Cervids or deer belong to the family Cervidae. The musk deer has been placed in the separate family Moschidae. There are more than 40 species and 190 subspecies of deer distributed in Europe, Asia, South and North Americas and North western Africa. Deer, however, have been introduced to almost all the land areas inhabited by human beings. They are predominantly found in Asian countries as antelopes in Africa. These fascinating creatures are characterized by having elongated bodies, slender legs and necks, angular heads, short tails, and large and round eyes. The size ranges from the largest Alaskan moose deer measuring 90 inches at the shoulder with a body weigh of 800 kg to the smallest pudu deer which measures a shoulder height of 14.5 inches with 4 kg body weight. Generally, males are larger than females. The body colour may be brown, red or grey. The mature animals are generally lighter or more reddish in summer. The body is almost covered with hair. Another anatomical feature of deer is that they have a large fissure in the skull just in front of eye socket. Lateral hooves are well developed. All species (except musk deer and mouse deer) have no gall bladders. Preorbital or facial glands are present in all deer (except roe and musk deer). The upper jaw has no incisor teeth. Most species lack canine teeth in upper jaw. The upper canine teeth develop into tusks in males of musk deer, Chinese water deer, the tufted deer and muntjacs. The premolars and molars are used to grind fibrous materials. So, the total number of teeth is either 32 or 34 (I: 0/3; C: 0/1 or 1/1; PM: 3/3; M: 3/3). In warm climate, deer may have several ruts annually. However, in temperate climate they breed in particular season. The most striking physical feature of these animals is their antlers that are shed and renewed each year. Males usually have antlers while females do not possess antlers. The males of musk deer and Chinese water deer, however, lack antlers. The females of reindeer (caribou), on the other hand, bear antlers. Females of roe deer occasionally may have antlers. Antlers are used for marking territories, weapons in fight etc. It is also believed that antlers have mystic healing properties and this is one of the reasons why deer populations have been dwindling in their natural habitats of many parts of the world. Antlers are solid bones without a marrow. They grow directly from the permanent bony growths of the frontal bones of the head called pedicles. The development, maturation and casting of antlers are closely related to the physiological and reproductive activities. Under the influence of hormones, the mesodermal cells of the pedicle proliferate and thereby start new antler growth. In young deer, antler looks a simple spike. However, it takes a familiar form of an antler when the animal becomes older.