Yeah it could be pure cutthroat, i've only caught one trout in my life so i can't say i'm an expert on them, but i still love multi species fishing and try to be as of much help as i can be on these "ID" posts. The body looks very much like a rainbow imo, with the spots on the back, not to mention the fins look like a rainbow to me as well. Cutthroats i see seem to have a different body to them, if that makes any sense.