If you've ever seen a photo of a cow with what looks like a circular hatch in its side, you weren't imagining things, and it isn't a costume. It's a surgically placed device called a cannula, and it's been standard practice in agricultural research for nearly a century. What a Cannula Actually Is A cannulated cow, also called a fistulated cow, has undergone surgery to … [Read more...] about What Are Those “Portholes” on Cows, and Why Do They Exist?