When you think of a ”porthole,” you probably picture a small round window on a ship or airplane, right? Well, prepare to be shocked: portholes are also used on cows. Yes, cows. For decades, farmers and scientists have been installing portholes — or cannulas — on cows to access their stomachs.

This practice has been ongoing for almost a century, and while it’s not commonly known to the general public, it plays a crucial role…

What exactly are cow portholes?
A cannulated cow — also called a fistulated cow — is a cow that has undergone surgery to have a special device, called a cannula, installed in its side. Its essentially a surgical opening created in the side of a cow’s stomach.