Manga by author Raccoon (iii) - Status ongoing

A webtoon in the isekai genre where you become a pet, guaranteed to make you feel like flying high. This is the story of a middle-aged man who is reincarnated as a horse in the world of a novel he once read. Along with that, he's stuck with a system that forbids him from going OOC (out of character) in his horse form. On top of that, there are characters acting like NPCs, constantly giving him quests to complete.