on him for 5 minutes, then give him a little break. They eventually got him done and he looked great and they didn't have to sedate him. I didn't get into any details of how exactly they did it because I probably would have been embarrassed to know how bad he was.
They are professionals. They have tactics that we've never dreamed of using probably.