This Is What's Really Inside Your Hot Dog Every time you bite into a juicy hotdog, you might find yourself pushing its potential contents to the back of your mind. But if you'd like to know what you're eating, here's the lowdown. No matter if your hot dog is made of beef, pork or chicken, they all start with "trimmings." This is a more pleasant term for leftover meat cuts such as fatty tissue, sinewy muscle, head meat and sometimes liver. "Trimmings" can also include blood, skin and feet, and it's all USDA-approved. Once combined, the gristle is pre-cooked to kill bacteria and formed into a paste. At this point, any number of additives could be introduced. The meat paste is then pumped into casings to attain its shape. Then the franks are rinsed, the casing is removed, and they are ready for consumption. If you'd like to stick with muscle tissue instead of organs, feet and blood, opt for hot dogs labeled "all beef" or "all pork."