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.

47. That these words contain arcana concerning regeneration becomes additionally clear from the fact that verse 24 above spoke of the earth bringing forth 'living creatures, beasts, and wild animals of the earth', while in the verse that followed the order was different, namely that God made the wild animals of the earth first and then the beasts. Indeed a person does first produce things so to speak from himself, and continues to do so until he becomes celestial. And so regeneration begins with the external man and moves on to the internal. This is why there is a different order here, with external things coming first.