Hot dogs contain pieces of beef, pork and poultry. This mixture is enclosed in a casing to hold the shape. It is then cooked completely.
Most hot dogs have ingredient lists on their packages. The majority of them are made with a mixture of beef, pork and poultry parts. Companies used hearts and livers at one time, but that is rare now. Some companies use only beef or only pork. After the pieces are chopped and mixed, they are put into a casing and cooked. If a natural casing is used, the hot dog is ready to be eaten. If it is not a natural casing, the hot dog is sent through a machine for the casing to be removed.