It’s not a euphism, it developed in the English language because the aristocracy, which could actually afford meat and ate it regularly, spoke french, therfore using french terms for the meat e.g. Porcine -> pork or Bœuf -> beef ) wheras the farmers who actually raised and dealt with the animals, but rarely if ever could actually afford to eat them, used anglo saxon to refer to them, hence this dichotomy in names for meat vs. animal in English.

It has nothing to do with being a euphism. It’s also evident that the cheapest meat, and pretty much the only one that even peasants could somewhat regularly afford, chicken, did not undergo this split.