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.

4056. The preliminary sections of Genesis 26-30 in Volume Three explained what the Lord has said and foretold in Matthew 24 about the Close of the Age, or the Last Judgement. Those sections covered verse 3 through to verse 28, and now the statements next in line come up for explanation. The preliminary section of this chapter deals with what is stated in verses 29-31 in the following words,

But immediately after the affliction of those days the sun will be darkened, and the moon will not give its light, and the stars will fall from heaven, and the powers of the heavens will be shaken. And then the sign of the Son of Man will appear in heaven, and then all the tribes of the earth will mourn; and they will see the Son of Man coming in the clouds of heaven with power and great glory; and He will send out His angels with a trumpet and a loud voice, and they will gather His elect from the four winds, from one end of the heavens to the other end of them.