In Ezekiel 26:11, this signifies the love of learning or intellectual things. (Arcana Coelestia 3727)

In Revelation 6:2, this signifies the love of understanding the Word. (Apocalypse Revealed 298)

In Zechariah 12:4, this signifies that the intellectual should be filled with falsities. (Arcana Coelestia 2383[2])

In general, 'a horse' signifies knowledge or understanding of the Word. In an opposite sense it signifies the understanding of the Word falsified by reasonings, and likewise destroyed from self-derived intelligence. 'A dead horse' signifies no understanding of truth from the Word.

3486. The preliminary section of the previous chapter, paragraphs 3353-3356, explained what the Lord has said and foretold in Matthew 24:3-7 about the close of the age or end of the days of the Church. Here, in the Lord's Divine mercy, let the next section be explained, that is to say, verses 8-14 of the same chapter in that gospel, where it is said,

All these are the beginning of sorrows. At that time they will deliver you up to affliction, and will kill you, and you will be hated by all nations for My name's sake. And at that time many will stumble, and betray one another, and hate one another. And many false prophets will arise and will lead many astray. And because iniquity is multiplied the charity of many will grow cold. But he who endures to the end will be saved. And this gospel of the kingdom will be preached in the whole inhabited earth as a testimony to all nations; and at that point the end will come.