When I first started driving, the first piece of advice my father gave me was to never swerve to avoid hitting an animal. He had a friend that had swerved to avoid hitting a dog, and lost control, wrecked and was killed. I told the same thing to my kids, and now to my grandkids. I brake or slow down when I can, otherwise, I just let what happens happen...........except for squirrels, as I never give those destructive little critters a pass.