Ivermectin for humans is in pill form as we can take pills.
Giving pills to horses sucks and can be dangerous. Equine ivermectin is in paste form. It can be squeezed into their mouths and the sticky paste is hard to spit out. Best way is to mix it in a grain or feed for them. It is suppose to be flavored so they will accept it better. hah
Ivermectin is for sale, in pill form, on the internet, or you can muck about with the nasty paste.