Doodledog
Do they just have them in the mating season to fight off other males? I think I assumed they grew them at maturity and kept them for life.
Antelopes keep their horns for life, but male deer shed their antlers once a year and grow new ones. Antlers are usually only present for a few months before being shed and, apart from reindeer, only occur in males (but female reindeer have antlers, too. Rudolph may be a girl )
"Antlers are paired, branched structures that are made entirely from bone and are shed annually.
Horns are unbranched, two-part structures with a bony core and covered by a keratin sheath (the same material found in human hair and nails), which grows from specialised hair follicles.
Antlers and horns also have different functions. While antlers are mainly used for mate selection during the breeding season (either to attract females directly or to deter rival males through display or combat), horns are generally used for social dominance, territoriality and anti-predator interactions."
www.discoverwildlife.com/animal-facts/mammals/whats-the-difference-between-horns-and-antlers/