People regularly refer to the “headgear” worn by male deer, elk, and moose as horns.  However, these structures are not horns at all, but antlers. Antlers and horns differ in these ways:

Antlers are grown and shed annually by most male (and a few female) members of the deer, elk, and moose family. Antlers are composed of bone, and are some of the fastest growing structures and tissue in the animal kingdom. Antlers grow anew each year, beginning in the late spring, and are covered in a soft furry skin referred to as velvet. Hardening in late summer and early fall, and the males will rub off the velvet on shrubs and trees. In the late fall and early winter, the entire antler is shed at the pedicel (antler base). New antler growth begins very soon following shedding.

Unlike antlers, true horns are a bone core covered in a keratinous sheath (similar to finger nail and hair) and are restricted to the sheep, goats, “true” antelope, bison and domestic cattle.  Males and females have horns, and they are neither branched nor shed; horns continue to grow throughout the animal’s life. The single exception to this rule is displayed by our own pronghorn, which produces a branched keratin covered horn sheath over a bone core. The horn sheath is shed and replaced annually.