Will they still groom my cat if he's snappy?

[Erin]

I've never taken my long-furred Blondie-cat in, before, because he -bites- sometimes when he's brushed, but his poor fur is tangled and it's very hot in oklahoma. Do they have harnesses or sedatives or anything to keep a rowdy pet at bay? Do they even -accept- biters? It would worry me if they medicated him, because my baby Galileo is Ten years old.

Thanks in advance!