We have had a few cows over the years that we have had to dehorn, depending on the size you can use a dehorning gouge, or just saw them off short & blunt - on adult cattle, the danger with a gouge is making a hole so deep that you open up the sinus cavity - even if you're careful and gouge the horn out above the sinus cavity there will be alot of blood & you'll have to cauterize the holes and watch for infection - a long acting anitibiotic is recommended. If they're older cows I'd just saw them off and grind them blunt - alot less stress for the animal and no danger of accidentally losing one. You should be able to saw them off 3-4 inches from the head without a problem and just blunt them with a hand grinder. Oh - make sure you've got a good head squeeze! Good luck