You can dehorn a bred cow. Keep in mind that if you do a regular dehorn, it will knock the cow for a couple of months. If she is within 2 months of freshening, she could get off to a rough start with raising the calf. I cut the horns off a couple of inches from the head after tying off the blood supply and it doesnt knock them at all. I like to do the regular dehorning in November, after the flies are gone. If you do it now, you will have to have a place inside for her at night and out of the snow or rain. You will have to watch for her to get problems from the cold getting into her head. Dont do a regular dehorn when flies are present because of screw worms and infections. Good luck with your decision.