‘Rockingham’ (writing in the Boston Evening Transcript, June 19th, 1909.) asserts that the English ‘tabu’ against eating horses could have a theological origin – in the form of a Papal Bull.
“Horseflesh and its eaters are said to have been declared unclean by Pope Gregory III (731 – 741) evidently to discourage a then-prevalent yearning for the ‘flesh pots of Egypt’.”
Rockingham signs off with an observation which may still have some relevance today.
“The prohibition against horseflesh, like many others governing our daily life, has descended in full practical force to us, though the reason therefor has generally been forgotten ages ago.”