Adjective
around the anus
Source: WordNetThese autoinfective larvae penetrate the wall of the lower ileum or colon or the skin of the perianal region, enter the circulation again, travel to the lungs, and then to the small intestine, thus repeating the cycle. Source: Internet
When two prairie dogs encounter each other at the edges of their territories, they will start staring, make bluff charges, flare their tails, chatter their teeth, and sniff each other's perianal scent glands. Source: Internet