As a rule, don't ever swerve or leave your lane when a collision with a deer happens. Hit the brakes and blow the horn if you have time, but smack them if you must. Most injuries and fatalities to people happen when they try too hard to avoid hitting the deer. Many head on collisions happen when you swerve and lose control. Just smack 'em and head on your merry way, put your life ahead of them critters. They breed like rabbits anyway.