Can you talk to a therapist about violent urges/fantasies?

I'm going to therapy for the first time on Tuesday, and one of the things I want to talk about are the violent urges/fantasies that I have and have been having more frequently recently. I'm just afraid that if I do tell them they could put me in an asylum against my will. Is this a realistic possibility or am I just imagining things?

Talking about these things is a normal part of therapy and as long as youre not psychotic theres no reason for hospitalisation.

I discussed killing dogs and other animals with my therapist. Nobody in white coats came to take me away.