Deer usually grow their first set of antlers at one to two years of age, and these first-year horns are generally short, almost straight spikes. The antlers become larger and acquire more points in succeeding years until the animal is mature, when the antlers attain the shape typical of the species. Normal antler growth is dependent upon an adequate diet, for if certain minerals or vitamins are lacking, the antlers may be stunted or dwarfed. Nearly all deer have facial glands, located in a depression in front of the eye. The pit is lined with a continuation of the skin of the face.
Glands also occur on the limbs.
There is a cannon bone that is formed by the fusion of the two main foot bones. The ulna and fibula are reduced. As in other artiodactyls, the first digit is absent from each foot. The third and fourth digits are well developed and bear the weight of the animal, and the second and fifth digits are small. The stomach is four-chambered and ruminating.