I'm not at all surprised your store carries those products. Even among non-zoos, animal and other non-human toys are very popular! If you disconnect "knot" from "dog" it is still a very sexy concept that attracts interest from all kinds of people. Horse cocks are synonymous with impressive length and girth, so they also have mass appeal among folks who want to imagine or act out stretching themselves to their limits. Tentacles have become a symbol of depravity in erotic culture far detached from whatever the creature controlling them may be. As the sex toy market continues to evolve, these are inevitably shapes that will catch the attention and interest of "normal" folks who may not even realize that they are sharing a space with others who are into the real deal.