Never swerve to miss a deer. You are more likley to cause damage to yourself and your car if you do. Plus if you don't hit it and have an accident the accident is deemed to be your fault.
A few years ago I was driving the motorhome thru Saskatchewan and a deer poped up in front of me. I swerved to miss it and ended up recreating the scene from the movie "Blues Brothers" where the motorhome goes off into the water. The motorhome skipped across the water till it hit a stand of willows where it stopped suddenly. I ended up upside down with my back against the windshield. Water/muck/mud had sprayed up thru all the vents and on to everything inside. Even snail shells made it inside. I grabbed for the door handle thinking the ship was going down, but it only settled till water was about 1" below the floor. This was at 2am, so a night playing houseboat stuck in the middle of the slew till a tow truck arrived at 5 am. Dealing with a pissed off hung over COP and spending the next 3 days in a Saskatoon hotel room having front end damage fixed, replacing all the bearings, brakes, all fluids (twice), filters, draining both gas tanks, cleaning the inside and having to pay the $500 deductable because I didn't hit the dam deer, was not my idea of the end to a good holiday.
Oh ya, the motorhome had deer whistles on it.
I get even every hunting season, sometimes twice.