an article from the 1800s
"There was a Scotch gentleman here....After living here some time he conceived the idea of going over to the Pacific country by way of British Columbia; his objective point may have been the Fraser river gold diggings, but I forget. He fitted out a party, and when in the wilds of the north country he became frozen in and was compelled to spend a long winter in camp; provisions soon gave out and the party were compelled to eat their pack animals for support. My friend selected a fat young mule for his especial eating, and allowed no one to share it with him. In the course of the winter he consumed the whole animal. He preserved one of its dainty hoofs, and when he got back to civilization he had it beautifully polished and a silver shoe put on it, and always at his meals he placed it by the side of his plate. People thought it was a salt cellar, or some article of table furniture, but when asked by some one what part it played in his menu, he would relate his adventure and say, that he had eaten so many awfully bad dinners out of that mule that he always kept its hoof near by to remind him of them so that his present dinners might be improved by contrast."
In view of the fact that we all have computers, one supposes that none of us has to decide on whether to eat the pet dog/cat or die of starvation.
That is near enough the way of life still in some places in the world. The semi pet goat used for milk has to be killed or sold to provide food. The Ox which pulled the plough.
The dogs who pull the sleigh which contains food on the way out are killed in Arctic expeditions for food on the way home.
Saving a horse shoe or another inedible part of the animal which kept the human(s) alive as a souvenir is not uncommon.
Often, beasts of burden became 'sacred' to try to prevent them being sacrificed, so that they could remain to be used the following year. It all depends on just how hungry one gets. Even humans have been used as meat.
Records and Archeology proves that it has (and probably still does) happen.