By August or early September antler growth ceases and the velvet is shed or rubbed off by the buck as he rubs saplings, shrubs, or rocks with his antlers. Polished antlers are carried throughout most of the breeding season, which can last into late February. The antlers are shed at the end of this period, and a new set begins to grow in March or April. While antlers grow they're soft and subject to injury. Bent and twisted tines and main beams are a result of injury to the antler while it was growing.
Broken antlers occur after the antler has stopped growing and is hard.
The small cavities sometimes seen in polished antlers are a result of botfly larvae damage during the growing period. The antler cycle is influenced by secretions from the pituitary gland. Changes in length of daylight periods and, to a lesser degree, temperature influence the hormone secretions from this gland. Hormones are believed to be a factor in the initiation of new antler growth. Increases in the amount of testosterone in the blood of whitetail bucks in late August and early September cause blood flow to the antlers to stop.