Things sacrificed to idolatry are forbidden to be used. Rav Huna in the Gemara holds of one does an act on an animal that even someone else owns, the animal is still forbidden to derive benefit from. And that is the way the Raavad decided the law. But Rav Nahman, R.Amram, and Rav Isaac decided the law is that when one does an act on an animal that he does not own, then the animal is permitted. And that is how the Rambam decided the law. But when they say an "act" they mean slaughter, not just bowing down.
So that is what makes it a bit confusing when it comes to a different kind of prohibition that when an animal is worshipped even one that belongs to someone else, that animal forbidden to be brought as a sacrifice in the Temple. And there the Rambam holds that is even any kind of worship. But the Raavad holds there too there needs to be a physical act on the animal to make it forbidden.
Rav Shach has an explanation for the Rambam in this case. He brings that the prohibition of bringing a worshiped animal to the Temple is learned in two different ways. One way is from the beginning of Leviticus. "Bring from the sheep". That verse is extra since we already know you can only bring sheep or goats or cows as a sacrifice. So the Gemara learns that the verse is coming to exclude something. That is a worshipped animal. But there is a different teaching that that same prohibition comes from "their destruction is in the their defect is in them". Rav Shach shows that the Rambam holds from the second teaching and then that implies that any kind of act in which the animal is worshipped makes it forbidden to bring to the altar.
