The family Moschidae (the musk-deer), which was long subsumed as a subfamily within the deer family (Cervidae), is now widely recognized, based on a range of evidence, as quite distinct from the cervids and possibly not even their closest relatives. Musk-deer may be more closely related to cattle and antelopes (family Bovidae) than to the Cervidae.The musk-deer family includes just a single genus, Moschus. Although this genus was long considered to be monotypic (i.e., including just a single species) it is now generally believed to include at least seven species.
Musk-deer are small (70 to 100 cm), hornless ruminants with hindquarters considerably higher than their forequarters. They have long, rabbit-like erect ears; long limbs; a small tail; and a thick grayish or brownish coat with erect hairs on the upperparts of the body. Male musk-deer have long, slender, curved upper canines (used for fighting), a large glandular musk-producing sac on the belly in front of the genitalia (the source of their name), and a glandular tail. In the rutting season, the musk sac swells dramatically, apparently in response to elevated testosterone levels.
Musk-deer are found in forests and alpine scrub in mountains and hilly country in much of eastern Asia. Over much of their range, the ground is snow-covered for at least half the year. Musk-deer are generally timid and shy and when startled bounce rapidly away on their stilt-like legs, usually along a zig-zagging path. They are sufficiently light and agile (the largest musk-deer are little more than 60 cm at the shoulder and at most 18 kg) that they can leap into and climb trees to escape predators or to forage on lichens and leaves.
Male musk-deer are strongly territorial and both sexes scent-mark extensively. Males mature at around 1.5 to 3 years of age; females may conceive at just a year old. Males begin to secrete musk in their second year and may continue until around 20 years, but peak production is from around three to nine years.
Musk from male musk-deer has been used in perfume making and in traditional medicine in China and elsewhere for more than a thousand years. Unfortunately, this has resulted in the trapping and shooting of enormous numbers of musk-deer (causing even more inadvertent deaths of females and young males--which don't produce musk--than of the intended adult male targets) and all or nearly all musk-deer species are now endangered. Conservation efforts have included the development of synthetic musk (which is now widely used in perfumery) and the establishment of musk-deer farms. The main hunting pressure on musk-deer today is to fuel the demand from traditional medicinal uses.
(Groves 2011 and references therein)