Perianal refers to the area around or involving the anus and rectum. It may also refer to conditions affecting this region, such as perianal abscesses (infections) or hemorrhoids (swollen veins in the anal canal).
Treatment of perianal fistulas with human embryonic stem cell - derived mesenchymal cells: a canine model of human fistualizing Crohn's disease. (cuvs.org)
Neutered males, likewise, will not get testicular cancer, and their risk of perianal tumors is greatly reduced. (bethayresveterinary.com)
Many times, dogs with tapeworms will actually have worm segments stuck to or crawling on the fur around their anus (this is called the «perianal area»), and in their feces. (petwave.com)