The full name of the canned substance mentioned in the opening post is "Potted Meat Food Product". I take that to mean that the stuff isn't really meat at all, but a product made from meat food.

Now, as I understand it, the process of feeding meat is quite simple. First, the meat must be part of a living animal, such as a cow or chicken. (It's difficult to get a rump roast to eat meat food after it's been removed from the cow.) The meat food is introduced to the animal via its mouth, and is processed by its digestive system, yielding a finished product which is excreted out of its anus.

In other words, "Potted Meat Food Product" is shit! It says so right there on the label!