An iron is heated to red hot, then held firmly to the horn bud for about 20 seconds, destroying the horn-producing cells and preventing further growth.
Advantages: Bloodless, can be used in calves up to four months of age.
Disadvantages: More painful for the animal than caustic paste*; iron may fail to get back up to heat between calves, resulting in ineffective disbudding; requires more physical restraint of animal than paste disbudding; poses a risk of injury to the handler.
Watch a video of a calf being disbudded with a hot-iron. Caution: Graphic content.
*Vickers, K.J., et al. Calf Response to Caustic Paste and Hot-Iron Dehorning Using Sedation With and Without Local Anesthetic. J. Dairy Sci. 88: 1454-1459, 2005.