The
even-toed ungulates (Artiodactyla) have many specialized skin glands, the
secretions of which are involved in semiochemical communication. and the inguinal glands in the lower belly or groin area. Like many other species of Artiodactyla,
deer have seven major external scent glands distributed throughout their bodies. The interdigital glands of male and female black-tailed deer contain three volatile ketones, 2-tridecanone, (
E)-3-tridecen-2-one and (
E)-4-tridecen-2-one. (
E)-3-tridecen-2-one was shown to have antibiotic activity against some skin pathogens. These compounds are absent from white-tailed deer interdigital glands, which contain a number of 2-methylcarboxylic acids. The tarsal gland appears to operate by a different mechanism than the other external scent glands. A behavior called
rub-urination is central to this mechanism. During rub-urination, the animal squats while urinating so that urine will run down the insides of its legs and onto its tarsal glands. The tarsal glands have a tuft of hair which is specially adapted to extract certain chemical compounds from the
animal's urine. For example, in the
black-tailed deer (
Odocoileus hemionus columbianus), the major constituent of the tarsal gland secretion is a
lipid,
(Z)-6-dodecen-4-olide. This compound does not originate in the tarsal gland itself, but rather it is extracted from the animal's urine by the tarsal hair tuft during the rub-urination process. In white-tailed deer, the presence and concentration of certain chemical compounds in the urine depend on the season, gender, reproductive status and
social rank of the animals. This fact, along with the observation of rub-urination behavior in this animal (at least in the male) indicates that urine probably plays a role in
olfactory communication in deer. ==In carnivorans==