The Messenger of Allah ﷺ forbade sacrificing an animal that has lost most of its horn or ear. Qatadah said: I mentioned that to Sa’eed bin al-Musayyab and he said. [That refers to] one that has lost half or more (of its horn or ear).
أَنَّهُ سَمِعَ عَلِيًّا يَقُولُ نَهَى رَسُولُ اللهِ ﷺ أَنْ يُضَحَّى بِأَعْضَبِ الْقَرْنِ وَالْأُذُنِ