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.

3751. The preliminary section of the previous chapter explained what the Lord has foretold about the final period of the Church in Matthew 24:15-18. In the preliminary section of the present chapter, in which the same section-by-section method of presentation is adopted, the explanation is given of the words that follow in verses 19-22 of that chapter in Matthew, which are these,

But woe to those who are with child or giving suck in those days! Pray that your flight may not take place in winter or on a sabbath. For then there will be great affliction, unlike any from the beginning of the world until now, or any in the future. And unless those days were cut short, no flesh would be saved; but for the sake of the elect those days will be cut short.